wild foamy Posted May 18, 2009 Author Share Posted May 18, 2009 i doubt its running lean at less than full throttle, if i am coasting to a stop or down a hill and drop the throttle back to about half/quarter the bike will sometimes bog down and only after returning the bike to WOT will it clear out and begin to fire again, it also has a tendancy to fourstroke at less than full throttle. surely raising the needle would make this worse? Link to comment Share on other sites More sharing options...
Moderator Cynic Posted May 18, 2009 Moderator Share Posted May 18, 2009 i doubt its running lean at less than full throttle, if i am coasting to a stop or down a hill and drop the throttle back to about half/quarter the bike will sometimes bog down and only after returning the bike to WOT will it clear out and begin to fire again, it also has a tendancy to fourstroke at less than full throttle. surely raising the needle would make this worse? Isn't this fun. So what it looks like is the bike is lean at full power but richens up on part throttle. Do you have one of the fancy open filters or a performance filter in the original housing. Link to comment Share on other sites More sharing options...
wild foamy Posted May 18, 2009 Author Share Posted May 18, 2009 nothing fancy, just a chrome K&N style filter instead of the original air filter. Link to comment Share on other sites More sharing options...
Moderator Cynic Posted May 18, 2009 Moderator Share Posted May 18, 2009 nothing fancy, just a chrome K&N style filter instead of the original air filter. That might be the issue, they are only any good for flat out wide open throttle, on my DT years back i got the best results with a sports element inside the std housing with a few 'extra' holes in the dirty side of the housing. It don't sound as fast but the engine worked better. TTs tuned my suzuki, got it up to around 90bhp (pretty good for something that starts with 74) and they kept the original airbox. They will only remove it on express orders from the customer as VERY few bikes work better on the road without one. Link to comment Share on other sites More sharing options...
JimR Posted May 18, 2009 Share Posted May 18, 2009 nothing fancy, just a chrome K&N style filter instead of the original air filter. Don't forget to check for water in the float bowl using K&N type filters will allow the ingress of water to the carb, which the runs down the jet needle into the float chamber and produces the noted problems. so adjustments to a bike that was running correctly (jet & clip position change) means that the bike may not run correctly until it is returned to how it was. As this bike has a CDI fitted this then brings in another point the pulse coil on 50cc Yamahas of that era played up a bit (through dry joints & the coil itself going ape) When the coil lost spec the ignition timming went out the window and the bike would run like a c/b points system with the condensor nacked .... older people may remember that .. the dry joint used to create the same problem and also a total loss of spark. So I guess just return the bike back to a known good point (this sounds like microsoft windows ?) and adjust one thing at a time. Regards Jim Link to comment Share on other sites More sharing options...
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