Mikuni RS on Commando

hello!
just finished test ride and fine tuning phase with my new mikuni rs flatsliders. they work realy fine....very good idle....superb, powerful response!
the whole characteristics of the engine as it is now can`t be compared to the engine as it was with my old amal mk2s.

it isn`t the same appearing as it is with amals, but imo they don`t look that "new" as keihins do.

my commando is used for daily purpose and also as my official car ahhh bike [tax detuctible ...of course!!!!] the original appearance is secondarily.

i post here some pix fyi....


...put carbies on....put carbies off....experimenting with manifolds....but now they fit!


cable is just pull as a temporary solution...should be push pull...


professional welding.....i know! ...never mind! someday when i am filthy rich i buy me a new head :lol:


hard angle...but it doesn`t affect the function... velociyt stacks missing - coming soon



Have a nice day!
Chris

Chris - looks great - i love the Mik RS's - put them on my laverda and was shocked at the difference compared to the old Del'otros
whats size did you go w/ on the RS's and did you have to do any mods besides a new throttle setup also if you could please post you jet setting that would be great as i would like to try this setup if i can track down some reasonably priced RS's to adapt myself
thanks
Mike

That looks like a Norvil headsteady?

Hey mike and swooshdave!

The most difficult thing was to get the right manifolds.
First try....with the standart curved alloy commando manifolds and the mk2 rubbers on you are touching the frame with the lever assy and with the idle adjuster screw.
Second try.....with straight triumph t140 alloy manifolds and the mk2 rubbers....almost the same problem
Then i did a search on internet and found in the uk those nitrile plate manifolds at allen`s performance.
They fit... there is not plenty of space for velocity stacks...but it`s enough to put some 30mm long stacks on.
The next thing i had to do is to shorten the idle adjuster screw.

I think, as you know, these carbies are flatsliders with an adjustable accelerator pump as the keihins...but they cost almost the half of the price as the keihins do!

These are 34mm rs and the jetting is:

mainjet 125#
[but i think it may be a bit too small….cause when i go from fullthrottle to est.7/8throttle the engine pulls better…seems tob e too lean…i have to try a larger one!]

pilotjet 15#

jet needle: 9DZH5-5C

needleposition is grove #2 [counting from bottom….more on the rich side oft he needle]


pilotscrew is 1¼ turns out.

ad swooshdave ...This is a headsteady from norton motors deutschland.
The difference is: the norvil base-plate which is attached to the head is welded together with the other parts.
The base construction from the norton deutschland headsteady is cnc-milled.
But i think the system is the same.

have a nice day! chris

great thx Chris - in addition to having to deal with manifold rubbers did you have to modify the linkage between the 2 carbs - or did you find a particular setup that allowed a straight fitting - i know on the laverda triples you have to alter the linkage a bit to accommodate the difference as the distance between intakes is a bit different that just removing one of the carbs from a 4 cylinder kawy setup?
thx!
Mike

hey mike!
i orderered my carbies at a dealer in my hometown and he built the carb rack to the pitch that i gave him.
the pitch i gave him was 68mm....fit perfectly!

i post here 2 companies from the uk where you can order the manifolds.....they cost about 30euros each:

http://www.motocarb.co.uk/index.php/manifolds/c_7.html

or

http://www.allensperformance.co.uk/prod ... folds.html

the one that fits perfectly is the plate manifold number PM03.....just bolt the manis directly to the head and stick carbies on!

the only thing that you have to do is to grind some mm off the material on each inner side of the flanges [i mean shorten the flange on the innersides where the manifolds touch....i hope you can get me....i am no english native ]. it`s just a 2 minutes job with a good file....

bye, chris

For Mikegray660 and those of you who also interested to Mikuni RS on:

i changed the mainjet from #125 to #120........
thought that i was too lean with the #125 because engine pulled harder when i went from fullthrottle to app. 7/8 throttle.....
but this was a misbelief or had something interpreted false in the mikuni manual .

the #120 mainjet is right!

There are mikuni alloy velocity stacks from 15, 30, 50 and 70mm length.
But the only ones that fit without touching the frame are 15mm - real short! but better than nothing! :lol:
You also have to file some material off on the innersides because the stacks touch each other......`cause of the pitch of 68mm [the minimum pitch for rs]

chris

Chris Zet said:

The most difficult thing was to get the right manifolds.
First try....with the standart curved alloy commando manifolds and the mk2 rubbers on you are touching the frame with the lever assy and with the idle adjuster screw.
Second try.....with straight triumph t140 alloy manifolds and the mk2 rubbers....almost the same problem

Click to expand...

Hi Chris, I had to deal with the same manifold problem on CNW Keihin flatslide kit. The added curved manifolds are to long (carbs touched the frame), so I shortened the manifolds 3/8 inch and this cured the clearance problem (see pictures).

This trick might work as well for your Mikuni's and using the shortened curved manifolds would allow you to use longer velocity stacks or an airfilter.

Those are great carbs and you've done a superb job.

Gee Constant,
you're a real teeze!! Whats in those two pics looks superb. Do we get to see more, I look forward to it?
Foxy
Love that Domiracer of yours!

hey!

@Nortonspeed: yes, it may work....have to try it!
I`d like it more `cause the angle of my carbs is realy hard....but it works.
and...wow! you did a great a job with your commando!!!

@Jseng1: you are right! those flatsliders you mentioned are cheap.
But i chose mine `cause they got an accelerator pump [and this thing brings real fun!!!] and they are bolted together and use a common linkage for operating.
This is what i searched for because the keihins are too expensive for my small wallet......and the mikunis rs got the same main features as the keihins.

have a look:

okay, I'll be the one to ask haha- these are better than the amals, but how do they compare to the single mikuni's 34 or 36? Significantly better or just a little better?

Any idea about fuel economy?

hey pelican!

Flatsliders react in general faster than roundsliders mikuni vm34/36....and they are smoothbore venturis.
The real noticeable improvement is the accelerator pump.
On normal carburetors the mixture drops lean when you quickly open the throttle....and it takes a little to get the right mixture again.
with the accelerator pump you spray fuel into the venturi exactly in that time when it normally drops lean.

so, your acceleration realy changes noticeable! pushs aggressivly...
first ride amazed me when the acceleratorpump started to work!!!!

another thing is: you can balance 2 cylinders only with 2 carburetors.....so that you can get the best results out of your engine.

- of course: depends what you want from your bike.....one carbie....less stress....no synchronizing....and so on....and works also perfectly!
had only one carbie on my old bsa rocket goldstar....and was absolutely satisfied! -

But to come to the point:
i think the vm can be compared to the amal mk2 [I just compare the technique, not the materials!].
There is a big difference in improvement between rs and vm!

@Diablouph: in any case better than with amals! my experience...

Chris Zet said:

hey!
@Jseng1: you are right! those flatsliders you mentioned are cheap.
But i chose mine `cause they got an accelerator pump [and this thing brings real fun!!!] and they are bolted together and use a common linkage for operating.
This is what i searched for because the keihins are too expensive for my small wallet......and the mikunis rs got the same main features as the keihins.

have a look:

Click to expand...

Two questions:

1. How do you fit all four carbs on your Norton?
2. How much and where did you get them?

hey swooshdave!

ad 1.) would be a new experience to fit 4 carbies to a commando!
but this is just an advertisement sheet ...just an example

ad 2.) i paid 450euros incl. VAT for the 2 carburetors, machined and bolted together for my pitch.
i got them from a local dealer who is into racing motorcycle tuning.
gave him all my details from my amal mk2s and my engine:
compression, valve sizes, pitch [from venturi center to venturi center], throttle size, mainjet, needle jet, jet needle and so on....
he converted my details into details for the mikunis and so i got them.

they work realy great for my engine [2s cam, 10.5:1 pistons, big 1.6" inlet valves, .....]

the main reason why i took the mikunis was the price! keihins cost here in austria about 900euros!!!!!!
and the main features of the mikunis are the same as of the keihins.......

Hello,

some update about fitting Mikuni RS on a Commando.

Finally i managed that i can use the curved manifolds and longer velocity stacks [50mm] with my RS carburetors.


For those of you who are interested putting Mikuni RS on a Commando……the working steps:


First i had to cut the crank bell…..no more push-pull…now it`s just pull

Removed the existing crank bell bracket ….on that bracket was also the idle adjuster screw located

Made a new bracket for the idle adjuster screw [2 alloy angle brackets bolted together and attached to the existing threaded M5 holes]

Made a new bracket for the cable adjuster….this bracket also links the carburetors together

Made a new idle adjuster stop on the crank bell

And cut the curved manifolds est. 8mm

Filed the velocity stacks so they fit


The pictures are from the test assembly…..it works!!!!!

Nice job. What size are they?

Fast Eddie said:

Nice job. What size are they?

Click to expand...

Thanks! these are 34mm...