can not remove idle mixture screws

[Nessism]

I'm rebuilding a set of 1150 carbs at the moment and the tunnel isn't threaded all the way to the top. This makes sense since Suzuki pressed a cap into the tunnel to discourage messing with the mixture (for emissions reasons).

Not sure what to suggest other than keep trying. Hopefully you are getting a good feel for how much force can be applied before stripping the heads on the screws. At some point you may have to gamble and use a little extra force and hope for the best.

A fix for a damaged pilot screw slot is to cut into the tunnel with a dremmel cut off disc and cut a new slot in the screw. You have to chop off the top section of the tunnel first for obvious reasons. There is no harm in doing this other than cosmetics so consider that your back up plan.

[old_chopper]

You might try turning the screw all the way in and chasing the top threads with a tap. I THINK it's M4 x .7 but wouldn't guarantee that.

[hampshirehog]

You might try turning the screw all the way in and chasing the top threads with a tap. I THINK it's M4 x .7 but wouldn't guarantee that.

It's M6 X 0.5. Might be worth a go though getting the ends of the thread to match up will not be possible.

I would wind the screws out as far as they go and measure. Then using a depth gauge drill slightly oversize down to that depth and then unscrew. You don't need threads all the way down to keep the things in.

[karllmt]

Ebay/new carbs would be my first suggestion.

This was my first thought also. I may try drilling or threading suggestions as well. SPCHIPS has a set of carbs for sale (for parts) from a 81 650. http://s94.photobucket.com/albums/l1...650GL%20Parts/ Does any one know if the bodies of his are the same as mine (80 750) ? Last year I bought a bank of carbs for spare parts, but turned out to be not compatable. Mine seem to be exactly like the set in the carb cleaning series; which I am using for most of my instructions.

[karllmt]

to change carb bodies, or drill away?

This was my first thought also. I may try drilling or threading suggestions as well. SPCHIPS has a set of carbs for sale (for parts) from a 81 650. http://s94.photobucket.com/albums/l1...650GL%20Parts/ Does any one know if the bodies of his are the same as mine (80 750) ? Last year I bought a bank of carbs for spare parts, but turned out to be not compatable. Mine seem to be exactly like the set in the carb cleaning series; which I am using for most of my instructions.

I heard from spchips. He said the bodies from his '81 650 are the same as my '80 750. Can anyone else confirm this? I'm hoping to go look at them; he isn't too far a drive.

[Tom R]

I had this problem on my 1100's carbs. The PO buggered three of them up pretty bad, and the other one really bad. I used a 1/2 or 7/16" drill bit and cut away all the material (and bad threads) until the bit just touched the top of the mixture screw. Then I filed it flat by hand, which went pretty quick, before I turned a thin file on its edge and cut a new slot in the screws ( and carb body) - and presto! The screws are still kinda buggered, but they're out.

[karllmt]

Bet you folks thought I had given up - No Way!

So, here's the up date. I now have one of the stuck screws out. I improvised on the "drilling" suggestion. Turning the screw in as far as it would go I used a 5/16" bit to enlarge the hole. This made no difference, backed out a couple turns and stopped. At this point the slot in the screw was, well screwed. Rather than grinding the top off and using a cut off wheel to cut a new slot; I used a 7134 Diamond Point Dremel engraving bit, and reamed the inside of the tunnel around the top of the screw & using the same bit, carved a new deeper slot. This gave me another turn, but still not out. Then I realized that the tunnel and slot was now big enough for my impact driver bit. So I gently tapped away and presto! It's out. I still have no idea what was holding it up. After reaming the tunnel there were clearly no damaged threads in the way. Well, today I'll start on the next one.

[snicrep5]

same problem

I just had the exact same problem. Got used carbs from salvage place, Insides were beautiful. However three of the mixture screws wouldnt budge. Heres whart i did:
1. soaked them over night in wd40 and tried snugger screwdriver tip, just messed up the screw head more.
2. repeated #1 with heat this time. Didnt work. Ive had alot of experience with frozen fasteners, (I called myself the master extractor).
3. I drilled out one of the screws to accept an extractor, used heat and wd 40. This in retro spect was a mistake. Of course it broke off, making it nearly impossible to drill out.
4. In the mean time I gradually drilled out the other two with the intent of rethreading them if I could find a tap in that size. I went up larger bit sizes at a time and to my suprise the remaining outer part of the drilled out screw came out with the bit and the threads were ok. I just had to coax out the needle part of the screw.
5. Back to the broken easy-out (not). I cut away enough of the tunnel as someone else suggested, so I could get vise grips on the easyout. I used the smallest bit I had to drill around the broken easy-out, to give it wiggle room. And lo and behold it finally came out. I then used the method I used for the other 2 which worked. It looks a little chewed up on that one, but the screw threads down in fine. It remaines to be seen if its going to adjust well due to any bad sealing but looks ok. Ill just apply a blob of silicone when Im done to protect the adjustment.
The caps the factory put on them helped keep out the weather which leads to the seizing. So we sould at least apply some antiseize to the screws and/ or cap off the hole where they reside. if screws were brass this wouoldnt b a prob. youll have to drill and dont use an extractor. good luck