Carb Help Please

I have a 2005 DRZ125. How do I remove the white plastic retaining cap that is within the carburetor slide. I want to adjust the needle but I can't remove the cap to access the needle. It has a flathead slot on the top of it, but there doesn't appear to be any threads, so I'm not sure how to remove it.

Also, does any one know the thread size specs for the fuel screw. I had trouble getting the stock one out because who ever removed the cap from the bottom of the carb messed up the inside quite a bit causing the fuel screw to come out very hard. I would like to pick up a tap to clean up the threads before trying to put a new screw in.

Thanks for any help!!

The VM20 carb on your bike may not have a needle position other than stock... I know the 2006 and newer Mikuni VM20s don't. You can take an older VM20 and swap needles or just order an older model's needle if you need to make that adjustment.

I am assuming the throttle cable and spring assembly are out of the way leaving the black plastic tube with the enclosed needle assembly. The way to remove the needle is to simply find a soft surface (balsa wood or pine with a folded cotton rag) and hit the bottom (point) of the needle on that surface. The needle striking the surface causes the cap to pop up and give you access to remove the needle and it's assembly (clip and spring). The white cap is a press fit into a small groove. If the needle didn't come out on its own with the light thump you gave it, it should just slid out. On reinstall make sure that one of the holes in the edge of that plastic cap lines up with the throttle cable. It isn't difficult to reassemble, just be patient. Small hands work best.

As far as the fuel screw goes, you shouldn't have had to remove it unless it was damaged or you couldn't adjust it (cross threaded??). If the brass anti-tamper cap wasn't drilled to the exact same size as the opening, the left over ring of the cap acts as a retainer for the screw and spring if you over adjust. In your case you'll need to drill that hole with a bit the same size as the opening to clean the burrs. Drill it to the point where the threads start, go further and you'll need a new carb or loose at least some of the adjustability. Take the old screw to the hardware store to match the thread and pitch for tap. You'll have to order a stock replacement, nobody makes a replacement aftermarket version.

Hope that helps,


Thanks for the info, I would not have guessed that you need to lightly tap the bottom of the needle to remove the retaining cap, but that worked! Yes, I was trying to get the fuel screw to back out a few turns, when I hit the ridge from where the cap was removed. At first I didn't see the ridge and after a couple of attempts to back the screw out the head of the fuel screw got messed up. I figured that while its still cold here in NY I would take the little extra time to finish removing the old one, clean up the threads, and put a new one in. Thanks again

The Yamaha TTR-125 uses the same carb, but has an adjustable needle. You can buy it for about $20.

The Yamaha TTR-125 uses the same carb, but has an adjustable needle. You can buy it for about $20.

Not entirely true. As you can see by the sig, the family has both bikes - TTR and DRZ - and neither has a needle with more than 1 position. Sometime in the past three or four years, probably for the same reason as the brass cap over the fuel screw, the VM20 only came with a single position needle in TTRs and DRZs. If you order the needle from an older model bike with the VM20, then you may get the multi-position needle.

It's a crap shoot, but look at years prior to 2003.


The TTR-125 adjustable needle, which also works in the KLX/DR-Z125, is part number 5HP-1490J-00-00. Remember, this is a Yamaha part number, not a Suzuki one.

Create an account or sign in to comment

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

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now