What would cause hesitation at 10,000 rpm
 

OK -- I think this'll solve the last series of my problems.

My bike accelerates great up until 9-10k rpm, at which the bike really hesitates, almost like no fuel.

I've replaced the following parts in the past 3 months:
FPR (hose wasn't wet, but still replaced)
Fuel Pump
Fuel filter
Battery
Stator
R/R
spark plugs are clean and correctly gapped

I pull the codes and I get nothing.

Bike is an '02 F4i, about 20k miles.

Thoughts?

Thanks.

how old are the spark plugs? I'd start by replacing those. Also, have you replaced the air filter?

How did the fuel pump look? Do you have any rust in your tank? I've seen bikes that idle and run great all day, but the fuel pump gets clogged up with rust and causes the bike to bog at high rpm. There is a fuel pump volume test that I would highly recommend you do.

Thanks for the reply:

Spark plugs are less than 2000 miles. No signs of wear . But I suppose its worth a shot.
Air filter, I haven't cleaned out, I will do that.

Old fuel pump looked fine. What prompted me to do change it out was the pitch of the pump whine changed. I figured the motor was going bad. But this new one sounds the same. No rust in the tank period. But if the old pump motor whined, and the new pump whined, probably not the pump. Will have to do a volume test.

Thanks

-John
BT

Are you running the stock exhaust, air filter or does the bike have other mods? Maybe a remap is needed...

Unless it's a K&N, don't clean the air filter, trash it.

Thanks for the replies guys,

I've had the bike for about 15K miles. Never had a problem with the bike until a few months ago when I started having battery / charging problems. Since then I've basically been replacing all of these components with no success.

The air filter IS a K&N that I put in at approximately 10K miles. Hasn't been cleaned since. As stated, I will clean it. There was an aftermarket pipe on the bike when I bought it, but as I said, I only started to have problems recently.

This hesitation is only under load. The bike can be in neutral and I the tach easily goes beyond 10K without hesitation. I'm trying to determine that the hesitation occurs in any gear. So far, 1st and 2nd gear exhibit the problem (meaning I don't believe its a transmission problem). Will confirm with 3rd gear.

Will also conduct a pressure test for the fuel pump.

A faulty coil can cause these issues. Pull them and measure the resistance across the leads on them. I'm not sure what the specs are, but a service manual will have the specs. That would be my first check.

Also, since you replaced the RR and stator, what did the plug connectors look like? if they were melted, discolored or corroded, it could cause issues at higher rpms. The higher your rpms, the more load on the electrical system, and if it can't keep up, the spark gets weak and you can get hesitation.

Also, you may want to look into the fuel pressure regulator. Pull the vaccum line off and see if there is any sign of gas. If there is any at all, change the FPR.

FPR was the first thing I thought, and had replaced it (its the first item on my list) As noted, the one hose was not wet, but i still replaced it as a cautionary measure.

Stator/RR plug and wires were in perfect condition. No sign of burned insulation, bent pins, corroded pins, melted plastic, or broken connections. Since both sides of that connection were replaced at the same time -- the RR and the Stator, the connection should be perfect now. Correct resistances and voltages are measured when the bike is off and running/revving.


I will consult the manual for coil resistances.

Do you have a power commander on the bike? If so, the charging system issues may have altered the settings. You may also want to try and re-map it just in case.

no power commander on this bike.