Hello,
I recently purchased a 1992 KX80 which just had a new top end put in (0 hours on it).It is jetted completely stock, idle air screw out 2 turns. Upon start up, white smoke billows out the exhaust and is more intense when the throttle is opened a bit --like a crop duster. I warmed it up for about 10 minutes idling and cracking the throttle a bit, but I'm not sure if that was really warm enough. The pipe was dripping black spooge. When I pulled the plug it was dripping black and wet. The bike has no problem starting and holding idle. Cracking the throttle 20-30% make a low throaty and bogging sound, which make sense giving the richness.
I tried adjusting the idle air mixture screw, but it didn't have any effect. With stock jetting and it being only 40F outside, I figured it'd be on the lean side if anything. So I suspect the following:
1. the crank seal is going bad and tranny oil is making its way into the combustion chamber
2. the guy who installed the top end did something wrong? He said he heavily lubed the cylinder, piston, rings with pre-mix oil when he put everything together. (I've heard people swear by dry assembly) But wouldn't that have burned off after a minute or two? Also, compression test after running for a few minutes looks good, around 180PSI.
I did not know how it ran before the new top end was put in so I'm relying on current symptoms to diagnose the issue. I'm relatively new to 2 stroke bikes in general so any help (even obvious advice) is appreciated. I'm not sure what I should expect to see running 10 minutes idle with blips after a fresh top end. Maybe this is normal? I plan to take it for an hour ride in a few days, but the place I ride is far so I want to get a feeling whether this is normal first.
Other questions:
1. Can I rule out leaky crank seal by draining the tranny and running the engine (not riding) to see if the amount of smoke changes? Is that safe?
2. If it is the crank seal, are they accessible from the clutch cover or do I need to split the case?
Thanks!