Issues with my Mikuni VM34

baz · Sep 4, 2019

Fullauto said:
Hey! No problem here. Always good to get some other opinions.

Ok I'll dilute it further
I also ran a single CV 32mm mikuni on an fj 1200
The bike ran almost the same down low as it with 4 carbs (which surprised me!) but it had a massive hole in the power in the midrange I had to shim the needle and fit a bigger needle jet and main jet
The reason I did this was to see how flexible a 1200cc four would be on a single carb, also the fuel consumption as standard was pretty dire
I think from memory it went from 33mpg to 38mpg
I only had it on there for a month or so
I still have it if anyone should want it, you could turn it backwards and fit to a commando with four amal concentrics !!!!

Time Warp · Sep 4, 2019

baz said:
I still have it if anyone should want it, you could turn it backwards and fit to a commando with four amal concentrics !!!!

That statement makes the most sense for the whole thread.

A new design of the single carburettor manifold is long overdue all the same.

ericg · Sep 4, 2019

Tornado said:
Seems to me if Japanese parts work so well for people, may be they should switch the whole bike to a Japanese make? ;-)

Thank you! Amen to that! Why don't they replace their Norton engines, frames, forks

Tornado said:
Seems to me if Japanese parts work so well for people, may be they should switch the whole bike to a Japanese make? ;-)

Amen to this, thank you very, very much!!! It always amaze me when people wants to ride an old bike and wants it to perform like a modern one. Glad Brough Sups are out of their reach or they could fit them with disc brakes and Japanese carbs!
Back in the 80's and 90's there was this great UK magazine called "British Bike" and through the letters pages some keep asking the editor for Japanese features in the mag. Funny isn't it?

Hortons Norton · Sep 4, 2019

baz said:
Ok I'll dilute it further
I also ran a single CV 32mm mikuni on an fj 1200
The bike ran almost the same down low as it with 4 carbs (which surprised me!) but it had a massive hole in the power in the midrange I had to shim the needle and fit a bigger needle jet and main jet
The reason I did this was to see how flexible a 1200cc four would be on a single carb, also the fuel consumption as standard was pretty dire
I think from memory it went from 33mpg to 38mpg
I only had it on there for a month or so
I still have it if anyone should want it, you could turn it backwards and fit to a commando with four amal concentrics !!!!

I'm sorry but who in their right mind could even think a 32mm carb could feed a 1200cc bike? Really, don't even try to tune a Mikuni! lol.

baz · Sep 4, 2019

Hortons Norton said:
I'm sorry but who in their right mind could even think a 32mm carb could feed a 1200cc bike? Really, don't even try to tune a Mikuni! lol.

Erm I did and it worked and it was fun
Cheers

Fast Eddie · Sep 5, 2019

concours said:
....and I never need to mess with my twins.
Set up once, they don’t just “go out of tune”.

I’m my experience it’s the cables that are the issues.

On my T120 that has two cables from carb to wrist grip, I seem to be synchronising the carbs quite often.

On my T140 which has short cables from carb to junction box then a single cable to the twist grip, I never have to re synch, I do have to sync them whenever I disturb them for any reason, but in use, they stay synchronised.

Of course, on my Commando with the FCRs that are on a fixed gantry, I never have to sync them.

The madass gantry is surely the best fix for those wanting twin Amal’s and dead reliable fixed synchronisation.

Issues with my Mikuni VM34

baz

Time Warp

.......back to the 70's.

ericg

Hortons Norton

baz

Fast Eddie

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