I have a 2000 Explorer 400 with these mods
Bubba ported cylinder
Wiseco piston (std.)
V Force reeds
39 PWK carb
K&N carb mount filter
Dyno Port pipe
55 S primary weights w/ green spring
stock helix w/ hot seat spring
26" 589 ITP tires

what im looking for is some help dialing in the jetting and clutching, I have an exhaust temp gauge on it to watch for lean conditions, but I only have a small hot spot at about 1/8 th throttle 1250 -1300 degrees the mid and full throttle read about 1000 degrees. I dont know where I should be for jetting with these mods, I'm thinking I might be a little rich on top. Does anyone have similar mods that could give me some advice. I dont know where to start with the clutching either, I thought it was close but for the mods I have done it seems way to slugish, I dont know witch way to go, PLEASE HELP[img]i/expressions/face-icon-small-sad.gif[/img][img]i/expressions/face-icon-small-disgusted.gif[/img][img]i/expressions/face-icon-small-frown.gif[/img][img]i/expressions/face-icon-small-confused.gif[/img]

 

i have a 95 xplorer 400 2 stroke with:bubba advised porting,38mm TMX flatside, AAEN pipe, turned flywheel, 40 over wiseco, .010" off head, dual stage reeds, uni air. for my carb i use a 390 main jet, 35 pilot and 2 turns out on air screw( i have to recheck now that its hot) and i run mine just a little rich using premium gas 40:1 with klotz oil super tech. In my primary- Heelclicker (scrambler version and weight settings)with a HPD mid level spring, in the secondary i use the stock spring at a 1:1 setting, napa kevlar belt. I went back to the stock secondary spring because i was spinning my tires to much on dirt and even pavement. this help out alot and i may go to a softer spring in the primary to futher reduce take off wheel spin- i'm was spinning a set of 25" all track's for over 30 yards hard now. this has also helped greatly with flattrack racing- my American racers are hooking alot better and not breaking loose all the time.
hunt

 

The 39pwk is almost famous for having a small lean spot at part throttle. I never used a gauge for jetting and most of my driving was done at WOT [img]i/expressions/face-icon-small-smile.gif[/img] HPD sets them up with a fat pilot and a mild main jet. I cannot remember what the pilot was. Modquad needs to answer this one as I know he got his tuned in real well. Ken..... Oh Ken..... Where art thou Ken????

 

Bubba ,I had a set of S 58 weights in but I couldn't tell the difference from the 55's, so I think I should get the carb just right then tackle the clutching, what do you think?

 

Make sure you have the EEG needle ,which is suppose to be the richest needle.I have been running a 35 pilot for over 2 years with no problems.When HPD sent the carb it had a 38 pilot and a 172 main i am now running 178 main with the needle clip in the middle.

 

What kind of EGT gauge do you have and were is it mounted?? How far from the cylinder face??? Mine is the recommended 7" , SLP EGT gauge with race probe. If yours is like mine, you are way rich on the main. Mine should run 1250-1350 WOT and mid about 1000, 1/8 about 900-1000. At 1/8 I think you are way too lean, maybe raise the needle clip postion and see if it cools down and/or turn the airscrew in a turn or two. You should definately not be that hot that soon. But... don't just rely on the EGT gauge, check the plugs also and do plug chops to get it right.

 

I am running the EEH needle all the way up and still a little lean, I just changed to a 152 main and only got to 1150, also did a plug check at WOT and it looked a little to dark, so rich. It used to pull the front end real easy and take off like a bat outa hell , now it seems kinda slugish.

I just got the motor back together a month ago and went through break in, there might still be some oil left in my gas, in addition to the injection, but I dont think that would make that big of a difference. Well anyhow I fried a crank bearing this spring right after I put the Bubba cylinder on, It ran really good until the lock up of the crank, so I put all new crank bearings on and reassembled and it doesn't run near as good as it did.

 

Is it possible I could have the timing off?? I lined up the marks , but dont know if I should have advanced the timing for the mods.

 

No, I don't think you should mess with the timing unless you are race modded. I could be wrong though. If you put it back on the marks, the timing should be fine.