Engine running like crap

The original 2-stroke Genuine scooter and its 4-stroke manual and automatic offspring

Moderator: Modern Buddy Staff

Post Reply
Chatis
Member
Posts: 12
Joined: Tue Mar 31, 2015 1:01 am
Location: Kansas

Engine running like crap

Post by Chatis »

I have had my VBB for 10 years and it has always been a reliable scoot. Last fall it started idling high without me making any adjustment. I turned down the idle screw and thought nothing more of it. That was the only issue I have had.

This spring I battled to start the scoot. I did get it to run but it was running like crap so I decided to rebuild the carb. Did a complete strip and soak and rebuild. Stripped the stud torqueing the carb down but that is another story and posting.

Now the scoot still runs crap. It doesn’t idle unless the idle screw is all the way in. It has no power. It’s a bitch to start. The mixture screw makes no difference.

I have put in bigger jets but still no luck. No idea as to what is going on. I have started over several times. Just cannot get it to run properly.

Any other ideas??
Robbie
Member
Posts: 536
Joined: Wed Apr 25, 2012 2:46 am
Location: Desplaines Il.

Post by Robbie »

Most likely, assuming compression is at spec, would be the fly side crankshaft seal....trans side will suck oil into the case, making much smoke and fuel will thin out the trans oil.

The clue was your increasing idle speed last year, a sign of a crankcase vacuum leak.
When the seal leaks, it allows air into the crankcase but reduces the amount of air/fuel pulled through the carb.....result, leanout.

Continued operation will burn the piston and possibly cause the flyside bearing to fail since it is being starved of oil mix.

Rob
Post Reply