Throttle stop screw sheared - options?

[Lord McThor]

The throttle stop screw is sheared off on my H100 and the bike doesn't idle (gotta hold the throttle open). I figure I've got two options, new (well, used) carb or somehow remove the stud and get a refurb kit. I can't find any carbs on the internet apart from a couple from America at ridiculous prices, I've emailed a couple of breakers so might have some luck with that though. Is there a way I could get the remains of the screw out?
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Honda CB1, Honda H100SD Cafe Racer

[stirlinggaz]

hi,
i presume you mean the screw on the carb body?
can be drilled out easily (usually brass ime) with hss or cobalt drill bit.
start small 1 or 2mm then work up through drill sizes till screw collapses on itself.
shouldnt take more tham 15mins.
then buy a replacement screw.
i have done it a few times with dellorto & mikuni carbs & spares are readily available.
cheers,
GAZ
PS : just looked at cmsnl, & im looking at right schematic https://www.cmsnl.com/honda-h100s-1988-england_model3444/partslist/E__1000.html#results its a mikuni carb,& its 9 euros for new screw, i presume you'll get it in UK for around same price. if your stuck, i may have one in my big box of carbs, which i have collected over the years (i have had umpteen 2 strokes) if you tell me size/thread. is it a 21mm carb?

[bikenut]

pic would help and any of the screw sticking outside of the carb??

is screw steel??

maybe heating carb to expand the alloy the alloy a bit and gripping " stubb" may release??

pics would help..........

i would suspect that drilling out ( left hand drill ) would be last resort..........for you.
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nuts about bikes

[stinkwheel]

If you take the carb off, remove the throttle valve and start drilling out the stub of the idle screw slowly and carefully, the drill will eventually bite and screw the stub further in.

Because it is in an open hole, it'll eventually screw all the way through and fall out into the throttle tube.

You might even have enough showing through to grip the inside bit with some needle nose pliers and unscrew it that way.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[stirlinggaz]

[Lord McThor]

There's not enough stub sticking out to get any sort of grip on it. Should be able to get some help drilling it out from my Uni's motor club, spose I might as well give it a shot, especially if I can locate a replacement in case things go awry. While I've got the carb apart is there any way to make the choke stay out? I've got to hold it out while starting as it just pops back in otherwise.

Cheers for the suggestions by the way.
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Honda CB1, Honda H100SD Cafe Racer

[stinkwheel]

You can take the carb off, clamp it firmly in place and drill it in a pillar drill. Really shouldn't be able go wrong doing it that way

There may well be a bit sticking out on the inside of the carb which is what I was meaning to grab hold of.

I used to put a clothes peg under the choke button to hold it on and clip it on the fuel line when not in use.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[_Iain_]

Bin carb, add fecking huge pitbike carb & pod filter.
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Please be aware that the above post may be full of complete nonsense.
Riding: '07 KTM Duke II, Baotian BT49QT-20 Driving: '88 Volvo 340

[bikenut]

:D as stated before, is screw steel??

check........as it may be brass........but its on a h100 so may be steel, cg125 idle stop adj screw is steel............

the idle stop adj screw will not simply screw straight thro and drop out on the inside as the inner hole is a different ( smaller ) diameter.......but check check and re check on yours.....your in uni you say, what you studying?? :karma: 8o)

pic of carb may help :D
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nuts about bikes