A Partial Carburetor Reference Page

Why another carb page?

I recently rebuilt the Bing CV carburetors on my R75/5. Most of the truly useful information that was needed was already out there on the web, most notably is Jim Buchanan's carb page. There were a couple of little gaps in the coverage of this well-covered topic, and here are the ones that I found.

Where do all those O-rings go?

I purchased carb rebuild kit from Capital Cycle. In addition to the diaphragm, float bowl gasket, and enricher gasket, which are easy enuf to figure out where they go, the kit included a number of different O-rings and a tiny paper gasket. Here's where I put them:
item location
tiny red paper gasket vacuum take-off
large rubber O-ring main jet
medium large rubber O-ring throttle
medium small rubber O-ring enricher
2 small rubber O-rings idle mixture & idle jet

The screws are stuck!

You bet. And the ones holding the throttle plate on are supposed to be stuck. As for the rest, the best way to get them loose is by using an impact driver. Unfortunately, mine wouldn't fit into the slotted screws at the top of the carb! I managed to get them loose, and during the rebuild, I replaced all the screws with stainless. Unfortunately, the only metric stainless countersunk screws I could locate were Philips head -- but at least I have an impact driver bit which will fit these. Also, if in the unfortunate circumstance that I must drill them out, Philips are easier to do than slotted.

Countersunk hex socket head screws would be ideal, and rumor has it that they are available out there somewhere. Good luck. Here are the sizes of the screws needed to rebuild one carb:
Qty Size Location
2 M3x10 countersunk throttle plate
4 M5x16 countersunk diaphragm cover
4 M4x12 countersunk enricher cover
2 M4x12 socket cap throttle stop

M4x16 would be better than M4x12 for the enricher cover, but that's all my local hardware store had. I couldn't figure out what size the vacuum take-off screws were. New stainless M4 lockwashers accompanied the screws for the throttle stop.

Be generous and use anti-seize paste on all the screws, except the ones holding the throttle plate. Those have to be on very securely -- if one fell out, it would get sucked into the cylinder! Clymer recommends blue Loctite; the factory used long screws (like the ones listed above) and damaged the threads after installation of the throttle plate. To remove these screws, careful and prolonged use of a jeweler's file is required. On reinstallation, I tried to damage those threads the least amount required to insure they couldn't back themselves off the throttle shaft.

One final word: the phone for the Bing Agency is 316-862-5808.

Return to Roger's techpage.
Return to Roger's homepage.

Last updated Feb 13, 1997