1st Gen Carb Diaphrams

[MasterGuns]

There is a lot of posts concerning 1st Gen carb diaphrams being bad, how to repair them, how to replace them, places they may be obtained at varying costs, etc, etc. What I would like ask those that have much more experience than I concerning diaphrams on the lst Gen, is how does one know when one or more need replacing in the first place? What are the symptoms of a bad diaphram and should the diaphrams be regularily checked for issues? Also, if I were to find one bad can one be exchanged from a another set of carbs? Can only the diaphram be reutilized from another carb or would it be wise to exchange the entire assembly diaphram and slide together? Just curious. I don't have any carb issues at the present time but one never knows what the future may hold with a 20 year old bike.

[Condor]

There is a lot of posts concerning 1st Gen carb diaphrams being bad, how to repair them, how to replace them, places they may be obtained at varying costs, etc, etc. What I would like ask those that have much more experience than I concerning diaphrams on the lst Gen, is how does one know when one or more need replacing in the first place? What are the symptoms of a bad diaphram and should the diaphrams be regularily checked for issues? Also, if I were to find one bad can one be exchanged from a another set of carbs? Can only the diaphram be reutilized from another carb or would it be wise to exchange the entire assembly diaphram and slide together? Just curious. I don't have any carb issues at the present time but one never knows what the future may hold with a 20 year old bike.

 

The bench mark for replacement is, if they are torn, replace them. If they have small pin holes they can be repaired although some folks will replace. The only difference between the 83-85 diaphragm and the 86-93 is the air hole in one housing housing is bigger. Otherwise they're the same. I've repaired pin hole diaphragms with success using a product called Plasti-Dip spray. I guess it's time to whip up a tech page on the process.

Generally with the lid of the aircleaner off and reving the motor you should be able to see the plastic housing moving in the venturi of the carb. If one doesn't react in unison with the others, or not at all, it's probably bad.

You can exchange diaphragms from one carb to another as long as it from 1200 to 1200, or 1300 to 1300. Some guys have punched the hole out on the smaller...can't remember which series has the larger hole... and used it on the larger.

[Gearhead]

Generally with the lid of the aircleaner off and reving the motor you should be able to see the plastic housing moving in the venturi of the carb. If one doesn't react in unison with the others, or not at all, it's probably bad.

 

I would add that this can be hard to judge. Three of mine were pretty badly cracked and leaking, with the one good one having been replaced by the PO. I could not visually tell a difference by watching them dance.

 

Another classic symptom is bad top-end power. My top-end power was not that bad either, but I did certainly notice the improvement with the new diaphragms.

 

The slide and diaphragm come as an assembly and are put together with some sort of crimper. I don't know how you'd separate them without special tools.

 

Keep in mind that these are 20-yr-old diaphragms that are going bad. If yours are old and original as far as you know, remove the slide covers and check them, which is an easy job on this bike. Once replaced, they should last another 15 -20 years.

 

Jeremy

[Yammer Dan]

If they are moving like they should and you can't see holes take them into a dark room and use flashlight to check them.