Winter jetting

[pyromaniac]

Im trying to get my 00 rm125 to work good in my winter conditions by jetting.

-15 celsious 180 main 45 pilot. Starts first kick and works pretty good. The sparkplug is pretty white or a little light gray. The onlything is that it bogs down on the low rpm when i get into the snow. Its not normal bogging when it gets too much, it should work good.

An example, i do this long slide on high rpm, the slide gets sharper and sharper and the slower the bike goes. Finaly when the rpm gets down too much it makes this boooo sound. If i then straighten the bike up and try to gain speed by opening the throttle is just boooo. I close the thottle and open it just a little and when it finaly gets a little rpm then it jumps away to the high rpms pretty quick. I tried to use the choke and it doesnt change the bike much other than the idle rpm is higher.

What do you think this is, too lean pilot? too lean main jet?

 

[Studboy]

It sounds like your main jet is too small, I would go up at least 2 sizes and try it again. The bogging and white plug are tell-tale signs that it is too lean.

 

[marcusgunby]

Yep it sounds like its staving of fuel on full throttle-or mabe the float height is too low??

 

[pyromaniac]

Its really not on full throttle but it seems to be on more than 1/4 open. My next richer main jet is 188, i guiss ill try it.

Usually how do you change your jetting for the winter?

 

[atc3434`]

Pyro, your RM125 sounds like it runs EXACTLY like mine. Identical symptoms. Mines a 94, but its doing the SAME thing. Turning in my air screw helped some, but hasn't helped a ton. I think I need more needle and main. It does that same jumping right up once the rpms come up enough. I let you know how I make out with mine, keep me posted with yours. :)

 

[Chief]

Pyro,

We don't have the same bike. As temps drop the 1st jetting I do is going richer on the pilot. I've heard it said go up one size on the pilot for every 20 degrees F drop in temp. Going from 80 to 20 degrees f I raise 1 or 2 sizes on the main. (also been said go up one on the main for every 30 degrees drop in temp f) I found both to be fairly accurate. I raise the needle from 4th to 3rd notch when the temps range to avg 25f. Once spring hits and it starts to get gurgly at mid throttle I drop the needle back down again.

Like ATC, I have a hunch that raising the needle one notch will give you dramatic results. If it's starving at mid throttle, the needle is what you should check out.

The A.S. is a fine adjustment for the pilot. It gets me through when the temps start to change, When I have to richen up on the A.S. it's a sign that I think about going up one on the pilot.


Good Luck & Happy Roosting

Chief

 

[SndyRds]

Could it be carb icing?

 

[pyromaniac]

I changed to the 188 main jet. It was -20 to -24 today so it was pretty cold. Still the same problem but i think it may have been better, maybe. I'll try the needle. Couldnt it be the pilot thats too lean? The sparkplug is still white.

 

[Studboy]

Unless you are running 0-1/4 throttle around those turns, the pilot is not your throttle. If it is bogging out in the approx. 1/4 to 3/4 range, try lowering your needle clip a position (raising the needle) to get more fuel in the mid-throttle openings. Is it possible to do a "plug chop"?

 

[pyromaniac]

I tried a 48 pilot today and the problem were still there, the only difference was that the plug got black so i swiched back to 45 again. I raised the needle two steps but havent tried it out yet.

I'll do a wide-open sparkplug check, if its brown or black and i have the needle clip as low as i can then what? If its not brown or darker i guiss i try my richest main jet, 190. If thats not enought damn the bike gotta drink alot of fuel.

 

[Chief]

Pyro,

2 steps on the needle is overkill. If it doesn't work try just one.

You can probably accces the needle by loosening the boot clamps. Pull in the throttle cable, vent hoses, wires, etc so you can rotate the top of the carb towards you. If you give yourself enough play w/ the carb attachments you won't bend anything up. Make sure to put them back into position. Check throttle play, etc.

Just one more thing I wonder about, if this is only happening when the bike is leaned hard for a few seconds, it could be that your floatbowl is draining out during a slide...... ? Try leaning the bike at the same angle rpm and time frame while stationary and see if it bogs.

Chief

 

[pyromaniac]

Originally posted by Chief
Pyro,

2 steps on the needle is overkill. If it doesn't work try just one.

I think not cause it worked pretty good today when i tried it. It was only -5 so that can have something to do but hope not. I will try raise it even one more step.

You can probably accces the needle by loosening the boot clamps. Pull in the throttle cable, vent hoses, wires, etc so you can rotate the top of the carb towards you. If you give yourself enough play w/ the carb attachments you won't bend anything up. Make sure to put them back into position. Check throttle play, etc.

I tried that but it bends the throttle cable. I found a better that, just remove whatever its called that holds the airbox to the carb. Then press back the airbox rubber behind the frame. Its way eaiser this way.


Just one more thing I wonder about, if this is only happening when the bike is leaned hard for a few seconds, it could be that your floatbowl is draining out during a slide...... ? Try leaning the bike at the same angle rpm and time frame while stationary and see if it bogs.

No its not the leaning that does it. Its the same thing if i ride straight and have the same resistance.


Chief

 

[pyromaniac]

Ops kinda messed up quote and now i cant edit :( . Well hope you can see what i wrote.

 

[Chief]

Glad to hear you found the problem, hopefully.

Chief