Yamaha ybr engine change problem?

Question

Hey, I ve just changed my entire ybr engine because of leaking and clutch problems. Was cheaper just to replace. Anyway I ve mounted it in all tight and connected the electricals up fine but for some reason when I turn her over she revs ridiculously high and some smoke came out from near the engine. Also the neutral indicator isn t working either and the kickstart won t turn her over as well. Any suggestions would be great? Much appreciated guys

Candid Chris · Answer

Guessing that you don't have a Shop Manual to look at. The high revs are most likely due to the throttle cable being tweaked out of shape OR the carb slider was put in backwards (the small arch is toward the air intake end).
The smoke is probably for being revved too high with a cold engine and should disappear once you get that straighten out.
The Neutral light could be a few different things but first ckeck would be the wiring.
Pretty sure it has a Neutral relay from the kickstand-down relay so that may be a problem area also.

Highly suggest you get some sort of Shop Manual to guide you through a few things, weather it's a piss-poor PDF files or A real Manual.

guardrailjim · Answer

Does the new engine have spark plugs in it?
Without any compression, the crankshaft will spin ridiculously fast.

The neutral light problem is most likely due to the wire is not plugged into the neutral light switch.
The switch is down near the counter shaft sprocket.

Anonymous · Answer

Cheers for the reply guys, turns out the manifold gasket was worn. And the neutral sensor was broken. Now all sorted however when I'm riding I have really bad stumbling/rumble coming from the bottom of engine, plus when hit third gear it starts sqealing like metal rubbing together.. And ideas please. Thanks again

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Yamaha ybr engine change problem?

3 Answers