TOPIC:

I installed the Speed Moto Co VM30 kit, and despite their shortcomings they advertise being great at customer service they are not.  So like I said after riding about 3 miles (about enough to thoroughly heat the engine I'd guess), the bike boggs when pulling from from a stop and I have to give it a lot of gas to get on up.  I also get black smoke out the right side.  This seems to me like either a valve or carb problem?  What yall think?  Haven't heard anything from SMC in about a week.

Forgot to add:  81 KZ440A LTD

Every now and then someone will report a jet had unscrewed itself and fallen out.  I would check for that.

But the main thing is to check the basics.  Start with valve clearance to make sure that has not changed and is within spec.
You could swap plug wires and/or plugs just to eliminate the remote possibility it's one of those.
Adjust the fuel level in the carb.
Make sure both throttles move together and by the same amount.

The fact that it was running ok before means the carbs at least have a decent basic starting point for the jetting.

Thank you for some ideas.

This bike has just less than 5k miles on it, it's in darn good condition.  When I first got it (about 150 miles ago  - likely less).  It had compression of 170 on each side.  I just checked it and it's got compression of 164 on the left "good" side, and only 120 on the right "bad" side.  These were taken cold.  I know you can take comp test numbers hot, but I don't think that'd be any help (someone tell me otherwise).  I find it hard to believe the engine could just crap out like that after so few miles, but I guess and old unused engine could do that.  So it sounds like I need to replace the rings.  I suppose I'll do it both sides.  Is there anything else I should do when I'm in there?

edit:  Also, any chance the new carbs could have done this to me?  I've posted pics of the spark plugs before after riding maybe 40 miles.  Link coming soon if anyone reading now.  LINK TO SPARK PLUGS  

Also, someone please tell me if I'm wrong with my plan.  I'm not a mechanic.  The most intensive thing I've done is replace rocker arms on my '12 Jeep JKU - and for those forums that's a frightening job, they typically spit out $1,200 or much more to have a $8 piece replaced.  Also, If there is a "big bore kit" for this engine, I'd be game for it.  I've done some searching and haven't found one, but I'm not a google god.

Have to ask you about your stock carbs. What could be wrong with them after 5000 miles?

When I bought it the PO said the diaphragms were shot or near shot (some sort of problem - don't recall exactly I was more amazed of how good of shape it was in), I'd also read somewhere that they were very undependable and finicky so a lot of owners switch to a Mikuni VM carb replacement.

Hell, what could be wrong with my piston rings after 5k miles?  They're shot in less than 150miles of driving them since buying the bike.  Old things don't seem to do so well when you start using them again.

My father is in town.  He says I should pretty much just change out the rings, re-hone the cylinder and re-seat the valves.  As ignorant as he is, he knows mechanical stuff fairly well, so that's my plan.  Question is can I use stock rings if I need to re-hone my cylinder?  My father tells me to do it no matter what, but my opinion is to only do if if there is an obvious problem - ie a ring broke and scarred up the cylinder.

Again, any and all feedback is welcome.