mikuni fuel screw problems

[brainrush]

This relates to a gang of vm22ss's on my 78 GS550 E.

so I decided that it was time to properly rebuild the carbs, but the gorilla of a "mechanic" who owned the bike before me got there first. After clearing out the air screws, I went to work on the fuel screws to find 3 of the 4 fuel screws blunted by the previous owner. in a way its a relief because now I know why the carb was only running with the choke, but here's the problem, on all 3 the tip broke off inside that passage way.

So here's the deal, I don't have a drill bit small enough to drill out the old needle without damaging the carb. and I can't make a tool small enough that'll fit inside the venturi to push it out. So here's my plan: apply a very small ammount of epoxy (weldit / jb weld / 5 min quick epoxy etc.)to the tip of a tool and let it set against the brass, effectively bonding the two, then when the glue dries, try pulling it out.

Am I crazy? Will I ruin the carbs even more? because the only other foreseeable option is to show up at my dentist carbs in hand.

 

[Steve]

Stop. Before trying anything drastic, use your finger.

No, not that one.

Feel inside the carb throat where the screw should be. If you can feel the tip of the screw, just take something small and hard, roll it across the tip, it might just push it through. I have used the round blade of a Phillips screwdriver, but you could use a socket or anthing else that is round, hard and smaller diameter than the carb throat.

.

 

[hampshirehog]

3 things that have worked for me (in addition to the one Steve describes - that works too and it's easiest).
1. Boil the carb in a sauce pan - some times those tips will fall out.
2. Use a darning needle as a punch (a gentle punch - you don't want to booger up that hole).
3. Compressed air. Make a good seal round the tip and give it a few shots of 120psi. Make sure you get a good seal around the hole.

 

[brainrush]

the socket didn't seem to work... using the darning needle, I'd be pushing the tip through into the carb throat? same question for the compressed air.

 

[hampshirehog]

push from the top of the carb so that the tip falls out of the bottom.

 

[hampshirehog]

Just added a bit more to be clear. don't push or blow air in the hole where the rest of the screw cam out - you'll only jam the tip in more. Push / blow on to the very point of the tip from inside the carb.

 

[brainrush]

no luck, what's worse, the very tip of the darning needle broke off when I had it in the throat of the working carb to measure fit, and I sneezed.

This is going to be a looooong day.