Mikuni carb model?

Found a local ad for a Norton Mikuni single setup....carb designation is "34B 168 H3 9 1" and genuine Made in Japan. Unsure on that designation...normally these are VM34-168, correct?

Yup , as far as I know , the mik on my bike say VM-34 don’t recall noticing anything more ....

Could be off a 1975 Yamaha XS650 - the guy in this forum appears to describe some of the numbering you refer to: http://www.xs650.com/threads/mikuni-carb-indentification.35292/

Is yours a CV (diaphragm at top)? I ask this because I'm pretty sure all XS650 were fitted with CVs.
Will have different performance and economy to standard (cable pulled slide) VM34
Cheers
Rob

Didn't find much on the Yamaha site yet. Signed up for an account and have reached out to someone there that had mentioned 34B-168 carb in an old posting. Might be a snowmobile version is my best guess right now....
Though the seller states it's a Norton setup with a MAP-labelled 2n1 manifold.

I think have a set of 32VM’s with the intake manifolds etc. available .... tried them and decided I liked single setup ....

You have a left hand 34mm VM spigot carb, what I used to supply for the Norton carb conversion or the 34-275, right hand equivalent.

So all I'd ne

RoadScholar said:

You have a left hand 34mm VM spigot carb, what I used to supply for the Norton carb conversion or the 34-275, right hand equivalent.

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Thx RS. So all I'd need to make it work OK is the rubber flange adapter and a throttle cable? Looks like it needs rebuilding. Price is pretty nice at $100 CDN with manifold.

Why do you want it? I only ask as I thought you had a single MK1 32 mm concentric fitted
If you are looking for more performance you need twin carburettors or a TM 40 single
If you change from a single 32 amal to a single 34 mikuni I doubt you will notice any difference, unless the amal is completely worn out

Tornado said:

So all I'd ne


Thx RS. So all I'd need to make it work OK is the rubber flange adapter and a throttle cable? Looks like it needs rebuilding. Price is pretty nice at $100 CDN with manifold.

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Yes, the manifold adapter, the cable and an air cleaner. I suggest that you open the carb up and see what the jetting package is, and at least purchase a #35 and a #40 idle (pilot) jet.

baz said:

Why do you want it?

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Good question. My original Amal seems to be OK. But have been contemplating to try the dual setup if I can get the other one I have functioning better. It was the one installed when I got bike but seemed to have idle circuit plugged up, unable to clear with the drill method.
So, the Mik came up at such an attractive price, it might make a more reliable operator than my old amal. It may even perform better.

RoadScholar said:

Yes, the manifold adapter, the cable and an air cleaner. I suggest that you open the carb up and see what the jetting package is, and at least purchase a #35 and a #40 idle (pilot) jet.

Click to expand...

Yes it will need all new jets and other components.

Tornado said:

Yes it will need all new jets and other components.

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You paid top money for that used carb. I suspect that it might have mixed air and fuel for a Norton at some point, as it has the MAP manifold; I could easily be wrong. If the parts were properly selected you may well have the correct slide, needle, needle jet, maybe the right main and idle. The idle jet is the one that should just be replaced, the others can be cleaned, unless they have enter the realm of forensic archaeology.

If the carb is out of spec (for your application) it could easily turn into a tuition payment, tells us what's in there.

Have not actually purchased it...still in the indecisive phase. Seems $100 CDN (that's about $75 for the Yanks) for it plus manifold is a decent deal, no?

Tornado said:

Good question. My original Amal seems to be OK. But have been contemplating to try the dual setup if I can get the other one I have functioning better. It was the one installed when I got bike but seemed to have idle circuit plugged up, unable to clear with the drill method.
So, the Mik came up at such an attractive price, it might make a more reliable operator than my old amal. It may even perform better.

Click to expand...

It probably will perform better than your single Amal but if you already have two Amals and two manifolds why don't you try them?
If your pilot jet is completely plugged then drill out the casting at the back of the carb (drill the hole 4.2 mm) then clear the pilot jet bush then tap the hole 5mm and put a blanking screw in to seal it
If it still doesn't run right you will need to dig out the welch plug and clear out the mixing chamber,new welch plugs are available from rgm in the uk
Contaray to what a lot of people will tell you Amal concentrics have to be really worn out before they won't run right
But they do need to be perfectly balanced and tuned with the engine at working temperature and you will need to cable tie the cable splitter box to the frame or get a madass carburettor top conversion
There are plenty of posts on here about single verses twin carb opinions and I realize your question was about a single mikuni I'm just trying to save you a bit of time and money
I've had a single Amal 32 a single mikuni vm 34 a single mikuni vm 36 a single mikuni cv 32 and a single mikuni tm 40
And guess what i now run pair of 32 mm MK1 concentrics and the bike runs absolutely spot on,
Although the TM 40 was the best for performance but it wasn't easy to start with a knackered nee