Information for my Mikuni installation

Spondonrider

Spondonrider

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Location
Colorado
I started looking into fitting the RS Mikunis to my RGS today and have some questions for those who have gone before me.

Throttle cable: What cables are you using? I thought the stock RGS cable would work but the inner cable is too long in relation to the housing and theres no way I can pull in the slack.

Air filters: I would prefer to use the stock airbox if I can. Its a tight fit and I guess I have to use an adapter for the connecting tubes correct? In case I decide to go this way, which model K&Ns work?

Anyone have a good picture of the accelerator pump linkage? I'm curious about the parts that fit on the throttle shaft. I'm not sure mine is correct but don't see any other way it can fit so a picture would be appreciated.

 
Ed, I have an extra set of Suzuki cables that should do the job, I can send them to you if you want so you can get set up. I think they're off a GS750, I can check. Remember many 70s bikes were offered with at least 2 different handlebar heights so you have to work out which OEM cable length to use.

The K&Ns are RC-0981 (chrome end cap) and RU-0981 (rubber end cap). They don?t really fit all that well, the side covers hit the outer filters unless you jack out the front sidecover mounts a lot. DNA OVI-5404 are made to fit Kawasaki Zephyrs (whatever they are) and have the outer pods angled in to clear the frame tubes, also fit just as well on Breganze triples and maybe breathe better than K&Ns, bit hard to say. DNAs are hard to get in Seppland, supposedly Vance &Hines are dealers. Red has them in Australia, though, and also has an adaptor that accepts the standard airbox rubbers, but it takes up space between the carb mouth and the airbox. What people have done successfully is to drop the airbox rubbers in hot water to soften them, then stretch the rubbers over the carb mouths. You have to stretch them a lot and I think they'll split. The other end of the rubbers have to be pushed deeper into the airbox holes than the standard fitting but will still seal if you're careful.

You can take about 1cm depth off the airbox by trimming it carefully with a bandsaw with a fine blade, but it will reduce the already small airbox volume even further.

Sorry, I don't have a piccie of the throttle linkage, I can try tomorrow if nobody else can help before then.

Ken

 
The Mikunis will require a push pull throttle which can be sourced at Suzuki from one of the GS series and looks just like the Laverda unit. Manifold rubbers from a snow mobiles can be used on aluminium manifolds to get the angle to allow entry into the airbox. Manifolds that are tapered from 36 to 32 help smooth out the airflow...angled manifolds are another option
I have more specific info stashed away so PM me if it doesn't surface here.
 
Try Reiner at GTReiner1@aol.com

He stocks Suzuki GT 750 gear and carries the throttle assembly and cables. The switch block is identical to the original ND unit fitted to our bikes but has fitment for the "push-pull" cables. He is also way cheaper than any Suzuki dealer.
 
Use Motion Pro cables, 01-0234 12 04 30 push and 01-0233 09 11 19 pull. If you I use Mikuni rubbers and manifolds I have made which allows the use of the standard airbox and rubbers, no adaptors.

Can't post a pic from here as my work laptop is an idiot.

  Keith
 
Ed,
Your conversion kit is based on the photo that Keith posted ages ago showing how he sets up his Mikuni's with a standard RGS airbox.
Is not how I do them normally but as you wanted to use your airbox then I copied Keith's photo's.

You don't want the Mikuni rubber adaptors, buy a set of straight through rubber adaptor couplings from Wolfgang as used on the 81 Jota set ups and mount them to the modified couplings that I supplied you in the kit.
Wolfgang's coupings have no internal spigot so you save some room (about 5mm) and you also don't have a 32mm ID Rubber spigot upsetting your airflow as supplied with couplings from Germany or UK.
Mikuni couplings are okay, they have a 36mm ID but have the rubber spigot still so you lose the 5mm as stated above.
Ignore the advice on the angled Snowmobile couplings, they will not work if you wish to use your standard RGS airbox and then if you do find it all too hard to mate up to the airbox then I'll send you a set of angled inlet manifolds when I get home.

Reggie has explained how to fit the Airbox rubbers to your airbox, if you use the alloy adaptors that we used to make you lose another 10mm and they also are a real tight fit up against the RGS airbox, if fact, they don't fit so you have no choice but to do the stretching exercise as explained by Reggie on an RGS

Ken, you cannot cut down a RGS airbox, the method you explained only works on the 180 airboxes

Red

 
Thanks to you all for the reply's, very helpful!

Keith, I have a set of those Motion Pro cable on the way. Question for you. Are the grip end threads the same on both cables and do they use the same thread as a stock Laverda cable? I need to drill the push hole on the bikes ND switch block and just need to know what size and thread to use.

Ken, thanks for the offer of the Suzuki cables but the Motion Pros will be here in a couple days. I was also able to determine that my accel pump was ok so no pictures needed.

Red, I have the couplers from Wolfgang and everything else is ready to go. I was a bit shocked at how much I'll be stretching the boots to fit over the carb inlets but what the hell, if it works it works. Thanks again for the info and the kit, all top quality and much appreciated!

Ed
 
No, threads are different on both cables, I guess to avoid confusion.... and the Suzuki push pull, there is no room in the Suzuki switch body to tap a thread for the Motion Pro cable either, ask Motion Pro for one of their push pull twistgrips is the easiest way round it.


    Keith
 
laverdakeith said:
No, threads are different on both cables, I guess to avoid confusion.... and the Suzuki push pull, there is no room in the Suzuki switch body to tap a thread for the Motion Pro cable either, ask Motion Pro for one of their push pull twistgrips is the easiest way round it.


     Keith
Click to expand...

OK, same setup as on my Montjuic then. Parts are ordered, thanks Keith!
 
blade981 said:
Don't forget to fit the cable choke as the fuel tap is right in the way, I used a universal cable from fleabay.
and you need parts 110,111,112 from mikuni,very easy to fit-just remember to take out the indent ball and spring from the lead carb.
cheers will
Click to expand...

I may do that in the future, need to see just how much this bike feels it needs a starting circuit. My Spondon, with the Keihin FCRs starts fine with just a couple twists of the throttle to squirt some fuel. If the Executive is as easy then I'll be fine without.
 
What float height are you Mikuni guys running? I set mine to 17mm and am having problems with the carbs overflowing.

The bike does idle nice though...  :D
 
17mm is the recommended height by Mikuni but at 28 degrees you are close to maximum recommended operating angle for those carbs which is 30 degrees
set them at 18mm and see how you go, works most times

your needle valves are in good condition ?
with good o-rings on their outer OD ?

 
All set now. No more leaks and the bike idles much better than it did before. Also jumps off idle quicker. Should be doing the first test ride tomorrow!

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The Spondon is waiting for a new lower triple clamp. The machinist has been slow, going on 5 months now I think, but I knew going in it could take a while. Hopefully soon!

I wont be getting to Wolfgangs this year. I thought I might, but its just too far away taking much time at a time of year with a lot of other things going on.
 
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