1985 250r pilot screw adjustment

[k00leo]

I was doing some maintenance on the 85 250r yesterday and i noticed that the air screw was turned all the way in. I thought that turning the air screw all the way in, or all the way out make an atv cut off? The bike was running fine with the screw turned all the way in.




Now, I know that if you can turn the air screw (all the way in/all the way out), and it does not stall, then you need to go up/down on your jets, right?

The funny thing is, the bike (according to the owner) is "original" and completely stock. Stock silencer, stock pipe, should be stock carb.


This is my first 2 stroke so i am still learning. Can 2 stroke air screws be turned to each extreme and not have the bike cut off?




Once i noticed that the air screw was turned all the way in, i screw it out two turns, like the manual says. I rode it for about 30 min and it seemed like it was getting hot. Which i suppose it would, i basically leaned the mixture by turning the screw out correct?

For the 85 250r

to richen the mixture turn the air screw in, correct?
to lean the mixture turn the air screw out, correct?

The manual says pretty much the same thing, but it talks about the 86 carb, not the 85. I just want to make sure.



I suppose the next step would be to turn the screw to 1 turn out. Ride it, and see how it feels.

[dougspcs]

In is lean, out is rich..

You sure it getting hot wasn't just in your mind since you were paying more attention to it..

I guess the simplest way of checking the condition of you bikes fuel mixture is by checking the plug. Nice toasty tan color is best..black is too rich..white to lean/hot. 2 strokes usually tell you they are lean by popping/backfiring at idle before they get turned so far down that they quit.

If your plug is white on the tip..deal with it now. Not doing so will probably result in burning a hole in the top of your piston..

Check the plug, I'd start there..

[k00leo]

In is lean, out is rich..

I'm pretty sure thats wrong. On page 3-26 of the 1985 atc 250r manual it says that "Idle mixture can be adjusted by turning the air screw: turning it in richens the mixture, while turning it out leans the mixture." Is this the same for the 85 and 86 atc 250r carburetor? I know the two carbs are different.

I think your referring to most 4 stroke carburetors.

You sure it getting hot wasn't just in your mind since you were paying more attention to it..

This could be the case....

I guess the simplest way of checking the condition of you bikes fuel mixture is by checking the plug. Nice toasty tan color is best..black is too rich..white to lean/hot. 2 strokes usually tell you they are lean by popping/backfiring at idle before they get turned so far down that they quit.

If your plug is white on the tip..deal with it now. Not doing so will probably result in burning a hole in the top of your piston..

Check the plug, I'd start there..

I plan on doing this tonight, just doing some research before i do.

Thanks for the help.



Anyone else?

[dougspcs]

Sorry, I consulted 'A Manual'..he says you are right. Since this carb isn't equipped with a fuel mixture screw, but an air mixture screw.

Should have checked before I spoke..