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Twin Mikuni TM 32mm recomendations #118372
06/18/07 2:30 pm
06/18/07 2:30 pm
Joined: Oct 2005
Posts: 68
Hilton Head, SC
John Friday Offline OP
BritBike Forum member
John Friday  Offline OP
BritBike Forum member
Joined: Oct 2005
Posts: 68
Hilton Head, SC
I am looking at using 32mm Mikuni TMs on my mildly tuned (balanced, polished, hotter cam) '78 T140 motor. Does anyone have some starting point as to what the set up should/could be? Any other comments or thoughts are welcome.
Thanks, JF


"I never drink water because of the disgusting things that fish do in it."
- WC. Fields
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Re: Twin Mikuni TM 32mm recomendations #118373
06/18/07 2:37 pm
06/18/07 2:37 pm
Joined: Apr 2005
Posts: 2,337
Bega NSW Australia
Mark Parker Offline
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Mark Parker  Offline
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Joined: Apr 2005
Posts: 2,337
Bega NSW Australia
Maybe;

I have only used 38mm so don't know how close this will be with the 32mm size but its definitely where I'd start.


mark
Re: Twin Mikuni TM 32mm recomendations #118374
06/18/07 4:08 pm
06/18/07 4:08 pm
Joined: Jul 2006
Posts: 1,090
Westminster, MD, USA
J
J. Charles Smith Online content
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J. Charles Smith  Online Content
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J
Joined: Jul 2006
Posts: 1,090
Westminster, MD, USA
JF, I am also planning to use TM32s on my T140 with much the same mods (though my bike is still months - years? - from completion). I will be very interested in what you find out. Where did you buy your carbs? Were they just generic TM32s, or were they actually a kit?

Re: Twin Mikuni TM 32mm recomendations #118375
06/18/07 8:34 pm
06/18/07 8:34 pm
Joined: Oct 2005
Posts: 68
Hilton Head, SC
John Friday Offline OP
BritBike Forum member
John Friday  Offline OP
BritBike Forum member
Joined: Oct 2005
Posts: 68
Hilton Head, SC
J. Charles, I got them from Top Shelf Parts on eBay already supplied with the recommended jetting as per Mark's earlier reply. I am using K&N part number RC-1252 which are two cchrome cone filters. I now need to get a 2-1 throttle cable to fit a Mugura throttle. All said and done for about $400. It too will be a while before I get it up and running. Thinking about getting sweptback pipes and Goldstar mufflers from RGM in the UK unless I can find something as good here in the US. Any thoughts? JF


"I never drink water because of the disgusting things that fish do in it."
- WC. Fields
Re: Twin Mikuni TM 32mm recomendations #118376
06/18/07 9:22 pm
06/18/07 9:22 pm
Joined: Oct 2006
Posts: 187
MA USA
coz Offline
BritBike Forum
coz  Offline
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Joined: Oct 2006
Posts: 187
MA USA
Clubman racing in CT has sweptbacks for your bike. you may save some money... Shipping and weak dollar is killing us.
http://www.clubmanracing.com/

Re: Twin Mikuni TM 32mm recomendations #118377
06/18/07 10:45 pm
06/18/07 10:45 pm

A
Anonymous
Unregistered
Anonymous
Unregistered
A


Please note that the settings in the illustration above are only how Mikuni supplies the carburetor for almost all purposes. It doesn't say single, dual, engine size or even air vs. water cooled, 2 stroke vs. 4 stroke. If strong vacuum signal is a feature, why the rich jets (45, Q2, 250)?
It can't be too far off, because M.A.P. sells the same numbers. However, Sudco etc. used to sell the VM by the same method: pick the closest generic Mikuni factory jetting #, and ship it. They weren't very close.
On the plus side, they use the same common pilot and main jets as the VM, so those parts will be easy to find. Expect some work to straighten these out. It's only a better carburetor than a Concentric or VM if the jetting is accurate.

Re: Twin Mikuni TM 32mm recomendations #118378
06/18/07 10:46 pm
06/18/07 10:46 pm
Joined: Oct 2005
Posts: 68
Hilton Head, SC
John Friday Offline OP
BritBike Forum member
John Friday  Offline OP
BritBike Forum member
Joined: Oct 2005
Posts: 68
Hilton Head, SC
Thanks, Coz. I've been speaking with Frank on the pipe subject. He now is only carrying a set of pipes from a new supplier and is not sure about the fitment at this time. JF


"I never drink water because of the disgusting things that fish do in it."
- WC. Fields
Re: Twin Mikuni TM 32mm recomendations #118379
06/18/07 11:55 pm
06/18/07 11:55 pm
Joined: Oct 2005
Posts: 68
Hilton Head, SC
John Friday Offline OP
BritBike Forum member
John Friday  Offline OP
BritBike Forum member
Joined: Oct 2005
Posts: 68
Hilton Head, SC
Thanks, Panic. I respect your comments. Has anyone done any experimenting with dual TMs on a British twin? Inquiring minds want to know? JF


"I never drink water because of the disgusting things that fish do in it."
- WC. Fields
Re: Twin Mikuni TM 32mm recomendations #118380
06/19/07 1:51 am
06/19/07 1:51 am

A
Anonymous
Unregistered
Anonymous
Unregistered
A


Probably the jetting will be rich, but at least that's safer than the alternative. I don't have a good mental picture of that slide size (4.0), but the TM sizes don't run like VM so it may be fine. With any luck a few needle jets will be the only expensive parts since I see the std. needle is dual taper, which is what I generally start with.
I would prefer the RS, but of course pairs are $$$ and used you have to get 4 (usually).

Re: Twin Mikuni TM 32mm recomendations #118381
06/19/07 2:05 am
06/19/07 2:05 am
Joined: Jul 2006
Posts: 1,090
Westminster, MD, USA
J
J. Charles Smith Online content
BritBike Forum member
J. Charles Smith  Online Content
BritBike Forum member
J
Joined: Jul 2006
Posts: 1,090
Westminster, MD, USA
JF, I like the look of swept-backs on a cafe bike too - very classic style. I haven't really started looking into mufflers, but IMHO, if I were going with swept-backs, Goldie or Dunstall replicas would be the way to go. Panic, you have mentioned the RS carbs before. I don't believe they are available any smaller than 34mm, which seems too much for bikes like JF and I are building. That said, do you know anyone who has tried the RS carbs on a British twin? How did they work out? The notion of buying a bank of four off eBay and being able to split them up for two bikes is certainly appealing.

Re: Twin Mikuni TM 32mm recomendations #118382
06/19/07 8:22 am
06/19/07 8:22 am
Joined: Jul 2006
Posts: 25
LasVegas Nevada USA
George Timmons Offline
BritBike Forum member
George Timmons  Offline
BritBike Forum member
Joined: Jul 2006
Posts: 25
LasVegas Nevada USA
I have a 71 T120 w/VM32s Pilot jet 25, air jet 1.0,main 210, needle jet P2, needle jet needle 6DH2, slide 2.5. Don't know if this will help on flat. Good Luck you have a lot of worrk ahead. If I had a chance to go back I would not switch, Cables hit tank,fuel fittings point up, there longer less clearence 4 filters air/fuel. air screw on left carb on the inside AND I COULD GO ON AND ON FOREVER! $ in to deep to go back and still sinking$!


69 TR6
71 T120
73 TR7RV
73 T140
Re: Twin Mikuni TM 32mm recomendations #118383
06/19/07 3:45 pm
06/19/07 3:45 pm
Joined: May 2005
Posts: 3,776
ohio
shel Online content
BritBike Forum member
shel  Online Content
BritBike Forum member
Joined: May 2005
Posts: 3,776
ohio
Quote:
Originally posted by Chicken George:
air/fuel. air screw on left carb on the inside
that's my biggest complaint about the Mikuni kits they sell for british twins. they come with two right hand carbs. there must be left hand bodies availible because I picked up a couple slides at a swap meet and when I got home I found out they were for a left carb.


When given the choice between two evils I picked the one I haven't tried before
Re: Twin Mikuni TM 32mm recomendations #118384
06/21/07 8:11 am
06/21/07 8:11 am
Joined: Apr 2005
Posts: 2,337
Bega NSW Australia
Mark Parker Offline
BritBike Forum member
Mark Parker  Offline
BritBike Forum member
Joined: Apr 2005
Posts: 2,337
Bega NSW Australia
Shel, I don't think thats what you got precicely, because the 38VM carbs we have on our 750 A65 are off Yamaha MXers and they have the oposite side machining to what can be bought from Mikuni. I had to do some mods to the carbs to make new slides fit, or buy them from Yamaha.
I doubt you will get a Left and Right unless one is a Yamaha supplied carb and even then the mixture screw position may not change.


mark
Re: Twin Mikuni TM 32mm recomendations #118385
06/23/07 3:35 am
06/23/07 3:35 am
Joined: Aug 2001
Posts: 4,259
Owego, NY, USA
Mark Z Online content
BritBike Forum member
Mark Z  Online Content
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Joined: Aug 2001
Posts: 4,259
Owego, NY, USA
Hmm, I must have two LEFT-hand Mikunis, because the air mixture and throttle stop screws are on the outside on the left carb. (These are VM32s I bought in 1983). I always figured they were all the same. Interesting that the AMAL slides are interchangeable right to left, but the Mikuni slides have that beveled groove for the throttle stop screw.


Mark Z

'65(lower)/'66(upper, wheels, front end, controls)/'67(seat, exhaust, fuel tank, headlamp)/'70(frame) A65 Bitsa.
Re: Twin Mikuni TM 32mm recomendations #118386
06/23/07 2:01 pm
06/23/07 2:01 pm
Joined: May 2005
Posts: 3,776
ohio
shel Online content
BritBike Forum member
shel  Online Content
BritBike Forum member
Joined: May 2005
Posts: 3,776
ohio
Mark Z, I also have VM32s that I bought as a kit from MAP around 1982-83 and mine are both right side.
aside from the stop screw bevel they have the groove down the opisite side for the locating pin.
maybe I'll stop at the motorcycle salvage yard and see if I can find a left.


When given the choice between two evils I picked the one I haven't tried before

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