Custom Fighters - Custom Streetfighter Motorcycle Forum banner
1 - 8 of 8 Posts

·
Full Combat Fighter
Joined
·
206 Posts
Discussion Starter · #1 ·
Rebuilt my head, getting huge amount of smoke coming out. Internet research suggests that at worst case scenario my rings are bad and need replacing.
Thoughts?
 

·
Remi's Dad
Joined
·
17,593 Posts
at idle? Does it get less when you are on the throttle? What are the compression numbers like?

How long has it ran since the rebuild? Is it water cooled? There are many things we/i need to know before i can tell you what it might be
 

·
moron with a hammer
Joined
·
119 Posts
When you rebuilt the head, did you by any chance remove the valve seals and forget to replace them?

I ask, because I've been there. "Heavy smoke" pretty well describes the result.
 

·
Registered
Joined
·
740 Posts
Severely shot rings can cause smoking at startup and under acceleration...was this an issue before you had the head apart? You'll also have lousy compression, low power, and it's probably hard to start when cold.

I'd think it's more likely a valve seal wasn't seated properly, and was ruined almost immediately when you started it up. You get a blueish, smoke that smells like burnt oil.

On liquid cooled bikes if you fuck up the head gasket or forget an o-ring or something, you can leak coolant into the cylinder, which produces a white, sweetish smelling smoke. In addition to rapidly losing coolant, if you take the rad cap off you can see the fluid level bounce in time with RPMs.
 

·
Full Combat Fighter
Joined
·
206 Posts
Discussion Starter · #6 ·
Thanks for all the input guys. I took the engine apart to replace the head gasket. I didn't redo the valves, just checked to make sure that there was no obvious damage or scoring or excessive wear on anything. Had the head in possession of a shop, they gave it the clear. I didn't check compression, but it wasn't an issue the last time i had it start. I am really hoping that it just needs to run though. I used a lot of starter fluid to get her going, more than I needed because it started right up. Hopefully this week I will get a chance to do more to it tracing the issues.
It's a Katana so it's an oil cooled 750. It was dark out so I couldn't tell you what color the smoke was with certainty.
 

·
Registered
Joined
·
740 Posts
If it continues to be difficult- needing ether- to start, that's a classic sign of low compression. A common mistake after the head comes off is you get the timing one tooth off. This is often the result of failing to take up the slack on the "pull" side of the chain before noting the timing marks. The engine will still run, but it's hard to start and doesn't have much power, the incorrect valve timing results in low compression.

This wouldn't really explain the smoking though. If it wasn't an issue before and you didn't touch the valves, not sure what changed. Did you use an OEM head gasket and torque in sequence, to spec? This is important on heads to prevent warping or deforming the gasket.

A brief period of smoke after an engine has been apart is no big deal but it should clear up pretty quickly if everything is OK. Take it for a rip and see what happens.
 

·
Registered
Joined
·
4,653 Posts
1 - 8 of 8 Posts
Top