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Crack in manifold leaking smoke.


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Hi all, having an issue with my Aprilia Mojito 125. I was test running the engine, and after powering down I noticed grey/white smoke leaking out of a crack in the intake manifold.

After an appropriate interval in which my bike didn't burn to the ground I tested it a bit more - the smoke only appears after powering down, not while running, and the engine seems to run fine - not that I've tested it for more than a few seconds in it's current condition.

Obviously I'm replacing that manifold, but is there anything else I should be worried about here? Is the smoke just some exhaust gases floating back up from the engine? Is that normal?

Here's the best I could get pic-wise, bit of smoke visible under the boot:


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Looks like it's exhaust from EGR nothing to worry about. May be wrong but looks like it's inbetween carb/throttle body and air box so shouldn't affect running (apart from sucking in unfiltered air).

Smoke wouldn't be noticeable during running as would be sucked into engine rather than seeping out of crack.

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  • 3 weeks later...

Thanks for the reassurances everyone, that was all as I suspected but it's good to have 2nd and 3rd opinions! I did wonder about excess air screwing up the tuning - I never noticed it running poorly, but I've no idea how long that crack was there (Via - this is the manifold between the carb and the engine, not the airbox side)

Anyway, I changed the manifold and then re tuned the fuel screw. Seems to be OK but I haven't taken it on the road yet..

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