Mikuni RS on Commando

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Mikuni RS on Commando

Postby Chris Zet » Tue Apr 20, 2010 1:17 pm

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!
Image

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

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

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


Have a nice day!
Chris
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Re: Mikuni RS on Commando

Postby mikegray660 » Tue Apr 20, 2010 1:59 pm

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
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Re: Mikuni RS on Commando

Postby swooshdave » Tue Apr 20, 2010 3:42 pm

That looks like a Norvil headsteady?
You probably want to go into town, and find a up to date Jap Bike store,
With a full spares department, a clean workshop, and kean young mechanics.
And ask them if theres a Grumpy Old Bloke out in the Hills, who knows how to fix Real Motorcycles.

Matt
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Re: Mikuni RS on Commando

Postby Chris Zet » Thu Apr 22, 2010 1:45 am

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
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Re: Mikuni RS on Commando

Postby mikegray660 » Thu Apr 22, 2010 2:39 pm

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
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Re: Mikuni RS on Commando

Postby Chris Zet » Fri Apr 23, 2010 1:07 am

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 :D ]. it`s just a 2 minutes job with a good file....

bye, chris
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Re: Mikuni RS on Commando

Postby Chris Zet » Fri Jul 23, 2010 1:39 am

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
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Re: Mikuni RS on Commando

Postby nortonspeed » Fri Jul 23, 2010 6:23 am

Chris Zet wrote: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


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.

Image

Image
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Re: Mikuni RS on Commando

Postby jseng1 » Fri Jul 23, 2010 9:56 am

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

But for $425 you can't beat the price of flatslides that fit right in and are already dialed for Norts (from jsmotorsport).

Image
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Re: Mikuni RS on Commando

Postby Foxy » Sun Jul 25, 2010 4:37 am

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
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Re: Mikuni RS on Commando

Postby Chris Zet » Mon Jul 26, 2010 1:00 am

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:
Image
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Re: Mikuni RS on Commando

Postby pelican » Mon Jul 26, 2010 2:08 am

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?
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Re: Mikuni RS on Commando

Postby Diablouph » Mon Jul 26, 2010 2:18 am

Any idea about fuel economy?
Herman the German

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Re: Mikuni RS on Commando

Postby Chris Zet » Mon Jul 26, 2010 3:06 am

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...
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Re: Mikuni RS on Commando

Postby swooshdave » Mon Jul 26, 2010 8:42 am

Chris Zet wrote: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:
Image


Two questions:

1. How do you fit all four carbs on your Norton?
2. How much and where did you get them?
You probably want to go into town, and find a up to date Jap Bike store,
With a full spares department, a clean workshop, and kean young mechanics.
And ask them if theres a Grumpy Old Bloke out in the Hills, who knows how to fix Real Motorcycles.

Matt
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