I noticed there is a washer ( or 2 ? ) underneath the spring, on top of the piston, whatˊs itˊs function? ( inside the vacuum area in the bell housing ) , I am missing a washer on 1 carb, is it a problem? If so anyone has info on their thickness?

Edited March 4, 201313 yr by bartsscooterservice

This thread shows how to reassemble SU's with lots of photos and exploded drawings.

http://www.classiczcars.com/forums/articles-our-members/43176-su-reassembly-step-step-%5Bpart-1-tear-down-torn-n-tattered-worse-wear-n-tear%5D.html

Cool, thanks Blue!

I noticed there is a washer ( or 2 ? ) underneath the spring, on top of the piston, whatˊs itˊs function?

There should be one plastic washer on each carb, and best as I can tell, that washer exists simply to prevent metal to metal contact when and if the piston rises all the way to the very top. When the piston reaches end of travel in the upwards direction, that's where contact is made.

About the sizes... I don't think the thickness is that critical. If you've got one in the other carb, can't you just measure the thickness of that one?

Most of our younger members bypass the search feature and ask direct questions......by doing that there is a TON of information that they are missing due to not searching. Not saying you are but it is the common error, IMO. There is tons of information buried in these threads and by looking - researching - and digging you will find a lot more info that just asking members their opinions. Now once you have researched and have a question any member would be more than willing to assist. Best of luck with your project.

I did look at the tech articles and use the search function many times, but couldn't find the exact info on that washer, just a exploided view where it's in..

There should be one plastic washer on each carb, and best as I can tell, that washer exists simply to prevent metal to metal contact when and if the piston rises all the way to the very top. When the piston reaches end of travel in the upwards direction, that's where contact is made.

About the sizes... I don't think the thickness is that critical. If you've got one in the other carb, can't you just measure the thickness of that one?

good point, will do..thanks

Problem fixed, it runs, no leaks from carbies.

Problem fixed, it runs, no leaks from carbies.

What did you do? Just to finalize the thred

http://www.classiczcars.com/forums/help-me/43311-rpm-650-balance-screw-set-unisys-flow-even-mixture-knob-disks-need-many-turns.html

Here's a thread that has the temp/altitude mix setting graph from the FSM, along with some good comments.