Ok, i have a 2002 xr50. It came with the spark arrestor removed and the air box taken off (filter still there). The needle is on the richest setting (clip on the lowest position) and it runs fast, but when i crank on the throttle there is a horribly bad low end bog that will make the engine die. I tried going up to 60 jet but that didn't help and caused my plugs to foul out so that's too rich. I put it all back to stock (but the spark arrestor) and I lost all the power i had and i still have the bog. This is way more than the normal lack of low end cause i rode a stock fiddy the other day and it didn't do what mine does. What is wrong and what should i do? I have a brand new plug on it and i just cleaned everythign out on the carb. If i try to lower the needle to make it run leaner the engine idles super high and i can't get it to stop.

thanks for your help

 

Go search on ThumperTalk.com forum... or try the sanomx.com forums.

there are jetting posts there. Might be your air screw.. or you might have to change jets an move the needle. I can't remember the specifics for the stock bore and stock carb.

I can tell everyone this though:

If you get a Takegawa 88cc S-stage big bore kit.... toss the main jet that's in it (92) and replace it with the smaller one provided in the kit(85). This will eliminate the cutting out that occurs at full throttle. I live at sea level too. So the settings that come with the kit are too rich.

 

thanks for the info on the 88cc kit


anyone know anything about this bog though on my stock motor? i've tried every setting and it still does it.

 

I know you said you cleaned everything out in the carb but did you make sure you could blow air through all of the passages? No vacuum leaks around the carb insulator? What air screw and needle settings?

 

i sprayed stuff in all the passages and fluid passed through them all so they are cleared.

I don't know about that vacuum leak, how do i check that? and what is the insulator? is the black spacer? I don't think i have a leak around it.

I've tried every setting on the needle and and screw. the only setting on the needle that i can use is the most rich (clip in lowest position) because it will idle damn near full throttle if i try to lean out the needle.

 

You should try to clean out the carb again and make sure you can blow compressed air through all of the passages. Afterwards, set the needle clip to the middle and the airscrew to 1 1/2 to 1 3/4 turns out. When you have the carb off you can check the insulator between the intake and carb for cracks or a missing O ring.

 

no cracks and oring is good. I checked everything and did the settings and still bog.

my friend's dad said that the valves might need adjusted. He said his minibike bogged when his valves got too tight cause it wasn't letting the exhaust flow.

What are the valve clearances for the 2002 xr50?

 

.03~.05mm

 

thanks, i'm gonna try that today.

 

any luck ?? if it is from idle it would be the pilot jet or clean the air filter if it is exposed cuz of him taking iff that cover it can dirty really easy also my spark plug cap kep[t on com,ing lose and it would cut out so checkl ur wires in there ... hope this helps

 

i'll try a new filter.

after he blew it with high psi air it's working better but still a little bog and the plug is a sewty black looking.

 

no valve clearance is going to make the bike bog. air filter or jets can do this . take the whole carb apart and clean all jets ..

 

i took it all apart and cleaned everything. It runs better but still has a dead spot. not the killer bog that it had, just like a loss of low end.