UPDATE:
Fuel pressure regulator turned out to be the culprit. Not any of the wires, plugs, RR, Stator, battery, injectors, etc, etc. Kaldek gets the credit for saving me from some serious mental problems in fixing this, and thanks to all who contributed some thoughts!!!
Curiously enough, we agree that in the end that part may also have been going bad on his VFR, causing some longstanding issues on his bike. So in a way it's a lesson that helping someone else may actually end up helping yourself. Kudos to all the helpers on this great site. :idea3:
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Hi there everyone. I've been perusing this forum for a year since I bought my 2002 VFR800. I have learned a lot and been scared a lot (about electrical gremilns) by everyones comments! I bought mine from the original owner May 2010. He said it's the only bike he'd ever owned and he bought it new in 2002. He took beautiful care of it and I have all the receipts showing the maintenance and work done. Overall it's been babied and garage queened for the most part. My intention is to get it out and stretch its legs to Deals Gap this summer.
I've had a few issues, such as an occasional stall after a long freeway run in hot temps, and a reluctance for the bike to go into first gear occasionally in hot weather (then starting off in second or third gear and stalling it while pulling into traffic.....scary). This current problem is the only engine issue I've had though.....and it has me perplexed. I'm no mechanic but I can pass as one on occasion, electrical is not my forte though. I've studied a lot of posts and tried to figure it out myself but I'm out of ideas, so I implore the powers of the collective group to unite and please help my cause!
So here it is:
The bike stumbles and feels like its missing at low revs up to about 4000rpm at which point it has some power back in the high revs. I have to slip the clutch a little more and give it a bit more gas to get going. It sounds like it's missing a little bit below 4k, then it seems to run fine from there. It only has 11,000 miles on it, and I've put about 1500 miles on it since I've owned it for about a year. The battery is about 3 years old and has been charged on a battery tender when it's left sitting for more than a week. The bike has had the stator and harness recalls done by the previous owner.
I thought maybe its electrical so I checked the voltages across the battery and got:
12.81 V sitting.
12.14 V key on.
13.19 V idling.
13.70V at 4500rpm.
I'm thinking possibly it's just the battery and it's making the bike run lousy at low revs before the voltage kicks up???
Other stuff:
I checked the stator output at the 3 yellow wire connector and got 23V between each plug 1-2, 1-3, and 2-3. It jumped up to 50-60V when I revved it up. So I think the stator is OK. The bike only has 11,000 miles on it, so I don't think the RR is bad, although who knows based on some of the horror stories I've read on this forum. I also checked all the harness electrical plugs and found no brown or burnt connections. They all look good, although I know that may be deceiving.
I pulled the plugs and interestingly 1 and 2 were perfect looking (left side), while both 3 and 4 (throttle side) looked black and soot covered and looked a bit fowled with gas. I cleaned them up and put them back in but it didn't make a difference to the way it's running. The gaps were all good on them also.
The air and fuel filters were just replaced at 9400 miles, so that's not likely it.....
It ran fine the first few months this year, granted I don't get out as much as I'd like, but I still regularly get it out at least once a week from March through November. It just started doing this after about 2 weeks of sitting in the garage and it doesn't seem to be getting worse or better. I'm stumped, any ideas?
OK, so I have some good news and some bad news for you. I also own a 2002 VFR800, and what you describe sounds exactly like how my own bike behaved! And I mean exactly.
It used to stall after a hard and fast run, and it would constantly have low rpm stumbling issues (little or no power, then BAM once you hit a certain throttle position), which would mostly occur when it was warm weather. I've had the hard to shift into 1st gear problem a couple of times, but not consistently. If yours is quite consistent, then I'd say that maybe you have bent gear forks. However, lots of things can amazingly be cured by an oil change and replacement with good oil. A fully synthentic 10w-40 is what you want, preferrably JASO MA rated (although this increases the price a bit).
I now have over 80,000 miles on my bike, and by and large the problems have been resolved. Here are the things I would definitely do:
Run some seafoam through it, or have the injectors professionally cleaned. Mine gummed up, and since your bike is as old as mine and has obviously sat around a lot, it could be they need a good clean.
Fix/replace the 30-amp fuse connector and wiring with heavy gauge wire and a weatherproof fuse holder. This part WILL fail at some point, so do this mod even if it looks OK.
Run a dedicated ground wire from the blue connecor (front-left fairing, behind the indicator).
Bypass the O2 sensors using O2 sensor eliminators.
Synchronise your throttle bodies (also called air bypass valves) within 20mm Hg of each other.
Fit a powercommander 3 or 5 (preferrably 5), and run Cozye's map.
If you're curious what else I've done to my bike, you can read my signature! Note though that there are some things I have NOT done to my bike. For example, I still use the flapper valve in the airbox because I do believe that it helps low rpm airflow in the airbox.
Your charging system is typical of a 2002 model, with possibly a weak stator. The stator in the 02 model is very small, and unless the original owner had the stator/flywheel recall performed your charging system will always be weak at idle. 13.7 volts at 4500 rpm is a sign that your regulator is also regulating a bit low. A replacement R/R will bring that up to over 14 volts, and the consensus seems to be the FH012A regulator is the best replacement. These are commonly available on eBay. Personally, I have an SH589 fitted to my bike, as sold by a local auto electrical shop. They're super reliable apparently, even though they're not MOSFET units like the FH series. This won't show up in a Google search though, but I know it was fitted to some Ducatis.
I'm fitting a 2006 stator and flywheel to my 2002 in about three days. I'll be posting a video and thread on how to do it which you may be interested in.
Thanks for the reply kaldek. I figured it must have something to do with the electrical system. My guess was battery, hoping against the RR or worse yet the stator. I will do the electrical grounding mods just for future insurance, but I don't think that's causing my current problem. I think I might have 2 separate problems, one is the stumble; the other is something with the right side plugs fowling. Of course the stumble could be because the plugs. What would cause both right plugs to fowl, while the left ones look perfect? Not enough blinker fluid?
[image: View Post]WildsViFfeR, on 12 June 2011 - 08:17 PM, said:
Thanks for the reply kaldek. I figured it must have something to do with the electrical system. My guess was battery, hoping against the RR or worse yet the stator. I will do the electrical grounding mods just for future insurance, but I don't think that's causing my current problem. I think I might have 2 separate problems, one is the stumble; the other is something with the right side plugs fowling. Of course the stumble could be because the plugs. What would cause both right plugs to fowl, while the left ones look perfect? Not enough blinker fluid?
Hmm, only one side fouling you say? Could be a dodgy O2 sensor massively trimming the mixture to rich on that side, because the two O2 sensors service each side of the bike. O2 eliminators (basically 330 ohm resistors) will diagnose that pretty quickly. You can make your own, as show in this thread for a couple of bucks! Just fit the eliminators, clean your plugs up and ride around for a while before checking the plugs again.
If they're still fouled after that, you have either leaky injectors on that side or a weak spark. I'd say injectors, because mine started to leak too. Yours are probably at more chance of that happening due to the bike being as old as mine but ridden less. Stagnant fuel causing the injectors to gum up and not seal properly, or condensation and rusting of the injector pintles are real possibilities.
I wonder if fuel injector cleaner additive would make a difference. I am going to get the resistors today from radio shack and try that out as well. That's my project for the night after work. I'm going to try the synthetic motor oil too and see if that helps the shifting into 1st. Its a bummer that the bike is sitting there un-rideable.....I have to figure out something so I can ride it instead of working on it. I have had 4 Honda bikes over the years and only one (hawk gt) was free of issues. Still love the looks of the VFR though!
Like Kaldek said, put some Seafoam (fuel system cleaner) in the tank and ride the bike around for a while.
Also, fuel injection systems (injectors, computer, etc.) work best when they are provided with a steady source of electrical power. Even if your R/R is still 'working' that low of a voltage at the battery indicates it is not working at optimum conditions. I would suggest you seriously consider getting a good MOSFET regulator and replacing your existing one. Also make sure all the ground connections to the frame are clean, tight, and corrosion free.
I've heard of seafoam cleaner, just never figured out if it's worth it, but I've not got anything to lose by trying it.
I finally got the pics of the plugs available.
This is the number 3 plug in the back throttle side
[image: Attached Image: plug 3.jpg]
And this is the number 4 plug on the front throttle side:
[image: Attached Image: plug 4.jpg]
Both plugs on the left side had the perfect golden brown look to them like marshmallows roasted perfectly.....the right ones look like they were set ablaze in the campfire.
So heres my to do list:
Seafoam injector cleaner.
O2 eliminator mod.
probably new RR. Compufire one from what I've been reading here.
Synth oil (for smoother shifting hopefully).
Thanks for the ideas, I'll post my progress.
[image: View Post]WildsViFfeR, on 13 June 2011 - 12:09 PM, said:
So heres my to do list:
Seafoam injector cleaner.
O2 eliminator mod.
probably new RR. Compufire one from what I've been reading here.
Synth oil (for smoother shifting hopefully).
Good idea on the Compufire. I would have recommended that but it's still early days for these to see how well they work I think.
(This coming from the guy who is literally about to fit a LiFePO4 battery to his bike in about an hour!). Yeah sometimes I'm a bit bleeding edge.
Oh, don't be surprised when the Seafoam makes the bike blow a big white cloud. That's normal.
Wow. That battery must cost a fortune. It's equivalent to unobtanium at this point in time, no? I was meaning to ask why you were replacing your stator too?
I did the seafoam and 330ohm O2 sensor eliminator mod. I'm riding it to work tomorrow to see if there's any differences by the time I get home (40 miles RT). I tested voltages across the battery again and this time I hit the high beams to see what happens. As I understand the voltage should jump up after a second or two. Mine dropped (!) to 13.2 V range whereas it was running 13.8 V range with low beams. Prolly the regulator I'm guessing. Grasping at straws here.
[image: View Post]WildsViFfeR, on 13 June 2011 - 08:33 PM, said:
Wow. That battery must cost a fortune. It's equivalent to unobtanium at this point in time, no? I was meaning to ask why you were replacing your stator too?
Nope, the battery cost me $145 USD. I just fitted it not two hours ago, and it's pretty darn good - it weights two pounds!
I'm replacing my stator because it's already weak output when it gets hot. There was a stator/flywheel recall in the USA where you guys got the bigger charging system for free, but we never got that recall here in Australia. So, I'm fitting the bigger stator and flywheel myself - in fact the new flywheel arrived today so all I'm missing now is the flywheel removal tool. I'm not sure if the one I ordered will fit so I'll pop down to the bolt shop today to test fit a bolt for it.
OK, I rode to work today, and its obvious this bike is sick as a dog. Above 4000 rpm its tolerable, just with no power. Under that and it sputters and stumbles. Idles fine though. The kicker is that I have 98 miles on this tank of fuel and its down to one bar of fuel on the gauge. Roughly 20 mpg maybe? That's obviously terrible and abnormal. What next?
Any ideas out there. All the experience collected on this forum someone has to have had a similar problem. Thanks for the responses so far. Any other ideas......?
I am ready to give up and bring it in to a shop. I called Gainesville power sports, a Honda dealer, and the service guy said "a vfr? Is that a motorcycle?" So I'm kind if reluctant to bring it to someone, but I'm ready to tap out.
[image: View Post]WildsViFfeR, on 14 June 2011 - 04:16 PM, said:
OK. Gassed up and calculated 22 mpg. WTH?
Any ideas out there. All the experience collected on this forum someone has to have had a similar problem. Thanks for the responses so far. Any other ideas......?
I am ready to give up and bring it in to a shop. I called Gainesville power sports, a Honda dealer, and the service guy said "a vfr? Is that a motorcycle?" So I'm kind if reluctant to bring it to someone, but I'm ready to tap out.
Sounds like serious fuel delivery problems mate; your bike must be running super-rich. We need to get to the bottom of it - I wish I was in the USA because it would be a lot easier to help you out! Right now I'm thinking that there's something wrong around the airbox area.
If you're relatively handy with a spanner, we can do this cheap (but slowly - do you need your bike to ride to work?). Are you willing to let us help you run through FI code diagnostics, followed by other tests?
If it comes to it, I have a complete set of '02 injectors handy - they've been ultrasonically cleaned three times and are as good as they're gonna get. Happy to send them to you if we need to!!
Well I thank you for the assistance so far kaldek. I figure something more screwy is going on than the charging system causing the problem. I'm going to test the spark strength tonight to see if I'm getting a nice strong spark on the fouled cylinders. Yesterday I took the plugs off again and found them covered in fuel on the right side. I've only ridden 50 miles since I cleaned them so they weren't to carbon fouled. They didn't look nearly as black as before.
Possibly the O2 sensor on that pipe was bad and sent a rich mixture to that side for so long that it ruined the plugs? I'll find out how good a spark they can still give tonight. If they spark strongly then I would guess it is the injectors. I can remove them and have them cleaned next.
I can do just about any of the wrenching myself. I just need a little help figuring where to go next. I think I'm going to try your injector leak test that I read about in your other thread after the plug test. If the plugs do lousy I'm guessing RR.
Thanks for the help....and the injectors might be migrating stateside after all is said and done!
[image: View Post]WildsViFfeR, on 15 June 2011 - 11:10 AM, said:
I can do just about any of the wrenching myself. I just need a little help figuring where to go next. I think I'm going to try your injector leak test that I read about in your other thread after the plug test. If the plugs do lousy I'm guessing RR.
If your battery is charged, even if your RR is completely disconnected the bike will still run and the spark will fire. In other words, a dodgy regulator won't cause bad spark unless the battery is also flat. Before that happens though, you'd be having problems with your injectors, fuel pump, dash, and a bunch of other stuff that demands more current than the coils. Having said that, your coils could be stuffed or they could be not getting a spark command from the ECU.
A good way to test this is to get the bike running, then unplug the coil connector on each cylinder individually to see how it affects the engine rpms. If there's no change when you disconnect a plug, then you know that it's not firing on that cylinder correctly. Lots of possible causes here, including so much fuel from the injector that the plug is just too wet, even if the spark is good. Coils can and do go bad, but mine have waaaayy more miles on them than yours and they're fine.
Remember that with the injector leak test the idea is to fold the paper towel back on itself so that it can be hooked into the injector port while you hold the throttle open and prime the fuel rails a few times.
I'm really looking forward to finding out what the root cause problem on your bike is though. It's fascinating me what's gone wrong!
What temps are you running at normally? If it's below 168 you'll be running rich and likely have a bad thermostat.
WhenI got my 2002 I was getting 23 mpg. I replaced my thermostat at the mpg went up to 29, then I replaced the plugs and I'm up to mid 30's to low 40's.
The open thermostat will never let the bike get to normal running temp, which causes the computer do dump fuel into it trying to heat it up. This constant rich fuel mixture will foul the plugs. My bike had all 4 plugs fouled.
Once I got the Tstat and plugs changed it's had new life.
Holy crap (palm smack to forehead). I did the paper towel test to see if the injectors were leaking....wow.
I guess there's not supposed to be any fuel in the throttle bodies either while the bikes sitting or when you turn the key on.....only when you hit the start button should fuel be injected. Sooooo..............
I took off the air filter and looked inside the throttle bodies after twisting the throttle to open the butterflies. The intake valves were black and soot covered on 3 and 4, and there was actually fuel sitting on top of the intake valves! None on 1 and 2, and while they were black they weren't covered in as much soot, but definitely no fuel sitting there. I didn't even bother sticking the paper towel in 3 and 4, instead I just turned on the key to see what would happen, and fuel was leaking all over down the inside of the throttle body walls. That's not supposed to happen, right? (mild sarcasm). :blink:
I did stick a paper towel in there because I wasn't sure if I was seeing things straight, and the bottom 1/2 inch of the paper towel got soaked with one twist of the key.
So to recap, 1 and 2 normal. 3 and 4 leaking fuel so bad it's pouring down the inside of the throttle body and pooling on top of the valves. And I only turned the key to prime the fuel pump once.
So I guess the question is what to do now?
BTW, the 3 and 4 plugs had a nice strong spark when I tested them, so no issue with them working.
Go straight to pulling the injectors and have them cleaned I guess? Pardon my ignorance but this is my first fuel injected bike. I'm beginning to think the old crappy carbs weren't so bad after all.
edit.......I'm going to post pics here of the 2 and 4 intakes later.
[image: View Post]WildsViFfeR, on 15 June 2011 - 11:58 PM, said:
Holy crap (palm smack to forehead). I did the paper towel test to see if the injectors were leaking....wow.
I guess there's not supposed to be any fuel in the throttle bodies either while the bikes sitting or when you turn the key on.....only when you hit the start button should fuel be injected. Sooooo..............
I took off the air filter and looked inside the throttle bodies after twisting the throttle to open the butterflies. The intake valves were black and soot covered on 3 and 4, and there was actually fuel sitting on top of the intake valves! None on 1 and 2, and while they were black they weren't covered in as much soot, but definitely no fuel sitting there. I didn't even bother sticking the paper towel in 3 and 4, instead I just turned on the key to see what would happen, and fuel was leaking all over down the inside of the throttle body walls. That's not supposed to happen, right? (mild sarcasm). :blink:
I did stick a paper towel in there because I wasn't sure if I was seeing things straight, and the bottom 1/2 inch of the paper towel got soaked with one twist of the key.
So to recap, 1 and 2 normal. 3 and 4 leaking fuel so bad it's pouring down the inside of the throttle body and pooling on top of the valves. And I only turned the key to prime the fuel pump once.
So I guess the question is what to do now?
BTW, the 3 and 4 plugs had a nice strong spark when I tested them, so no issue with them working.
Go straight to pulling the injectors and have them cleaned I guess? Pardon my ignorance but this is my first fuel injected bike. I'm beginning to think the old crappy carbs weren't so bad after all.
edit.......I'm going to post pics here of the 2 and 4 intakes later.
LOL!! OK yeah dude your injectors are SNORKED! There should be NO fuel evident anywhere; even when the bike is running, ALL fuel should be getting sucked into the motor and burned.
Get those suckers cleaned ASAP!!! Have all four cleaned because you want to have them "flow matched", so that they all flow the same amount of fuel for a given pulse width. If they can't be flow matched, it's probably because they're internally rusted and aren't sealing.
When you remove the injectors, use a sharp tool to mark the cylinder number they came out of somewhere on the injector body. That way when they're getting tested or cleaned you can ask the guys cleaning them to keep the reference to which one they're testing. I have a feeling you are going to need to buy some new ones; this can make flow matching with the ones you don't replace very difficult! A full set is going to set you back a bit from Honda - mine are "OK" but I don't trust them fully.
I recommend using Witch Hunter for injector cleaning - they confirm a 2 day turnaround.
Honda Parts House online is quoting $105.21 per injector for replacement injectors for the '02 (Part #16450-MCW-004). However, if you buy 2006 model injectors they only cost $85.09 per injector (Part #16450-MEL-003 - same injector used on '04 and '05 CBR1000RRs). These are the injectors I have in my bike. Personally I have a custom tune but one of our members rode around for ages with '06 injectors in his '04 bike without a tune! Witch Hunter may be able to get you a sharper price on replacements, but again I'd replace them as a set.
It's a pain in the arse I know, but if you can't get your current ones flow matched, you basically need another four injectors - even if only one injector is off. I could sell you my spares, but the reason they're spares is that even after cleaning I didn't trust them. High rpm "hot" testing showed that one of them gets weak and the solenoid starts to not open fully, resulting in that cylinder leaning out. Initially I was thinking I could just send them to you to help with diagnosis but since your injectors are pissing fuel everywhere, we can bypass all the diagnostics!
Alright. The injectors are out...as is a lot of spilled fuel. I should've drained the tank first...doh!
Kal, I Googled "vfr800 injectors cleaning" on my phone, and somehow your YouTube videos popped up in the results, so I got to see what to do and hear you live. Ain't technology great? When its working, that is.
I found a place called "fuel injector connection" near where I live in Atlanta, Georgia and I'm dropping off the injectors tomorrow to have them cleaned and flow measured, etc. I can't wait to get them back in there to see how they work. Any good tips on the reinstall? Do I really need new o-rings, etc?
[image: View Post]WildsViFfeR, on 16 June 2011 - 10:05 PM, said:
Alright. The injectors are out...as is a lot of spilled fuel. I should've drained the tank first...doh!
Kal, I Googled "vfr800 injectors cleaning" on my phone, and somehow your YouTube videos popped up in the results, so I got to see what to do and hear you live. Ain't technology great? When its working, that is.
I found a place called "fuel injector connection" near where I live in Atlanta, Georgia and I'm dropping off the injectors tomorrow to have them cleaned and flow measured, etc. I can't wait to get them back in there to see how they work. Any good tips on the reinstall? Do I really need new o-rings, etc?
Good luck WilldsViFfeR. I don't know much about bike mechanics but I live in Atlanta as well. When you get your bike back together, holla and maybe we can hit the mountains or at least the twisties in Vinings LOL
[image: View Post]WildsViFfeR, on 16 June 2011 - 10:05 PM, said:
Alright. The injectors are out...as is a lot of spilled fuel. I should've drained the tank first...doh!
Kal, I Googled "vfr800 injectors cleaning" on my phone, and somehow your YouTube videos popped up in the results, so I got to see what to do and hear you live. Ain't technology great? When its working, that is.
I found a place called "fuel injector connection" near where I live in Atlanta, Georgia and I'm dropping off the injectors tomorrow to have them cleaned and flow measured, etc. I can't wait to get them back in there to see how they work. Any good tips on the reinstall? Do I really need new o-rings, etc?
New O-rings are a good idea, considering the fuel rail is at 36psi of pressure. The injector cleaner guys should give you new O-Rings with the cleaned injectors. At least the blokes I used did. The big fat ring at the top is the "dust seal" and you can re-use that without too many problems, but the smaller O-rings where the injector connects to the fuel rail I would replace if possible. The lower O-ring where it sits in the throttle bodies you can also re-use as long as it's vacuum tight.
As for tips on re-install, make sure you've definitely got a tank of good fuel. I'd recommend draining the tank, putting a cup of denatured alcohol in it (also called methylated spirits) and shaking it around, then draining it again. This should soak up any water that may be in it.
Essentially we're asking ourselves why the injectors went bad in the first place? With only 11,000 miles on the odometer, the most likely answer is that the fuel went bad and gummed up the injectors, or the fuel had water in it and rusted the injectors. Water will pass through your fuel filter, so that's why I suggest giving the fuel tank a good clean with the denatured alcohol.
The alcohol will absorb the water, and then the combined alcohol/water will mix into the fuel. This means that it will be safely consumed by the engine rather than sit around in blobs.
Interesting way to clean the injectors. With my expertise I'd certainly fry the injector or something. The place here does it for $60 for all 4. My thought is if I go through all the trouble to pop those suckers out, I better make sure they're as clean as possible before I put them back in. It must be more thorough to do the ultrasonic / disassembly / flow rate testing too.
Good call on the methylated spirits to clean out the tank.
I was wondering how the injectors could have gotten gummed up myself. The only thing I did different than any time before is I parked it at the end of my driveway with a full cover over it for 10 to 14 days in the hot sun (90+ F degrees ambient temp). I didn't ride it at all and after that is when the problem cropped up. Probably coincidence and no correlation to my problem. It's always been garage kept it's whole life. Perhaps the daytime heat and cool of the night caused some fuel to gum up over that time while I didn't touch it. (?) I'll try to run the seafoam stuff in it a little more regularly now. Maybe even do it every tank?
The injectors are supposed to be done Monday and then they go back in with fingers crossed.
BTW, these were the intake tract photos:
Intake valves on cylinder 2 showing carbon buildup, but dry:
[image: Attached Image: VFR800 intake cyl 2.jpg]
Intake cyl 4 showing fuel:
[image: Attached Image: VFR800 intake cyl 4.jpg]
No need to run Seafoam every tank, but using that or anything labelled "upper cylinder lubricant" will be needed next tank or so to burn off the carbon on those valves, and most likely your piston crowns too. I would recommend just a regular tank of gas immediately after getting your injectors cleaned to set a baseline of how the bike feels.
Honestly, I think the bike just has dirty injectors simply because it's over 8 years old with only 11,000 miles on it. It needs to be run more regularly, and stored with fuel stabiliser in winter. When you pour that stuff into your tank, you should run the engine for 5 minutes so that the stabilised fuel ends up in the fuel rail and in the injectors, otherwise the fuel in the tank will be great but the stuff in the rails will be varnish!
If you took a long, thin piece of clear vinyl tubing and snaked it down your throttle bodies, just above the valves, you could spray some of that carb cleaner down onto the tops of all 16 valves and let it sit for a few hours, then turn the engine over a few times with the starter, being sure the FI fuse is pulled.
Although with your fuel tank removed, and the fuel pump unplugged and far away from the bike, that last bit's probably a non-issue.
Or maybe use the seafoam in the same manner instead of carb cleaner?
Interesting video on the DIY injector cleaning. Wouldn't do a damn for the flow matching side of things, but it's probably a decent farmer-fix for plugged injectors on one's cheap old car or something like that.
One other question that's popped up since I have the airbox off. I labeled the velocity stacks when I took them off and turns out the front are both short and the back ones are long. I saw another thread where the person was having issues with the bike hesitating while on the freeway. Turns out when he changed the stacks around to stagger them the problem was gone. I don't remember what made him think of changing that. My bike does that on the freeway. Since I'm not the original owner I'm wondering if perhaps the bike had been messed with before and that's why it has that hesitation. So I'm wondering what others with 02 MY have; staggered or same length stacks on each bank of cylinders?
Another little observation. In examining the injectors I counted what appeared to my 43 year old eyes to be 12 injector holes. Isn't an 02 supposed to have just 6 little holes at the end of the injector?
If it were me, I'd wait until after seeing how the bike runs with the cleaned injectors. Change too many things at once, and it'll be difficult to pinpoint what fixed the problem.
[image: View Post]WildsViFfeR, on 21 June 2011 - 10:54 AM, said:
One other question that's popped up since I have the airbox off. I labeled the velocity stacks when I took them off and turns out the front are both short and the back ones are long. I saw another thread where the person was having issues with the bike hesitating while on the freeway. Turns out when he changed the stacks around to stagger them the problem was gone. I don't remember what made him think of changing that. My bike does that on the freeway. Since I'm not the original owner I'm wondering if perhaps the bike had been messed with before and that's why it has that hesitation. So I'm wondering what others with 02 MY have; staggered or same length stacks on each bank of cylinders?
Another little observation. In examining the injectors I counted what appeared to my 43 year old eyes to be 12 injector holes. Isn't an 02 supposed to have just 6 little holes at the end of the injector?
[image: View Post]WildsViFfeR, on 21 June 2011 - 10:54 AM, said:
So I'm wondering what others with 02 MY have; staggered or same length stacks on each bank of cylinders?
Staggered is correct. Can't remember where short/long goes off the top of my head but both banks (front and back) need to have one short and one long.
Intake stack length essentially changes where your best torque is in the rev range. For example the new Crossrunner 800 has longer intake stakes for better torque in the midrange, sacrificing some from higher rpms. Tunable intake length is done in lots of places including cars, and even in our 6th-gen VFRs the flapper valve is essentially trying to do a similar thing but across the whole airbox.
I do seem to recall there are some bikes out there with servo controlled intake stacks which raise and lower as the revs change. Can anyone remember which bike(s) they are?
Oh and if you ever decide you'd like to work out a better intake stake length for better power, save your money and time and buy a supercharger! Once you start forcing air into the engine, all this techno-waffle about air velocities goes out the window. :-)
End of thread · 30 posts recoveredWayback Machine snapshot 14 Jul 2011