Alright..Kind of a long story but here goes.

The idle mixture screw plug of my 97 was gone when I bought it. However, when I talked to the previous owner, he mentioned that he had taken it to the dealer after some backfiring problems and they "Fixed" it, so I a am assuming that after he complained enough the dealer removed the plug and turned the mixture screw out some. Anyhow, one k&n filter and SEII muffler later, it's beginning to run quite lean again. The mixture screw was so badly stripped (I guess from previous owner, I have never touched it), I managed to move it about 1/2 turn out and then it wouldn't budge AT ALL. After reading around here, I picked up some fluted screw extractors and after about 30 minutes had the damaged screw out, spring and all. When I tried to put the new screw in, all oiled up with anti-seize, I couldn't get it anymore than 3 or 4 turns into the carburetor body before it got tight. It was barely flush with the side of the carburetor. Upon some close inspection of the original mixture screw, it seems the threads were quite badly banged up, even with a small piece of metal wedged in one of them. I made sure to be very meticulous when drilling the screw for extraction, making certain all the shavings were gone before attempting to remove it, so I'm certain this wasn't from me. The threads are so tore up now however that I can't get the screw in more than a few turns at all. When comparing the two screws side my side, they are EXACT, so it's not the screw.

Now, after all that, my question. I took the screw up to the hardware store, and it looks to be M6X0.5 size, can anyone confirm this?

I am trying desperately to find either a high grade steel bolt that size that I can thread in and hopefully straighten the threads, or buy a tap from somewhere that I can use to make them true again so this new mixture screw will go in. I cannot seem to find a M6X0.5 bolt or tap around here anywhere, closest I can get is M6X0.75.

Any suggestions on how to get this fixed would be great, it's been almost 3 weeks since I've gone out on it.

If you can find any correctly threaded bolt or screw, use a 3 cornered file to make a simple tap out of it.  If you cannot find one consider using the old mixture screw as a donor tool and file it, you know it is correct. Max

Well, after trips to just about every hardware store in a 15 mile radius of me, and hours of internet searching I have still nothing solid.

A call to a local dealership basically yielded a typical "No we don't know the size, and no we can't fix it. Looks like you'll have to buy a new carburetor, let me forward you to the sales department".

I can't really use the original air screw as a tap because the threads are pretty messed up. The closest I have (still) found is M6 X 0.75.

I have found an online place(e-taps.com) that sells lots of very obscure taps and dies. Luckily they do sell a M6 X 0.5 tap, however I cannot for the life of me confirm this being the correct size. I took the new mixture screw to the hardware store and it will begin to thread into a M6 X 0.75 nut, but will stop after about half a turn. It seems M6 is the correct size, and when comparing the mixture screw to an M6 X 0.75 they look very similar though the mixture screws threads are slightly smaller, which leads me to believe M6 X 0.5 is the correct size, though I have nothing concrete and I'd hate to order that tap and destroy the carburetor body completely.

If anyone could confirm the size of this screw I would appreciate it greatly. I have found nothing online that even so much as hints to the size of it :/.

Chris9450 wrote on 12/31/69 at 16:00:08:


Idle mixture screw 6x0,5 mm ( Took the measurements of my spare carburator, lucky me)
Everybody should have one, cost me 20 bucks and 1 cleaning hour.

Greetz
Kropatchek 8)