Yamaha 1987 FZ 750

[roofman72]

Yamaha 1987 FZ 750 possible ignition problems. runs great when it is cold. when it warms up the bike developes a mid throttle bog. the carbs,charging system and plugs have been replaced or rebuilt by a quality yamaha mech. the clymer book says the chances are greater that it is a ignition problem. the bike has less than 27000 KMS and runs vary fast. but its hard to drive at low RPMS. Any insite would be greatful.

[Easy Rider]

Originally Posted by roofman72

Yamaha 1987 FZ 750 possible ignition problems. runs great when it is cold. when it warms up the bike developes a mid throttle bog. .

An electrical problem causing poor running ONLY at mid-range RPM....not to likely, I think.

Unless......it is old enough to have a "conventional" ignition with a mechanical advance mechanism that might be sticky or have weak springs.

What does your "qualified" mechanic say ???

[Aussie Steve]

Possible electrical fault with the coils is my guess.

[87gsxrnut]

Yeah, coils would be a good bet.

- Nut

[Aussie Steve]

Had another thought! Could be carbs....is the float level OK?....best way to check if its running way too rich mid range is to do a plug chop...run the bike at mid range...ignore the bogging... for a couple of miles and then cut the engine using the kill switch and coast to a stop with the clutch pulled in. Try to end the trip close to home so you can remove the plugs....on mine and on most others removal of the tank is necessary ergo close to home.

Major PITA I know and for this very reason I have a small mower fuel tank I can set up on my bike/s so if I choose to do a plug chop I can do it at the side of the road......watch out for hot plugs!!!!