300ex top end rebuild issues

[not2hi]

I just redid the top end on our 98 300EX. It had a Wiseco piston that was worn, so we bored it .020 over and installed a Pro-X piston and rings. (You can see below the other goodies it has). As far as i can tell, the Wiseco was hi-comp (11:1) and the Pro-X is stock comp (8.9:1).

Finally got everything back together and went to start it...runs OK under choke, tries to stall when the choke is off...after about 5 minutes of starting and dieing, the head pipe was glowing bright orange...is this a jetting issue thats causing all this mess? I'm guessing it was jetted for the old compression.

Any suggestions?

:confused:

[mysticfalcon]

sounds like youre running lean. richen it uo and it'll runn better and cooler.

[mxracer08]

you shouldn't have to richen it up since you have less compression. Check the plug and see what color it is and go by that

[ridered86]

if the header is red than it is running lean,and very hot

[not2hi]

due to a lack of understanding of our Mukini, i put the orig Honda carb back on and installed the Dyno Jet kit per their instructions. I believe that this is a 40 needle (PN dn0140), clip on groove 4, and a 128 main jet (PN dj128), and turned the mixture screw out 3 full turns. (803 ft above sea level).

Its cooler than it was last night, but still way hotter than it was before. Popular opinion was that it was too lean. To richin it up a bit, do i move the clip to groove 5 or play with the mixture screw? The largest main jet that came with the kit was the 128.

FMF recommends a 40-42 pilot 130-135 main. with no airbox lid and a 38 pilot and 128 with lid. mines got 6 1" holes and a 3" hole in the lid.

These terms are really starting to confuse me. Pilot jet, main jet, needle jet, jet needle...ahhhhhhhhhh!

If someone can help this mental case...