My bike has been giving me hell, with no power at about 5k RPM. Didn't matter what gear, although in 1st it would occur later in the rpms. At about 5k rpm it'd sometime act like it was stalling, dropping speed till I downshifted or jerking back up to where it was. Only to drop again. A friend following me back from NJ said it looked like I was back on a horse in TX with all the bucking.

Final reason: Bike was starved for air at high speed
Final cause: air control valve (aka solenoid) is not functioning.

Steps to reach this conclusion:

1. Cleaned the carbs twice
2. Replaced non-functioning fuel pump
3. Replaced clogged fuel filter
4. Re-jetted bike for aftermarket exhaust + K & N air filter
5. Adjusted pilot screws according to jet kit's instructions

All of the above improved performance in some way but the flat spot remained. Included in the Dynojet Stage 1 kit were instructions on how to bypass the solenoid for race purposes. Just did that and went for a trip around the block a few times... A very, very quick and powerful trip.

Flat spot = gone.

Thanks to everyone that helped through all this with instructions, suggestions and theories. Waaay to many to list tho JohnnyX and Dissevered a big up there.

 

damn dude, im happy for you. i've been following all your posts about your issue with the flatspot. i've been waiting for you to post what it finally was! congratulations.

on a side note... why was the solenoid causing this problem?

 

The speedo is out for some reason. I'm faaaar too tired of all these issues to figure out why right now. But tracing the electrical path in the manual, the air solenoid is connected to the speedometer via a relay. My guess is fixing the speedo will fix the solenoid (or narrow it down to the solenoid or relay)

 

Nice dude!
Glad to hear you finally fixed it. While I'm pretty sure my solenoid functions, I'd be really curious to see what kind of a difference it makes going from a functioning solenoid to a bypassed system.

I wonder if bypassing the solenoid altogether would actually increase performance..

 

From what I understand, it shouldn't affect performance bypassing the solenoid.

The solenoid is supposed to switch air flow from the tiny intakes to the ram duct at XX mph (some debate whether it's 12 mph or 30 mph). So if yours is functioning correctly, you're getting the duct's air at the right speed.

 

generally if you jetted the bike, you should ground the solenoid so its always open.

 

Hey Johnny,

How tough is it ground the solenoid? I am stuck in ND and with the winter coming I'm doing a tear down to the frame and figured while I was in there...

Thanks!

 

I just sent this to Johnny on how to bypass and remove the solenoid.
hardest part: removing the tank

 

Thanks Kuroshio, you're too good. I printed out the schematic and will definitely be doing this during the cold months!

I don't think I've spent much time below 12mph since my license test.

 

thanks for that kuro