Thinking of going back to Amal

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Do you guys actually fit new carbs out of the box and expect them to work properly without tuning ? Perhaps you are buying a compromise set up for worst case scenario as far as the exhaust system is concerned ? When I bought my Mk2 Amals from the UK, I specified the alcohol kit. The jets and needles which came with them were ridiculous, however how would anyone with no experience ever know? The bike would still have run with those carbs - JUST !
 
acotrel said:
Do you guys actually fit new carbs out of the box and expect them to work properly without tuning ? Perhaps you are buying a compromise set up for worst case scenario as far as the exhaust system is concerned ? When I bought my Mk2 Amals from the UK, I specified the alcohol kit. The jets and needles which came with them were ridiculous, however how would anyone with no experience ever know? The bike would still have run with those carbs - JUST !
It has always been my contention that no 2 Nortons breath alike. Some may come close, but there are too many variables. Age, carbon build up, normal wear and tear, Or new with countless different scenarios.

I would assume that nothing works out of the box and but rarely sometime I can be surprised.
 
pete.v said:
acotrel said:
Do you guys actually fit new carbs out of the box and expect them to work properly without tuning ? Perhaps you are buying a compromise set up for worst case scenario as far as the exhaust system is concerned ? When I bought my Mk2 Amals from the UK, I specified the alcohol kit. The jets and needles which came with them were ridiculous, however how would anyone with no experience ever know? The bike would still have run with those carbs - JUST !
It has always been my contention that no 2 Nortons breath alike. Some may come close, but there are too many variables. Age, carbon build up, normal wear and tear, Or new with countless different scenarios.

I would assume that nothing works out of the box and but rarely sometime I can be surprised.

My Mikuni worked right out of the box.... since I had no idea where to start, I just bolted it on to test it out and I haven't looked back. IMO, the Mikuni is simple, reliable, and easy. Dual Amals would be great if you're wanting to hit that missing top end or keep that stock look.
 
PeterJoe said:
One advantage to returning back to twin carburetors is that you don't have to worry about the allen headed screws inside the intake manifold working loose then taking a walk to the inside of the engine and really screwing things up

A drop of loctite will solve that problem, however loctite won't stop chipping lower edges of the standard Amal valves (happened twice before I switched to a single Mikuni) :roll:
 
Fast Eddie said:
OldBalz said:
Bonwit said:
Thanks for the replies everyone. Yes, I looked into the single back plate to restore the stock filter, but I really want the full effect.



Care to share where you found the "ham can" front plate that has a single hole? I never knew that such an item was available.
Try here: http://www.rgmnorton.co.uk/buy/commando ... b_1668.htm
Norvil webs site has them too I believe.


Fast Eddie,

Thanks for the info about the plates from RGM and Norvil....
 
I think that Mikunis were primarily intended for two stroke engines where if the jetting is even slightly wrong, the motor won't even start and sometimes won't pick up when you open the throttle. Perhaps the fine low throttle jetting adjustments are largely irrelevant for four stroke motors? I believe the air jet was intended to work when the throttle is snapped shut on a two stroke at the ends of the straights. I can't see why a Mikuni would be better or worse than an Amal on a four stroke engine, except for the needles. I use Mk2 Amals with Mikuni needles.
 
Abso friggen lutely go back to the Amals. Nothing wrong with them. And I'm still running the originals al be it with the new Premier hard anodized slides. Never fail and work great. With points it's still a 1 or 2 kicker. Can't beat that tickler for getting a cold bike going.

Plus it's a badge of honor to have the stink finger after riding your Norton. :)

There is just something so wrong with a jap carb hanging off that beautiful pair of sloping cylinders and those wonderfull polished valve caps.

Just My Opinion but based on years of ownership and enjoyable riding.
 
'There is just something so wrong with a jap carb hanging off that beautiful pair of sloping cylinders and those wonderfull polished valve caps.

Just My Opinion but based on years of ownership and enjoyable riding.'

I agree with you. I don't own a standard commando however one thing really annoys me about my Seeley - I still have about three Japanese parts on it. I try to make it at least look authentic. Most people would not even notice the Japanese bits, however they really irritate me. I know they are there ! Every time I see something which can replace one of them, I buy it and fit it to the bike. It is probably some kind of fetish, however nothing looks worse than a beautiful classic British bike with what are obviously Japanese parts hanging off it.
I also feel strongly about the reverse. I hate seeing good British parts being wasted on Jap crap.
A Mikuni carburetor is a beautiful instrument - not on a Norton. (Like using acrylic paint to touch up the Mona Lisa.)
 
acotrel said:
I think that Mikunis were primarily intended for two stroke engines
Most of the Mikunis currently used on 4-stroke engines ARE 2-stroke carburettors.4-stroke Mikunis use a different needle jet,with lots of air holes drilled in it (like an emulsion tube in a Weber carb).

The best thing I ever did to a pair of Amals was turn the slldes down and fit stainless steel sleeves on them.I've never had a bike with a more consistent idle than that;and now have a lot less slide and body wear.
 
Yep Amals over 30 mm size come distorted right out the box d/t casting size cooling not being compensated for. The out of round bore correction of resleeve is big part of the benefit as well and replacing worn away bore and slide clearances. Real died in the wool Norton tinkerers use a rod/pipe to blacksmith bore back to more roundness. That and anodized slides pretty much solves long wear air leak issues. The flanges in 939 size are not the flattest things out the box either. The bores can be a few .001th's off in diameter too. Wall thickness and spray tube heights vary too if any one cares. Good ole Amals for the price back when could take a Commando into lower 12 sec 1/4 mile. Some got to keep the faith pure to the Good Book but upgrades within that are proper for healthy use. Just natural for fellas to reach down and tickle the bowls a bit now and then...

Thinking of going back to Amal
 
X-file said:
acotrel said:
I think that Mikunis were primarily intended for two stroke engines
Most of the Mikunis currently used on 4-stroke engines ARE 2-stroke carburettors.4-stroke Mikunis use a different needle jet,with lots of air holes drilled in it (like an emulsion tube in a Weber carb).

The best thing I ever did to a pair of Amals was turn the slldes down and fit stainless steel sleeves on them.I've never had a bike with a more consistent idle than that;and now have a lot less slide and body wear.

So tell me, why do you say that most of the Mikunis currently used on 4-stroke engines are designed for 2-stroke engines?? I want references. The Mikuni VM round slide carbs are available in both 4-stroke (bleed-type main fuel system) and 2-stroke (primary type fuel system) designs. In fact they were standard equipment on Honda CB750s for a few years, among other motorcycles.
http://www.mikuni.com/pdf/vmmanual.pdf (See part 3-2-1 on page 4.)

So why would someone install (or sell) a VM 2-stroke design for a 4-stroke motor if the proper one was available? Only if they didn't have a clue of what the differences were. One of the main sources of Mikuni conversion kits that I am aware of is Sudco (where I got mine) and they sell both styles depending on 2-stroke or 4-stroke. They also have specific kits for vintage 4-strokes such as the Norton. http://www.sudco.com/mikuni.html
 
Well, I decided to throw the switch and began the restoration back to Amal. Not an easy decision considering the bike's running so good. But after I pulled off the Mikuni and its single manifold, I was able to hold the old stock air filter and an old carb in place to see how it looks. Sweet! Now I've got a few questions.

When the previous owner made the switch to Mikuni, he was forced to relocate the ignition switch and so apparently cut it off from the spam can and clamped it a frame tube. I was never crazy about the switch being positioned this way, and so relocated it a couple of years ago. Now it needs to be moved again, and I'd like to put it back where the factory intended.

Thinking of going back to Amal


I assume this is where it goes, and I have this piece, but I think it's going to be a little short so I may have to make a new one. Did the MkII's switch really mount this way? Seems like a crazy design to have the switch facing forward against the weather. I'm sure there's probably a better way to mount it, but I really want to keep the stock look. Any ideas here?

Can someone tell me what the purpose of the metal hook welded to the backplate is? I can't quite figure this out.

Also, since I'm going to have to repaint these parts, I'm trying to figure out if what I have is correct.

Thinking of going back to Amal


Was the backplate black and the front plate matt silver as shown here? Or was a glossy finish?

I'm sure I'll have more questions as I get into this and I really appreciate the help. Next step, get the carbs ordered from Rockypoint.
 
Larso, If your thinking is in the 1970s, most Mikunis were intended for two strokes. In fact if you fitted some of them to four strokes, the higher vacuum could cause the slides to hang up. The guide system for the slide was unsuitable and even massively strong springs wouldn't fix it. The later carbs are obviously different, however if you are going that way why wouldn't you fit fuel injection and an EMS or buy yourself a modern motorcycle ?
 
Larso1 said:
X-file said:
acotrel said:
I think that Mikunis were primarily intended for two stroke engines
Most of the Mikunis currently used on 4-stroke engines ARE 2-stroke carburettors.4-stroke Mikunis use a different needle jet,with lots of air holes drilled in it (like an emulsion tube in a Weber carb).

The best thing I ever did to a pair of Amals was turn the slldes down and fit stainless steel sleeves on them.I've never had a bike with a more consistent idle than that;and now have a lot less slide and body wear.

So tell me, why do you say that most of the Mikunis currently used on 4-stroke engines are designed for 2-stroke engines?? I want references. The Mikuni VM round slide carbs are available in both 4-stroke (bleed-type main fuel system) and 2-stroke (primary type fuel system) designs. In fact they were standard equipment on Honda CB750s for a few years, among other motorcycles.
http://www.mikuni.com/pdf/vmmanual.pdf (See part 3-2-1 on page 4.)

So why would someone install (or sell) a VM 2-stroke design for a 4-stroke motor if the proper one was available? Only if they didn't have a clue of what the differences were. One of the main sources of Mikuni conversion kits that I am aware of is Sudco (where I got mine) and they sell both styles depending on 2-stroke or 4-stroke. They also have specific kits for vintage 4-strokes such as the Norton. http://www.sudco.com/mikuni.html

Amen, Brother. And well said. :mrgreen:
 
In addition to my other questions above, I found this in my box of parts that came with the bike. Any idea what this is?

Thinking of going back to Amal
 
Bonwit said:
In addition to my other questions above, I found this in my box of parts that came with the bike. Any idea what this is?

Thinking of going back to Amal


Handmade coil bracket?
 
concours said:
Handmade coil bracket?

Great observation, and I think you're right. The holes for the coil clamps all line up. . . but I don't know why it was needed. The original is in tact.

Thanks. Another part I don't need!
 
hobot, Thanks for posting that carb tip. The engine is so thirsty that I need to open both taps when running WOT - this might get a bit more out of the old girl. :lol:
 
fastback said:
hobot, Thanks for posting that carb tip. The engine is so thirsty that I need to open both taps when running WOT - this might get a bit more out of the old girl. :lol:

I am curious if this is necessary? Do the new Premier Amal Mk1's have this feature?
Has Hobot or anyone else on the forum completed this mod for his or her Commando?
Fastback I would check your flow rate on each petcock. Something doesn't jive here.... the mains are what allows the maximum amount of fuel into the induction system when running WOT???? Is your float height correct?
I don't know maybe I am missing something???
Regards,
Thomas
CNN
 
CanukNortonNut said:
fastback said:
hobot, Thanks for posting that carb tip. The engine is so thirsty that I need to open both taps when running WOT - this might get a bit more out of the old girl. :lol:

I am curious if this is necessary? Do the new Premier Amal Mk1's have this feature?
Has Hobot or anyone else on the forum completed this mod for his or her Commando?
Fastback I would check your flow rate on each petcock. Something doesn't jive here.... the mains are what allows the maximum amount of fuel into the induction system when running WOT???? Is your float height correct?
I don't know maybe I am missing something???
Regards,
Thomas
CNN
Since the cut is above the needle valve seat, I believe the idea is if you have a highly tuned engine capable using enough fuel to run the fuel level too low in the bowl, this cut will offer a bleed to allow a bit more fuel to enter earlier than when it has to travel up the three little flat sides of the needle itself and spill over into the bowl. Maybe can deliver a bit more too, but not sure about this as ultimately the amount of fuel that will flow is governed by what squeaks by the needle/seat.
 
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