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Discussion Starter · #1 ·
I'm hoping you guys can help me with this problem we've been having.

I have an '08 KFX at a local engine builder. Out of fairness to him, I won't mention his name. He is my friend and a good, reputable builder who builds pro and pro am motors for national level bikes. I took my bike to him, and we had plans to build a healthy stock bore motor to run the TT nationals with. Well, the bike is done, but has "issues", and the engine builder is just frustrated as hell with it, and I'm frustrated because we can't use the bike.

Here's the mods I know of:
*high compression piston
*intake and exhaust cams
*ported head
*power commander
*HMF full exhaust
*Fuel ATV intake w/ K&N filter
I don't know the specs of the piston or the cams

The bike will run and run GREAT. It makes awesome horsepower and torque #'s, and has a very nice and linear power curve. The problem is that it will just all of a sudden lean itself out. Not just a little either, I'm talking full on with the glowing pipe, POP POP POP, etc. It's not a power commander issue because we've replaced it 3 times. We've replaced the fuel pump as well when we replaced the fuel tank for the factory recall. We have the computer at a company that builds diesel truck programmers (superchips) to see if the issue is in there. Have any of you experienced anything like this? Any thoughts?

Also, I've watched Creamer blow a crank, and heard he blew another one within the same month. I've also been told that Frank Batista has blown up several as well? I've been hearing the stock bottom end can not handle high compression,. I guess if we ever get this thing running right, and like it, we'll tear it down and put a Falicon crank, rod, etc in. Anyone else heard this or have any thoughts on this as well?

Thanks for any help you guys can provide.
 

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Get some deelectric spray and spray all the connections and clean out your injector its one screw to take it off. Its common that gets dirty. thats the best thing i can tell ya
 

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When does it happen? after it gets hot? does this happen after 4min of run time? TPS has been checked? down sensor glued? Look for intake air leaks, take a can of starting fluid and carefully spray around the intake boot where it meets with the head while the bike is idling, you can check other areas as well, the quad will rev up if there is one. It sounds like an air leak or fuel delivery problem.
Is the quad running lean at low rpm or just at very high revs? coming of the gas at high rpm? Will the motor bog or sneez then rev up when you snap the trottle open? give us some more info please.

Moto1
 

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Discussion Starter · #5 ·
QUOTE (moto1 @ Feb 16 2008, 08:45 PM) index.php?act=findpost&pid=6555
When does it happen? after it gets hot? does this happen after 4min of run time? TPS has been checked? down sensor glued? Look for intake air leaks, take a can of starting fluid and carefully spray around the intake boot where it meets with the head while the bike is idling, you can check other areas as well, the quad will rev up if there is one. It sounds like an air leak or fuel delivery problem.
Is the quad running lean at low rpm or just at very high revs? coming of the gas at high rpm? Will the motor bog or sneez then rev up when you snap the trottle open? give us some more info please.

Moto1
The engine builder is at the Indy show. When he gets back, I will get more detailed info. Thank You.
 

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Discussion Starter · #7 ·
OK, the engine builder is still out of town, but my friend who rode the bike and watched its runs on the dyno gave me a little more info.
The bike will be on the dyno, running fine for a couple of pulls, and without warning and for no apparent reason, it will just lean itself out. It doesn't do it every time either. For example- One day he made several pulls with no problems while tuning it. It was getting warm, so he had plans to do power pulls the next morning. The next morning on it's second pull it just leaned out. It's a pain in the azz.
 
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