Desperate now 4pt. smoking on start up
 

We are stuck in the UK waiting to go east. The bike was recovered from Lile 2 weeks ago due to cutting out, found to be blockage in carb and cleared.


The bike smokes on start up and the right hand port has oil, the left one is clear. the smoke clears after a couple of minutes (as though oil is has been burnt off) and the bike runs well. Had the head off, the piston seems fine ,new valve stems seals fitted all looks good. no visible cracks in the head. No obvious signs that the bike is burning oil. Now does anyone have an ideas? Can we Take a punt and go with it since everything seems fine except for a smoky start up? As you can guess we are stressed, desperate and sofa surfing.

Sounds like the classic overfill of oil.

Proper oil level check requires you to warm up the bike by riding around the block or two, then return, with bike shut off and held upright, check oil immediately and adjust as necessary. Reason? oil can seep past the check ball and sit in the crankcase after sitting a while. Only way to get a good check is to run it until warm assuring oil has returned to the tank.

I am in the middle of a top end rebuild from a bike that has been sitting for about 25 years, low mileage, good shape, low compression.

Upon draining the oil from the crankcase, I got almost 3 quarts of what smelled like 90 weight transmission oil out. PO had not only overfilled it but put the wrong oil in. The intake tract was saturated with oil and the intake valves had pits as well as the valve seats due to moisture sitting there I guess. The crankcase vent line going to the air box is saturated with oil as well.

I expect the bike smoked terribly as the top of the piston was caked with gummy oil as well as the rings. No damage done save the valve seats and they most likely pitted over time.

Other than that the engine is very tight, piston to cylinder is at new clearances as bike only has 9000 miles on it. Hurray for me, easy fix and almost new condition engine. I am replacing rings after a light hone and 2 intake valves plus recutting the valve seats. Should be a runner soon.

Steve

If it turns out NOT to be over filled with oil ... then it may be bad valve guide seals. Since you just had the head rebuilt, possible something screwed up with the part or install? Classic symptom is smoking on start up.

If your bike is over filled ... another tell tale could be a soaked oil filter or air box after high speed on motorway. Also, make sure crankcase vent hose is not blocked.

Good luck. If it's valve guide seals ... I'd ignore it and just GO! A bit of smoke on start up is all it will ever do. If you get an oil level drop after high speed running all day ... then you got some issues. Otherwise, OK. Alway check level HOT, not just warm ... HOT! You want oil level FULL ... but never OVER full! bier

Have a safe ride! :scooter:

Good input. Sharing info is what these forums are all about... I have learned lots of "good to know" info on here and other good forums...