Smoking on startup

[Bauer]

Well I knew it was too good to be true. My 80 special finally started smoking on startup after never smoking before in its life. A close buddy of mine recommended that it was probably the valve guide seals? Any trueness to this. It also has developed a serious "stutter" when either cold, or very hot. About 2 or 2500 rpms it will bog down until I let off the gas, then will catch back up with itself. It kinda reminds me like its running out of gas but I know its not. Could this "stutter" be another indicator of bad valves???

Whats the Guru opinion?

Thanks

[DiverRay]

Smoking is always bad for ones health! I would not worry too much about the "puff" of blue on the first start of the day. "daily ride" has done that for the past 10K miles, and still runs well. Your "stutter" is probably a carb problem. The first thing to try is drain the carb bowls, looking for water or dirt. I would then run about 1 cup of seafoam or berryman's B12 chemtool in the tank, to clean the fuel system.
Ray

[Bauer]

I just had a good friend of mine, a Certified yamaha/honda/polaris technician and now Senior Tech at a Honda powerhouse dealer here in bismarck do my carbs.

One of things this guy knows better than he knows his daily routines is carbs. and I do have inline filters, as well as the petcock filters, So though neither is ruled out , its HIGHLY unlikely that it is in the carbs.

Its not so much that im worried about the smoke, but the fact that it ran beautifully on tuesday, [never smoked a puff in its life (since ive owned it)], started stuttering yesterday, and started smoking last night has me thinking something mechanical is wacky with it.

Thanks for the input though Ray, I appreciate the quick response. I smoked for 2 months when I was young and dumb, thats 2 months of my life I will never get back

[DiverRay]

I would STILL run the berrymans through it. A bad tank of gas has caused a LOT of problems for me, and that may be all you have.
If you are NOT lucky, you may have had a valve stem seal break, and are now sucking oil through a valve.
Ray

[Bauer]

The sea foam might not be a bad idea as a catch all.

Thats why I was thinking it was a bad seal, If I am in fact sucking oil through, that would explain the bogging down of the motor, smoke, etc. etc.

Has anybody priced out seals through yamaha lately, what do they run a piece?

[DiverRay]

I would just get a complete rebuild gasket set. I think P&M has one for about $75.00, and it includes new seals...
You will need the head and valve cover gaskets anyway.
Ray

[Ken Talbot]

Worn valve stem seals can cause heavy oil consumption and some smoke, but on the bikes, the seal sits well above any significant amount of oil when the engine is not running. I don't believe you could get much oil seeping past the seals to pool in the intake or exhaust chamber to then cause the smoke on startup. Fuel seeping past a poorly seated float valve will seep into the intake chamber, and possibly the cylinder and even the crankcase, and could well cause excessive smoke on start-up. Coupled with your observed recent stutter, I would place my bet on one or more float valves. Yes, I know you said they've been done by a very good mechanic and that you have in-line filters.

Leave the top end alone for now. Take the carbs off and check out the float valve operation as detailed in some of the carb tech articles.

[excess11]

Fouled plugs

Fouled plugs can create some strange conditions. If you are having problems with oil consumption,than fouled plugs are likely to be the problem. Pull a plug and see if it looks oil fouled(dark and oily looking). Try a fresh set of plugs if you can spare the cash. See what happens!! Good luck!!

[HobbyMan]

Does it only smoke on one side? If it is left on the side stand and the left pipe is smoking then it could be a number of things like carburation. If it is left on the center stand and both smoke then, it is remotely possible that it is valve guids. Does it smoke if you shut it down and immediatley start it back up? As said before, there isn't a lot of oil there to drain in, but it doesn't take much to smoke. My 86' chevy 350 has worn guids and smokes a bit on start up, but that wouldn't cause the "stuttering." I would check the carbs again, just to make sure it isn't them before you venture into the head. It is easier to do a carb job than a valve job. Also, before doing anything, check the plugs to see if they are rich or lean, or not running at all. In my opinion, it could be anything, even two unrelated problems, the smoking and stuttering. I don't know enough yet to tell, I can only relate to my personal experiences rebuilding my Dad's and my bike. Oh, yeah, how many miles does it have since any major overhaul, like valves or anything? One more reminder: I don't believe that you can truly clean the carbs 100%, there will alwayse be someting you missed.