dying at stop, but it's not the valves By OMN (Read 920 times)

[OMN]

hello again, all! well here's another chapter in the saga...

MC-45B; just replaced fuel pump. while running, fuel is now pulsing well, to the point where it fills up the clear fuel filter i have inline just a couple inches from the carb.

on the center stand, scoot will fire right up, idle well. "goose" it, it returns to a strong idle; rev it then hit the rear brake, the engine immediately slows but recovers just fine.

but it still stalls and dies every time i stop! it will even die while i'm rolling but just let all the way off the gas.

i've set the idle while on the center stand and warm; it's around 1800rpm.

here's what's weird: if i start the scoot on the center stand, it idles great. i throw a leg over and sit down, and it idles great. i roll forward to drop the center stand, and the idle drops 200-300rpm. i lean it over on the side stand, it dies.

(this isn't a side stand kill switch thing, btw - it normally runs while the side stand is down...)

any ideas? i've adjusted the valves only a few hundred miles back. i re-adjusted the exhaust tonight to .005 inches (it was very loose, about .012).

could i have a stuck variator maybe? any other thoughts?

thanks mucho!
ron

[alleyoop]

I believe it is one of two things, a bare wire grounding out when you move it or your Carb bowl is not filling up to the proper level and when on its side the gas level drops below the pilot jet.

So start it up and first thing I would do is wiggle some wire around by the carb the ENRICHER wires and any wires you see near the carb and see if it dies. If nothing then loosen the clamp by the intake a little not a lot then twist the carb a little to the side stand side and see if it dies. If it dies then pull the carb off and adjust the float.
Alleyoop

[justbuggin2]

Alley cover it perrty good one other thing is to make sure the carb is level it self if it is twistedout of level it can cause problems

[OMN]

good ideas - i'll try those. thanks!!

[OMN]

i may just be missing it, but what is the proper float height on these things?
thanks
ron

[OMN]

found it elsewhere... for now, i'm using the clear hose trick and eyeballing it. would you believe it was actually flooding? probably never had the problem with the old/weak fuel pump. gotta run to some school programs, but will finish tweaking tonight. it's definitely improved, but i'm not quite there yet.

i'll keep the board posted. accumulated knowledge is helpful!
ron

oh also, here is a link to the tuning and adjustment procedures from Mikuni: .mikuni.com/pdf/hsr_tuningmanual_021003.pdf" rel="nofollow" target="_blank">.mikuni.com/pdf/hsr_tuningmanual_021003.pdf

[alleyoop]

Look at the picture I put up it tells you 18mm +-2mm, Just make sure the float is level up and down while holding it sideways like in the picture and that it is touching the pin and with a little gentle push it closes the FUEL INLET.
Alleyoop

[OMN]

ok got it mostly done. it's running reliably now. still a little bog on throttle, but it's rideable. the float was definitely very high - not sure how long it's been that way, but i assume the old weak fuel pump never got enough gas in there to see there was a problem.

i've got lots of other bike projects to finish up first, but then i'll work on tuning this one better. always something!

thanks, all
ron

[alleyoop]

Little bog all it needs to adjust the FUEL RATIO MIXTURE and it will take the bog out of it.

How you want to adjust the FUEL RATIO MIXTURE OR AIR RATIO MIXTURE depending of the type of carb you have on it is to GET THE HIGHEST IDLE AFTER IT IS NICE AND WARM at least 5 minutes of idling so the ENRICHER cuts off the extra fuel.
Alleyoop