YT6700 Engine smokes on startup

[Ben S]

I have a YT6700 that started to burn oil (a significant amount of white/blue smoke) on startup. After a minute or so when it warms up, it stops smoking. Oil level is fine. I'm purely guessing that it's valve seals or piston rings.
Does anyone know what the compression spec is?
Are any oil additives worth a damn for this sort of issue?
Maybe try a heavier oil weight? (I'm using 10w30)
I'm not familiar with this engine and I'd prefer not to rebuild if I don't have to. Depending on the cost, it may not be worth it.

I've found a YT6800 service manual for $50. Same as 6700 I presume?
Is there a service manual available for just the engine?
Does the manual give step by step instructions to diagnose the issue or just list possible causes?

Sorry for so many questions. Just covering all the basis. I'm a new member and am very fond of this cool mower. :)

Thanks in advance!!

Ben

[Denny]

i would check the choke system. it does not cost anything. my 6800 was very hard to start on initial start up. after warm up was not a problem. just for kicks i checked the choke. did not seem to close all the way on start up with lever on all the way up. i hooked up a wire on the choke lever and closed the choke with the wire and it started right up and has started right up ever since. i still use that wire to pull up on and it starts right up. have seen other members with the hard start problem like i had and i would advise them to check the choke valve and make sure it's all the way closed on start up. choke linkage looks a little complicated to me so i'll just use the wire for now. bad choke position can cause lots of smoke.

[yama]

might check your crankcase vent or pvc valve