started a thread thinking my trouble was with the carb no longer sure thats the issue anymore

redid top end new cylinder, new top end, with pro x piston, cleaned the power valves, cleaned carb up.

i broke in the top end and have goten a chance to ride it, not hard but it doesnt do anything but bog down at anything more than 25 percent throttle and along with the bogging it smokes what seems to be very excessive, as well as that it has a large amount of black spooge coming from the silencer to expansion chamber. i have not left 3rd gear yet but when your just lightly on the throttle it seems responsive and you could throw a wheelie but if you try to get on it suddenly there is zero power just get smokeyer.

i should also state the bike did this when i purchased it i got a good deal thinking it was just a burned up top end, wich it was the cylinder had a crack in it and needed a top end so i replaced all of it, now the problem continues.

i pulled rc vavle cover off and it looks like they are working ok the move when i give it throttle. i have not played with the jetting or the idle mixture screw, there is a second screw on the carb a philips im not sure what it does all just yet.

i do not think its clutch slippage as it does this in idle as well, if i rap on the throttle when in neutral it will bog down not rev up, im wondering if the power vavles need adjusting or is this a terrbile problem due to jetting,


please help !!

Have you been into  the Carb.? This could be so easy but alot more info is needed. You bought the bike , but do you know how its been treated? Stored long? Is it a stock Mikuni? Plug #/ Heat range? Has Timing ever been messed with/ loosened set screws on CDI pick-up?What Pre-mix and what ratio?   Have you ever heard it run good or did you get it not knowing...
  Mostly sounds like gooed up carb.complete rebuild or replaced completely with a Keihin PWK38 that all the guys in-the know on these threads will explain to you.  After I completely changed over to the PWK off a 2006 YZ250 to my 2007 CR I got in a hurry and did'nt pay attention to what carb. I was dealin with and accidently left out the main jet and pilot..(I made sure all was right but I was looking at the carb I took off by mistake and thought the PWK was ready to go) It started 1st kick but ran exactly like you described SPOOGE...RICH>>COUGHHHH...Get that info and someone will surely figure it out probably faster than I can surely type  Ha!!!!

Could be a lot of things, also check your reeds for cracks. My 250 was playing up really badly and ended up being my reeds.

 motomonster360, on 30 May 2012 - 09:04 PM, said:

does it have a nut on the outside of it locking it in place? mikuni carbs have a setup like that which controls the idle.

have you checked for intake leaks and really inspected the reeds for cracks?

Edited by schrode, 30 May 2012 - 10:07 PM.

ok reeds are brand new v force reeds, i bought the bike how it was running i dont no the history of it honestly, and yes when i re did the top end i completly diasembled the carb and cleaned it, and it is the stock mikuni, as far as i see the reeds are brand new, the carb looks to be in good working order, and yes that second adjust is a idle it has the nute to lock it. never had a carb with idle adjust on it like that.

only rode it when i bought it and it ran like this, i wanted to start with the basics so i bought a new cylinder and top end rebuild kit, there was a crack in the power valve brigde in the cylinder wich is why i bought a new one.

i am wondering if possibly some re jetting and idle mixture screw mite help but this seems to be a very extreme case unless the jetting is just completly rediculous, truthfully i rebuilt the carb but didnt think to check what the sizes where i was planning on rejetting it so i didnt bother. but i have never seen jetting take this much of a tole.

i was going to start buy getting the recomended jett off the fmf website for the pipe i have on the bike

I think on another thread he said he has V-Force reeds (new) installed.Biggest and easiest fix if carb is problematic is to go with a Keh.PWK.Forget that Mikuni if you have to spend money rebuilding....Most whom have dealt this same senerio on other threads have been amazed  with the results..

i agree this new carb sounds like a great idea, i just feel at the moment the bike should at least be able to run properly, i mean honda didnt send this bike out of the factory running how it is so if i can narrow it down to it being definatly the carb then i will definatly just go do a searchon ebay and see if i can get a deal on a used pwk, or splurge on a new one. but rite now im not even sure if its the carb doing this or not ?