Carb Identification

[egsols]

I have a rough idea of the difference between the 78-79 carbs and the 80-81 carbs but I can't find and markings on my second set (I think 80s off an SG) to indicate what they are. Anyone have any clues. BTW there is a faint number just below the diaphram but it doesn't seem to correspond with any of the numbers listed in the manuals.

[Crazcnuk]

Well, first off, the early carbs have idle mixture screws that stick out of the carb body, top front, whereas the later carbs have the screw down in a well.

The 80-81 carbs inset the screw so they could put a cover over it after so we plebes couldn't tamper with them.

2nd, the early carbs have bowl vent hoses that go to the aircleaner box, the later ones don't.

My 80 has the idle adjust thumbscrew on the front, bottom of the carb bank, and 79's have it at the rear top of the carbs.

[TopCatGr58]

Hey Ernie,

Also, looking at the intake mouth, there will be 4 holes for the 80-81 series since the bowl vent is routed there, but on the 78-79 carbs, the vent is on the side of the carb body, the upper "T" fittings, so there are only 3 holes on the intake horn!
T.C.

[MattWenrick]

1978 should have a E stamp on the bowls.

[egsols]

Thanks guys, was originally wondering if Mikuni had actually stamped any numbers on their carbs for id.

While I'm here got another quick question, kind of pertains to another thread. Brass floats on 78-79 and plastic floats 80-81 interchanging. Other then the drain on the 80-81 float bowls, is the capacity of the bowls different then those on a 78-79/ I have been thinking of swapping the bowls off a set of 80's onto my 79's so that I can do the float adjusment based on the actual fuel level. Sorry, I guess I just answered my question, if I use the fuel level then I don't worry about 23-25.7mm, I go by the level of the fuel to the carb body don't I?

[AlanB]

hi Egsols,

I thought that most (or all?) of the carbs were originally marked; some with stamped numbers on the body (which should still be there!), and some "printed" on the side of the diaphragm chamber. Some of those markings will be gone. Try looking down by the float bowl for stampings, or on the side of the centre top chambers; they are less likely to be rubbed off. Apparently, all four carbs of a set were marked.

AlanB

[egsols]

Thanks Alan,

Mine are not marked per se but do have some numbers printed on the side of the diaphragm chamber. Prob is they don't seem to relate to any of the numbers stated in the service manuals? I know they are either 80 or 81, plastic floats, no vent tubes, drain screw in bottom of bowls, 110 mains, etc.

[AlanB]

Hi Egsols

Side of the chamber sounds right!. What are the numbers? You might need to check 'em all to get the full sequence.

AlanB

[pggg]

Can someone tell me why I can NEVER find any numbers stamped, printed or engraved on my carbs no matter where I look? apart from E on the bottom

Al, those wire spoked rear wheels, GX750 maybe, XS750 rear wheels, wire spoked I'll check out some bike-wreckers soon, they're possibly around, will let you know

[Just In Case]

On my early carbs, there is a very faint etching on the CV chambers. But each carb has the etching in a different position, either left, right, or back, or somewhere inbetween. In the photo you can make out 9 00 and then something below. By shining a light at different angles I can make all the numbers out- 2H9 00 E9X



On my later carbs, the number is stamped on the LHS between the throttle butterfly rod and the angle bracket. In this one I can see 5K7 00 132. Black paint might hide them?



PGGG, if you see an ad in Motorcycle Marketplace looking for wire wheels, that's me for Al. No one around here has seen any. Hope you have better luck.

Dave

[egsols]

Hey Alan,

I wrote them down and lost the %$##^& paper. I'll check them again this weekend.

[pggg]

nothing to see here

[Just In Case]

pggg, those carbs look like my early ones (my top pic). The numbers I found are very faint etchings on the CV chambers. They can be
anywhere on the chamber sides. The numbers are that faint that I'd think a good cleaning may remove them It's the later carbs that
have the numbers that would show in your pic.

Dave

[petejw]

Pggg,
Ive got no numbers on either set of carbs
i have, both later models (81/82)
they have no numbers on the needles either.