Jump to content
Sign in to follow this  

125 fuel screw problem

Recommended Posts

we all know how fun these carbs are, but just when it get it idling right and starting easy the fuel screw vibrates it's way almost all the way out and wont idle or even start. i'm just going to torque strip it to keep it in place.But i dont get it, shouldn't it idle high when the screw is further out.

has anyone else had this problem. also, how many turns from bottom are you guys running on your idle and fuel screw. i think mine were at about 2.5 each but not sure.

Share this post


Link to post
Share on other sites

The idle screw and fuel/air screws are different. So the fuel/air screw adjustment wont affect the idle. I have never had your problem but I would replace the screw. See the cool ones that are in the parts store on this site. Also go to the sticky at the top of this forum for your settings. Very informative and spot on.

Share this post


Link to post
Share on other sites

the parts store here is a little to corn-fusing for me. i found one on ebay but i dont like to order stuff online. i'm going to check out the local shop this saturday. but i think it's not idling/starting because it's getting way too much fuel.

Share this post


Link to post
Share on other sites

35 Ki you need to check the sticky! I think you need to start at 1 1/2 turns on the screw. Have you ever done any carb work to the bike?

Share this post


Link to post
Share on other sites

yeah i done pretty much all the free diy mods and re-jetted the carb from the sticky. i was just trying to see if others have had this issue.

Share this post


Link to post
Share on other sites
we all know how fun these carbs are, but just when it get it idling right and starting easy the fuel screw vibrates it's way almost all the way out and wont idle or even start. i'm just going to torque strip it to keep it in place.But i dont get it, shouldn't it idle high when the screw is further out.

has anyone else had this problem. also, how many turns from bottom are you guys running on your idle and fuel screw. i think mine were at about 2.5 each but not sure.

There are two types of screws for 0-1/4 jetting on a carb, fuel and air screws. Air screws are on two stroke engines, they allow an adjustable amount of air into the system. Turning the screw in will richen the mixture, turning it out will lean it. Richening the mixture will drop idle speed, while leaning it out will increase it.

This is the opposite for four strokes, such as your bike, that use a fuel screw.

Share this post


Link to post
Share on other sites

I have had the issue. But here in california it may be a little different. Of course its cold blooded so if its been cold I would try and kick it a bunch before hitting the magic button. My problem was bad gas. I changed it and it fired up and ran great. The jets can get clogged in just a month or so and if the weather has been real cold then it may happen quicker.

Share this post


Link to post
Share on other sites
There are two types of screws for 0-1/4 jetting on a carb, fuel and air screws. Air screws are on two stroke engines, they allow an adjustable amount of air into the system. Turning the screw in will richen the mixture, turning it out will lean it. Richening the mixture will drop idle speed, while leaning it out will increase it.

This is the opposite for four strokes, such as your bike, that use a fuel screw.

Not necessarily true. Some 4-stroke carbs use a air screw, like my Kitaco Mikuni VM26 carb. You could say it's a modified 2-stroke carb and I won't argue that, but it's a four stoke carb now.... and rips. Basically, if the screw is behind the slide it's a air screw and if it's in front it's a fuel screw.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×