Smoke coming out of crack in manifold

Hi everyone, just started my scooter after having tried to tweak the autochoke, and it was kind of stuttering when I tried to rev it.

I turned it off and noticed grey smoke coming out of a crack in the intake manifold (engine side). The crack looked kind like the manifold had melted along the fault line, but I'll have to double check that in the morning in better light.

Any ideas? Seems serious!

 

Prognosis sounds bad... get some pics in the morning

 

Well in better light I can see it's just cracked, not melted. I ran the engine for a few seconds - it runs fine, and the smoke comes out only after I cut the engine. Could it just be exhaust fumes? I tried to smell it but it was hard to tell. I'm not sure if exhaust coming back up the manifold after cutting the engine is normal?

 

No. Thats not normal.
What bike is it?

 

It's an Aprilia Mojito 125

 

Does it have a sort of EGR valve type thing? Could be that doing it

 

Please explain this bit?

"tried to tweak the autochoke"

 

could u senda photo?

 

Here's a pic, the smoke was quite uncooperative but you can see a bit to the right of the boot (it's coming out of a crack on the side that's out of view- the crack you can see on top only seems to be on the surface).

Stevep, I was trying to reduce the difference in idle speed between when the autochoke was engaged/vs when it was disengaged. When I would first start the bike it revved too high, I would have to hold it still with the brakes. But then after a minute or two it dropped to almost cutting out.

 

Sounds like your pilot screw is wrong.
And get a new intake manifold.
Oh top tip.
On installation, make sure the jubilee clip doesn't wedge the throttle open... I speak from experience there....

 

that intake has certainly had it. Unfortunatly for you the torx secure screws are a pain without the bits.

 

No probs there, I ordered the torx bit at the same time as the new manifold. What do we think about the smoke?

In response to scuba's question about the EGR valve, I don't know. It's a piaggio leader engine, I couldn't find any info about whether it has it. Do scooter engines typically have those?

 

im not that familiar with these engines. but if the smoke comes out of intake then i would replace it and see how it runs then. update us when u put it on. 4 stokes have crankcase vents that go the the airfilter often to reduce emitions.

 

Yeah, I mixed it up I was thinking of PCV and not EGR valve

 

Well I changed the manifold and then re-tuned the fuel screw, seems to run ok now. Consensus seems to be the 'smoke' was exhaust and nothing to worry about

 

Good to hear.