VF500 Exhaust

Hi All,

I've got a VF500F2F that I'm busy restoring.

I've looked at the various mods that people have done, and am going to do the CBR6 wheel swap (both ends) and the CBR F4i shock swap, for now.

One thing I need is an exhaust. Being a practical kind of guy, I'd like to make my own exhaust. Before anyone tries to dissuade me I know how much work goes into doing this! I've done it before on a university project.

So, the original Honda exhaust is a 4-into-1-into-2, but what type of exhausts do these bikes like? I was thinking a 4 into 2 into 1, with front and rear cylinder pairs merging together first, and then all merging together to try and maximise the pulse effects. I've got a Micron silencer that will go on it nicely.

Anyone tried this before? What lengths did you use for the various pipes?

Looking forward to hearing what people have done.

Gareth

Somewhere there is a thread floating around on VF500 exhausts. They were trying to get one of the manufacturers to make a production run of exhausts, but there was an argument of the correct configuration.

I had done a few sketches of what should fit and merge correctly. It's important to step the diameter up correctly and not go too big anywhere. Headpipe diameter and length before the merge is the most important. I'd use the OE headpipes, or most of them, and go from there. Make them all the same length before they merge.

Rough headpipe estimates for an engine that redlines at 10,500rpm is 20" to 24" long before merge. Depending on how much of the OE headpipe you can use, step up only one pipe size, like 1" to 1 1/8", until they merge.

A proper merge is 30 degrees combined angle. Meaning each pipe is at a 15 degree angle from the centerline. This can be done with a chopsaw using a wooden jig to hold the pipe correctly.

The shape I came up with for a 4-2-1 was an "H". The fronts merge with the rears as they all bend towards the center. Then those two merge and bend towards the rear in the middle of the "H" cross bar so to speak.

What is the ID or OD of the original headpipes?

InterFester

I had done a few sketches of what should fit and merge correctly. It's important to step the diameter up correctly and not go too big anywhere. Headpipe diameter and length before the merge is the most important. I'd use the OE headpipes, or most of them, and go from there. Make them all the same length before they merge.

Rough headpipe estimates for an engine that redlines at 10,500rpm is 20" to 24" long before merge. Depending on how much of the OE headpipe you can use, step up only one pipe size, like 1" to 1 1/8", until they merge.

A proper merge is 30 degrees combined angle. Meaning each pipe is at a 15 degree angle from the centerline. This can be done with a chopsaw using a wooden jig to hold the pipe correctly.

The shape I came up with for a 4-2-1 was an "H". The fronts merge with the rears as they all bend towards the center. Then those two merge and bend towards the rear in the middle of the "H" cross bar so to speak.

What is the ID or OD of the original headpipes?

Right. armed with a tape measure, my camera and the grinder, I've had a bit more of a look at this.

The original pipes are 30mm ID, and the front pipes are ~450mm (17") long. Using the formula for the resonant frequency of a single organ pipe (F = Speed of Sound / (Length + 0.3*Diameter)) gives ~11,000 RPM.

The rear pipes themselves are much shorter, but the extra length is hidden in the collector. Like this:-

[image: DSCF3986.jpg]

[image: DSCF3985.jpg]

So doing a 4-1 with those lengths, using a merge collector is going to be difficult.

So I've decided to try to use the exhaust to help boost the mid-range, by using a 4-2-1. This may sacrifice some top end power but should help general road manners. The RC30 and RC45 are both V4 engines with 360ª cranks, and they both use 4-2-1 systems with front pipes into one side of the "2" and both rear pipes into the other. It doesn't seem to hurt them!

I don't know if the organ-pipe modelling methods work for this type of thing, it definitely does for inlets. But here goes:-

Using the organ pipe-type method for the resonant frequency of a pipe, and using 7700 RPM (128Hz - pipe resonating twice per cycle) and 11000 RPM (183Hz), I've got 460mm and 659mm for the lengths of the primaries and the primaries + the secondaries respectively.

If the length of the tailpipe (which I've assumed includes the straight-through silencer I have) is 659mm + 75mm, as recommended by A. Graham Bell in his book "4-Stroke Performance Tuning" then the resonant frequency of the entire system should be at 3600RPM. I've assumed that primaries and secondaries are both 30mm ID, and the pipe linking to the can is 50mm.

Does anyone agree/disagree?

Color me intrigued.

Keep up this thread and I may have to ship you a factory ehxaust to use as a jig (if needed). (edit - I was typing that as you were posting post mortem pics of your exhaust).

I've been a wonderin' what it looked like inside the collector box on the VF500F. Makes sense that they would extend the length of the rear headpipes so they are equal or closer to that of the front.

It does come down to what will ultimately fit so even the best design usually has to have compromises. Where does the centerstand pivot in relation to the collector box, in front of it?

A 4-2-1 would be better fit and more streetable power.

InterFester

I've been a wonderin' what it looked like inside the collector box on the VF500F. Makes sense that they would extend the length of the rear headpipes so they are equal or closer to that of the front.

It does come down to what will ultimately fit so even the best design usually has to have compromises. Where does the centerstand pivot in relation to the collector box, in front of it?

A 4-2-1 would be better fit and more streetable power.

The centre stand pivots behind the collector box. So I'm planning to keep the exhaust 4 into 2s in the space that the collector box originally took, then route the pipes around the centre stand, because I want to keep it.

If the lengths of the four branches varies slightly it'll help spread the power around a bit at the expense of a small amount of top-end, so I think that's OK.

Keeping the lengths equal helps across the rev range.

Is there room in front of the collector box under the engine or does it hang down?

There looks to be plenty of room just in the area of the collector box to merge both left side headpipes together and both right side headpipes together and then merge both of those pairs together. My idea is to have both of the front headpipes turn towards the center using a 75 degree pipe. The rear headpipes would do the same but since they are spaced closer together there would have to be more bend in the pipe. Now both left and right are merged and facing each other. They would merge the same way in the center bent to face rearward. There should be plenty of room under the right rear headpipe for the collector to follow the same path out as the OE muffler does. It could even be split back into two mufflers.

A merge like this:

[image: post-20193-099919900 1278690625_thumb.jp]

My drawring of the system expanded slightly:

[image: post-20193-025150300 1278690700_thumb.jp]

Are the OE headpipes 30mm ID ? That seems large to me for 125cc per cylinder. Keeping the headpipe the same as OE or just one size larger and then increasing the size out of where they merge to just under 2X the area into the final merge and then ~2X that area for the tailpipe. The tail pipe can be stepped up to make it easier to find a common muffler ID. Something like 1" headpipes merging into 1.5" merging into 2" for the tail pipe.

That collector looks just the job! Did you make it with 2 bends with the mating section cut out and then seam welded?

I've had a look at the engine in the bare frame, had a rough estimate with the tape measure and the issue with your sketch is that the cylinders collect in the wrong order.

The cylinders are numbered from left to right in the order that the con rods connect to the crank. So no1 is back left, number 4 is front right. (EDIT - All lefts and rights are as you sit on the bike). The firing order is 1-4-3-2, so for the 4-2 bits to work properly we have to link cylinders that fire 360° from each other. So that's 1 and 3, 4 and 2.

This means that the front two and the rear two have to join together first.

My idea is to run the front primaries together down the left hand side of the oil pan and then join them roughly where the OE front pipe finishes. The secondary pipe will then turn to the right side of the bike.

The rear pair would initially turn to the left, to maximise the length of pipe tucked behind the engine (as there's no longer the convoluted pipes in the collector box). They'd come down together and then merge, before turning to the right side of the bike to meet the secondary from the front cylinders.

These would then collect and go to the silencer.

Oh and if all the cylinders have the same length pipe attached to them then they all make the peak power at the same time. If the lengths are staggered slightly (+/- 25mm) then each cylinder makes peak power at a slightly different RPM, so making the power curve broader but reducing peak power slightly. As you've said before, making the thing fit is the driver behind this as much as anything!

My idea would look something like this:-

[image: ExhaustSketch2.jpg]

It looks to me like the front bank of cylinders is set wider on the VF500F and the rear is narrow so left front would be #1, left rear #2, right rear #3 and right front #4. Other VF motors, like in a Sabre on another thread, look to be opposite, wider set in the rear.

Where did you get the info on the firing order and cylinder arrangement numbering system?

I've seen a Yosh 4-2 system on this site that merged left front to left rear and right front to right rear. I'll have to thing about this for a bit as to how many degrees of rotation takes place between each cylinder firing. All rods mount to a single pin crank and the "V" is 90 degrees so it fires like a V-twin two stroke since the front pair of pistons move together as do the rear pair.

Another primary length rule that Ducati uses is if they can't be equal then the longer pipe must be 1.5 times as long or 2.0 times as long as the shorter. The longer pipe should not be 1.25 times or 1.75 times.

The merge in the picture is the beginnings of a 2-1 system for my Suzuki TL1000S. Instead of starting with two straight pieces of pipe, welding them at a combined angle of 30 degrees and then trying to connect to that merge I just used two bends and welded them together about an inch from where the bend stops and the straight leg begins. I coulda/shoulda shortened that to about half an inch of straight and saved me some space but it'll still work.

It's a proper merge as described by the folks at Burns Stainless, http://www.burnsstainless.com/crossoversmain.aspx I just wish their beautiful work wasn't so expensive.

[image: post-20193-018546600 1278703661_thumb.jp]

The info regarding the firing order and cylinder nomenclature came from my Clymer manual. Not infallible, I know, but it's the only info I have.

The firing intervals are:- (assuming the Clymer is correct)

1 - 0°

4 - 90°

3 - 360°

4 - 450°

I believe that this is the same as the RC30 (also a 360 degree crank), which on Honda's own 4-2-1 system links both fronts and both rears, as shown on CMSNL.com's parts diagram.

[image: RC30exhaust.jpg]

The early V4s have a different firing order to the VFRs, as I'm sure you know, as the VFRs have 180 degree cranks.

GazVF500

The info regarding the firing order and cylinder nomenclature came from my Clymer manual. Not infallible, I know, but it's the only info I have.

The firing intervals are:- (assuming the Clymer is correct)

1 - 0°

4 - 90°

3 - 360°

4 - 450°

I believe that this is the same as the RC30 (also a 360 degree crank), which on Honda's own 4-2-1 system links both fronts and both rears, as shown on CMSNL.com's parts diagram.

[image: RC30exhaust.jpg]

The early V4s have a different firing order to the VFRs, as I'm sure you know, as the VFRs have 180 degree cranks.

I didn't know that about the VF and VFR having different firing orders and different cranks. I don't really know too much about either model at this point, I'm in the market for a VF500F and thought I'd visit the experts before buying one. I had an '84 way back in 1987 and really loved it. I recently moved to hilly and curvy Eastern Tennessee and just realized how unnecessary alot of horsepower is here not to mention likely fatal for a Florida native.

The above exhaust system is more like a 4-2 since it has such long secondary pipes that slowly merge into 1 just before the muffler. More like they merge so as to have only one muffler than to take advantage of the tuning benefits of a 4-2-1. I've seen some I-4 pipes do this too, for what reason I'm not really sure.

Ok, I found a nice top pic of some cases. The cylinders are spaced the same between each other but the rear bank is offset to the left. It's rear headpipes must be spaced more narrow just for fitment reasons in the frame.

So Left rear is #1, Left front #2, Right rear #3 and Right front #4.

http://cgi.ebay.com/ebaymotors/Honda-VF500F-86-upper-crank-case-/330407253641?cmd=ViewItem&pt=Motorcycles_Parts_Accessories&hash=item4cedce9689

Yes, you're absolutely right about the cylinder numbering. At least we agree! Phew, was doubting myself then!

GazVF500

Yes, you're absolutely right about the cylinder numbering. At least we agree! Phew, was doubting myself then!

Visualizing a picture and getting things straight in my head isn't as easy as it used to be. So....

#1---90*---#4---------270*---------#3---90*---#2---------270*---------#1

Pairing the fronts together and rears together would give you 360* between pulses.

Pairing the left side together and the right side together would give you 270* or 450* between pulses depending on how you wanna look at it. This is also how my TL fires, only half as much since it's a twin.

I wonder if the different pairings sound much different. A parallel twin with 360* crank, what the front or rear bank by itself is basically, does not sound awe inspiring. A single pin 90* V-twin, or L-twin, does sound pretty sweet. Times two in an uneven phase and who knows. Too bad I can't find a YouTube video of a 4-2 Yosh system. I've heard they were loud that's it.

InterFester

Keeping the lengths equal helps across the rev range.

...except that doesn't work on a V4. The 90° phase angle between the front and rear cylinders make that fly right out the window. If you look at only the front two cylinders (or rear two) separately then equal length is ok, but as soon as you join them you are hosed. The phases will never lay over top of each other at all rpms. Lots of theory involved with that, but there are ways to determine "sweet spot" rpm range for a 4-1, but normally it's easier to just take your best stab at it and see what the dyno says - then iterate.

Keep us up to date on your progress!

JamieDaugherty

InterFester

Keeping the lengths equal helps across the rev range.

...except that doesn't work on a V4. The 90° phase angle between the front and rear cylinders make that fly right out the window. If you look at only the front two cylinders (or rear two) separately then equal length is ok, but as soon as you join them you are hosed. The phases will never lay over top of each other at all rpms. Lots of theory involved with that, but there are ways to determine "sweet spot" rpm range for a 4-1, but normally it's easier to just take your best stab at it and see what the dyno says - then iterate.

Keep us up to date on your progress!

I wondered about that and asked the guy who came up with the headpipe specs for my TL if an uneven firing order should be compensated for with different length primaries but didn't really get a clear answer. He worked for Graves MotorSports at the time and used an exhaust design program. Ironically the lengths he came up with are very similar to the OE exhaust system but with larger OD piping. He also said specs for the collector after the merge involve many other parameters and the options are many but weren't nearly as critical as the headpipe length and OD.

Fitment and sound are as important to me as squeezing out every last bit of HP. The design I have for my TL is not for peak HP but for best all around and lagest area under torque curve with little peakiness, a street pipe. This is what I'd shoot for with the VF500 as well.

The OE system on the VF500 is technically a 4-1-2 just with a large merge "box" volume. I'd think a properly sized 4-2-1 that steps up correctly to keep velocity high would improve on it across the range.

InterFester

The OE system on the VF500 is technically a 4-1-2 just with a large merge "box" volume. I'd think a properly sized 4-2-1 that steps up correctly to keep velocity high would improve on it across the range.

Agreed!

InterFester

JamieDaugherty

InterFester

Keeping the lengths equal helps across the rev range.

...except that doesn't work on a V4. The 90° phase angle between the front and rear cylinders make that fly right out the window. If you look at only the front two cylinders (or rear two) separately then equal length is ok, but as soon as you join them you are hosed. The phases will never lay over top of each other at all rpms. Lots of theory involved with that, but there are ways to determine "sweet spot" rpm range for a 4-1, but normally it's easier to just take your best stab at it and see what the dyno says - then iterate.

Keep us up to date on your progress!

I wondered about that and asked the guy who came up with the headpipe specs for my TL if an uneven firing order should be compensated for with different length primaries but didn't really get a clear answer. He worked for Graves MotorSports at the time and used an exhaust design program. Ironically the lengths he came up with are very similar to the OE exhaust system but with larger OD piping. He also said specs for the collector after the merge involve many other parameters and the options are many but weren't nearly as critical as the headpipe length and OD.

Fitment and sound are as important to me as squeezing out every last bit of HP. The design I have for my TL is not for peak HP but for best all around and lagest area under torque curve with little peakiness, a street pipe. This is what I'd shoot for with the VF500 as well.

The OE system on the VF500 is technically a 4-1-2 just with a large merge "box" volume. I'd think a properly sized 4-2-1 that steps up correctly to keep velocity high would improve on it across the range.

Yes, you've hit the nail on the head there. You never get an exhaust to work over the entire range of engine speeds. So the tuned lengths of all the parts in the 4-2-1 must be calculated to boost output in strategic places. I've chosen numbers on mine that, when multiplied, do not match other areas of the system. For example I would not have a tailpipe tuned to exactly 5000RPM and then have the primaries tuned to 10000RPM, as the two may well cancel them out. That's why, in the original post, I mentioned 3600, 7700 and 11000, as these numbers don't cross over

I think I plan to make my first system a test one, and have adjustable slip joints as far as possible, so that it can easily be tweaked and then fixed where it works best.

Are you going to use Steel or Stainless? There is a vendor in Oregon that sells mandrel bent 304 stainless pipe pretty cheaply but the shipping to the UK would surely offset the savings. Actually there is a vendor on eBay who sells muffler core tubing in SS cheaper than I can find anywhere else, he might have bends too.

http://cgi.ebay.com/3-inch-90-degree-Mandrel-Bend-3-T304-Stainless-Tube-/220579025669?cmd=ViewItem&pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item335b88d305

Can you weld SS? I can weld steel and have a MIG but not SS yet.

I can't yet, but plan on learning. You can weld SS with MIG, apparently you need a shielding gas with low (<3% CO2 content).

It's a practical skill that I'd love to learn, and hope to in the course of this project. Lots of practicing before I touch any tube, methinks!

GazVF500, I'm very interested in how you are making out with your 4-2-1 exhaust system. Any updates on this project? Thx!

InvisibleCities

GazVF500, I'm very interested in how you are making out with your 4-2-1 exhaust system. Any updates on this project? Thx!

Interesting you mention that. I have now got a box of stainless bends waiting to be chopped up, I'm just trying to work out exactly the best way to calculate the lengths required.

I've seen a very common equation for the lengths required, but with no derivation or evidence to back them up.

Once I've done this I will update this post!

GazVF500

InvisibleCities

GazVF500, I'm very interested in how you are making out with your 4-2-1 exhaust system. Any updates on this projectThx!

Interesting you mention that. I have now got a box of stainless bends waiting to be chopped up, I'm just trying to work out exactly the best way to calculate the lengths required.

I've seen a very common equation for the lengths required, but with no derivation or evidence to back them up.

Once I've done this I will update this post!

Good deal! I look forward to seeing what you design.

On a side note, I've added a sketch to help clarify the exhaust sequence.

I've read that 4-1 systems or 4-2s (paired 1|3 and 2|4 with a staggered exhaust) are the best systems for the VF500F based on the pulse sequence.

Any thoughts would be most appreciated.

Thx!

[image: vf500fexhaustsystemsketch01-10-11.jpg]

Yes please keep us posted. Plus any info you have gathered on diameters of pipes and the incremental step ups you plan would be great since I want to attempt this on my VF1000R.

Thanks

Right, finally had some time to crack on with the exhaust. I found a good source for stainless steel bends, in 316L grade - www.allstainlesssteel.co.uk for anyone who's interested. They only sell pipe in 3m sections, though, which was pointless for me.

The diameters I'm using (basically driven by what was on the bike as OEM and what is available) are 1.25" OD for the primary ( 2 x 4-into-2s), 1.5" OD for the secondary (2 x 2-into-1s) and 2" OD for the tailpipe (as that's what the silencer needs).

So far I've bought 15 off 1.25" 90 degree bends, 4 off 1.5" 90 degree bends, and 2 off 2" 90 degree bends, all seam welded hygienic grade stainless.

I'm only at the tacking-together stage at the moment, but think I have a pretty good idea of where everything is going to go, remarkably similar to my original sketch above! Been working on the back 2 cylinders today, as they seem to be the most challenging to route, but think I'm doing quite well! If all goes well I should make a start on the front pair next weekend.

I need to get some straight pipe sections, as I've got most of the bends cut, just need to fill in the gaps! I've "borrowed" InterFester's collector design from his photo above, hope he doesn't mind!!

And lastly, I know, I know! If there are no pictures, it doesn't exist.......... When I've done some more I will certainly post some up!

GazVF500And lastly, I know, I know! If there are no pictures, it doesn't exist.......... When I've done some more I will certainly post some up!

Thanks for the update, I'm looking forward to seeing the progress on this very interesting project!

If I could clarify, your design is a 4-2-1 system?

Yes, 4-2-1 system, joining both front cylinders and both rear cylinders first, then front and rear banks.

Tuned lengths kind fo go out of the window as they're fairly impossible to package!

I'm trying to keep the 4-2 parts of both banks the same length, but there's going to be a difference front to back in the 2-1 part because I can't hide the extra length in the back.

It looks like I'll be able to keep the centrestand too, which is nice.

GazVF500

Yes, 4-2-1 system, joining both front cylinders and both rear cylinders first, then front and rear banks.

Tuned lengths kind fo go out of the window as they're fairly impossible to package!

I'm trying to keep the 4-2 parts of both banks the same length, but there's going to be a difference front to back in the 2-1 part because I can't hide the extra length in the back.

It looks like I'll be able to keep the centrestand too, which is nice.

Sounds like you are making good progress on the design. Kudos on working the design around the bike's centerstand. It is nice to have the option of using/keeping this.

On a side note, will you be using the mounting points on the oil pan?

I guess I missed the most recent updates, 'bout time you got busy welding. :biggrin:

So it's been a few months, how does it look? Surely you have pictures by now.

I recently purchased a really nice '84 VF500F so I can start moddin'. I really should leave it alone but I know I won't. I can justify mods if they are easily reversible right?

The more I think about it, the more important fit and sound are to me. I still plan to pair 1/2 and 3/4 for fit and easy plumbing sake. They aren't 360 degrees apart but they aren't super close either, at least 270 degrees. Besides, if they all merge into one then they are all gonna share all the pulses.

I'm looking forward to working with smaller diameter tubing, lot's tighter designs can be done the smaller it is. 2"OD gets to be tough.

Yes, I really should be welding now!

I have made some (very slow) progress with this, but should have something to show for it soon!

Pictures as soon as I have them!

Thanks for all the info. I was going to ask questions regarding firing order for the same reasons and was trying to work out how to route the rear bank so that they would be the same as the front. If I have read this thread correctly, then it does not seem to really matter as long as the longest (front are either 1.5 or 2X the length of the shortest). Am I correct? I don't really need to worry about the centre stand as this will be going onto a Vf1000r.

I purchased a manufactured collector box from one of the members of the UK VF1000 forum members and will try that first before attempting 2 x 2 into one sets.

Thanks for the thread.

Right, back from the dead! Finally got some time to finish the exhaust, its' fully welded but I need to clean it up a bit as it's not that, er, pretty at the moment!

So anyway, here are a couple of pics so you can see how I've routed it!

[image: DSC00828.jpg]

[image: DSC00823.jpg]

And here it is fitted to the bike with the end can, I've made it so that it is a snug fit with the footpeg bracket

[image: DSC00824.jpg]

Hope you guys thought it was worth the wait, lol!

Very nice! I hope you set up a jig so you can make a few more...

Love to hear a sound clip once its fired up. Great work :fing02:

Hey, you got it done! A lot of folks just talk and never build, but you finished it.

We would love to hear it when it is running.

I'm guessing with that Micron can meant for a much larger bike that it'll be quite quiet.

Is the can E-legal or roadrace only? Even a roadrace can is going to be quite quiet, given it's size and the 500's displacement.

Looks good,

I went with the new collector box, some additional bends and two Akropovich cans from a GSXR 1000.

[image: post-22870-0-28193500-1319905138_thumb.j]

[image: post-22870-0-83255100-1319905159_thumb.j]

Thanks for all the feedback, guys! As you can see, I'm a little way off firing the old girl up!!

As for making more, I'm not sure I'd go through the pain again :-)!

It'll be interesting to see how it runs when it's finished - there's a DynoJet centre just down the road so I can check the mixture, hopefully!

Managing to make some progress now, this week I got the forks rebuilt (you can see them in the last pic), and the brake calipers refurbished. My CBR6 F2 wheels are ready to go on, just need to work through the rest of the bike and get her back together.

Looks great GazV! Now hurry up and start the engine so we can hear it. JK, worth the wait.

Duc888, those cans look right at home on yer 1KR. Sometimes mixing old and new really works.

Veefer800Canuck

I'm guessing with that Micron can meant for a much larger bike that it'll be quite quiet.

Is the can E-legal or roadrace only? Even a roadrace can is going to be quite quiet, given it's size and the 500's displacement.

The can is not e-marked, but as I understand it for UK MOT (yearly roadworthy inspections) regulations the can doesn't have to be, it just can't say "NOT FOR ROAD USE" or cause your ears to bleed. I'm not too sure how loud it will be, it's 2" bore straight through. If it's too bad I'll get it a dB killer/baffle.

Duc888, I bet the VF1000 sounds great with those on!

Mine said not for road use, and it wasn't too loud on the 800. On your 500 I thInk you will not have any noise issues.

Interfester, thanks for the feedback.

Gaz, they are not too loud, just a nice low growl. They MOT place that did mine said it was mostly up to the testers discretion. Like you said "as long as they don't make yer ears bleed".

Give me a shout if you get stuck and I'll give you the address of the place that does mine.

Next job on mine is to fit some drilled discs and rear sets.

cheers

Nice work. That exhaust looks great!

A before and after dyno would have been nice, as i have heard that making an exahust for the V-4's takes alot of science to keep the exhaust pulses from running into each other and hurting performance.

Very nice work and way to stick with it!

Please keep us posted on the rest of the build.

Looks cool. I can tell you from experience that they are not fun to build from scratch. Mine are 2, 2-1's. My first try had the rears way too short. I ended up adding about 10 inches to them before they merged into one. The fronts are about 27 inches before they merge. Making the rears longer dropped the mid-range down a few k's. It flows really good mid to high now but definitely lost some low end, not a huge deal with a 1000cc V4.

I'd say I'd like to see your fronts a bit longer but can't do much about it now. The fact that you have all four merging might help. You can chase your tail trying to get it right at all rpm's but even the best pipes will have a dead spot somewhere so I wouldn't sweat it. Proper jetting will get you far. I sand blasted and applied a ceramic coating myself which has held up really well so far. Just spray it with any spray gun and bake.

Can't wait to hear it.

KelI'd say I'd like to see your fronts a bit longer but can't do much about it now.

If I could ask, is the goal to have the front and the rear tubes the same length before they merge?

InvisibleCities

KelI'd say I'd like to see your fronts a bit longer but can't do much about it now.

If I could ask, is the goal to have the front and the rear tubes the same length before they merge?

It seems exhaust building involves as much folklore as science. I think everyone has heard that pipes must be equal length. How much of that is true is unclear. The Sudco 4-1 for an R that's hanging on my wall has unequal length pipes(fronts are longer). My comment was speaking more to the front length before a merge regardless of rear length. I'm only speaking from experience with my exhaust which is a 2 x 2-1 system and clearly different form Gaz's. My rears were very short before the merge. When the bike was idling, you could feel the difference from the fronts to rears. If you put your hand over the end cap of the fronts(right side), you could feel a steady flow of slight pluses. If you did the same over the rear side, you felt larger pulses and not so steady. I tore off a small piece of paper and held it right in front of the right(fronts) side end cap, the paper fluttered out in a steady arch. The left side(rears) however would swing back and forth, blowing outward then sucked back in to the opening. This had everything to do with length before the merge into 2. Now this was at idle, half to full on the gas, my bike pulled hard and didn't pop on deceloration but I had lost lower rpm power. By lengthening the rears before the merge, I gained back some of that.

This may all be mute if they all eventually merge into one but this was just my experince. I know some have added a simple crossover pipe to gain some midrange, but again, who knows where to add it and what diameter. This is probably like an oil thread, there will be a million opinions most backed up with "what they heard".

Very impressed with your handiwork! I've heard many talk about making an exhaust for a V4 but very few actually have done it.

I also would like to see your front head pipes somewhat longer but like what you've done.

My exhaust on the R is also 2 X 2 into 1 and also the header pipes are not exactly the same length. Seems to work well though.

Also have a 1000 Interceptor with a Holeshot 4-1. Seems a little softer in the lower rpm range.

Well done.

VF1000RS

I also would like to see your front head pipes somewhat longer but like what you've done.

Looks like with the placement of the engine's sump, that may have been challenging to say the least.

Veefer800Canuck

VF1000RS

I also would like to see your front head pipes somewhat longer but like what you've done.

Looks like with the placement of the engine's sump, that may have been challenging to say the least.

Yes, the length of the front primaries is limited somewhat not just by the sump but also by the frame rail and fairing lower. Obviously, originally there would have been 1 pipe running through that space - now there's 2!

GazVF500

Veefer800Canuck

VF1000RS

I also would like to see your front head pipes somewhat longer but like what you've done.

Looks like with the placement of the engine's sump, that may have been challenging to say the least.

Yes, the length of the front primaries is limited somewhat not just by the sump but also by the frame rail and fairing lower. Obviously, originally there would have been 1 pipe running through that space - now there's 2!

It will be interesting to see how the jetting will change as you tune the engine for the new exhaust.

If I could ask, what set of carburetors will you be installing (i.e. 32mm or 30mm)?

Again, super nice work. Kudos!

InvisibleCities

GazVF500

Veefer800Canuck

VF1000RS I also would like to see your front head pipes somewhat longer but like what you've done.

Looks like with the placement of the engine's sump, that may have been challenging to say the least.

Yes, the length of the front primaries is limited somewhat not just by the sump but also by the frame rail and fairing lower. Obviously, originally there would have been 1 pipe running through that space - now there's 2!

It will be interesting to see how the jetting will change as you tune the engine for the new exhaust. If I could ask, what set of carburetors will you be installing (i.e. 32mm or 30mm)? Again, super nice work. Kudos!

The bike is an '86, so at the moment I plan to use the original carbs (are these the 30's?). Has anyone tried using the earlier carbs on a later bike? Does it make a difference?

Here are the carb specs:

[image: vf500f84serialnumbervfrworld04-29-1.jpg]

[image: vf5008586serialnumbervfrworld04-29-.jpg]

From what I have read the 32mm carburetors are good upgrade on the stock engine. These may be a good fit for your new exhaust system as well but I agree best to start with the 30mm carbs and not change too many things at once.

Actually I started a post on this here:-

http://www.vfrdiscus...__fromsearch__1

and it seems that I have the VD41A carbs - so according to your table could they already have been swapped?

GazVF500

Actually I started a post on this here:-

http://www.vfrdiscus...__fromsearch__1

and it seems that I have the VD41A carbs - so according to your table could they already have been swapped?

I am not as familiar with the UK VF500FII. If I could suggest measure the bore and check the main jets, jet needles, idle jets and emulsion tubes. This should give you the intel needed to verify what you have.

InvisibleCities

GazVF500 Actually I started a post on this here:- http://www.vfrdiscus...__fromsearch__1 and it seems that I have the VD41A carbs - so according to your table could they already have been swapped?

I am not as familiar with the UK VF500FII. If I could suggest measure the bore and check the main jets, jet needles, idle jets and emulsion tubes. This should give you the intel needed to verify what you have.

I'll try and do that tonight and post back. The plot thickens....

It's great to have a forum with such knowledgeable people on it!!

Since it's a 4-2-1 or a tri-y the individual head pipe length can and should be shorter. They all don't merge and jump up to collector size like a 4-1, the pairs step up and then merge. Different program to figure all this out.

I checked all the components last night.

Carbs are 30mm bore:-

[image: th_DSC00829.jpg]

Carbs are all marked VD41A

[image: th_DSC00831.jpg]

Front cylinders use a 90 main jet, 38 idle jet and unmarked emulsion tubes with equally spaced holes, as you can see here:-

[image: th_DSC00835.jpg]

Rear cylinders use a 92 main jet, 38 idle jet and unmarked emulsion tubes. These are different to the front tubes by having two holes closer together, as i hope you can see here:-

[image: th_DSC00846.jpg]

All carbs are using 3JV needles, and 2.6mm float valve seat diameter.

Here is the info I have based on my '84 (US model). Carbs are marked VD56A. These carburetors have a 32mm bore with #102 Front / #105 Rear main jets. The float level is 6.2mm.

[image: jetneedlesandemulsiontubes10-20-10.jpg]

[image: fsmjetneedlesvfrworld10-19-10.jpg]

[image: fsmcarbschematicdwgnote10-18-10.jpg]

[image: 84origcarbsmainjetemulsiontubes410-18-10copy-1.jpg][image: 84origcarbsmainjetemulsiontubes110-18-10copy-1.jpg]

Also, I have this info from a previous carb thread on VFRWorld which noted the specs for European FSM (I haven't verified this with the actual manual being in the US and all).

Model No. VD41A - 30mm Throttle Bore, 6.8mm Float, 95F/92R Main

Typical good info and drawing from IC. :fing02:

Following your VF build now, but this is a great thread on the exhaust build. Have a friend that does custom HD work, specializes in exhausts and watching first hand the efforts involved there (which a V-Twin is worlds easier than a complicated V-4 build), can fully appreciate your from scratch build up.

Had I seen this thread earlier in your quest, I could have posted some pics from a vintage Hindle catalog I still have that shows the Hindle 4-1 fairly well. The full V&H 4-2 system I ran back in the mid 1980s on my VF500 was closer to equal length than the original Kerker 4-2 systems for the VF750s that had the right side exit for the rear bank much longer than the left side pipe.

HRC did quite a bit of exhaust tweaking when you look at the evolution of the HRC race bikes (Moriwaki too from that era) during the VF/VFR builds. 4-2 and 4-1 variants often from weekend to weekend (180 vs. 360 cranks as well). My wife thinks I'm nuts when she finds me in the basement from time to time reading Road Racing World and Cycle/Cycle World magazines from the 1980s that I still have stashed, amazing some of the fine details you can still pick out after all these years in the photos.

lsc86Had I seen this thread earlier in your quest, I could have posted some pics from a vintage Hindle catalog I still have that shows the Hindle 4-1 fairly well. The full V&H 4-2 system I ran back in the mid 1980s on my VF500 was closer to equal length than the original Kerker 4-2 systems for the VF750s that had the right side exit for the rear bank much longer than the left side pipe.

Please post! Thanks, lsc86.

On a side note, here's what I've come up with for VF500F exhaust systems from back in the day:

Hindle 4-1, requires a modification to stock chin cowling (a slot cut into the right side), mounts to oil pan - possibly two versions: '84/'85 and '86 (see note below)

Kerker 4-2, paired with cylinders 1|3 and 2|4 *considered the best pairing for 4-2 systems*

Mac 4-2

SuperTrapp 4-2, equal length system (staggered mufflers)

Vance & Hines 4-2, paired with cylinders 1|2 and 3|4

Yoshimura 4-1 (Japan only) and 4-2, paired with cylinders 1|3 and 2|4 *considered the best pairing for 4-2 systems*

From what I have read the Yoshimura and Hindle systems require the removal of the centerstand. The V&H does not (it does require an easily fabricated stop for the centerstand) .

The Yosh system looks to have been designed for the shallower '84/'85 oil pan. Not sure about the Hindle or the V&H, or if versions of the Yosh, Hindle and V&H were made specifically for the '86

Good list IC.

I had a Basani exhaust for my VF750F, nit sure if they made one for the 500 also.

I'll start a new thread, no need to clutter this one up. Besides, I'm curious to see/hear his finished product!

We never had a video to see and hear it run did we? :goofy:

(yes it is an old thread but with the bikes parked up I'm just digging through the archives here.....)