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.

Today, 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). The DynoJet Stage 2 kit does not include pilot jets?

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...

 

With all those holes in the box,you are more than likely running real lean,hence the glowing pipe.Are you running it around,or just letting it sit and run? without some airflow,it will get real hot sitting in one spot,run a fan on it if it is just sitting while you are running it. First,lets get it running right. Pilot jet(the little,long one)is for idle up to 1/4 throttle,and the mixture screw on the bottom of the carb tunes it in. Needle jet,is the main,jet needle,the needle itself you move the clip on. Once it idles the way you want, I would check the jetting specs,and since you are running so many holes,go up 4 sizes on the main and take it out for a run.Runs ok on the top end? keep going up until it skips or misses on the top,or close to the top,then drop back one size. If it skips right away,go down a size at a time until it runs smooth on the top. Now top and bottom should be close,not perfect,but runnable. cruise at about 1/4 throttle,then accelerate quick to about 3/4,if it stumbles,you are lean,drop the clip(raise the needle)to get it smoothed out,if it surges,you are rich,raise the clip(drop the needle). To fine tune the bottom ,get up to speed in 3rd gear,then let go of the throttle.If it pops through the exhaust,turn out the mix screw under the carb 1/4 turn at a time until it stops,if you have to go 4 turns or more,go up 1 size on the pilot jet and start over at 1 1/2 turn.Now it should take off the bottom nice,and idle good. Then just go over the mid and top again,make any fine adjustments to get any pops or stumbles out,and it should be set up for your modified air box. I'm no expert,this is just off my experience,I'm sure others will have some good advice for you too.

 

i installed a 133 jet along with a duncan bouble barrel pipe and a uni filter on my 02 300ex, and have had no heating problems.

 

to clear this up a bit. The lower compression does need bigger jetting.

Before you make any more adjustments put tape over the six holes to get that problem out of the way. Then if you aren't idling still turn the air/fuel mixture screw open 1/2 turn more.

Get the thing back the way dynojet exspected it to be by taping off those holes first.

Call dynojet and get some bigger mains ($2.50 a piece). Now once you have it running decent threw the rpm range now you can drop the c-clip one notch and bump up your main with the six holes back open again.

If you would like to sell the mukini or the stock carb to recoop some of your money I am very interested. PM or email me.

Best of luck,
Gaff