bogging in 1st and 2nd

[quadracer585]

I have an 87 trx250r I recently purchased and am mixing 32:1 with caster927, its bored 10 over, port polished, boysen reeds, paul turner pipe and silencer, hot rod crank and connecting rod. It bogs in first and second upon acceleration, not sure if this is a carb issue and was wondering if anyone had any thoughts

[86 Quad R]

it's possibly a jetting issue but before tackling that, you'll want to make sure all else is ok with the carb before hand. i/e the float is set properly as well as making sure that the float is shutting the fuel off as it should. the slightest trickle of fuel once the float shuts off can give you fits while try to jet.


does the bogging take place after an initial cold start/warm up or does it do it once it's good and warm and allowed to sit a couple minutes, then start the engine and ride some more? also, does it clear out and run ok after you've run through the gears a bit?

[gandgracing]

Whats your gearing and tire size?

[quadracer585]

it's possibly a jetting issue but before tackling that, you'll want to make sure all else is ok with the carb before hand. i/e the float is set properly as well as making sure that the float is shutting the fuel off as it should. the slightest trickle of fuel once the float shuts off can give you fits while try to jet.


does the bogging take place after an initial cold start/warm up or does it do it once it's good and warm and allowed to sit a couple minutes, then start the engine and ride some more? also, does it clear out and run ok after you've run through the gears a bit?



It bogs all the time, doesn't matter if it's been running a while or not. It doesn't seem like it wants to clean itself out.

[quadracer585]

not sure about gearing or tire size cause i just bought it but not sure why that would matter with a bogging issue. Can you clarify?

[86 Quad R]

does it smoke excessively and have a weird smell?

since ya just got this thing and are unsure, id suggest a leak down test on it while your at it. i've seen cases where the slightest bit of tranny oil being drawn in would cause this. just a thought. :cool:

[Motofool250r]

unproper gearing and tire size could make it bog in low gears

does it have good strong compression and a leak down test good to go?

new spark plug, cleaned carb and have you checked or changed the pilot jet for low speed accelleration?

[quadracer585]

does it smoke excessively and have a weird smell?

since ya just got this thing and are unsure, id suggest a leak down test on it while your at it. i've seen cases where the slightest bit of tranny oil being drawn in would cause this. just a thought



yes it does smoke. Doesn't seem like its not cleaning its self out. I would say it smells weird dosen't smell like caster 927. also it dont like to clean its self out in the powerband just gets loaded up. not even sure if i am mixing it right.

[quadracer585]

unproper gearing and tire size could make it bog in low gears

does it have good strong compression and a leak down test good to go?

new spark plug, cleaned carb and have you checked or changed the pilot jet for low speed accelleration?



i dont know just bought the thing i did the topend gaskets and such. also checked the ring gap seemed to be good. so i just replaced the topend and base gaskets. i have whent through so many plugs already cleaned the carb but never adjusted anything inside the carb. not sure how to do that i am new to this hole thing.

[RyanWsly]

Duncan Racing used to have directions on jetting on their site, it will walk you through the process. Idle screw set to high out will make it run like it's on choke on a PJ style carb like the stock one, same mechanism operates both, screw it down and start over. Retainer that holds needle in slide should be snug, if it gets loose, floppy loose, it will run bad on bottom and midrange. checking float height was already mentioned, don't ignore that, do it or have it done, it's very important. Funny smell is bad, smell like burning engine oil or gear oil, will depend on what you run in low end of engine, if so crankcase seals could be bad, test it as previously stated. pilot jet should be around 50ish or higher, main should be 160ish clip on needle 4th or 3rd position, just general reference points for you in case someone has put crazy jet sizes in for some reason. needle taper may also be a factor, may check and see if number on it is correct if it has one.

[86 Quad R]

ryan purdy much covered it. start with checking the float level and those jet numbers and needle position as stated. then re-assemble and make sure the pilot screw is around 1-2.5 turns out. if it still runs the same, put the next smallest pilot in and retry and so on.....