help, blowing smoke...

[darkness05]

hey guys, today when i went to start my 426 it made a loud crack/bang noise and then when it started it was blowing alot of smoke. so i stopped it immediately but don't know what to do now? have my rings gone??

[FLjoyride]

Since it started smoking all at once, I would check your valve seals first.. I don't think its your rings since that usually starts gradually and gets worse over time.

[grayracer513]

... it made a loud crack/bang noise and then when it started it was blowing alot of smoke.

> Was the noise from the exhaust, or was it a mechanical/metallic noise?

> Is the smoke white or bluish, or is it black?

> Does it still have good compression?

> If you start it now, what does it do?

[darkness05]

I couldn't tell where the noise came from it sounded as if the ignition happend with the exhaust ports already open not to sure. the smoke is not black and more of a whitish colour. the bike still has good enough compression that i cant kick it over without the decomp. and i started it once more after the first time and it does the exact same thing just puts out alot of smoke.

there had been a small crack in the cylinder wall that had been repaired with liquid weld on the side the timing chain goes through and it appears that it has started to come off. this must of happend while riding on the weekend. from looking at it oil hasnt been pouring out just occasionally dribbling out.

so i don't know if i should be running it at all or if i should just repair that with more liquid weld stuff or if i just need to replace the whole cylinder and whatever else must be broken?

[grayracer513]

Better plan on a tear down to find out what's going on.

[Racer24]

if its white smoke than it could be :Piston oil ring worn, Cylinder worn, Valve oil seal damaged, Valve guide worn, or Engine oil level too high...

how many hours on the bike?

[bboyce]

Part of a valve?

But dude, any large thump is badd ?

[kowaly2183]

If you're experiencing white smoke most likely you have a leaky head gasket or a crack in your cylinder or head. The whiteness comes from burning coolant. Make sure you dont give it throttle when starting the engine. The carburator automatically does the idling when the engine is cold. If you give it gas it may flood your engine resulting in excess gas in your exhaust, when it ignites it sounds like a gun shot.

[darkness05]

I'm thinking the small crack that was previously patched up may have gotten larger and possibly caused a crack in the cylinder wall.

I guess ill have to tear it apart to figure it out. can anyone point me in the right direction to tear this thing down or should i just take it into a shop??

Also if i replace the cylinder should i replace piston and rings if they are still in spec?? Is there anything else i should replace at the same time as the cylinder??