Smoke after rebuild

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1/28/2019 4:06 PM

Just had my bike rebuilt, new piston, rings, valves, cam chain and tensioner. All gaskets replaced. All parts OEM except wiseco piston rings and wrist pin. 2 heat cycles were performed at the shop and I did another at home. After cooling I started it and rode 50%. I've noticed a fair amount of white smoke coming from my exhaust during the idle heat cycle and again during and after my 50% ride. It's fairly cold and wet outside so I'm wondering about that being a possible culprit.

Any ideas? Is this normal until the rings seat.


2018 CRF250R

1/28/2019 5:23 PM

It really depends. 4 stroke engines smoke in cold temps until theyre fully warmed up. Youll notice this on your car for example.

It only takes 30 mins to break in a rebuilt motor. Let it rip after that.

The engine builder should have used assembly lube on most of the top end. It could be slowly burning off.

Junk in the exhaust could be burning off too.

Ride it for an hour and monitor your oil and coolant levels. Either they go down or your bike stops smoking.


1/28/2019 6:21 PM

Mine always smoke extra for a few minutes after a full rebuild because of all the extra oil I put on assembling bearings/shafts. Definitely shouldn't last a full riding session.


1/28/2019 7:18 PM
Edited Date/Time: 1/29/2019 12:10 AM

modern ring technology and nikasil bores don’t require nearly as long of a break in period as the older steel bores did... most engines will burn a minuscule amount of oil during break in because the rings haven’t fully seated, especially if during assembly the rings and cylinder wall were coated with an excessive amount of oil... my recommendation would be pay attention to your oil level and ride it...if it has continuous oil consumption/ smoke problems after the initial break In then I would be worried that the bore may have glazed over...