Cleaning Carbs

[gggGary]

5Twins got the seals and screws Yesterday you are the bomb! I had the shaft out of a 34 so tried them on it they fit great but it looked like there was room for two in the recess so I put in 2 on both sides seems to work great on the 34 that way Don't know if there is room for two on each side on the 38s but I guess I will find out soon.
Now the $64,000 question; how do you get the throttle plates back in and tight and not have them bind!

While searching to find this thread I found an old thread from 650rider and sure enough XSJohn pops up and says "5twins sent me some seals he got from Mcmaster Carr....that's all I know about them....maybe you could chase him on 650 Garage...running them now and they seem to work.......see if you can double the seals if there is room.....like I said on another post 2 would be better than one.....just getting into this idea and on the left on my Bs34's 2 will fit and work......"
That is too spooky. John you are the man!

 

[TwoJugs]

Mcmaster is where I got the 4mm nylon screws for the Reg/rectifier mod that is popular. I still have about 96 of them left.

 

[XSLeo]

I picked up a metric set of Nitrile o-rings at Harbor Freight. #97 pieces. ID sizes from 2.8 to 47.7 mm. OD from 6.6 to 54.7 mm Section diameters of 1.9 to 3.5 mm. I think it was like $9.99. Just checked the site, on sale know for $7.99. I figured they can't be worse than some of the rubber parts from our favorite parts supplier.
I have used them in quite a few places on the bike. Float valves, needle jets, other places I can't think of right now.
Even if they aren't the greatest parts, it's nice to have a variety on hand. If I have one that fits I know just what size to order a better one for it, if and when it fails.

 

[weekendrider]

gggGary
Don't completely tighten the screws till you've snapped it shut a few times to center them.

 

[5twins]

I'm not sure doubling up the seals is a good idea. They work by vacuum. They fit loose on the shaft and in the hole, get sucked tight into the body and against the shaft by the vacuum through the main bore. In fact, the ones I sent you are Viton rubber which is about 5 points harder on the Durometer scale. In this case, the softer Buna-N ones might be better. I noticed that cycle o-ring place you linked to sells the Buna-N ones. Apparently, they're all that's needed for a carb o-ring. I went with the Viton ones because they had a higher temp rating and supposedly better oil and chemical resistance. I'm thinking now that Buna-N may be better because they're softer.

OK, on to proper throttle plate install .... Like WE said, you need to open and let the plates snap shut several times. Also, you have to back the idle speed screw off so it doesn't touch the cable arm, so the throttle plate can close completely. Install the plates just snug, then install the return spring and other brackets. This is the secret or "trick". When you install the return spring, it pulls the shaft towards it slightly. If you already have the plate tightened, it can bind against the side of the bore. So ..... throttle plate snug, spring and cable arm installed tight, idle speed screw backed off, open and let snap shut several times, tighten butterfly plate screws the rest of the way. Check your install by holding the carb up to a good light and looking through the bore. You should see no light around the plate in the bore, it should be completely closed.