What's best Mikuni model?

Hi all,
I apologise in advance for asking a question that may be in an archive, but I'm not smart enough to find it. I'm restoring a 1974 Commando Roadster for a friend of mine and he'd prefer to use a single Mikuni over Amals, which I always use. Which kit should I get...i.e. jet size, body type, manifold, throttle cable etc and where is the best place to find it, please?
Thanks in advance,
Paul

I would use the original Amals with your bke. They are not as bad as some say they are. I tried other carburetors and the Mikuni pumper years ago. The Amal concentrics were better.

The bike will run better with a set of sleeved Amals than it will with any single Mikuni set up. The VM series of Mikunis that everyone uses are inferior in operation but superior in longevity, compared to the Amals. Assuming that the Amals are worn out, sleeve the Amals, replace the needles and needles seats. Done. Better. And, for a lot less money.

Better than messing around sleeving poorly designed pot metal Amals or restricting performance with fitting a single carb conversion, take a look at the excellent OKO 32mm carbs sold in the US as "PWK's" which are available for $31 each from a wholesaler in China.

I am with montelatici ~

I even have a set of Mikunis which was an option on my latest project bike ~ And I entered the fray regarding the two options.. well more if you really want to be pedantic ~

The Animal is essentially a proven design and simple. They will run with even badly worn slides ` My first triple ran sweetly even on idle with rattling slides ~

But if you opt for Mikunis, really expect a time of it, just getting the jets right ~ Of course you may get lucky and have an easy time too~

I am up for 'inserting' the Amal carbs and keeping the issue simply, after all a tidy set Amals will be totally reliable ~

Another bonus is that Amal jets and parts are quite reasonably priced ~

And BTW ~ if you are renovating the Concentrics ` ALWAYS replace the needle jet ` They really do wear big time `

The original post asks for specific recommendations re: a single Mikuni. Four posts later nobody has even begun to address the question, instead talking about the benefits of the alternatives. What's that about.
Dredge up my thin knowledge, the general advice is to buy a 34mm for an 750 and a 34 or 36mm for an 850. Buy a kit pre-jetted Sudco kit for the Commando from one of the many usual suppliers. Some folks find they need to play with jets from there. Check the archives for further details - it has been well covered in the past.

Stephen Hill
Victoria, BC

I concur with Stephen. The VM round slide have a great history of success. If you have a Combat a 36mm will be great. 34mm will work all around, great economy to performance factor. Rocky Point is the supplier the got me started.
If you are into fiddling, The TM flatslide 34mm is fantastic once you get it right. I actually transfered all the jetting from the VM 36 to get functionality.
Although things have change a lot with my 750, I would keep my Amals on the shelf and put them on once in a while to remind me of why I changed to the single in the first place.

Speak with Bill at Rocky Point Cycles, he sell's the Mikuna kits and is quite knowledgeable.

OK, I'll weigh in on the Mikuni question....after I do a little Amal bashing. :wink: From 1978 to 1986 I ran dual Amals on my bike with no problems. Tickle the carbs, bring it up to compression via the kickstart, turn on the key, solid kickstart technique and it started 1st kick most of the time. These were the original Amals.

When I had my bike restored by GrandPaul, I sent him BRAND NEW Amals to install. They never worked correctly. Very poor idle, coughing an carrying-on cruising at 30-40 mph, and backfired off-throtle approaching a red light. I had two more people look at them, Scotty Cameron who's worked on Norton-Triumph-BSA's with his Dad for 30+ years and Mike Carter of the Carter Brothers fame in Central Florida. We all just gave up and branded the new Amals a piece of crap. BTW, Scotty and the Carters run Mikunis on ALL their bikes.

A friend of our's at the Carter Brother's garage convinced me to go with the new TM34 Mikuni flat-slide. Not the VM model. It came pre-jetted, etc. which, by the luck of the draw, was pretty darn close to what my bike wanted / needed. I know that varies from 750s to 850s, year to year and even bike to bike. My particular TM34 setup runs rich at idle, but the midrange and top end is perfect. I corrected this, or as some may say - eliminated the "symptoms" - by going with the BP6ES NGK's instead of the standard BP7ES. Also switched from the Sparx E.I. (another piece of crap) to the Pazon.

Two years now and 8000+ miles:

1. The bike starts 1st kick, every time. And, to be clear, I mean 1st kick! And this is true even if the bike's been in the shed for 3 or more weeks.

2. Plug chops and just pulling the plugs at the end of the day show a nice golden brown plug color.

2. The idle is rock-steady...sits at 1000 rpm cold or hot, whether I've been racinig my buds in the twisties of Central Florida or puttin' around the beach all day at 30 mph.

3. Don't let anyone tell you that performance is compromised. It absolutely isn't. My Combat with 21-tooth setup is a screamer and I rarely see the back ends of my friends. And believe me, I don't have big Kahunas when it comes to diving into turns. I'm talking about flat out acceleration.

4. The TM34 is absolutely maintenance free. I've never been inside it except the first week to drop the needle. The floats never need adjusting.

5. All this and I run ethanol gas (liike most of us) out of an original Dunstall fiberglass tank that has been carefully "Caswelled" with three applications.

Wonder how many of those who advocate sleeved Amal carbs, have ever tried modern carbs on their own bikes? Flat slide TM carbs are very good, but in terms of cost the OKO's beat them hands down, as 2 brand new carbs cost less than having a pair of Anals sleeved.

Ooh er, we have the Amals on one side & the aftermarket carbs on the other side.
You can add me to the Amal side, I love 'em.

I've had single and dual Mikuni VM34s but went back to Amals. For midrange the single Mikuni can't be beat. Acceleration is violent in second gear with 19T! But it did run out of steam compared to the Amals at over 80mph or so. The dual Mikunis were great on the high end but had less midrange.

There is more involved than just plunking on the carbs themselves. There is the aircleaner and mounting considerations to think about. I used the cable operated enrichener kits to avoid the reaching under the tank to find the lever(s). I also like having both adjusting screws facing me on both sides. Is there an aftermarket carb that will allow that?

If I have to hear about the OKOs for $31 again and how Jim Schmidt is making a fortune selling them I think I will scream. We get it.

Carbonfibre said:

Wonder how many of those who advocate sleeved Amal carbs, have ever tried modern carbs on their own bikes?

Click to expand...

You know, I was just thinking the same thing as I headed back to the computer.

On another note, with the countless Amal "threads" on this Forum and other web sites that discuss adjusting float levels, crappy pot metal, blowing compressed air thru the circuts, buyiing a #78 sized drill bit to clean out some hole I can't remember, sleeving the slides, 1 1/2 turns out, messing with air screws, idle screws, synchronizing dual carbs, problems with throttle cables, etc., etc. etc. I'm beginning to think the Amal group loves issues so that they can tinker with their bikes and solve problems. I, on the other hand, like to turn the key, start, go fast. Simple.

And lastly, for those who think that not having Amals "ruins the Classic look"...c'mon. I'm sure there's lots of classic-minded Amal folks out there who accept their "classic" Brembo setups, hydraulic clutch reservoirs, Corbin seats, mag wheels, Avons, etc.

Sorry if I've offended anyone, not my intention. However, if it's simplicity, reliability, performance and great mileage you want, the answer is clear.

For criminy sake! Too many devils advocates. So many poor souls simply looking for a simple answer to a simply question. Instead they get a raging debate on the moral issues. BIZZARO WORLD!
I think Ludwig was right to take a break. Let's just stick to task and leave the irrational thoughts to Hobot.

Again, I think the safest answer to your question is the VM34mm from Rocky Point. With a 260 main in there you will get 60 to 70 MPH with good driving habits. If you want a little more performance, slap in a 300. Middle of the raod go with a 280. With this carb you will have that option with little to no change in plug color.

I've had great dragster 750, idle 600 and instant BANG to 9 grand with dual Amals.
I had 2 34 Miki kits and they worked a treat also but had a tad more lag on low end response, enough I prefer dual Amals now for mostly sane riding as more responsive though the 2 springs make twisting and holding more effort. A UFO kit can bump up Miki carb response and full flow so it out performed my dual Amal on 2 Combats, after the speed built way over legal rates.

There can be so many things wrong with an Amal right out the box R-L different casting and sag cooling out of round and sizes, bad float level so takes an anal expert at times to diddle them to perfection. Miki's look foreign and are as not Norton, but so what if you like the single simple better built carb, but its a statement you ain't being faithful.

We all should get 2 Cdos, one to test your manhood only ordering from parts book and another to take as far away from Nortondoom as you have money time and imagination. To spank sports bikes I'd go with 36 mm Miki, to just enjoy the perfect balance of response and looks and easy starts I'll stick with Amals.

Well this stirred things up a bit!

Having lurked on the site for quite a while trying to educate myself a bit, it's time to 'fess up and say hello, especially since the question relates to my bike that Paul is using for a form of self abuse. But we won't go there...

So far, the TM interest me more than the VM - I'm looking for great bottom end, reliability, low maintenance & general ease of use. Sounds like the ideal wife, come to think of it, except I'd like mid-range too.

Has anyone tried anything like a single Keihin roller flat slide? I've put pair on a Moto Guzzi (a bolt on "kit" that became a one year saga) and a set on a Laverda triple - highly adjustable and they worked beautifully.

Any suggestions for the best supplier of a TM kit - seems the best bet so far? It would need to be really complete as the bike has nothing at present - this isn't a converion so much as installing where there is nothing.

And once again, hello to all.

Alex

PS For the purists out there, Paul has tried hard to persuade me that the Amals are the way to go.


'06 BMW GS - '77 Laverda Jota - '74 Mk IIa in many pieces but fewer than it was a while ago. Prettier too - it was truly fugly.
Lafayette, LA.

Holy cr*p! I'm (almost) sorry I asked the question. At least nobody could accuse this group of not being passionate about our Nortons!

Thank you all for your input - yes, I'm very happy with dual Amals on my bike, but Alex desires something different and it's his bike so he'll get what he wishes

It would appear that, if I've sifted through these and other comments correctly, for regular service through the majority of daily riding circumstances, the VM, round-slide, 34 is the handiest. For performance, dual flat-slides (32s?) would be preferable but that introduces considerable complexity that I think Alex wanted to avoid with the Amals in the first place.

Sound right?

Paul.

I agree with one of the earlier posts - the OP asked about which Mikuni was appropriate. That shouldn't generate a bunch of "you should use Amals" responses (even though I am a big Amal pusher). But I think the thing to understand is that any new carb(s) is a "kit." IOW, it will need work to get it right on the bike and you need to be prepared to go through some fiddling as opposed to expecting to bolt it up (Amal, Mik, Keihin, etc and having it work perfectly. Frankly, that just won't happen.

Well recommendations ?

These blokes from M.A.P. Cycles regularly advertise via EBay ~

This kit looks the business ~ for triples and I am sure they have the Commando kit as well ~

http://cgi.ebay.com.au/ws/eBayISAPI.dll ... K:MEWAX:IT

http://cgi.ebay.com.au/Norton-750-850-M ... 3cb33e40c2

( I also recall some where ~ well I think it was Dave Madigan in California~ or another triple tweaker that is currently working on gantri/es to fit Mikunis which would tidy up the cable set up. )

As for Amals I can tweak mine with ease to idle beautifully at 500 rpm ~

Sorry, but I will have to respectfully disagree with my colleagues who say that twin Amals are a superior carbureter option for a regular street Commando. I have many British bikes and they all have (sleeved) Amal carbs so I am not an Amal carb hater by nature. I actually prefer Monoblocs to Concentrics but the single Mikuni VM carb is a much more user-friendly setup than the twin Amals on a Commando IMHO. Many Commando owners who have switched to a single Mikuni have made statements such as "transformed the bike" etc. and I concur. We can debate until the cows come home about whether a Japanese carb belongs on a British motorcycle etc. and that is something you will need to decide. But the fact is that Mikunis are far superior carbs and everyone knows this. It may be true that you will lose some top end performance by switching to a single Mikuni but do you care? If you are not riding your Commando at the edge of its limits, you will find that a single Mikuni will make your Commando an easier bike to live with for day to day riding.

If you decide to go for a Mikuni, you should buy it from Rocky Point Cycle as it will be set up correctly for your bike.