RM85 FULL THROTTLE BOG

hi im new on here.. i got my son a rm85 and it bogs on full throttle it starts firts kick and ticks over fine but wen you rev it on full throttle wile standing still it gows bhbhbbhbh bhbhbhbhbh bhbhbhbhb then starts to scream rrrrrrrrrrrrr like it should its got 122 main jet and 40 pilot and a BR10EIX spark plug its a iridioum one.. the jets and plug was in it wen i got it ..only had it 2 weeks .. its anoyig me and my son he wants his kx60 back hehehe .so if aney one can help me ill be a happy man .thanks

Is the engine cold or hot when ur give it full throttle, I find with many 2 strokes the they don't like full revs when there cold and stationary

its warmd up even dus it wen its hot fresh from the track

What's the plug look like may need to be re-jetted? Sounds a little lean.

its abit wet i kant find aney info on the correct jets the air mixture screw way way out i set it to 2turns out and its a bit better.it seens a bit down on power aswell

Stock is #128 main, #50 pilot, clip on the 3rd groove and air screw @ 1-3/4 turns out. You got a pipe or any port work on that bike? RM85 also hate dirty airt filters. I would go back to the stock #128 main and put a #45 pilot, set the clip on the 2nd groove from the top and air screw @ 1-1/2 to 1-3/4 out. You may never get rid of the bog with the stock carb, but once you find the happy spot it will fly on the track. On the starting gate hold the throttle untill the skip starts (like a rev limiter) then back off just a little. Gate drops, then nail it to full, it will launch like a rocket. The bike shouln't bog out on the track.

thanks alot ill try them jets iv got a KEIHIN -V571GF7 carb .is that aney difrent and could i uce it . It hasent got a tuned pipe its got a short standard silencer also wen it gows into 6gear it bogs and hes got to change down and gear up and its off

I had the same problem on my 125..take off the carb and unscrew the big bolt on the bottom of the bowl and make sure the top part of the jet is screwed in

thanks alot ill try them jets iv got a KEIHIN -V571GF7 carb .is that aney difrent and could i uce it . It hasent got a tuned pipe its got a short standard silencer also wen it gows into 6gear it bogs and hes got to change down and gear up and its off

Thats not the stock carb so everything that was said is out the window. That carb is off a KX or CR 85, or (I forgot all the carb numbers) an RM or KX 100. Measure the inside throat of the carb (part that slides into carb boot before the reeds), if its a 28mm, came off an 85, if its a 29mm, came off a 100.

padget i mean i also have this carb its not on the bike is it aney beter ..your correct it of a kx80 i fink . i still have stock one on the rm is this one aney beter for my bike or should i stick to stock

05rm125 its all tightend up properly

how are your reeds, how's your compression, is your powervalve functioning properly, does your coil ohm out within service limits, is your stator timed right. there's a few things to keep you busy. my guess is low compression or coil.

itv fitted a new top end piston and rings .the stator is set to factory settings reeds look fine power valve moves as it should and it got a healthy blue spark iv checked all this allready ... i personly fink its overfueling .but its got a 40 pilot and a 122main arnt they ment to lean it ??

what did your coil ohm out at then?

thats the only fing iv not tested

just fine cuned the air screw and its fine now

itv fitted a new top end piston and rings .the stator is set to factory settings reeds look fine power valve moves as it should and it got a healthy blue spark iv checked all this allready ... i personly fink its overfueling .but its got a 40 pilot and a 122main arnt they ment to lean it ??

#40 pilot is to lean and #122 main is also to lean, if your jetting the stock carb. That jetting maybe about in the ball park for the keihin carb. If you want to use the keihin I would start tuneing with the factory jetting for the KX80. If you want to use the stock carb, then try the jetting I posted above, it works, but the bog will be there on the starting gate just teach your rider to do what I said on the starting gate and the bike will leave the gate like a rocket. The bike won't or should not bog out on the track if your rider is keeping the bike rmp up where it should be on a two stroke. Can't lug it around.

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