pilot screw thread pitch

[joe1856]

Does anyone know what diameter and pitch the pilot screw is? Ive got an 80 850GT. The threds on one of my carbs is messed up. When i took the screw out to clean the carb it brought some of the threads with it. I got it out though, now if i could find the right size tap I can chase the threads, get a new screw, and dont have to junk the carb.

[Detroit Diesel Man]

I would take a good screw out of another carb and go to your local hdwe store or auto store and see what nut fits..easoest way to find what thread it is.



DDM

[SqDancerLynn1]

4mm .7 thread I think

[joe1856]

Thanks ill try the 4mm x .7. None of the hardware stores in my area had anything with the fine pitch thread that it is.

[joe1856]

Well its not 4 mm. I have determined that it is 6mm but i still dont know the pitch .7 isnt fine enough. Im thinking that it might be .5 or something like that. Im still searching.

[Flyboy]

Yes, that thread is very fine indeed, to track down something like that you will have to find a dedicated engineering supply, I am afraid your normal hardware/motor/tool shop won't have it.
You will probably find that the tap will cost more than a good second hand body, but I hear you, I am not one to chuck something that can be saved.

[joe1856]

I was thinkin i might try 6mm x .50. That screw on z1 looks exactaly like mine except steel. thank you. I found a tap from victornet.com for $3.30. they need a minimum of $25 for an order. guess im going to see what else I can add to my tap assortment. Thanks every one. Ill let you know how i make out when i get the tap.

[joe1856]

Thanks guys. I ordered a 6mm x .50 tap from victornet.com. the tap was only $3.30. the only catch was they have a $25 minimum. O well good excuse to order some other odd ball thread sizes that ill never need or only need once, but ill have them. Ill let everyone know how i make out when i get the taps. Thanks to all for the help. This web site has helped me out many times over.

[joe1856]

Well it is definitaly 6mm x .50 thread. I ordered a tap and a die. The body of the carb rethreaded without any problems. These carbs did have the caps on them but and I removed them. No lip at the top. I used the die to clean the threads in the steel stock screw also. I hacksawed the grove in the top of the screw deeper because it was almost striped out. ran the die over it to clean up the threads as i cut into them to make the slot deeper so i could get a good bite on them with the screw driver. For $35 buck for some taps and a die I salvaged a perfectly good carb and have some extra taps for other odd metric threads. Now the screw turns in and out like brand new. Thanks for all the pointers everybody. Now im gonna do a full dissasembly, dip and rebuild. Ive already got the oring kit from Bob Barr. What a deal. Hes already done the hard part of sourcing out all the orings. Thanks again.

[joe1856]

Ill take a look at the idle screw tomorrow and see if its the same.

[joe1856]

The thread on the idle adjustment is 5mm x .50 just a little smaller than the pilot screw. I also have had the pleasure to find out the thread size of the pilot jet its self. The jet stuck and i had to drill it out. Same carb the pilot screw was messed up in. That thread is 5mm x .80. Saved the day again. Thanks.