jetting for pro circuit platinum pipes

[yamahalovr29]

hey i have a 1993 shee bored .040 over with wisecos...cool head with 22cc domes....ricky stator advanced 5+ degrees.....pro circuit platinum pipes and silencers...300 mains..stock pilots...needles in factory position. castor 927 mixed 32:1 . this shee runs strong..but when i "drag race" it a few times or ride it really hard it starts running poorly and sputtering and cutting out..especially if i get in the woods on some trails after riding it hard out in open. overheating?? no coolant leaks since built and mixed 50/50 ....mains need to be bigger ? pilots? needles? also the clutch slips badly when shee gets hott from hard riding..if you let her cool off clutch and engine works top notch! my elevation here is 931 feet. does the 300 mains seem too small for my elevation and pipes? thanks for any help guys! but this shee still out drag races a 06 piped and jetted trx 450r close on low end and midrange but im ahead on top. usually i get him on low and midrange too. seem about right? will some toomey t6's give me more of an edge ? thanks guys for your help!

[Handyman]

hey i have a 1993 shee bored .040 over with wisecos...cool head with 22cc domes....ricky stator advanced 5+ degrees.....pro circuit platinum pipes and silencers...300 mains..stock pilots...needles in factory position. castor 927 mixed 32:1 . this shee runs strong..but when i "drag race" it a few times or ride it really hard it starts running poorly and sputtering and cutting out..especially if i get in the woods on some trails after riding it hard out in open. overheating?? no coolant leaks since built and mixed 50/50 ....mains need to be bigger ? pilots? needles? also the clutch slips badly when shee gets hott from hard riding..if you let her cool off clutch and engine works top notch! my elevation here is 931 feet. does the 300 mains seem too small for my elevation and pipes? thanks for any help guys! but this shee still out drag races a 06 piped and jetted trx 450r close on low end and midrange but im ahead on top. usually i get him on low and midrange too. seem about right? will some toomey t6's give me more of an edge ? thanks guys for your help!

 

I believe you jetting fairly close... On my '99 at 200ft above sea level I am running a 310 main and a 27.5 pilot.. and I'm bored to the 2nd oversize(64.50 I believe). SO I THINK...and other may say otherwise but I think you should be at least a 310-340 main and for sure a 27.5 pilot..Clip in either 3rd or 4th position. the 310 main for me is dead on for jetting

[MILO]

you need to do a plug chop and see how the plugs look. it sounds to me like you're mains are lean for one. i'm at about 1250' with pc's and went up to 370's to get good plug chops. that's with no lid on the air box and the pro flow filter, v3's, noss head w/20 cc domes. are you sure you don't have any air leaks around your carb boots or anything? i can ride hard in the woods/trails all day long and not overheat.

 

some info:

check out this link about jetting. it may help you determine what throttle range you need to work with.

carb theory 101

 

2-Stroke Plug Chop how-to:

 

 

1. Get new spark plug(s), but don't put them in yet.

2. Warm up motor to operating temp on old plugs.

3. Install new plugs.

4. Accellerate through all gears to top gear with throttle pinned.

5. When you hit the top of the top gear, hit the kill switch and

pull in the clutch.

6. Remove the spark plug(s) and ride home on the old plug(s).

7. Hold the new plug in a vise and use a hacksaw to cut the threads

away from the center electrode.

8. You should see a brown 2mm "smoke ring" at the base of the

white center electrode if the main jets are dialed in perfect.

9. if the smoke ring is darker than chocolate brown or taller

than 2mm, you're rich on the mains, but if it revs clean to full

throttle, you can leave it there and be on the rich side.

10. If the smoke ring is smaller than 2mm or lighter than chocolate

brown, you're lean on the mains, go up a size and try again.

 

oh yeah, and you may want to try setting your timing back to +4. +5 may be a little too much with your mods.