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Stripped Idle/Mixture Screw

Posted: Sun Dec 23, 2012 11:30 am
by Rut Row
I'm rebuilding the Mikuni BS32 carbs that came with the motor test stand I bought. They are/were in pretty bad shape. I'm also installing a DynoJet Stage 3 jet kit because I'm going to individual filters and the hack has a 4-into-1 exhaust system.

And of course, on the LAST carb I stripped idle/mixture screw. :barf: :foul: :censored: :rant:

I've tried heat and got it a bit further but the head is stripping so bad I'm fearful of doing more damage. :frustrated:

:cry2: :cry2: :cry2:

Anyone have a super-secret guaranteed way to extract it?

Re: Stripped Idle/Mixture Screw

Posted: Sun Dec 23, 2012 12:11 pm
by Wingfixer
If your not in a hurry I can stop by on Sunday, the 30th, to take a look. If I need tools I will be coming back by on Monday, or I can take the carb with me and bring it back.

Re: Stripped Idle/Mixture Screw

Posted: Sun Dec 23, 2012 12:54 pm
by Rut Row
Wingfixer wrote:If your not in a hurry I can stop by on Sunday, the 30th, to take a look. If I need tools I will be coming back by on Monday, or I can take the carb with me and bring it back.
I'm not in a hurry. I'm waiting on more parts to come in. I still have to modify the slides and replace the slide needles.

This rebuild is not cheap! :huh: it better last a while!

Re: Stripped Idle/Mixture Screw

Posted: Sun Dec 23, 2012 4:44 pm
by Damage Inc.
Kyler wrote: Anyone have a super-secret guaranteed way to extract it?
No...try soaking the carb or at least the srcew and surrounding area in rust penetrant, overnight. Then try the heat method..don't forget the the penetrant will ignite so wash it in water before heating. If you can get to the head or the screw you can use a hacksaw, or smaller blade to recut the screw driver slot.

Re: Stripped Idle/Mixture Screw

Posted: Sun Dec 23, 2012 5:57 pm
by Rut Row
tried the soaking (not overnight - in a can of hot carb cleaner) and heating and ... everything except this which is what the guys over on the Suzuki GS Forums recommend

Image

Re: Stripped Idle/Mixture Screw

Posted: Sun Dec 23, 2012 7:05 pm
by Longboardr
If the screw you're talking about is a philips head two things that can help are

JIS Screwdrivers http://www.webbikeworld.com/motorcycle- ... rewdrivers

and

Screw Grab http://www.screwgrab.com/

If you can press down into the screw at the same time that you turn the screw that can help immensely too. If you can put a screwdriver bit into a drill press, press down into the screw with the drill press handle while turning the drill chuck by hand you normally can get the screw loose if you have enough meat left in the head of the screw.

Re: Stripped Idle/Mixture Screw

Posted: Sun Dec 23, 2012 7:54 pm
by Rut Row
this is a slotted screw and I was pressing hard. The head is pretty far gone. I did order some screw grab though - that looks interesting.

Re: Stripped Idle/Mixture Screw

Posted: Sun Dec 23, 2012 7:57 pm
by BillyGoat
For releasing the screw, didn't I see in this forum that mineral spirits + brake fluid (or something like that) beat Liquid Wrench? Also I like to put the screwdriver in the slot then hit it sharply with a hammer to loosen it before trying to turn the screw. What's even better is if you have a manual impact wrench driver with a standard bit on the end. It's like an air impact wrench but it's manual and uses a hammer hit to both do the impact and to turn the bit.

Re: Stripped Idle/Mixture Screw

Posted: Sun Dec 23, 2012 8:08 pm
by Damage Inc.
Just be carefull with aluminum, brass and hammers

Re: Stripped Idle/Mixture Screw

Posted: Sun Dec 23, 2012 8:16 pm
by Rut Row
I think the fundamental problem is bad threads. One carb unscrewed easily. Two had issues and only came out by using a lot of pressure and twisting the screw back/forth as if I was tapping the hole. The last one hates me.

I ordered a M6-0.5 tap set. I'm retapping the holes (assuming I get the last one out).