back 2 basics!

[03yam250f]

i recently purchased a '01 yz125. I am planning on a top end this weekend. Much is wrong with the carb though, sometimes it wants to bog, like landing off of big jumps, or holding it wide w\out shifting and after about 3-4 sec. of it being wot it hesitates, then starts pulling again. scary, i have a track in my backyard, and there is a 60ft. step up. and since all of our rain latley, there is a nice hole soft mud and deep water about 5 feet after the landing. well when landing off of this jump (3rd, 1\2 throtte) i go into a wheelie to keep the front end up out of the water....well it just bogs real bad when i try and do this. I need to know a good basic starting point for the carb, im guessing i has all factory jets\needle. i have messed with the air screw hidden right next to the boot AND with the (i believe) gas screw, the one that is asmall phillips head with the 8mm nut on it. So, clip positioning, how many turns out on the air screw, and where to put the (i think) fuel screw adjustment would be very much appreciated.
*&*on a 2nd note, i cant seem to get the carb spring out of the slide where the throttle cable connects. it seems to be jammed in the slide somehow, any thoughts on how to get it out? Thanks in advance guys.

 

[biglou]

I would start with the basics, like you said. Check the air cleaner-is it clean? Pull the carb, take the bowl off, hose everything down with a can of carb cleaner. Check the jets-pilot and main-what size are they? Stock size is a good starting point. Check your float height. Adjust if necessary. Check the clip position on the needle-put it at stock recommendation. Next, set the air screw at 1-1/2 turns out. Run it all the way in, then back it out 1-1/2 turns. Put it back together and try it out. Note how it reacts in different situations, and make adjustments from there. Sometimes just a thorough cleaning and adjustment can make a world of difference. Any tiny little fleck of dirt in a jet or carb passage can be a frustrating thing. Also, over time, people make multiple adjustments to their air/fuel screws and end up not knowing exactly where they are after several adjustments. I almost always run mine all the way in every time I adjust it. That way I know where it was, and where it is going to.

I can't help you with what the stock settings/specs are on your bike, but you should be able to find them somewhere on the net. A manual for your bike will have them, and is a great investment if you don't already have it. Good luck.

 

[atc3434`]

My '01 Yz has stock jetting, and is pretty spot on most of the time. Its a little fat on the bottom when its real warm out... but that keeps it pulling hard. I would say stock is a good starting point. The bogging after jumps and what not, that makes me think float level, and that its too low or too high. The bouncing around would definatly agrivate this condition. A thought cleaning and carb service will go a long way. Here is the link to Eric Gorrs carb guide... has TONS of good info... http://www.ericgorr.com/twostktech/carbtuning.html

Goodluck!