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If you've had problems positioning the rubber diaphragm in the groove after you've changed a needle or added a shim this tip should help.

In cold weather the rubber expands and is a sloppy fit in the groove, you can get it roughly positioned and put the chrome cap on, but the cap pushes the rubber out of the groove and you start again and again and again.

The simple fix is to take the slide and position it on top of a central heating radiator for ten minutes. Within a few minutes you can see the rubber diaphragm contracting and taking shape again. When the slide is very warm, but not to warm to touch, take it back to the carb, ensure the dimples on the slide are facing the rear and insert the slide in the carb body. You should now be able to position the diaphragm with the groove in the slot all the way round and then carefully lower the chrome cap in to position. Once the chrome cap is in postion, keep pressure on it until you have at least two of the screws tightened.

Good Luck
 

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Great advice Pieman!!

Only yesterday, while fitting Thrux needles, I had the same problem.
When you replace the slides/diaphragms in warm weather they seem to go back no problem,
but when your doing the job outside, when its only +3 degrees, the rubber seems to have a mind of its own!

10 minutes in the boiler cupboard did the trick!!

(I guess this wont be a problem for those guys with heated garages!
Something I dont have!!)


V.
 

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FWIW the slides are directional & will only fit in the correct orientation. As far as the diaphrams go, a few seconds with a low temp heat gun should accomplish the same result as above. I haven't personaly experienced the need to do it.
 

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I just brought mine in the house over winter! :D

It's a darn handy tip though, and not one I was familiar with. I will link it in the tech sticky!
 

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Or leave the rubber diaphragm in place. It doesn't have to come out to get at the needle and shims. A pair of slim long-nose pliers is helpful here, and maybe a slim magnetic pick-up tool to take out the shim(s).
 

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Or leave the rubber diaphragm in place. It doesn't have to come out to get at the needle and shims. A pair of slim long-nose pliers is helpful here, and maybe a slim magnetic pick-up tool to take out the shim(s).
this is what I do. It's a little frustrating and right before you finally get it you'll be saying to yourself, "i should take the tank off to see better". The magnetic tool is critical for picking up the shim. Too bad the needle head isn't magnetic.
 

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One of the diaphragms on my America went right on, the other one not so much. Tried heating it up a little (although I was nervous about melting it) and it wouldn't help. One side would always slip off. I ended up putting a small amount of grease in the groove in order to make it stick just a bit. It worked to get it on… Would that damage the diaphragm? Doesn't seem like it would prevent vacuum.
 
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