Replacing Carb Drain Screws

Pernig · World Chat Champion Joined: 24 Jul 2006 Karma :

I would like to hear from people who have had to change the carb drain screws on their bikes, particularly old Yamahas with the philips heads that are the same width as the threads and are concealed within the float bowl.

How did you get them out? Am I looking at delicately drilling them?

And another question, I am looking to replace the screws with the external cylindrical type hex head, so I won't have this problem again, but I can't seem to find anyone in the UK who can supply these. Have you any ideas?

Thanks for your help.
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H100 Breaking for spares

finpos · World Chat Champion Joined: 13 Sep 2005 Karma :

You may find that this will become tiring fast.

The reason that the screw a) has no head and b) is made from cheese is because the end you can't see is conical and seals up into a similarly shaped seat. If you drill it out you will probably ruin the seat.

However if you want to fit something with a head (and presumably a soft washer) you may as well just drill it out and re-thread it, in which case any machine screw type thing will do.

f.

Pernig · World Chat Champion Joined: 24 Jul 2006 Karma :

finpos · World Chat Champion Joined: 13 Sep 2005 Karma :

I've not heard of the modified screws - In all honesty I've had so much trouble with these in the past I've adopted the policy that carbs do not actually need draining and now either don't touch the drains or glue the screw in with sealant if they leak!

f.