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History of Amal MK2 and Mikuni, what is it? #450402
08/22/12 2:42 pm
08/22/12 2:42 pm
Joined: Oct 2008
Posts: 38
Houston, Texas (West end of th...
Lucky Strike Offline OP
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Houston, Texas (West end of th...
Can any of you educate me on the history of the AMAL MK2? I've read a few posts here and there that indicate that the Mikuni was actually manufactured by Mikuni either under license from AMAL, or using their patents with AMAL's permission.

But I have not seen any reliable source for this information.

Thanks.


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1973 T140V
1960 BSA C15
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Re: History of Amal MK2 and Mikuni, what is it? [Re: Lucky Strike] #450410
08/22/12 3:47 pm
08/22/12 3:47 pm
Joined: Feb 2007
Posts: 586
California
Don M. Offline
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California
I keep an old, small carburetor from some Japanese motorcycle or scooter as an artifact. The body has "Mikuni" cast in on one side & "AMAL" on the other. The float/bowl parts are typical Mikuni. Seems to be evedence that Mikuni did licence technology from AMAL. Cheers, Don.

Re: History of Amal MK2 and Mikuni, what is it? [Re: Lucky Strike] #450436
08/22/12 6:18 pm
08/22/12 6:18 pm
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Posts: 10,262
Scotland
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Stuart Offline
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Scotland
Hi,

According to the Mikuni website, Mikuni licenced AMAL from 1932.

Possibly additionally, many years B.I. (Before Internerd), I read a story that (and those of you who know anything about the Japanese will understand) throughout WW2, Mikuni banked all the AMAL licence fees and paid them over in 1945. Unfortunately, I've never seen the story repeated, and cannot remember where I read it originally, so I don't wish to start an 'internet rumour'.

Hth.

Regards,

Re: History of Amal MK2 and Mikuni, what is it? [Re: Lucky Strike] #450445
08/22/12 6:34 pm
08/22/12 6:34 pm
Joined: Sep 2002
Posts: 7,813
Seattle
Alex Offline

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Paging Mr. Healy...Mr. Healy please pick up on line five...


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Re: History of Amal MK2 and Mikuni, what is it? [Re: Stuart] #450479
08/22/12 10:00 pm
08/22/12 10:00 pm
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Posts: 38
Houston, Texas (West end of th...
Lucky Strike Offline OP
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Thank you Stuart, I did see that on the Mikuni website. Certainly that is some indication of the relationship of the two companies.

I wish I could find some more information on the AMAL Mk2 Mikuni connection. I've have overheard or seen several people refer to MK2s as Mikuni copies, but it may very well be the other way around.


Fast. Cheap. Good. Pick any two....

1973 T140V
1960 BSA C15
Re: History of Amal MK2 and Mikuni, what is it? [Re: Lucky Strike] #450522
08/23/12 3:51 am
08/23/12 3:51 am
Joined: Oct 2008
Posts: 5,285
Gnashville
DavidP Offline

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I've always heard that it's the other way round, Mikunis are licensed from AMAL. Consider the history of Japanese design. The bulk of the Japanese navy at the start of WWII was built for them by the British. They're like Microsoft, they don't innovate, they copy successful designs.
What I do know is that you can use 'Mikuni' parts to rebuild the chokes on a MkII AMAL. But, there the similarity ends. The Mikuni, as per Japanese nature, is more complicated than an AMAL MkII.


Stepping on others doesn't make you stand tall.

71 A65L "Zelda"
92 BMW K100rs "Gustav"
72 T120V cafe project "Mr. Jim"
72 T150V "Wotan"
Re: History of Amal MK2 and Mikuni, what is it? [Re: Lucky Strike] #450570
08/23/12 1:12 pm
08/23/12 1:12 pm
Joined: Mar 2005
Posts: 10,251
Boston, Massachusetts
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John Healy Offline
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Have you looked at the main jets for the VM? They are exactly the same as AMAL. They are interchangeable and the Mikuni part number: 4/042 the same as AMAL. Have you ever measured the critical parts in a VM and notice for a given application they are the same as you would use on a MK2?

Barry Johnston wrote an article on the history of AMAL's influence on Mikuni for a Japanese Motorcycle magazine before he died. I have been trying to get my hands on a copy for years. It would answer a lot of questions. Also Burlen seems to have some of the AMAL records. Maybe they could shed some light on the subject.


Re: History of Amal MK2 and Mikuni, what is it? [Re: Lucky Strike] #450668
08/23/12 11:52 pm
08/23/12 11:52 pm
Joined: Oct 2008
Posts: 5,285
Gnashville
DavidP Offline

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Good information, as always, John. In a pinch, it's easier to find Mikuni main jets locally. Nice to know they will also fit a MkII.

It's a shame that MkII owners will never experience the fun of playing around with all those lovely Mikuni needle tapers. laughing

Last edited by DavidP; 08/24/12 9:52 pm. Reason: incorrect info

Stepping on others doesn't make you stand tall.

71 A65L "Zelda"
92 BMW K100rs "Gustav"
72 T120V cafe project "Mr. Jim"
72 T150V "Wotan"
Re: History of Amal MK2 and Mikuni, what is it? [Re: Lucky Strike] #450696
08/24/12 2:46 am
08/24/12 2:46 am
Joined: Mar 2005
Posts: 10,251
Boston, Massachusetts
J
John Healy Offline
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Boston, Massachusetts
Who big fella, the 4/042 is used by AMAL in earlier models. Our Monobloc, and Concentric MKI & II models use part number 376/100.

While Mikuni lists a mirad of needles there are only about 5 that will work for a given needle jet. If you take a minute to understand the tapers and which bleed/primary needles they work with. Less when you separate the two and four stroke needles. Thisis not unlike AMAL. You will also find that the single tapers work best for tuning a Mikuni on a four stroke for the street.

With a bit of study it isn't hard to make sense of the Mikuini catalog which is unnecessarily complicated.


Re: History of Amal MK2 and Mikuni, what is it? [Re: Lucky Strike] #450831
08/24/12 10:32 pm
08/24/12 10:32 pm
Joined: Oct 2008
Posts: 5,285
Gnashville
DavidP Offline

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OOPS! My bad, I misunderstood you,John.
I found that experimenting with different needle jet/needle tapers can be just a whole lot of fun. laughing And, what works on my engine/intake/exhaust combination can be totally wrong for your bike. I've never found any suggestions for sizes on the bleed-type needle jets, though in theory they are more suited to 4-stroke engines. The 'hood' on the primary type does cut down on exhaust reversion, though.

Allan: I've heard that AMAL does indeed size main jets by flow. The numbers on the needle jets are the size, however (106 = 0.106"). According to the Victory Mikuni book, Mikuni main jets are numbered by fuel flow, #250 flows 250cc per minute. The same system might be used by AMAL? It gets a bit more complicated with needle jets. Each letter is 0.05mm larger than the lower letter, while each number adds 0.005mm to the diameter. An O5 measures 2.625mm, P5 is 2.675mm, P6 is 2.680mm.


Stepping on others doesn't make you stand tall.

71 A65L "Zelda"
92 BMW K100rs "Gustav"
72 T120V cafe project "Mr. Jim"
72 T150V "Wotan"
Re: History of Amal MK2 and Mikuni, what is it? [Re: Lucky Strike] #451884
08/31/12 3:03 pm
08/31/12 3:03 pm
Joined: Aug 2011
Posts: 111
UK
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TripleTown Offline
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UK
I believe the MK2's were made under licence from IMI-AMAL, by a company called Talleres in Spain, who manufactured them, along with the 16/19 etc MK1.5's as OEM for Spanish Motorcycle companies such as Bultaco (Montesa etc). The spanish company supplied Carbs and spares throughout the world.
As for Mikuni, they certainly copied the AMAL hexagonal pre Monobloc jets, but i don't believe they were made by AMAL.

Re: History of Amal MK2 and Mikuni, what is it? [Re: Lucky Strike] #451930
08/31/12 7:59 pm
08/31/12 7:59 pm
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Posts: 10,251
Boston, Massachusetts
J
John Healy Offline
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Quote
Am I not right in thinking that Amal measure jets by flow rate through the jet whilst mikuni measures using the physical aperture of the jet.


No, both main jets are referenced to flow. While both needle jets are referenced to dimension.

There is an old British industry reference that refers main and pilot jet sizes to an appropriate inch dimension. I posted a link to part of it on britbike a while back. It is useful in a pinch but I doubt you could get any results plus or minus 10% of the flow you require. Anyone interested in all this should be on the look out for a set of jet drills made by Anderson & Forrester located in Colorado. I have used my set in a pinch for years...


Re: History of Amal MK2 and Mikuni, what is it? [Re: John Healy] #452138
09/01/12 9:58 pm
09/01/12 9:58 pm
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Posts: 5,285
Gnashville
DavidP Offline

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Originally Posted by John Healy

With a bit of study it isn't hard to make sense of the Mikuini catalog which is unnecessarily complicated.

I created a spread sheet to compare the resulting areas open to fuel flow using different needles at different throttle openings to aid in choosing one. It helps to visualize the fuel 'curve' and compare it to where I need more or less fuel.


Stepping on others doesn't make you stand tall.

71 A65L "Zelda"
92 BMW K100rs "Gustav"
72 T120V cafe project "Mr. Jim"
72 T150V "Wotan"
Re: History of Amal MK2 and Mikuni, what is it? [Re: DavidP] #452144
09/01/12 10:26 pm
09/01/12 10:26 pm
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Hampshire, England
DoubleDiamond Offline
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Originally Posted by DavidP
Originally Posted by John Healy

With a bit of study it isn't hard to make sense of the Mikuini catalog which is unnecessarily complicated.

I created a spread sheet to compare the resulting areas open to fuel flow using different needles at different throttle openings to aid in choosing one. It helps to visualize the fuel 'curve' and compare it to where I need more or less fuel.


This is exactly where the Mikuni can score over the AMAL, but only if you get the fuelling correct, in particular with regards to better fuel economy. It is clealy more complicated than for the AMAL and really needs a rolling road to set up accurately.


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Re: History of Amal MK2 and Mikuni, what is it? [Re: Lucky Strike] #453426
09/08/12 5:08 am
09/08/12 5:08 am
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Gnashville
DavidP Offline

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The charts I made help somewhat. However, the Mikuni, "stations" really have very little to do with throttle position. It takes some interpolation and measurement to figure out what station corresponds to 1/4, 1/2, 3/4 throttle. I ended up marking a needle at each station. The D-1 station is virtually useless, being where the needle exits the bottom of the slide (clip in center groove.) laughing
I'm not really sure why Mikuni did things that way except that it's easy to measure diameter at each 10mm, "station."


Stepping on others doesn't make you stand tall.

71 A65L "Zelda"
92 BMW K100rs "Gustav"
72 T120V cafe project "Mr. Jim"
72 T150V "Wotan"
Re: History of Amal MK2 and Mikuni, what is it? [Re: Lucky Strike] #454269
09/14/12 12:23 am
09/14/12 12:23 am
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Gnashville
DavidP Offline

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I was just reading an article about a 1970 Suzuki 125.
"Confusingly, some sources (both American and European) indicate the Stinger uses twin AMAL carburetors. Chip says itís his understanding that Mikuni paid a royalty to AMAL for the rights to build an AMAL-designed carburetor."

Read more: http://www.motorcycleclassics.com/c...r-zmwz12sozbea.aspx?page=2#ixzz26OkWiu6g

Look at the photo gallery. One of the photos shows the carb. It looks like a side-draft with the float chamber turned sideways.


Stepping on others doesn't make you stand tall.

71 A65L "Zelda"
92 BMW K100rs "Gustav"
72 T120V cafe project "Mr. Jim"
72 T150V "Wotan"
Re: History of Amal MK2 and Mikuni, what is it? [Re: DavidP] #454517
09/16/12 12:49 am
09/16/12 12:49 am
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Posts: 62
melbourne australia
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G'day all, I just recently bought myself a pair of 32mm VM series Mikuni's for my iron head Thunderbird. This is a race bike and runs on methonal. I was hoping I could measure the existing jet sizes in the MK1 Amals (currently fitted) and use these sizes in the Mikuni's. I'm hoping this will be a good starting point. What does everyone think? I have a set of "methonal needles" to use.

Cheers Pete

Re: History of Amal MK2 and Mikuni, what is it? [Re: Lucky Strike] #454537
09/16/12 3:54 am
09/16/12 3:54 am
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DavidP Offline

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I have VM32's on my A65 street bike.
The same size main jets might be close, but Mikuni needle jets and needles are a whole 'nother story. With all the various needle tapers available you can get close to perfect mid-range mixture, given enough time and testing.
Better book a whole lot of time on the dyno.


Stepping on others doesn't make you stand tall.

71 A65L "Zelda"
92 BMW K100rs "Gustav"
72 T120V cafe project "Mr. Jim"
72 T150V "Wotan"
Re: History of Amal MK2 and Mikuni, what is it? [Re: Lucky Strike] #632100
12/27/15 10:57 pm
12/27/15 10:57 pm
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Re: History of Amal MK2 and Mikuni, what is it? [Re: Stuart] #632109
12/28/15 12:21 am
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Les P Offline

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Originally Posted by Stuart
Hi,

According to the Mikuni website, Mikuni licenced AMAL from 1932.


All manner of things were going on back then, not just carburetors so there is a much bigger picture.

I saw a WW2 Type 97 sitting under a banana tree when I worked in PNG in the early 1980's.

Link

Link


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Re: History of Amal MK2 and Mikuni, what is it? [Re: Les P] #632112
12/28/15 1:05 am
12/28/15 1:05 am
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Rohan Offline
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Originally Posted by Les P

All manner of things were going on back then, not just carburetors so there is a much bigger picture.


Indeed, Indian and Harley etc etc etc sold the patents, licences manufacturing rights and tooling for a number of motorcycle types back then - it was said the $$$ gained bailed them out of a rather sticky depression era situation, and also circumvented some tarriff restrictions

Google Alfred Rich Child - yes thats his name - as one of the real characters of the era.


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