White smoke

[smijaka]

OK, so i got a problem with the front cilinder, which is producing white/grey/also black smoke(exhaust). Why?
Push rods? Ignition? Bad seal?
Thank You!

[IronMick]

I would do these checks, in this order:
1. spark plug gap & clean; check quality of spark
2. intake and exhaust leaks checks
3. pilot screw setting
4. pushrod adjustment
5.

[thefrenchowl]

!!!!!!!!!

5) check your valves guides!!!!!

Patrick

[Vegas1200C]

Could it be bad fuel? White is usually water which on an air cooled engine is usually in the gas. Black is usually fuel which means you are too rich.

[242much]

I'm betting on valve guides. Are you positive it's white smoke and not blue? (white-ish with a blue haze)
Black is usually too much fuel. How does it run characteristically? Does it idle ok? Does it spit and sputter? etc..

[smijaka]

Hello!
Sparks are new, properly adjusted, today i'm gonna check the push rods. Question: to check valves guides - heads must must be dismantled?
Besides that, it starts very well - the ignition seems to be correctly adjusted, the engine has power but - it spits sometimes (from the seller it was said that it can be because of the keihin sceamin'eagle carb). My opinion is, that all settings with the carb and ignition are correct, since it smokes just from one cilinder, not both.

[smijaka]

OK,
push rods were also correctly adjusted.

[jagdprcp]

Have you done a compression test on it yet? It could be bad rings. If your compression is low in one or both cylinders, run a leakdown test on it to find out where it is losing compresssion.

[smijaka]

Jep. My worst nightmare-thoughts are also piston rings. What compression ratio would be 'enough'? I had one test made and it was 9.5 on the rear and 10.5 in the front (which is funny, as the front is smoking).
Another question, to exchange piston rings, do i have to dismantle the engine from the bike off or can it be done within the frame??

[Hopper]

You can do a top end overhaul - heads and cylinders and pistons - in the frame. The rear cylinder head has to be slid out with the rocker box intact, and can be a biatch to get a torque wrench into some rear head studs so you may have to do it by feel.

But try riding it for a little bit around the block first if you just got the bike, providing it is not making any scary death-knock type noises. It might blow the cobwebs out. If your compression check at 9 and 10 to 1 was correct, top end should be ok. IIRC, it should read somewheres around 140 pounds on a compression test. If it drops below 120 it is worn, below 100 is really worn.

It is worth checking that the previous owner has a good thick oil in the bike too, 50wt or more. If he just put thin car oil in it, that can make smoke too.