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12,600 ft.!!! Do you live on top of Everest??? LOL
These guys are right. You need the EEG needle. Don't risk riding the bike with the choke on. Get it fixed right, then ride. Go back to the 38 pilot. You should be way rich on top with a 170 main. If it doesn't blubber at WOT; don't change it. I swear by the HPD EGT gauge. It is the best insurance you can get. I think someone had one for sale in the Bad Boys forum. I'll second the recommendation to NOT take your motor to a dealer. Go to a performance shop or send it in to HPD. Are you serious when you say that the dealer took the seized piston out and put a smaller one back in? Big NO-NO!!! To check for air leaks around intake, head and base gasket; spray carb cleaner or starting fluid around these areas as bike is idling. If it revs up suddenly; there's your leak. (Don't get the carb cleaner on plastic parts.) I hope that you've mentioned your altitude to HPD so they could set up your clutch kit properly. At that altitude; you could run 3-4 gram lighter weights. Try not to get upset with HPD. It's up to you in the end to tune your bike properly. It's trial and error with no guarantees. One thing I can tell you is... When trail riding for long distances; blip your throttle ocassionally as you ride. Open her up once in a while. Gas cools the combustion chamber. Did you ever run an air cooled snowmobile on a warm day? Pop! Pop! Blahhhhhhh. Take a break during rides and have a drink and a snack. Let her cool down. Take in the scenery.
....and last but not least; warm it up before riding. I let my bike idle for 10 minutes while I put my gear on. The cylinder should be warm to the touch before heading out. Good Luck!

 

Here's an entry from "it worked for me". Since your sign says Quebec...I'm assuming Canada, you are subject to some cooler riding like I am, here in Minnesota. The 39PWK isn't a cold weather carb, but it can be made to work in cool. First of all, if you don't have an EGT setup, get one now!!! I have a HPD full race setup, and with the 39, it suffered a bad lean condition just prior to switching to the main circuit. I contacted many people, almost picked up a alcohol needle, but opted to mod the EEG. After talking with the people at Hypersports in Osseo, MN. They do extensive dyno work on bikes and snowmobiles. His advice was to gradually increase the throttle, monitor your EGT. When the temp starts to climb to an uncomfortable level 1100 at 3/4, 1200-1250 full throttle, somehow mark, or remember the throttle setting. I have a twist throttle with ribbed Scott grips, I lined up the splice on the throttle housing with whatever rib. Then remove your air-cleaner, with a mirror and a marker, place the throttle to the previous lean position. Reach in through your carb and mark the needle. Remove the needle from the carb, and chuck it up, Gently!!! in a drill or drillpress. With the needle spinning, take 320 to 400 grit emery and carefully "wipe" the needle. The goal is to take maybe a thousandth off at a time. You can mic the needle before and after, but as long as you do it conservatively, you should be o.k.. It took me 4 times to get it right. Patience!!! For the north country, I have a 35 pilot, turned out 3 turns on the screw ( beyond 3, HPD says it doesn't affect mixture) a 172 main jet, and #5 clip setting. All EGT readings are within the safe range. Good Luck!!

 

Xplor,

Wow, I feel your frustration. Total bummer with the burn downs.

Two things, the Wiseco pistons require more than the usually acceptable piston to bore clearances. Apparently the technician working on the piston installation is schooled in the replacement of OEM pistons and is not aware of the clearances needed for a Wiseco.

Secondly, from everything that I have read on this and other forums the 39PWK carburetor is the carb from hell. It has caused more mid range burn downs than Carter's has pills. I really wonder why these aftermarket companies recommened this thing. It only helps at WOT and gives up performance and economy in every other rpm range.

Good luck

 

Carb from hell is right...LOL [img]i/expressions/face-icon-small-smile.gif[/img]

I just ordered the EGT Guage and Probe along with the EEG needle. Hopefully this will work. With over 4000$ spent on this hyper-tank, what's another 200$?!?!? At least I will be able to get the exaust temperature just right. If the jetting still isn't up to standards I will shave the needle or jimmy something else up, or just ask a zillion questions on ATV Connection!

Long live stock machines! I don't think I will be touching the Raptor's motor...maybe just a pipe. [img]i/expressions/face-icon-small-smile.gif[/img]

 

Thor;
The 39PWK is a great carb. If you read back through many negative post about this carb; you'll see that many of these guys are not experienced tuners. HPD's racers use this carb weekly with no burn downs. If TT and MX racing aren't punishment on a motor; I don't know what is. Several years ago; HPD built a 400 that raced Pikes Peak. It had a 39PWK and had to endure miles of severe altitude changes. The steering stem broke on the bike just before the finish. No burn downs! A local guy runs nitrous on his ported 400 using a 39PWK. His bike is a '96 and still on the STOCK bore! The difference is that he's an experienced tuner. I can't tell you how many Wiseco pistons get blamed when a guy can't do something as simple as warm up his ride before taking off. Not to mention the guys who can't break in a motor properly.

 

not to be a smart a**. I guess rick ritter isnt experienced. It was rick ritter that told me that an extended run at 1/4 to 1/2 would cause a mid range burn down.

 

Define "extended." A NASCAR engine is only good for 500 miles. It's up to the crew to tune it to run that long. I can run all day at 1/4-1/2 throttle with the 39PWK. Then again; I know how to operate my bike properly and how to keep it cool. I ride in 110 degree weather here in the desert with no midrange burn downs. Not to knock Rick, but he also highly recommends the 38TMX. This is the worst carb for midrange burn downs. They don't make a needle rich enough for my bike. That's why HPD doesn't sell or use the TMX. I've converted many burn down victims from the TMX to the PWK. HPD has many hours of experience on the dyno and the track with the 39PWK. This is more time than many engine builders out there. Only HPD has racers beating the pros like Johnny Hale getting whooped on his Curtis Sparks 250R by a full race HPD bike. I don't think another Polaris engine builder can claim this. I didn't take your comment as a wise a$$ comment. Well taken.

 

I agree that the 39 is a great carb....for warm, summer ridding. I live 30 min. from both HPD and Hot Seat. HPD has great race machines, which are characteristically used during the summer, or in warm climates. As my previous post explained my probs, I still have to agree with Daryl (HPD) that the PWK has great response. I will still be purchasing a 42mm come fall. One walk through Hot Seats "R&D meltdown room" and you know they've tried it all. They sell more to the Rec-Sport rider, who might do some winter rides. I'd really like to try the PSI $500 external adjust carb, but at half the price, the 42 seems like it should do. I also have the HPD analog EGT, have to agree again with Fasterthangas, it works great!!!

 

I have a 39mm PWK, one of my problems was that it was too rich in the mid-range. I had to lower the needle to get it to run right. I have a ported motor with a Wiseco piston in it (.003" clearance) but here is where mine differs from the rest of you. I had my piston coated at Swaintech ( with ceramic on the top and Poly-Molly on the sides. Zero troubles yet and it's about a year old on this rebuild. If you start playing with the piston clearance with these soft wiseco pistons, you are asking for the piston to start coating the cylinder walls with aluminum. The Clymer manual backs up Wiseco with a tollerance between .0023 to .0037. I split the difference. Here is the link to Swaintech. It's cheap affordable protection. Swaintech

 

on my scramber 400 i had it bored .020 over and jetted stock carb with 200 main. warmed it up real good and a couple of hundred yards later it started to seize. starts right up but will start to seize again. any help? thanks