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T140V '73 + in bits T140V '73 & T140V '77
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Discussion Starter · #1 ·
Hello everyone
I'm a long way off yet, but wish to fit Amal MkIs on a T140E engine, and splay them outwards. The T140E engine is going into a T140V frame.
Don't want to buy a replacement cylinder head, as present one is low miles and excellent condition.

I'm looking for something like this:
Alternatively, could be something that screws into exhaust port.

Thanks
 

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Hi Alex,
From the pictures you sent and the other adaptors on the site that you linked to, the adaptors there angle the carb downwards, rather than sideways.

Have a look at the inlet tracts supplied for the Triumph 60-7625 these are angled enough for the carbs to clear the frame.
You will still need to buy a straight inlet tract hose to flange adaptor to get the Mk1 carb to fit.

I sure you have a reason for a change knowing the number of engine frame swap combinations you have, but the Mk1 Amal concentric is a pretty poor excuse for a carburettor (unless you have the premier carb, where the inherent problems have been overcome), the Mk2 is a much better carburettor, far from perfect but much better.

regards
Peg.
 

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Discussion Starter · #3 · (Edited)
Hi Peg!
Thanks for your detailed advice. I'll look into it.

I think MkIs are prettier. Work well on my 140V, at least relatively.

Had a beautiful T140E, mint. The Amal MkIIs on it leaked into the air box (see pic). Engine back-fired. The rest's, as they say, history.

What's better about the MkIIs? Serious question.
IMG_20210722_183708883.jpg


PS. Had replaced floats and needles, and gaskets, was in process of eliminating what was causing fuel escape.
 

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My T140D has the Triumph 60-7625 intake rubbers with Mikuni flatsides. It also the retro side covers...You be the judge to decide if the will work out ok

 
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Discussion Starter · #5 ·
Thanks. Yes, that'd work. Would prefer an elegant solution to splay MkIs, but the MkIIs on splayed rubbers such as these would do, or as Peg said, MkIs and adaptors on these splayed rubbers.
 

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What's better about the MkIIs? Serious question.
The Mk1 concentric.
I think the worst thing about them is the sh1t metal they are made from, the carb bodies wear away at an alarming rate, the slides are made from the same stuff. I would expect the carb to be worn out after 10,000 miles.
Here are some photos of some slides from spare carbs, the mk1 slides (lighter colour) have done about 7,000 miles, the darker Mk2 slides had done 54,000.
760671


The Mk2 slides are showing polish marks at the pressure points, the Mk1’s are deeply scored and worn out. Air will leak past the slides messing up the mixture.

The tickler system drops fuel over the engine at cold start.
The carb body is so weak, it easily distorts jamming the slide open. This distortion often occurs when tightening the mounting bolts.
The mounting flange is so weak it often bends and distorts the carb body. Triumph came up with several solutions, thin sealing O rings, thick sealing O rings and restricted tightening nuts.
The idle speed is not raised when the choke is used, leading to stalling when cold (Mk2 is the same).
The pilot jet is prone to blocking, but is not removable for cleaning.
The needle jets wear out rapidly (mk2 is the same)
The Mk2 is mounted on an anti vibration/anti heat transfer rubber mounting, the Mk1 bolts to the head.
————————————————————————————————————-
Premier carbs look like Mk1 amals, but have a lot of the inherent problems resolved.
Mikuni carbs are a reliable alternative.
The Amal Monoblock is a much better carb than the Mk1 Concentric , you also get more power out of the engine when using a monoblock.

regards
Peg.
 

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Discussion Starter · #7 ·
Yikes! Thanks, Peg.

Having a paranoid streak anyway, I do worry fuel will boil in the MkI bowls if stuck in traffic (actually thin Oring seems to work, but never pass by a chance to worry, I say).

Doesn't seem an elegant one-piece solution exists to fit and splay the MkIs.

So, Ok, I'll go for MkIIs on the splayed rubber hoses, and leave of choke connecting bar. Couldn't bring myself to fit mukunis--sound suspiciously unBritish.

I'll set about repairing my fire-damaged MkIIs. (Just seen price of new MkIIs, cough.
IMG_20210724_181446991_compress41.jpg
)
 

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Couldn't bring myself to fit mukunis--sound suspiciously unBritish.
I am the same, I know it’s a smart move to fit the Mikunis -but 🇬🇧

perhaps some low mileage second hand carbs?

you can get cable choke kits to replace the bar, also I have cut and shut a standard enricher lever, to make a right hand version of the mechanism. Then just use the enrichers individually on each carb.
 

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There's been some discussions about MK2's and a low speed stumble.. It seems the MK2 has an issue with US fuel evaporation rates. I had the problem with original MK2's on my T140D...I do know how to tune carbs and the stumble was resistent to jetting changes. Some riders may not notice it or care about it.If you use minimal throttle to pull away from a stop it's more noticeable..
I have fitted Mikuni TM flatslides to several Triumphs and a single carb A10, they are much better than any Amal but they are not exactly a bolt on..If you are feign of heart about carbs then use Amals....Personally, if you don't mind fuel on yor fingers, I believe new Amal Premiers are better than Mk2's and well work out fine for most riders
 

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Discussion Starter · #10 ·
Oh, yes, I'm feint of heart, so will avoid the Mikuni.
The MkI Premier does look nice and shiny, not square and nobbly like the MkII. Same cost (a lot; do they use platinum in the alloy? 😯).
It might be easier to get a compact air filter or bell mouth on the threaded MkI too, so easier to avoid oif and other filter.
Hmm...
There's these
but then cone filters or bell mouths wouldn't fit as said above??? Fitting an adaptor on end of splayed t140D hose must be getting a bit cumbersome and prone to wobbling...
 

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There's been some discussions about MK2's and a low speed stumble.. It seems the MK2 has an issue with US fuel evaporation rates. I had the problem with original MK2's on my T140D...I do know how to tune carbs and the stumble was resistent to jetting changes. Some riders may not notice it or care about it.If you use minimal throttle to pull away from a stop it's more noticeable..
I have fitted Mikuni TM flatslides to several Triumphs and a single carb A10, they are much better than any Amal but they are not exactly a bolt on..If you are feign of heart about carbs then use Amals....Personally, if you don't mind fuel on yor fingers, I believe new Amal Premiers are better than Mk2's and well work out fine for most riders
Just out of curiosity, did you try a smaller slide cutaway on the MK2's? I know I've had to do this on new MK1's in the recent past to cure just that problem.
 

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Same cost (a lot; do they use platinum in the alloy? 😯).
The premier’s are supposed to have addressed the problems with the Amal Mk1. They are made from good metal on the body and the slide. I have not used Premiers, but those that have swear by them, once they have cleared the machining swarf from the pilot circuit; Premier should address this quality control problem, but at least the pilot jets are removable to get access, unlike the Amal Concentric.

CBS Sales Pitch said:
Tired of fooling around with those Amal MKII carbs that never seem to work properly? Today I would like to introduce to you a new adapter which will allow you to run the Amal MKI Concentric carburetor on your Triumph T140 750.

CBS’s Sales blurb is a little disingenuous, encouraging a far worse carburettor to be fitted, if they had recommended the Premiers for the conversion it would have been better. I do not believe that CBS do not understand the limitations of EPA regulations jetting imposed on the Mk2 carb, or how to overcome it by re-jetting. or that most extra problems with a Mk2 are caused by the owner trying to set them up like a Mk1.
Is there any information on how the inlet end connects to the airbox!

I wonder if you could attach Monoblocks with these adaptors, I have the feeling that this would be a great setup, except I don’t think they would physically fit on a parallel port head.
 

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The premier’s are supposed to have addressed the problems with the Amal Mk1. They are made from good metal on the body and the slide. I have not used Premiers, but those that have swear by them, once they have cleared the machining swarf from the pilot circuit; Premier should address this quality control problem, but at least the pilot jets are removable to get access, unlike the Amal Concentric.

CBS Sales Pitch said:



CBS’s Sales blurb is a little disingenuous, encouraging a far worse carburettor to be fitted, if they had recommended the Premiers for the conversion it would have been better. I do not believe that CBS do not understand the limitations of EPA regulations jetting imposed on the Mk2 carb, or how to overcome it by re-jetting. or that most extra problems with a Mk2 are caused by the owner trying to set them up like a Mk1.
Is there any information on how the inlet end connects to the airbox!

I wonder if you could attach Monoblocks with these adaptors, I have the feeling that this would be a great setup, except I don’t think they would physically fit on a parallel port head.
Monoblocs will only fit with adjusters on the inside, and paired at that, unless you have chopped ones and a seperate float chamber. I have fitted a paired set to a '54 race bike where you don't much care about idle adjustment.
 

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Just out of curiosity, did you try a smaller slide cutaway on the MK2's? I know I've had to do this on new MK1's in the recent past to cure just that problem.
yes, one cutaway richer or leaner, and pilot jets. The carb bodies appeared unworn...
 

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Discussion Starter · #15 ·
yes, one cutaway richer or leaner, and pilot jets. The carb bodies appeared unworn...
I love reading posts I don't understand, for some reason, and this post has gone this way. (!)
Don't, therefore, know if following link is relevant, but do like the variation contained in it of the politician's mantra, "It's the economy, stupid."
 

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Discussion Starter · #16 ·
Hello Peg
You just posted this on another thread
downloadfile.jpg

Is that your (fine looking) bike?
Is that parallel MkIIs without air filters? Too small to see.
 

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So, Ok, I'll go for MkIIs on the splayed rubber hoses, and leave of choke connecting bar. Couldn't bring myself to fit mukunis--sound suspiciously unBritish.
here in america mikunis have been used on flattrack british bikes since they were invented in the mid 1970s. i know a guy who has period race bike photos. im trying to get him to send them to me

but youre right, they are not british looking.
 

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Hello Peg
You just posted this on another thread
View attachment 760815
Is that your (fine looking) bike?
Is that parallel MkIIs without air filters? Too small to see.
Hi Alex,
Yes, this is mine;
The carbs are 34mm Mk2 with velocity stacks hidden inside motocross foam sock filters.
They were a complete nightmare to fit.
The engine has been stroked and bored (900cc) so is taller and fatter than standard, the 8 valve head also puts the carbs further back. I had to make special inlet tract adaptors to angle the carbs further down, so they did not hit the frame, then used the TSS angled rubbers to angle the carbs out so the velocity stacks missed the upright tube.
The airbox and side panels had to go as nothing lined up, (the airbox is too heavy anyway), a rubber mounted assembly needed to be made to support the rear of the carbs on the frame.
Then a right hand enricher (choke) lever fabricated as the carbs were now splayed and the cross linkage no longer worked.
All of it heartache to sort out.

regards
Peg.
 

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here in america mikunis have been used on flattrack british bikes since they were invented in the mid 1970s. i know a guy who has period race bike photos. im trying to get him to send them to me

but youre right, they are not british looking.
Hi Kevin,
Amal and Mikuni had a very good working relationship going back a long time (1932).
Mikuni built Amal carburettors under licence.

760868


The British bike manufacturers pushed Amal to produce a carburettor that was much cheaper than the Monoblock. Amal had two genius design engineers , Jeff Binks and Barry Johnston, they managed to design a working carburettor at an incredibly cheap price, the Mk1 Concentric, due to price restrictions there had to be compromises in materials and assembly/machining techniques—BSA, Norton and Triumph,etc were happy. The bike owners perhaps not so much.

Jeff and Barry were already designing a much better quality carburettor, the design was first produced under licence by Mikuni, they called it the VM.
The new 1978 USA EPA laws made the cheap Mk1 not viable for use (you were not allowed to dribble petrol out of the ‘ticklers).
So Amal produced their own version of Jeff and Barrys better carburettor design for the now only remaining British Motorcycle Company, the Triumph Co-operative, this carburettor they called the Concentric Mk2.

surprisingly, the Mikuni VM and Amal Mk 2 turn out to be separate versions of the same carburettor design.

regards
Peg
 
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