hits rev limiter at 10 grand...Help?

[OB_cbxchris]

I have recently just completed my 00 busa. I never rode it before tearing it down...it only had one easy mile by dealer at prep. I have installed pistons, web cams(536-577),1mm over valves and head work. I`m running short stacks with a airbox like motorhead but no filter. It hits the rev limiter at 10 grand ..any gear...anyone had this problem? I have another busa to swap parts with but would like a little feedback first.It runs great until the rev limiter comes in. Any Ideas??? Could it be the ECM...tach...a sensor?? It does feel like it is not turning enough rpm`s but its hard to tell. HELP?

 

[OB_THE MOTORHEAD]

wow thats a first.sounds like the ecm reads a higher rpm than the tach so you need to find what the difference is from where the ecm reads and the tach reads.

 

[OB_cbxchris]

MH see your board i`m stumped....can`t figure this one out.......I think it may be a fuel problem after all.....

 

[OB_THE MOTORHEAD]

yes me too see my board

 

[OB_cbxchris]

First I`m not worried about the warranty...got a lifelong dealer friend..he`ll cover anything except engine. Compression is 12.7 to 1 (J&E), intake set at 110, exhaust 108,have not altered or checked fuel pump(thats next),pump gas(can not hear any detonation so far), have not checked cranking compression yet(was waiting until around 4-500 miles to recheck valves and change oil for 2nd time). I didn`t anticipate a problem like this. I`ve rode some more today...its the hardest thing to pinpoint I`ve seen lately...sometimes it will die at around 10 grand in second sometimes not..always in third..will tach through to redline in first and occasionally second. What blows my mind is on the slow roll on it won`t do it...it has to be fuel. I replaced all the fuel lines today to eliminate one thing at a time...I guess the screens are next.BTW went to all long stacks and really liked the way it felt...seems smoother,don`t know if it hurt it or not hp wise. If I shift at 10 grand it will go ahead and run out through 5th gear(hard to find a place to top it out here without getting killed or locked up)....puzzling.........forgot I am currently using yosh but have PC I`ve tried almost everthing you can think of...right now +5 +5 +10 idle at 11:45.....MH just sent me some OE maps that I`m going to try. I`m thinking of installing a shift light...I may have a screwed tach who knows...I hate chasing my tail not knowing where to really start...If it was electrical fine I`d start big time digging but I`m not sure what it is....and it appears from plugs and exhaust pipe to be running on the rich side...may have to make a trip to MH and his dyno to finally find this.......I` don`t have the fuel mixture sensors to check properly and no one around here I trust......anyone else want to jump in fill free...I`m all ears....

 

[OB_cbxchris]

Nope, haven`t put one on yet. This bike has only 240 total miles. I was trying to not dog it to death. read the post I sent to MH on his board..I`ve finally decided it must be a fuel starvation problem. MH gave some good advice. Murhy`s law always seems to find me...if its something that never happens it will happen to me. I probably am going the aftermarket fuel pump route. I`ll probably when I get time just check the screens...at 240 miles it would not seem that they would already be stopped up but MH says its common. Frank over a stock bore bike how much would a 3mm piston kit pick one up. I just went with stock bore pistons...I`ve got another cylinder...winter project maybe....BTW this thing has no heating problems at all..

 

[Guest]

Stupid question but, in changing all those engine parts? Would that not void your warranty on your new ride????

 

[Frank Adams]

I don't have any heating problems either.
There are very few honest builders out there but after talking with one I trust the 1390's are getting around 210hp(to the wheel).

I'm really not sure your having a starvation problem.

Answer these questions if you could?

1. How much compression do you have?(12.5,13.1???)
2. When you do a compression check, how much does it show when the bike is cold?
3. What is the centerline of your cams, what are they set at now?
4. How much fuel pressure are you useing with this motor, 143, 148pds?
5. what octane of fuel are you useing?

Now if you do have a starvation problem, try doing the TEST in the shop manual for the fuel pump?

Almost forgot!
6. are you useing the Yosh or Pw2? What settings or map are you useing?(this is important)

 

[Frank Adams]

Chris, I've seen this before... Do you have a airshifter or shift light on your bike yet?

 

[OB_cbxchris]

MH ...just a update.....fuel filters and screens looked great...nothing clogged...checked crank sensor...well within specs.......have you seen any bad tachs?...there`s nothing much left to check...I`ve read and read the manual...and checked all things...installing shift light now....got any more suggestions?

 

[OB_ZXALAN]

CBX, this is just a suggestion but if you put your bike on an EC997a Eddy Current dyno, it will give you accurate RPM readings, it does not hook to your ecm, it mathematically determines RPMS from the elec. brake motor on the dyno. Reads RPMS to the single digit. My tach was 300 rpms too fast. The dyno is also very accurate in determining real, brake horsepower. For example check out my rpm peak reading 156.45hp@9491 rpms. Use the dyno to calibrate your tach while you tune that monster. www.factorypro.com has all info along with a listing of nationwide dyno centers with that dyno. Cool site too!!

 

[OB_THE MOTORHEAD]

any good dyno will give accurete tach readings and thats how i would solve the whole issue.also the eec is available for thedynojets too.the eddie currents systems been around a while.even a good rpm activated swich will tell you.no i have not seen any bad tach.but there is always a first.