Bonneville America Forums Forums Technical Forums Performance Mods Need sugestions

Hoped this would go away with a carb tear down but it didn't same as in the fall . Out for a ride last night Temperature aprox 12c fresh gas in the tank. Ride for about 20 minutes in the city then out to the country roads running fine then notice missing and small back fire when bike is leaned to the left smooths out and power back when you lean it to the right runs ok when bike is straight up. Another 10 mile cruising at about 4000rpm starts to missfire and looses power hard to maintain speed full throttle catches it but as soon as I drop back on the throttle the missfiring resumes. Only happens at higher speed 40mph or over fine at city speeds no missing at all.


My head says Float bowl issues with low pressure issue causing problems with the levels at highway speeds and perhaps a change of airflow over the motor explaining the fact it will running better in a right hand corner than a left. Even when it is missfiring so bad I can't hold a steady speed it seems to run slightly better leaned to the right

AI removed air box removed K & Ns Home made freak tor short stock 45/ 150 jets stock needles 1 shim

I just hate to drop this of at Echo cycle with an intermitant problem that takes a half hour ride to produce I think that is just asking for abuse of the wallet with no results.

Is there a chance this could be an igniter with thermal issues that change with air speed over the module once it warms up?

Anyone around Edmonton with a bit of savey


I just want to ride with out wondering if I am going to get home.

i had the same problem with my bike and it turned out to be the hidden gas filter inside the tube connecting the carbs.

Almost certainly a fuel flow problem. There is a small screen in the T fitting between the carbs where the fuel line attaches and another screen in the tank attached to the control valve. Pull the hose to get at the one in the T fitting, pull the control valve (petcock) to get to the one in the tank.
Also, there is a possibility that the tank vent/overflow hose is pinched or the rollover valve in that hose is partly closed. To test for this, with no more than 1/2 tank of gas, ride untill it acts up and loosen the filler cap. If the problem goes away, the hose or valve are at fault.

Check fuel flow to the carb, float level and flow into the carb bowl would be the best place to start. Try running the bike with the gas cap loose for venting problems. Going to Echo is going to cost you.

Will cover a few with one here . inline filter at T removed , vent line not an issue because it happens with the gas cap loose. Good flow from tank yet it does seem to be leaning out yet it will accelerate when I crank it. Can anyone offer any that could explain the left and right lean issue.

Left or right lean sounds like it might well be a float height issue, easy enough to check: with a length of clear tube attached to the bowl drain and the open end well above the carb open the drain and check the fuel level. It should be around 1/8" (more or less) below the seam...any wild differences would be readily apparent. My guess: chances are the left float is way too low...

Checked them before and no issue but checked them again and right side was high droped it down and went for another test ride.... guess what the side to side carboration problem is gone and I was hoping it solved all my problems ....but nope on the highway coming home it started to cut out and lose power after extended cruising at about 4000rpm feels like the it does when you hit the rpm limiter . I have no problems under full throttle just when I try to maintain highway speed.



Think I have an ignition problem wish there was some way to monitor spark while you are going down the road.

Could be the ignighter ( my guess) or bad coils maybe

Have you checked your plugs? Try putting in a new set of plugs, they're cheap.

Changed out the plugs last year.... no change

Anyone know where I can pick up a cheap "Working" igniter

Well wanted to wait for a second test ride before posting but time and rain have delayed it again.

EUREKA! I might have found the solution to my problem. Such a simple fix it makes me want to laugh. out on a ride a couple of days ago there was a bit of a wind blowing and I noticed that my intermitant cut out was occurring at a much lower speed when the gusts hit me from the side and I was convinced airflow over the engine components was factor in my problems.

Wel I stopped at the side of the road and pulled the float bowl vent tube out of the normal place where it drops out the the bottom of the bike and routed it out the side and down ( it actually dumps right on top of my right side pipe right now which I will have to change )


It worked! Smooth riding no more cutting out.

It seems that airflow along the bottom of the bike must have been resulting in either positive or negative pressure in the float bowl air spaces which would effect fuel delivery. Differing airflows when I banked the bike left or right could turn it on and off.

I think cutting a V into the bottom of this tube might be enough to stop the air flow causing an issue.

Thanks to all that made suggestions.

Got in another ride later and once again it ran like it was supposed to .....yee hah. I can just imagine how much this might have cost me had I droppped it off at the dealer as it would have never showed up on the dyno with no wind to cause it.