I've been toying with the idea of putting a slip-on exhaust on my '95. Looks like Two Brothers is the only mfr still making new slip-on units for these bikes.
I can't get a straight answer if the bike will need a rejet to run correctly if all I'm replacing is the can. Several people have told me that they have replaced just the can on their 3rd or 4th gen and NOT rejetted and the bike runs fine. Then, of course, several others have said a rejet is a necessity or the bike runs too lean and gets flat spots, etc.
I live at high altitude -- over 5k feet. One hundred percent of my riding is at or above 5K feet. My bike is completely stock and runs very well until I start to get much above 8K feet (my favorite twisty is up a local mountain and the road rises up to over 10K feet). At that point it still runs pretty well but develops a flat spot/bog at more than half throttle around 6-7K RPM. I have always assumed this was because the high altitude is causing it to run too rich, and basically ignore it since it's not a problem 90 percent of the time. In my mind...this makes me think me bike is probably running a tad rich in the first place because of the altitude I live at, and a new exhaust can might lean it out just enough to be spot on perfect. If I'm wrong, thanks for clearing that up!
Lastly, do any 4th gen guys HAVE the two brothers slip-on? How does it sound? Sound is the MOST important factor in my decision -- I'm not putting a new exhaust on for more power as the bike has more than enough already for me.
My 4th gen came with a Staintune (very sweet sounding by the way) and I did not notice any problems with flat spots, but I didn't ever have a ride with a stock muffler so I can't compare. Now I have a full TBR left exit system and I have noticed that the mid range doesn't have as much punch as before, but above 7-8krpm it really pulls so I've been thinking about getting a kit, still fairly low on the list though (which is a very long list...)
I have a 93, with the collector, so it not apples to apples, but my slip is fine. I only get a pop once in a great while when decelerating, so I THINK its OK as factory jetted.
[image: View Post]vfrrider, on 06 February 2010 - 03:50 PM, said:
I have a 93, with the collector, so it not apples to apples, but my slip is fine. I only get a pop once in a great while when decelerating, so I THINK its OK as factory jetted.
Of course, for definitive answer, test on a dyno.
Larry
VFRrider
ANY change on the exhaust side should have another change on the intake/carb side...thats not to say that your bike will just run fine with the slip on install.
What I would recommend (especially since you are in a higher level) is bolt the exhaust on yourself and bring the bike into a qualified shop for a dial-in.
I am pretty cheap $$$ but imo this would be money well spent, bike may be off right now, so make changes, then get a good tuner to final tweak.
DONT GUESS or THINK ITS AOK, use TOOLs designed for tuning...plus OLD SCHOOL spark plug reading and look at plugs time to time.
From what I've heard, the 4th gens are jetted rich from the factory, and that a re-jet is not necessary for a slip-on change. I don't know yet from firsthand experience, just what I've been told by some 4th gen owners. YMMV!
Here is a simple answer. Bolt on the slip on and try it. If it's not right pull the carbs and change the jets. It's not hard to do, I could probably do a jet change start to finish in and hour and a half easy. You aren't in a racing environment where hundreds of a second matters, as long as it seems to run alright you will be fine. That said I'm running a slip on, a BMC fliter, and stock jetting and I have no decel pop.
I put a Staintune slip on on my 3rd Gen a couple of years ago. It made no discernible diference to anything but the noise. (and it's wonderful)I ride from sea level where I am, right up into our (lowish) mountains and haven't ever discovered anything of a fuelling problem. the pipe is a pretty freeflowing one too. No filter/airbox mods.
Hey! I have a 90 with a Kerker left exit that I have put many miles on. When I got the Kerker, I had a dynojet kit installed as well. The guy had a dyno, I have the sheet still (not bad 14 years later!). 96 HP if I recall correctly. But i pops like orville reddenbocker on decel. The guy said the pilots needed to be resized, and that there wasn't any problem. Rode it a long ways before the motor gave out lost oil somewhere:unsure: but got a 91 motor installed with same carbs. The slip on may give you some pops and stuff, but it's how it feels when you're on the gas. The jet kit/dyno is a good idea. If you have the cash. I remember saving for months to have that surgery done. I can't wait to grow up and buy a house with a garage!
Definitive answer: it won't kill your bike or you with or without the slip on. Put it on. Ride. If it huffs and puffs: re-jet or re-move. Don't sweat the small stuff!
Cheers!
Yup, there is no definitive answer because every situation is different. There are also stage 1 and 2 jet kits. Do you have a high flow filter? De-snorkeled? Sea level or mountains? Etc.....
On a related note: if you haven't "de-paired", the decel pops are also coming from that injection system.
Great info guys thanks! I appreciate the vids too.
I have not depaired my bike and it does pop mildly on the overrun with the stock exhaust. I already knew that was because of the air injection. Frankly, I love the sound of some minor burbling on overrun. :goofy:
Sounds like my best bet is to just get the can, slap it on and see what happens! :laugh:
[image: View Post]VFR72525, on 06 February 2010 - 09:15 PM, said:
Great info guys thanks! I appreciate the vids too.
I have not depaired my bike and it does pop mildly on the overrun with the stock exhaust. I already knew that was because of the air injection. Frankly, I love the sound of some minor burbling on overrun. :goofy:
Sounds like my best bet is to just get the can, slap it on and see what happens! :laugh:
V-FORE, on 06 February 2010 - 08:50 PM, said:
I would say not needed :biggrin: I have a TBR can on mine, stock jetting, no issues here is what she sounds like
Gary
Sounds tits Gary, hope you enjoyed the ride!! :fing02:
I have a '97 and went with the K&N air filter first and later added the D&D Stainless slip-on. I didn't change anything with the carbs and have put about 10k on it without any issues. I also ride at high altitude (up to 14k) on a very regular basis. I also did a run from CO to MI without any issues at lower levels. D&D does still produce the pipe for your bike. I have the link for the pipe below. NOTE: It says this pipe is for a 4th gen, but the photo is of a 5th gen. It has been that way for years but this model # is in fact for the 4th gen. I can't find any sound clips of a 4th gen but the 5th gen clip below sounds very similar to mine.
http://www.danddexha...5/07/81312a.htm
[image: View Post]FotoMoto, on 06 February 2010 - 07:12 PM, said:
Yup, there is no definitive answer because every situation is different. There are also stage 1 and 2 jet kits. Do you have a high flow filter? De-snorkeled? Sea level or mountains? Etc.....
On a related note: if you haven't "de-paired", the decel pops are also coming from that injection system.
My first bike was a Honda Shadow Spirit 1100 (a 1,099cc carbureted V-twin cruiser.) One of the things I got for it was a V&H Pro-Pipe. The people on the Shadow forum recommended I rejet the carbs and get a K&N filter for optimum performance. I did. The Dynojet jet kit I bought came with three sets of jets: Stage 1, Stage 2, and Stage 3. Stage 1 jets were for use on a stock setup. Stage 2 jets were for using slip-ons and Stage 3 jets were for using a full system.
With your slip-on, you probably don't have to have the carbs rejetted; however, for optimum performance, I'd have it done. If you do get the carbs rejetted, you'll also notice better throttle response as an added bonus.
[image: View Post]VIFFER93, on 07 February 2010 - 11:19 AM, said:
[image: View Post]VFR72525, on 06 February 2010 - 02:16 PM, said:
I've been toying with the idea of putting a slip-on exhaust on my '95. Looks like Two Brothers is the only mfr still making new slip-on units for these bikes.
I can't get a straight answer if the bike will need a rejet to run correctly if all I'm replacing is the can. Several people have told me that they have replaced just the can on their 3rd or 4th gen and NOT rejetted and the bike runs fine. Then, of course, several others have said a rejet is a necessity or the bike runs too lean and gets flat spots, etc.
I live at high altitude -- over 5k feet. One hundred percent of my riding is at or above 5K feet. My bike is completely stock and runs very well until I start to get much above 8K feet (my favorite twisty is up a local mountain and the road rises up to over 10K feet). At that point it still runs pretty well but develops a flat spot/bog at more than half throttle around 6-7K RPM. I have always assumed this was because the high altitude is causing it to run too rich, and basically ignore it since it's not a problem 90 percent of the time. In my mind...this makes me think me bike is probably running a tad rich in the first place because of the altitude I live at, and a new exhaust can might lean it out just enough to be spot on perfect. If I'm wrong, thanks for clearing that up!
Lastly, do any 4th gen guys HAVE the two brothers slip-on? How does it sound? Sound is the MOST important factor in my decision -- I'm not putting a new exhaust on for more power as the bike has more than enough already for me.
Thanks
There is no exact answer unfortunatly. My recomendation is make the changes you want and get the bike on a dyno. I have a TBR, K&N, Factor Pro Jet Kit and a stock air box. I thought I had all the settings dialed in (bike ran fine) until I spent $50.00 to have it dyno'd by someone who knows what they are doing/talking about. I was actually pretty far off on my settings so I followed his advice, called Factory Pro to verify and made the changes.
I felt the difference in throttle response and the bike did run better.
Every bike is different. Even bikes of the same model and year have small variations so I am not sure anyone could provide an exact answer.
Make the changes, get it on a dyno and see where your at.
And remember "my opinion is worth exactly what you are paying for it" :-)
Slight hi-jack here, but you keep talking about it and I'm curious. What causes the popping on deceleration, and is it a bad thing? That is, is having it an indication that you are running too lean and need to richen the fuel mixture with new jets?
I've always assumed it was unburnt fuel burning in the headers, in which case what some of you guys are saying wouldn't make sense.
But it could also be the combustion event continuing during the exhaust stroke because of spark overlap, either way, I don't see how leanness or richness affects it. A more restrictive exhaust would, of course...
At 5000 feet you will not need to rejet with the installation of a slip on exhaust. If you do notice a slight hesitation or bog off of idle your bikes performance will benefit from an additional 1/2 turn out (richer) on the fuel screws. This can be done with little expense; just the cost of the Motion Pro socket to fit onto the fuel screw heads and a 1/4 inch universal joint from Sears. Even with a free flowing K&N air filter, stock jetting is fine, especially at 5000 feet altitude.
[image: View Post]samaki, on 08 February 2010 - 06:47 PM, said:
At 5000 feet you will not need to rejet with the installation of a slip on exhaust. If you do notice a slight hesitation or bog off of idle your bikes performance will benefit from an additional 1/2 turn out (richer) on the fuel screws. This can be done with little expense; just the cost of the Motion Pro socket to fit onto the fuel screw heads and a 1/4 inch universal joint from Sears. Even with a free flowing K&N air filter, stock jetting is fine, especially at 5000 feet altitude.
My BS meter is going off, and i've got to call bullschite on this post, and much of this thread.
Before adjusting carbs it would be wise to understand what they are and how they work--go read a carb manual first so you don't screw up your bike.
The pilot screw only regulates the idle and barely-open throttle mixture. Popping on deceleration indicates a slightly lean condition at closed throttle and the fix is to slightly open the pilot, not change your main jet or raise your needles. At higher altitudes you screw it IN 1/2 turn to lean the mixture--RTFM. You don't want to add more fuel to an already overly-rich mixture condition.
Carbs are designed to meter fuel based upon the velocity of airflow thru the venturi. The venturi is a calibrated restriction to airflow into the cylinder, and the butterfly is the control valve to regulate how much air gets in. If by some magic you actually could get more air thru the venturi during the time that the cam opens the intake valves, then the carb will respond by supplying the necessary additional fuel.
Most of the time the mixture is controlled by the Partially-Opened Throttle (POT) position of the needle, the main jet is sized for Wide Open Throttle (WOT)--that's with the butterfly fully open and the needle/slide all the way to the top.
Dumping more fuel into a mixture is useless until you have additional air, so IMHO jet kits are just flow devices to direct cash money out of your pocket. Unless you bore your cylinders out to increase engine size, or change crankshaft to longer throws to increase stroke and change camshafts to something with longer duration or higher lift, or add turbo- or super-charging, etc. then adding a slip-on pipe or drilling the airbox does ABSOLUTELY NOTHING to increase the amount of AIR into your cylinder.
"I live at high altitude -- over 5k feet. One hundred percent of my riding is at or above 5K feet. My bike is completely stock and runs very well until I start to get much above 8K feet (my favorite twisty is up a local mountain and the road rises up to over 10K feet). At that point it still runs pretty well but develops a flat spot/bog at more than half throttle around 6-7K RPM. I have always assumed this was because the high altitude is causing it to run too rich, and basically ignore it since it's not a problem 90 percent of the time. In my mind...this makes me think me bike is probably running a tad rich in the first place because of the altitude I live at, and a new exhaust can might lean it out just enough to be spot on perfect. If I'm wrong, thanks for clearing that up!"
Yup, riding up to the Crest (and down) is a hoot!
I've got a '97 w/ a high mount Staintune and the rest is stock (jetting and airfilter). I've had the bike up to about 12,000 ft in Colorado and other than the decrease in power (to be expected at altitude) it runs great. For sea level they are jetted a bit rich at the factory, so at Albuquerque elevation they are even a bit richer. Putting on a freer flowing exhaust will only lean it out a bit-you could probably even run a K&N style filter without a rejet. I've got a Factory Pro jet kit for mine but because of time and the fact it runs so good, I haven't messed with it.
There are a couple other VFRD'rs on here that get together for rides, interested?
96 with a straight pipe here. No rejet. High alt. as well at 5200 ft. My rides often see higher alt going up to Mazamitla at 7k, then down to zero at the pacific. No problems ever.