Broken and stuck mixture screw - serious problem?

Pseudodeth

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Hi,

I recently got my carburetors off my bike for the first time and discovered that the tip of one of the mixture screws was broken off and really stuck in the carb. It wouldn't move so I screw the other one in as well to get even performance.

How will this affect the bike? Can it perhaps be compensated for by adjusting the idle screw?

It's a 78' by the way.
 
If the hole is even a little larger than what it should be the bike will not run right. I had the same problem with mine about 5 years ago and had to find another set of bodies. If the tip came out easy (no drilling or poking with another larger object) you might be ok.
 
Yeah, soft brass is soft. The needle could damage the hole, but the biggest threat is probably what you decide to use in order to get it out. I am pretty sure I have read about some people on here removing the broken tips successfully.

The idle screw will compensate for a plugged fuel screw, but it should not be used as a solution; you don't want to just bump your idle rpms to compensate for incorrect a/f ratios. The engine won't thank you for it.

Edit:

Thinking about this a little more I realized having a plugged fuel screw means you'll be running quite lean at idle. You could lower the idle, but it isn't going to be enough. I think this situation is sort of like running without a pilot circuit.
 
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Yep been there.

you need to grind a nail into a really fine needle and you have to punch out the brass into the carb. no point in trying to lift it. done it 3 times now and after a new pilot screw works ok. you can even just back off 1.5 turns just like the manual says :D

you will get high idle speed if you don't have your pilot system operational.

drewps
 
It does cough quite a bit which I guess could be caused by a lean mixture. I'll try to poke it out as soon I get access to a grinder or some other thin tool.

Does anyone know the name of the pilot screw? My local Yamaha pusher wants 20 euros for 1 screw which I find a bit steep and I can't find it on any european online shops.
 
I know it's an old thread, but I wanted to say that Drewpy's Suggestion was spot on! I probably would have destroyed my carbs had I not seen this advice.

:thumbsup:
 
So how about a screw driver ground down to a point? Just use a hammer with light taps till it pushes through?
 
you guys are "hammering" it out from the venturi side correct? How are you hitting it centered enough that its actually pushing back through?
 
you need to grind a nail into a really fine needle and you have to punch out the brass into the carb.
you guys are "hammering" it out from the venturi side correct? How are you hitting it centered enough that its actually pushing back through?

I am curious the of the direction as well. Drewpy, it sounds like you are pushing the need further into the carb until it pops out the other side, is this correct?
 
I had same problem, tip broke off and got stuck, but I actually managed to push it out from inside of the carb. Got few small scratches on the inside of carb, sanded them down with very fine sand paper and luckily it still works fine.
 
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