cruising speed trouble

[Anonymous]

:mrgreen: hi all this is my first time on this site, i've had a gs75e for the last 7yrs with little or no trouble then last yr it started to lose a bit of power at the 60mph mark, i blew the carbs and checked the fuel line and petcock to no avail it gradually got worse then i changed the rectifier this worked for a while but it overcharged the battery then the statar went so i replaced the statar (UK job) and new rectifier and new battery . went like a dream for the first week now its back to where i was at the beginning ie when you get to cruising speed its like being caught in the odd gust of heavy wind , its really frustrating.great site only found it this week,appreciate any reply.

[SqDancerLynn1]

Try running with the petcock on prime, check the gas cap vent

[Poot]

although im not that knowledgeable, i'll give some suggestions until someone can pipe inwith something more informed.


check the fuel filter, and the screen going to the petcock. Also, your air filter may be really dirty....

and by blowing, do you mean cleaning the carbs? If you didn't disassemble the carbs when you cleaned them , the needles could be a bit gummed up.


I know that the valve clearance on GS bikes is very important, but I don't know if it would cause this (although another possible option)

thats a lot of things, I know, but hopefully an idea will pop into your head.

[Anonymous]

thanks for the really quick replies unfortunatly i'm working nights at the moment so i'll not be able to try anything until to-morrow

[argonsagas]

A weak coil could cause those symptoms, but it would not be limited to cruising speed, and would not improve when you changed other electrical items, such as R/R and/or stator, unless you did not have sufficient voltage. You said the system was overcharging, so that idea goes away.


A condensor will also cause such things, but only under load, and it should run almost normally with no load. It would also happen without regard to the speed of the vehicle...just load.

I have no experience with the ignitors on these bikes, and do not know their exact symptoms.


Now, after that little logic trip, we are back to the fuel....and that is where I would start. If you have a poor gas cap vent, then the bike will run normally when first started, but, as the fuel level drops, the bike will reach the point where it poops out, and will only begin to work well if you take a break.

This break gives the air a chance to get in, and the bike will again run fine.

A partially blocked fuel line or filter can also do the same, since you seem to have the problem only when at sustained highway speeds, and there is a higher draw of fuel than at low speeds.

Additional point is the fuel petcock....if your bike has a vacuum line from the carbs to the petcock, it could be getting bent or blocked, thus causing the petcock to close, at least part of the time.

These are all fairly easy to check, but my first thoughts would be the fuel cap or the vacuum hose.