Bonneville America Forums Forums Technical Forums General Tech Need Help! Losing Power

My bike is a 06 TBA with 790cc engine. Starts good, runs smooth. I'm having some loss of power at mid to higher rpm ranges, poor acceleration, and the rev limit is now kicking in at a higher rev than it normally should. Any ideas anybody?

I've been having something similar -- I'm guessing for mine, anyway, it's the "hidden fuel filter."

Go to "Tech Corner" and snoop around in the "Carbs and Fuel" thread in "Known Problems."

--Jaeger

Yeah that could be just losing gas up high... Tech Vault is a good bet, there's info on that fuel filter there. Wouldn't be aweful to drop the bowls on the carbs and make sure there isn't gunk in there.

Did you buy it after April, meaning is it on warranty still?

Could also be ignition coil starting to go bad.

I've replaced the coils with Nology coils over a year ago. I recently replaced the plug wires with Nology hot wires. Had changed to thruxton needles several months ago which affected fuel economy but boosted performance. Recently went to stock pipes which resulted in some power loss. Changed needles back to stock to improve fuel economy. At that time power loss was more significant. Related that to stock needles. Went back to open pipes (modified stock slashcuts) but power loss issues are not affected. Except for the rev limit issue, I lean toward fuel/carb issues due to the fact that the most power loss seems to coincide with the rollback to stock needles. It is possible that I have a leaky or damaged diaphram. What do you think?

If coils could be going bad could that affect rev limit increase?

CDI and coils are directly related to RPM. If it runs fine to a certain RPM then breaks down that worries me a bit. So play with it and figure if its throttle position or RPM. If it throttle position then of course you have a carb issue.

Good luck

Uncle Phil lost a Nology coil last year around mid summer. Have you put the original coils back in play to eliminate the Nologys?

losing power at a higher RPM can also be fuel, the faster the engine turns the more fuel it needs to do so. If the filter has a partial blockage it can cause a higher RPM loss of power/cut out. Not saying that is the issue but start with easy/cheaper fix first.

Okay guys. Thanks for all your input. Sat. morn. Since I had recently change my needles back to stock I decided the first place to look was my carbs. I pulled the cap off the right one and the diaphram was seated nicely. I pulled the cap off the left one and it was not seated. Since I do this with the tank on, I was having some difficulty with the seal on the diaphram. I got some vaseline and put some in the groove on top of the carb to help hold the seal in place. That worked well and I got the carb back together. I left to go to a local event and she was running liked a scaulded dawg. A few miles down the road and I remember that I had left a hose off that connects the two carbs at the rear. I don't know what that hose is for, but if any of you know, let me know. I stopped on the side of the road and reconnected that hose with the engine running. Something clunked and it started running rough. I thought it may have thrown something out of balance and that it might settle out so I decided to continue on my way. Another 8 miles and still the same. I stopped and tried adjusting the air screw with no success. I blew off the event and went back home and tore my bike down and removed the carbs. The slide on the left carb was stuck fully open. I think the vaseline heating and oozing had something to do with that. I took the cap off the carb and cleaned the vaseline off the carb and diaphram with rubbing alcohol. I put it back together set my carbs air screws to 3 turns with the carbs off. I put my quite pipes back on and went for a ride and she is running very strong. So all is well here. I think the next time I plan to work on my carbs I'll plan on removing my tank or rasing it up at least. I pulled out that hidden filter while I had the carbs off. That wasn't the culprit but I got an inline filter from the parts store. That will be a better filter anyway.