Best value for money carbs - restored Amal MK1 ?

Talking about best carbs for the money I vote for a pair of restored Amal MK1.
If they are properly re-sleeved, the idle circuit is 100% clean, correct float height setting, and they are synchronized (using Carbtune or similar equipment) I think you have a great carb set-up for the money.

It takes a good portion of patience to get there but when properly done the MK1 works. I finally got mine sorted out and the bike now has a solid idle, great throttle response, pulls nicely from idle and up.
I can drive 25 mph on top gear, twist the throttle and it pulls without any hesitation
And I run with a slightly modified original points system.

Cheers,
Per

Hello Per
where did you have your re sleeving done and could you let me know the cost please ? any information would be helpful.

Tak and cheers Blaisestation

There is a member of Norton Sweden that is doing the re-sleeving for most people here. I believe he has done at least 30 pairs so far and he is doing a great job.

If you are interested I can help you with the contacts. You can send me a PM if you want to know more on pricing etc.
The only disadvantage is that he is only doing one batch per year so you have to send him the carbs in early November and then he will send you a Chrsitmas present

/Per

I agree Per, Concentrics work fine, especially after rebuilding with brass sleeves on the slide. I have three bikes with MK1 concentrics, two Nortons and a Vincent twin. The Commando and the Vincent twin have not yet been sleeved, but that is the route I will take when the slides get badly worn. The third bike is the 650SS that I just bought, it has been sleeved in brass. All three are almost always one kick starters, all three idle perfectly and pull smoothly thru the range.

Several of my fellow Vincent club members have informed me that Concentric MK1 carbs are junk and that I should switch to Mikunis for better performance and easier starting. In my admittedly limited experience, I have found the opposite.
My fourth bike is another Vincent Rapide. It has the benefit of having new Mikuni carbs. It runs well, but does not start as easily as the other three. It is also a bit slower than my Amal equipped Rapide, even though the bike with the Mikunis has higher compression and hotter cams.
I'm reluctant to change the carbs on any of the bikes fitted with concentrics, they all run so well.
I have considered changing the Mikuni equipped bike to Amal concentrics.

I have heard it said by others that the carb tickler on an Amal, though annoying to some, is a very positive way to supply a necessary shot of gasoline to start a cold engine. The enrichening circuit on a Mikuni does not seem to work as well for this purpose, at least mine doesn't.

I'm not traying to say that changing to other carbs is wrong but I think more people would keep the original carbs if they got them sorted out properly and by doing that save money and keep the original look

It is a lot cheaper to fix the Amal's compared to buying new carbs (regardless of make) and with the brass sleeves they seem to last "forever".
The MK1 is easy to work on and I think many people get problems (idle, starting etc) due to the difficulty to get the idle circuit properly cleaned out. With idle circuit clean I think it works great!

Regards,
Per

Nor did I mean switching to Mikunis or other carbs is wrong, it's just that as you say,there is no need to!
In my own case the one set of Mikunis I have came with on the bike, so I was interested to see how it ran in comparison to my Concentric equipped Vincent. After all of the strong advice I had been given by my fellow club members who insist that Amal Concentrics are crappy carbs that will not meter the gas flow properly at anything under full throttle, I expected the Mikunis to give superior performance, easier starting and smoother running than my Concentric equipped bike.

One fellow was quite insistent about my need to throw away the Concentrics as part of what he claimed I needed to do in order to make my Vincent "make power" like he claimed his did. His is heavily modified with 9.4 to one pistons, Lightining cams, Harley Screaming Eagle ignition, ported intakes and exhausts, large diameter headers, Supertrapp exhaust, huge twin 36 MM flat slide Mikunis, five speed Quaife and some other stuff I have forgotten.

Every time we met he would start in on my need to "spend some money on the bike and make it competitive".
Along with several other Vincents, we ended up riding together on a 3.000 mile trip to the southern US and home. In Idaho on a six mile long 10% grade he took off on his hotrod Vincent, passing the Group leader. We were both two up with gear, but my bike was loaded about 50 pounds more heavily than his. I decided to give chase and to my surprise managed to catch him and pass! He damn near fell of his bike when we cam up alongside. He later claimed that he could have dropped one more gear and caught us, but I think not! He said he didn't want to frighten his wife, pure BS., with his riding (fast)he had her scared out of her wits most of the time anyway!
Six months later we got into again at a Rally in central washington.
Again he passed our ride leader and I gave chase. This time we were solo and the speeds were greater. I caught him at something over 100 mph and backed off just a little to stay alongside, then opened the throttle and slowly pulled away!

He no longer tells me that I need to spend money on the bike to "make power" or that I should junk my carbs!



Initially the Mikuni equipped bike ran poorly at high RPMs but with several main jet changes that is no longer a problem. It runs just fine, as well as the other bikes but no better, but is sometimes difficult to start whereas the others are not. I remain uncovinced that the Mikuni is a better carb for these bikes, other than the slide, which as you say can be rectified by sleeving.

I, too, think highly of the AMAL carburetor (with the chrome brass slide). Heck, I even like the name. The AMAL performs well and is dead simple to work on and tune.

Jason

where do you make the call to have them sleeved? i have read that if there is any shiny spots in the slides, this is an indication on wear.

when i took mine apart for inspection, there is some slight evidence of this, but it seems to run good.

there are only 4k miles on the bike, it did sit for 25 years, but the age also plays a role?

I've always been pleased with Mk1 Concentrics and have set them up to run with various exhaust and air filter systems without difficulty. My current set were sleeved by Martin Bratby in the UK.

There has long been the idea that twin Amals are 'difficult to keep in tune' - I don't get it really. There are only two screws and a cable adjuster on each carb.

Back in the seventies, it was always said that Amals flowed more than Mikunis of the equivalent bore size. I don't know if this is true when compared with later versions.

On the subject of resleeving, I think it's true to say that you'll know when you need to ! The slide will be worn with groves on the thrust faces and if you grasp the slide through the carb openings, you'll be able to appreciably rock it back and forwards. If a new slide does the same, then it's time. On a properly filtered engine, I would expect 20,000 - 40,000 mile before it needs sleeving.

The guy who did my carbs told me that new Amal's has a too large clearance so even the new carbs would benefit from the re-sleeve mod.

It seems to be a good idea to perform the "Modification for blanking screw" proposed on Bushman's carb tuning secrets. This will make the idle circuit cleaning a lot easier. This mod is on my to-do-list for this winter wrenching!

Regards,
Per

iusedtolikehondas said:

where do you make the call to have them sleeved?

Click to expand...

AMR in Arizona and Lund up in Washington both provide this service.

2ndchildhood said:

iusedtolikehondas said:

where do you make the call to have them sleeved?

Click to expand...

AMR in Arizona and Lund up in Washington both provide this service.

Click to expand...

thanks for the info
i guess i worded the question wrong, i meant what to look for. but i'm pretty sure mine are fine after looking at them again.

Note that AMR in Arizona provide a complete, chrome plated brass slide.

Jason,
Please be careful who you give that advice to. This man (Per G) is in Sweden and will most likely need a choke from time to time. I believe the AMR mod does not allow it.

Yes, we need to use the choke (especially during spring and fall seasons) and I also like to have it for testing.

The mod I have on my carbs is very similar to the mod done by "Lund".

Regards,
Per

iusedtolikehondas,

I suspect even NOS concentrics can benefit from sleeving, but typically I look for movement of the slide in the bore and scoring. If I can move the slide laterally noticeably more near the bottom of the bore than at the top, it is a good indication of excessive wear. Boring the body and adding the sleeve trues the bore and reduces the clearance to provide more uniform air flow.

iusedtolikehondas said:

i guess i worded the question wrong, i meant what to look for. but i'm pretty sure mine are fine after looking at them again.

Click to expand...

If you have a micrometer and a T-guage, check that the bore is round and has no taper. Similarly for the slide. Amal specifies a clearance of .0035" to .004" between the slide and bore, if it gets to be greater than .006" you might think about sleeving or at least replacing the slide.

If the bore is good, I would strongly recommend getting one of the chromed brass slides that Amal sells (I think britcycle carries them in the US). This will minimize galling and extend the life of the carb.

A note on clearances: Some machinists will tell you that .004" is too sloppy and they can improve the carb by tightening it up. DO NOT DO THIS. It will not improve the carb but it will significantly increase the probability of a stuck slide, resulting in excessive excitement.

2ndchildhood,
Maybe you can use a bit smaller clearence with brass sleeves?
The guy who did mine mentioned that he's doing them tighter then factory new clearence but right now I don't have a number (but I will check!).

One the first few carbs he did many years ago I know there was an issue with sticking sleeves but now it seems to be gone.
With the tight sleeve you get excellent throttle response not only opening up but also when closing the throttle. Sounds very nice indeed

Regards,
Per

This season I have checked the fuel consumption on my Amal equipped Interstate -74 and I ended up with a 63 MPG average.
Still easy starting, solid idle and pulls nicely from idle and up.
I love the Amals
Regards,
Per

My Mk1's are running beautifully. Always starts 1st kick, & pulls like a steamtrain, good idle. I am running 10.25 to one compresion, PW3 cam & the rest of the motor is tuned, polished & lightened to match. No way would I put on different carb's on.