HeadSmess
Well-Known Member
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- Joined
- May 17, 2010
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- 3,048
youll find drills at an engineers supply, and take your wallet with you 
youll want 0.6 mm to 0.7mm usually in 0.05 increments... and a micro chuck.
solder, an iron, or torch.
screwdriver, new plug, plug spanner.
start by soldering up jet. be careful not to over fill it (the size of the CAVITY in the jet is also critical...for other reasons.)
now carfeully redrill the jet with the 0.6 drill.
(find someone with a lathe, or buy a few spare drills...)
reassemble carb, check that the clip on the needle is in the middle notch.
go for a spin... you may need a bit of choke now...
once its warmish, open throttle wide.
if it dies. its too lean, redrill the jet to 0.65....
if it goes hard....thats about it
then try raising the clip on the needle one notch (leaner mids)
better? try the next notch! if the clip runs best on the top notch, you could go smaller on the jet drill, then put clip back in the middle.
if it gets worse, then try lowering the clip this time. if you need to go to the lowest notch, the jet is too small, go up a size.
then with the new plug, go for a ride. kill the IGNITION with the throttle held in the area you want to check... usually just wide open BUT DO NOT LET IT IDLE! you have to kill the spark.
you want tan/brown. white is too lean. black is use less oil and too rich...
keep it just on the side of rich
etc etc.
its possible to do the low mid/idle mixture, and also "fuel enrichment" when opening the throttle, even on these basic carbs. but im not going to explain them here theyre irrelevant for this application.
your aiming for a fairly smooth progressive acceleration, no flat spots.
youll want 0.6 mm to 0.7mm usually in 0.05 increments... and a micro chuck.
solder, an iron, or torch.
screwdriver, new plug, plug spanner.
start by soldering up jet. be careful not to over fill it (the size of the CAVITY in the jet is also critical...for other reasons.)
now carfeully redrill the jet with the 0.6 drill.
(find someone with a lathe, or buy a few spare drills...)
reassemble carb, check that the clip on the needle is in the middle notch.
go for a spin... you may need a bit of choke now...
once its warmish, open throttle wide.
if it dies. its too lean, redrill the jet to 0.65....
if it goes hard....thats about it
then try raising the clip on the needle one notch
(leaner mids)better? try the next notch! if the clip runs best on the top notch, you could go smaller on the jet drill, then put clip back in the middle.
if it gets worse, then try lowering the clip this time. if you need to go to the lowest notch, the jet is too small, go up a size.
then with the new plug, go for a ride. kill the IGNITION with the throttle held in the area you want to check... usually just wide open
BUT DO NOT LET IT IDLE! you have to kill the spark.you want tan/brown. white is too lean. black is use less oil and too rich...
keep it just on the side of rich
etc etc.
its possible to do the low mid/idle mixture, and also "fuel enrichment" when opening the throttle, even on these basic carbs. but im not going to explain them here
theyre irrelevant for this application.your aiming for a fairly smooth progressive acceleration, no flat spots.
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