Mixture screw threads

[bobzdar]

I'm having some trouble getting the mixture screws to properly seat in 2 of my carbs. One side will thread in a few turns and then gets difficult to turn, the other will not even catch. I took an LED flashlight and looked at them and it looks like the threads need to be cleaned up. Does anybody know what I can use to clean the threads? It seems like it'd need a special type of thread chaser/tap to fit in there and I don't want to mess the threads and/or pilot screws up any more by trying to force them in. The bike will run with the one screw partially in and no screw in the other hole, but it (obviously) doesn't run very well.

BTW, the mixture screws are new and work fine in the other 2 carbs, so it's definitely the threads in the carbs themselves that are the problem.

 

[naughtyG]

It's a very fine thread so it might be difficult to locate the appropriate tap, which really is the preferred tool to chase a thread. I'm sure Sean Morley would know the actual thread size.

Other than that, I guess you could try a soft tiny brush on a dremel at low speed?

 

[tugla]

you try a little lube or wd40 on the screw first. i had the same issue and that totally helped it when putting it in. try it without the spring on just to make sure it will thread nicely all the way down.