Running lean By solymar (Read 906 times)

[solymar]

My bike was running lean which i could tell by my spark plug looking white/newish after I had ran it a while. Before I could up-jet my muffler went bad and I just replaced that with what looks to very similar to oem. Before the muffler change the bike ran fine, just hot really, now with the muffler change I get popping/backfires on deceleration.

My question is should I now go up 1 or 2 jet sizes to have it running ideally?

[solymar]

I should add the bike is a 150cc

[kagetenshi]

I believe the general rule of thumb is two sizes per mod.

[Alleyoop]

Ok you said POPPING/BACKFIRES which is it because each one is a different reason?

If it backfires on deceleration usually means it is leaking by the FLANGE(the exhaust PIPE)where it connects to the motor. Did you put in a new exhaust gasket when you changed the exhaust?

If it is just POPPING on deceleration(IT HAS NOTHING TO DO WITH THE MAIN JET) all that means it is just a little LEAN OR THE IDLE IS TO LOW. You can turn the FUEL RATIO MIXTURE screw about 1/2 counter clockwise.
Alleyoop

scooterdoc.proboards.com/thread/8628/motor-sounds-tells

[solymar]

It mostly pops, but their have been a couple loud ones.

I only changed the muffler and gasket at the muffler. I did not change the pipe from the engine to the muffler. Before the muffler change it wasn't making any noise.
The new mufflerr looks virtually identical to the old one...oem.

Was running lean prior to the muffler change. Spark plug gives that sign, looks white not toasted brown/tan colored as it should.

Before the original muffler went bad, I was gonna up-jet the carb from 112 to 115, but now with the new issue I was thinking I'd need to possibly go up 2 steps for the jet.

Could I still need to change the exhaust gasket at the motor?

Solymar

[Alleyoop]

Well start it up and listen if its leaking there you will hear it and usually you will see black soot around the edges if it is leaking.
If you say it is loud I would suspect that is a Backfire and not a POP, a POP is just that IT SOUNDS LIKE A POP a backfire is just that sounds like a gun went off "POW". TWO different reasons for the cause.

[solymar]

I'll definitely check it out. Thanks for the help Alley, I do appreciate it!


Solymar

[solymar]

Is their anyway of knowing what size the gasket at the flange is without taking it apart? Fyi my bike is a Jonway yy150t-12 150cc 157qmj if it helps


Solymar

[Alleyoop]

These are the best they cover the whole flange not just the center.
Alleyoop

www.denniskirk.com/264745.sku?utm_source=google&utm_medium=cse&gclid=Cj0KEQjw8-GtBRCMl7m54PzgjNQBEiQAIZckvz9pkNHv1I_tSAMGRVEDj1P6c0b4-0vMDLvUGs5E8TgaAq-e8P8HAQ

[solymar]

Nice...ordered

Thanks again Alley


Solymar