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  (#1)
boxing twins
 
hayabusafiend's Avatar
 
Posts: 581
Join Date: April 6, 2003
Location: Northern California
May 27, 2003, 01:28 PM

I've got an occasional misfire on my '00 Hayabusa that I have been unable to solve. I need the help of some other brains to nail this one.

Here's what I've got:
- 2000 Hayabusa
- stock exhaust
- K&N air filter
- Power Commander II (easily taken out of the fuel injection & ignition loop)
- an erratic, partial misfire at 1,000 - 2,500 RPM (thump, thump, thump, *stumble*, thump, *stumble*)

Here's what I know:
- misfire started at around 7,000 miles (I've now got 15,000)
- I changed spark plugs at 13,000 miles [the plugs were PERFECT]
- The misfire occurs whether or not the PCII is connected
- the misfire almost never occurs when the bike is cold
- ZERO fuel injections codes
- almost never misfires when the engine is cold.
- Unknown whether the misfire occurs at higher RPMs. The engine and transmission inertia smooth out any momentary power loss.
- I've lifted the tank and touched every fuel line to make sure it wasn't twisted or kinked.

Hypothesis:
1) Ignition is likely good because all the plugs are perfect. If one plug had a partial spark, it would eventually get fuel and oil fouled. They were a perfect light tan. Hell, I think I''ve still got the plugs.
2) 1999 Hayabusas had problems with one or more of their THREE paper fuel filters coming apart and getting pumped into the fuel rail.
3) 1999 Hayabusas had problems with their copper fuel screens getting clogged
4) I doubt it is the fuel pump since it would have completely failed a long time ago and/or the FI would have thrown a code.

My guts tell me periodic fuel starvation. If anyone's got other ideas, I could use the help.

[Edited on 27/5/2003 by hayabusafiend]

[Edited on 17/7/2003 by hayabusafiend]


-- Chris
BMW R1100s
(previous rides: '82 KTM250, '95 CBR600F3, '98 Buell S3T, 2000 Hayabusa, 2008 R1200R)

"Any sufficiently advanced technology is indistinguishable from magic." -- Arthur C. Clarke
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  (#2)
GP Racer
 
speednuts's Avatar
 
Posts: 1,184
Join Date: October 5, 2002
May 27, 2003, 01:37 PM

Call Nick at Champion Motorsports. He's the local dyno guru and can likely tell you the possible culprit and more importantly help you fix it.

Champion Motorsports
Herndon, Va.
703 471 6990

www.championmotorsports.biz

[Edited on 27/5/2003 by speednuts]


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  (#3)
Licensed Rider
 
kwoods's Avatar
 
Posts: 196
Join Date: April 13, 2003
May 27, 2003, 11:12 PM

hmm.....
interesting.


Does it do it at idle?
Can you reproduce it on demand?

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  (#4)
Got my Permit
 
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Posts: 46
Join Date: May 12, 2003
May 27, 2003, 11:43 PM

You might want to try and use a can of C4??? or some injector cleaner. Here is why-
The heat of the motorcycle might cause the gunk to expand causing for a bit of a stumble in the lower RPM's. Just a thought, a cheap fix for a bike that basically is bulletprooff.


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  (#5)
boxing twins
 
hayabusafiend's Avatar
 
Posts: 581
Join Date: April 6, 2003
Location: Northern California
May 29, 2003, 07:27 AM

Quote:
hmm.....
interesting.

Does it do it at idle?
Can you reproduce it on demand?
It stumbles at idle after it is warm. That's the confusing part. If it were a clogged fuel line or injector, it should stumble when cold too.

It does it all the time, about 10 times per minute (randomly of course).


-- Chris
BMW R1100s
(previous rides: '82 KTM250, '95 CBR600F3, '98 Buell S3T, 2000 Hayabusa, 2008 R1200R)

"Any sufficiently advanced technology is indistinguishable from magic." -- Arthur C. Clarke
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  (#6)
boxing twins
 
hayabusafiend's Avatar
 
Posts: 581
Join Date: April 6, 2003
Location: Northern California
May 29, 2003, 07:37 AM

Quote:
You might want to try and use a can of C4??? or some injector cleaner. Here is why-
The heat of the motorcycle might cause the gunk to expand causing for a bit of a stumble in the lower RPM's. Just a thought, a cheap fix for a bike that basically is bulletprooff.
I don't think there's any gunk in the system. Since new, this bike was ridden at least once a week in California , and I always use high-test quality (Exxon, Texaco, etc) gas. When I replaced the spark plugs, I also checked the throttle bodies, and they had very little gas varnish in them.

The stumble arose in California almost arbitrarily. The only event I that even comes close to the right time is California banned MTBE fuel oxygenation, and switched to ethanol/methanol. An occasional misfire I can attribute to alcohol in the fuel, but not a dozen or so a minute.

I'm really hating the idea of tearing apart the fuel lines and injectors.

Crap. I just thought of my throttle position sensor. If the ECU thought I was momentarily (hundredths of a sec) blipping the throttle, the bike could stumble since the ECU would add fuel, but the throttle body butterflies wouldn't be in the idle position, presenting an instant overly rich condition (I think).

Speednuts: Thanks! I'll contact him.


-- Chris
BMW R1100s
(previous rides: '82 KTM250, '95 CBR600F3, '98 Buell S3T, 2000 Hayabusa, 2008 R1200R)

"Any sufficiently advanced technology is indistinguishable from magic." -- Arthur C. Clarke
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  (#7)
AWOL
 
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Posts: 64
Join Date: February 3, 2003
Location: Herndon, VA
May 29, 2003, 10:44 PM

hayabusafiend

If you are close to Herndon just drop-in and we'll have a listen; ignition and fuel misfires have a very different character that is difficult to discribe here. I would doubt fuel blockage since the problem would be far worse at high load and RPM. I suspect two things:

Most likely - one of your coils is failing. This tends to be temperature related (the break down occurs as the coil heats up physically).

Long shot - dirty injector. As deposites build up on the tip of the injector, its ability to atomize the fuel properly is reduced (it tends to dribble rather than spray). This is most critical at low loads at operating temperature when the amount of fuel being delivered is tiny and poor atomization can disturb the mixture most.

Drop me $35 for a 'dyno assessment' and we'll see if we can't pin down the problem.

Call me at the numbers below to let me know



Nick Jennett
Humble Tuner

Lost somewhere in the Universe - back soon
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  (#8)
boxing twins
 
hayabusafiend's Avatar
 
Posts: 581
Join Date: April 6, 2003
Location: Northern California
May 30, 2003, 03:13 PM

Nick,
I see now why you come so highly recommended. Much appreciated. From your previous posts, I'll gladly pay $35 for your expertise. Your shop is only about 5 min from my house. I'll call to set up a dyno run date.

thnx,
Chris


-- Chris
BMW R1100s
(previous rides: '82 KTM250, '95 CBR600F3, '98 Buell S3T, 2000 Hayabusa, 2008 R1200R)

"Any sufficiently advanced technology is indistinguishable from magic." -- Arthur C. Clarke
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  (#9)
boxing twins
 
hayabusafiend's Avatar
 
Posts: 581
Join Date: April 6, 2003
Location: Northern California
July 16, 2003, 11:01 PM

I finally put my hayabusa into dealer mode (using a paperclip to jump the pins in the test connector in the rear cowl) and found the TPS out of adjustment.

I borrowed a torx T-20 security bit (WHY did they use a security bolt?) and adjusted the TPS about 0.1mm. The bike doesn't stumble in neutral at idle or at sustained revs. After a short 1 mile sprint around the neighborhood, the bike is a whole new, less tenacious animal.

I'll post again once I've got a few more test miles.

[Edited on 17/7/2003 by hayabusafiend]


-- Chris
BMW R1100s
(previous rides: '82 KTM250, '95 CBR600F3, '98 Buell S3T, 2000 Hayabusa, 2008 R1200R)

"Any sufficiently advanced technology is indistinguishable from magic." -- Arthur C. Clarke
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  (#10)
boxing twins
 
hayabusafiend's Avatar
 
Posts: 581
Join Date: April 6, 2003
Location: Northern California
October 7, 2003, 09:47 PM

Thought I'd finally close the loop on this one. The TPS was out of adjustment, but the misfire was still there. I disconnected the PCII and inspected all the wires and connectors and put it all back together.
(drum roll please...)
The misfire is gone.

I originally put the PCII on to correct a 2500RPM surge that was just plain pissing me off. I took the PCII off before the maintenance day and rode round-about fashion from Sterling to Winchester with not even a stutter. Guess I didn't have enough miles on the bike to iron out the stumble.

In any case, I'm putting the PCII up for sale. It'll fit 1999 thru 2001 Hayabusa.

I've also got dyno sheets that prove it gave me 5 additional HP on a completely STOCK bike.

Looking for about $225. I'll sell it to a DCSBN member for $200. I'll even burn the new software to CD.


-- Chris
BMW R1100s
(previous rides: '82 KTM250, '95 CBR600F3, '98 Buell S3T, 2000 Hayabusa, 2008 R1200R)

"Any sufficiently advanced technology is indistinguishable from magic." -- Arthur C. Clarke
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