Needle jets -wrong threads???!!!

[uebe]

The bike is an '83SH with stock BS34 carbs. I bought OEM needle jets and mains from Mikes. (Someone had buggered up the old jets.). The new mains will screw into the old needle jet, but not into the new one. The new needle jet appears to match the old - both are Y-0. I can thread a different screw in, so the threads aren't damaged. Is it possible the the new jets were simply threaded wrong?
Any insight?

 

[angus67]

mikes prolly sent you the wrong ones. and mikes dosnt sell genuine mikuni parts. Most of us get the good stuff from jets r us, or niche cycle source.
If you have too, go to a dealer. But get the right part number. If you tell them what your working on, they wont help you. but gladly sell you a new bike. Some dealers are cool with this, but most aren't.

 

[5twins]

It's very possible your new jets are threaded wrong. Will a standard M5 bolt or screw easily thread in there? A standard M5 thread pitch is .8mm. Mikuni mains use a slightly finer .7mm pitch.

 

[uebe]

Thanks guys. You nailed it 5twins. Perhaps I could make some earrings out of them.