TOPIC:

Kawboy: Can you "mic" your spacer. Confirm my measuring which is:
.020" thick X .511" i/s X .670" o/s
OR
.5mm X 13mm X 17mm

The O/S diameter is additionally critical as not to contact the needle-slides.

Hi Scotch,

Thanks for brothering up. I always like to give a laugh up at my expense. (Why else am I here)

Mic'd up the spacer @
.021" thick,
.512" I.D. (12.994mm)
.666" O.D. (16.90mm)

Just a thought, I have a few fiber reeds kicking around from some old 2 stroke reed cages. Going to mic them up for shits and giggles. Same material I think. Definitely gas compatible.

Thanks kawboy. He who laughs first has never owned a '1300". He who laughs last (probably) has.

So the big question is: "Are the spacers really required"?

Best answer would be in the form of a comment: Mikuni put them in there for a reason !

Since suggesting in my "79 Rebuild" article that the spacer is likely to prevent metal-to-metal wear between the raised "resting" area and the needle holder, I've just today discovered what I believe to be the real reason. The "plug" at the bottom of the vacuum-tube bore is "pressed" in. From the float side it's the round thing in the middle of the body with the 2 "cir-clip" pliers holes. Except they're not cir-clip pliers holes. They're holes used in the assembly process to orient and hold this "plug" as it's pressed into place. I believe the raised "resting" allows the center vacuum slide to be all the way down but not come in contact with this plug (by mere thousandths). The spacer may very well have been a supplement to that needed clearance AND additionally prevent metal to metal contact and wear at both ends of the tube.
I just took my "bench" carb-body and pressed this plug out of the body (just to see what it's all about). The picture clearly shows this plug in place. I'm not showing pictures of it removed because I do not want anyone to believe it's removal is part of maintenance. It was never intended to be removed for any reason and that's the way it should remain. Sure as shit: 1 picture of it removed and some would be pounding it out, screwing it up and replacing it incorrectly. (It's correct orientation is critical because this plug is ported to match those in the venturi. It's these ports which supply vacuum to the diaphragm.)

So my answer would be YES, the spacers are required.

Agreed, they're there for a reason. I've been searching on the net and found there are some reed valves out there with a thickness of .021" I've got 4 sets of reed cages for Yamahas and I'm pretty sure I'll find a reed close to the thickness. It'll be a pain to make washers, but I'll get 'er dun. (and they will be pretty)

Thanks for your thoughts.

If push came to shove I'd consider these.

With 2 to 3 stacked the multiple surfaces would reduce any potential for wear on the wrong piece$.



Hong Nor-X2CR-Pro-Diff-Bevel-Gear-Shim-13x16x0-2mm)

one of these should get you to ebay.

Thanks Scotch, I see they're listed at .2mm thick so that's .008". Still going to check the reed valves. I think one shim is better than a stack (more sturdy) but you're right something in there is better than nothing.

You're the best !!