White Smoke cb350 k3

[cgguy09]

Hey gents,
I recently rebuilt my cb350 & I've run into some white smoke, other than that, the engine feels perfect. Here is where I am so far:
Timing is good
Needles are adjusted to where they both work
the Left spark plug looks good, the right is fouled with oil
Confirmed spark and compression on all cylinders
I am a fucking point gap master...so that's fine.
Compression on both cylinders is at a 160.

The bike starts up on the first kick, the white smoke seems to only come out when I accelerate and some light smoke at idle after she's been run for about 30 min.

Because the compression test is good, I'm guessing its not cylinder rings (not to mention I replaced those about a year ago)
Could it be the valve guides? or perhaps just a bad gasket? I'm sort of leaning down these two roads but wanted to get 'expert' opinion.

Thanks homies.

 

[Kanticoy]

Could be valve guides or seals. Also could be rings if they haven't been broken in. How many miles since rebuild? Are valves adjusted to spec? Could be seepage from seats...

 

[cgguy09]

Could be valve guides or seals. Also could be rings if they haven't been broken in. How many miles since rebuild? Are valves adjusted to spec? Could be seepage from seats...

This is actually the second rebuild I've done on this bike...about a year ago I redid the gaskets and the cylinder rings. however, I had a slight leak on the outside around the Cam box...I guess it was just eating at me so I took it down & redid it.
The cylinder rings had about 1000 miles on them.
I never checked the valve guides (to be honest wouldn't know what to look for)
The valves were adjusted to spec, but that's a rather quick check (so long as I don't need to adjust anything)...I'll do that on friday.
As far as the seats go would that just be carbon build up?

Thanks

 

[GLENNWOOD55CAMEO]

Bad valve guides would be indicated by a puff of white smoke at startup since the oil would leak down the valve stem after the engine is stopped only to be burned when the engine is again started. If your getting white smoke opon acceleration and while hot and idling, then I would say its the rings. Maybe a broken oil ring.....

 

[cgguy09]

Bad valve guides would be indicated by a puff of white smoke at startup since the oil would leak down the valve stem after the engine is stopped only to be burned when the engine is again started. If your getting white smoke opon acceleration and while hot and idling, then I would say its the rings. Maybe a broken oil ring.....

Yes, those are the symptoms: White smoke on accelleation & white smoke after the engine is warmed. I thought that if a ring was blown there would be a drop in engine pressure (and my bike is pushing a little above 160 for each cylinder). Could I still have good presure and a blown ring? Thanks, boys.

 

[GLENNWOOD55CAMEO]

Yes, you could have a bad oil ring and still have good compression.

 

[cgguy09]

Forgive me for being a noob...oil rings = cyclinder rings right? (I feel like a dumbass, I should know this being I've done this once before. but I never put names to all the parts...)

 

[GLENNWOOD55CAMEO]

Yes, the oil ring is a cylinder ring. It is the second ring down from the top of the piston. The first ring is the compression ring. The next one, the oil ring is called the oil scraper ring. If this ring is broken, it would allow oil to seep by and burn in the cylinder.

 

[cgguy09]

Thanks for the info Glennwood.
Damn, well it sounds like I'll be riding with some white smoke til winter rolls around. I gave up spring to work on the bike, I'm definately not giving up Fall too!

 

[GLENNWOOD55CAMEO]

If it is a broken ring, then the more you ride it the more chance you have of scoring the cylinder walls . Worst case I guess would be having to replace the cylinder liner if you continue to run it.