The slide holder is the large white plastic insert that the plastic slide fits into and on first inspection looks like part of the carb body. If you remove the carb top and then the the slide it can then be seen from the top of the carb. To remove it you simply loosen the main jet a couple of turns and then gently push the main jet up into the carb, the main jet is held in place by the emulsion tube and as you push the emulsion tube will pop free into the space blow where the slide fits. Keep unscrewing the main jet and pushing it to completly free the emulsion tube and then the white plastic slide holder can be pushed up and out of the top of the carb using your fingers placed through the front and rear bore of the carb. Under the slide holder you will find a 10mm I/D o'ring that should be then replaced. If people need o'rings i suppply a complete set of 20 Viton o'rings to rebuild all 4 carbs at £11 posted, understand that i make no profit from this and just want to keep as many of these bikes on the road (engine in one piece) as possible.

Chris.

Thanks Variable, I stripped off my carbs again (much easier this time ) and managed to locate the seal in question. The 10mm seal seems much thinner than the original.
However, the problem was actually the main jet o-rings i'd previously replaced had split, causing it to run rich.
I don't suppose you could give the me the dimensions of the four sizes of o-rings that I need?
Hopefully I can pick them up on my day off on Friday, and get back on the road this weekend!

Hi J, What ones do you need to know the size of.
Chris.

Hey Chris,
I was looking for the diameter and cross section of the four different types.
Tony's page is great but I was a bit confused about the exact dimensions of the O-rings needed. I got some BS011 and BS010's, the float perch was fine, but the jet rings seemed to be too fat (as in cross section). They split when I reassembled the jets, so it ran rich when I re-assembled everything, hence me stripping it down again. Should the ring go around the jet before it screws in?
Also, I was unsure of the idle screw ring sizes, I guess that 2.5mm OD x 1.5mm was about right?
The slide holder ring also seems to be narrower than the OE, but seems to fit fine.
As it is, i've got some more BS010's for the main jets so i'll see how we fair when they're fitted.

J
The o'rings in the float are 1.5mm thick and 7.5 and 5.5mm I/d and the pilot is only 1mm thick and 3mm I/D. You GOT to have Viton as anything else will go off very quickly and your pinching them due to wrong size or most probs not using any lub when rebuilding.
Chris.