2Many, I still think your pilot jet is too big. That carb has a 35 from factory for the 400. My carb had a 30 factory and with my mods I am running a 25. Just my opinion, but I haven't ridden it, so I can't say for sure, but that is what it sounds like to me. It could also be a clutch problem. Make sure your alignment is good, your ctc distance is 10", your belt is riding 1/8" on top of the secondary at neutral, and you may also want to play around with your spring setting a little more. I had mine at 2-2 before and had a bog, I have since changed to 1-1 and it is amazing at the difference it made. The 1-2 setting seems kind of soft to me, but if that is what you like, then... But, I would try a 2-3 first then a 1-1 to see what happens.

 

Ok so should I start with the jetting first? I put the stock carb back in and it has a 170 main with #40 pilot. Should I go smaller on the pilot and/or main. Or should I start with the secondary clutch and set the spring different. If so on the clutch what setting would give me the quickest upshift? I dont really care about downshift to much. I am running the HPD gold secondary spring. I am about ready to dump the 250 and get something else.Even the mechanic at the dealer could not figure it out. He wanted to charge me for looking at it to see if he could fix it. I told him you did not fix it so why should I pay you. He even promised that he could fix it. But he didnt.

 

same problem w/ my temarary winter vehicle (when the snows too deep for my quad), its a 440cc 2 stroker (1976 bombardier tn't), anyways i've tried everything, from gas line atifreeze to rebuilding the carb, i cant find the problem, I assume that its the carb, so umm, try another carb if you got them laying around like me, sure theres a bit of work involved, personally, i got an oil injected yamaha engine off my buddy i'll thow that in her this fall and thats should work, if that doesnt work, then i dunno

 

If the bog is at take off, then it is the pilot/ air screw and possibly needle clip position. If it is a carb issue. I would try the clutch settings first. You may just be so soft that it is not shifting out right. Try the 1-1 setting and see what happens, it is kind of a medium between quick upshift and quick backshift. The clutch settings should make a very noticeable difference, if not then it is in the carb. To test the pilot jet, turn the airscrew out as far as 2.5 turns out (ccw) if symptoms don't improve, go to a 35 pilot starting at 1.5 turns out and see if it helps. It could also be a lean condition though, the real only way for you to guess correctly is to run it at a 1/4 throttle or where you feel the bog, flip the choke 1/2 way on and that will tell you instantly whether it is too rich or too lean. I use that method all the time and it works, I promise!! If it is too lean and you flip the choke, the bike will pick up and run smoother, if it is rich it will run worse or die. Try the clutching first, then the carb. Once you know the clutch is good, then you can work on the carb, just my opinion.

 

I took the belt off just to take the pressure off the enging. Now with the belt off when you go from closed throttle to WOT it bogs bad. It wont pick up untill I start to let off the throttle and then when it picks up I can open the throttle wide open and it wont bog. Everything is from a dead stop and it bogs when I go WOT. If the pilot jet was to big then why would it bog when I go wide open? What if I just scrap the roundslide and go with flatside. Would this fix the problem? What would I have to do to put reeds on it?

 

OK did you truy flipping the choke half on when it bogs?? What happened? The roundslide will work fine, not as good as the flatslide, but much easier to tune.

 

I don't want to scare you but, you have checked the compression and looked for air or exhaust leaks on the motor right?

I would start by getting the jetting dialed in. Try maxing out the seconary spring tension while you finish the jetting. Once you get it done, then play with the clutches. If you want to run the 34 then put it back on. The flat slides are not easier to tune. Mine still isn't 100%. I don't think it could ever be. You had the 34 on before you started into all this. Put it back the way it was and try going up and down one size on the pilot. Make sure you let the engine get good and warm before you draw any conclusions to these changes in jet sizes. Watch out for it going lean when you are coasting with no throttle on. I say this because I see you have the UFO on it. That kind of makes them like a flat slide.

Once you get into the clutch their are alot of things to check for. Check over anything that wears out and settings(slides, buttons, weights, rollers, helix, sheave faces, alignment, belt width,...). You say you are running the HPD agressive clutch kit. I believe that would come with 58g weights. I had 58g in mine, I dropped down to the 55g. Their is a few other little things you can do inside these clutches to tweek it that much more. To hard to get into them if I have to type it all out.

You know, I rode a V-Force yesterday. The guy just put on a set of alien exhaust. Man, did that thing sound cool. Ran pretty good too. Hmmm... was I think of a change? Oh yeah, the wife reminded me I wasn't. If I sell mine, I'll have to get another one.