Loved my 1973 Norton 850 Commando Roadster, It was the last British bike i owned. bought it in '74 almost new, Came with a Mukuni Carb which Idled too high no matter how it was jetted / tuned, had decent low end grunt but zero pulling power from 50mph on, no starting probs but exhaust sounded so tinny with the Mukuni carb, even with Dunstall pipes & muffs, Put dual Amals back on and it & it could breathe again, had a nice throaty exhaust note with original carbs& Dunstalls. and i always liked the tickler/primer feature on the old Amal carbs. Whitworth, Metric & SAE has always been a problem. I replaced most the Norton hardware & isolastic mounts with grade 8 & nylox as well as replacing all philips & flat head hardware with allen heads on most the old daily riders Had quite a few different bikes in the 60's, As well as a few American bikes, '38 Knucklehead, '53 Panhead & 46 Indian Chief, which were the very first street bikes i ever bought when i turned 16,Those old bikes could be had in decent running condition for $200-$300 back then, they were the vintage cruisers of their day and sadly most were chopped by idiots in the late 60's, along with a 53 BMW r 250 single & an odd Moto Guzzi. When i was 17 i got British bike fever, as older affordable Brit bikes were like the sport bikes of their day. Had a Matchless, AJS & BSA thumpers, BSA a-10 vertical twin, Early Norton 500 mongrol- hill climber turned street legal mad max machine made from various years & model Norton parts. a Velocette & a few other odd british makes mostly pre & post war up to the early 60's makes & models, If i had to choose a favorite blast from my past It would be the Triumph 200cc Tiger/ Mountain Cubs, i Had 2 of those fine little thumpers, one set up one for trials riding & off road and one set up as a cafe/sport & distance touring bike with a larger Triumph 500 petrol tank & some vintage panniers.. Rode that touring cub from LA to Vancouver Canada many times on PCH. In the 80's i Rode a 1st generation '79 GL1000 goldwing JDM model with a leading link forks my daily rider for for 12 years, put nearly 400k on that bike, wore it out and found another just like it & put 200k on that one. I am in my 70's now & dealing with old age physical failures, so small scooters fill my speed needs these days. My very last street bike was 10 years ago a '99 Hayabusa, a crazy sport touring death wish on 2 wheels. Rode it somewhat conservatively for a few months, and called it a good life after riding about 1.5m miles in 60 years without any serious incidents or accidents, so now i am back to to my scooter roots with a 1964 honda trail 55. manual 4 speed & hand clutch, my soul survivor. Amazing scoot gets 150++ mpg and climbs most anything it's aimed at.
Most people installed the single Mikunis because the original Amal Concentrics were worn out. The pulse of the intake beats the Amal slide oval and it starts shipping air around the slide. Once this happens it is impossible to set the idle. The single Mikuni has it's own issues. Cable routing is very important. We had a few of them stick open. It happened to me on a customer's bike and it is the only wheelie I have ever pulled on a Norton. I am running sleeved Amals on my '74 850 and they work great.
I had a 34mm flat-slide mikuni single carb on mine when i wanted to get rid of the worn original Concentrics back in 1998. Easy starting, perfect idle, less vibration but absolutely no grunt from 3000revs up. Then i invested in a set of new concentrics and boy what a difference. But as you mentioned, concentrics wear rapidly and after about 25000km you either have to bin or sleeve them. I am now on my third set of concentrics in 22 years 😅
@@stefansikora5183 It's the horrable pot metal slides that Amal uses. If you look at a Mikuni carb the slides are brass (heavy) and chrome plated (very hard). The sleeved Amals with anodized slides are the answer.
Rubbish. The mixture knows where it's going. It's going to low pressure created by the piston down cycle. It's not going to look for an alternate path. The idle is adjustable with loose slides.
The reason people did a mukini swap cause the Amals wore out in the bore. To be fair to Amal the Brit bike industry wanted their carb made to a price so the material used isn't the greatest. An article published by n Classic Motorcycle Magazine in the 80s covered this when they interviewed the general manager of Amal as they were gearing up for an expected revival of the British industry. He said when the cb450 came out they told the manufacturers they ( Amal) could do a cv carb for Brit bikes but no the carb was built to a price.
Looks like a pain getting those carbs on. I love my 1964 Triumph TR6 because it's only got one Amal 930. I can take it off and put it back on in less than 5 minutes. Those Norton's do seem like great bikes though.
It's all in the technique and having the right tools. (BTW I've owned 3 1/2 Commandos but I've always felt that the 500cc single carb TR6 Triumphs - or "Trophy" models - were about the perfect motorcycle, lightweight, good handling, easy to work on, "enough" power.
@@brucebear1 I have both a 1974 Norton with twin carbs and a 1966 Triumph T100 with a single Amal Monobloc. I much prefer the single carb set up. It's just so simple.
@@JR-bj3uf Yessir, I understand that principle and I agree that that's a valid choice for any rider that prefers it. But one of my favorite things about riding an 850 Commando is when you pass about 110 Mph, you're tucked in behind the fairing, the telephone poles are coming past like fence posts, and the engine is still winding faster and faster. *My* choice is twin carbs - not saying anyone has to make that same choice or agree with me, but that's what I want.
The problem with all the Amals was that both the slide and carburetor body was made out of the same soft materials that gauled up and wore down in fairly low milage and now the new anodized cnc billet aluminum slides completely cure the wear problem. All of our brit bikes have Amals with anodized slides and stay up floats. The only exception to that is the trident as they are smaller and more expensive and hard to find but it will get them fairly soon
Just before NVT's sad demise the experimental department fitted an 850 Interstate with an SU carburettor with special rubber mounting. I seem to remember it improved MPG significantly. That would be a possible English single-carb option. I also remember a British tuning house putting twin 36mm amals in conjunction with an SS camshaft which gave an 130mph top end.
I have nothing against mikuni carbs but this mikuni was put on because we didn't have a good set of Amals and a friend had that mikuni setup so I used it but never really cared for it truthfully just didn't start first/second kick like it should have and I liked how all my other bikes worked with good sets of Amals on them, that and I really like how the Amals look on my bikes also. Just my opinion on this.
I can under stand the chap wanting to keep his bike original. My carbs are worn on my commando making balancing difficult so I am considering a single set up for ease of tuning I'll be staying with Amal though. Tim
When you put a single Mikuni on a Norton Commando it loses the acceleration, the big torque and that beautiful grunt sound coming through those peashooters. Big mistake putting on the single Mikuni. It's cheaper to rebuild the Amals than to put on the Mikuni. Buying the Amal Premiers is the way to go if you don't trust your Amal rebuild learning curve. Getting the Amals back on gets you the grunt factor back. Just know that ethanol gas is the enemy of the Amal's idle circuitry and passages.
If your referring to the tightening of the intake manifold allen bolts? I was using a factory cut down allen wrench that is only 3" long. Those bolts need tightened to 8 ft lbs and it's impossible to use a torque wrench on them and yes I used a wrench to help lever past the tight areas and obstacles but I did not tighten it any more than what I felt was 8 ft lbs. I'm sorry if you thought it looked like I was tightening them down as tight as possible but I can assure you that was not the case. Its gotta be around 8 ft lb no more, ( do not over tighten and you can't leave it loose )
@@jessesvintagegarage765 thanks for your reply. You pulled one side down to the required torque then pulled the second one, that makes a gap on the second half of the flange. You should pull them down as evenly as possible. It is a fiddly job. I generally fit one carb as you did, then with the second carb at a bit of an angle screw in the Allen screw finger tight then fit the second screw tightening evenly. I also like to set the cables and slides of the bike so I can see down the chokes . Tim.
@@jessesvintagegarage765 If I were installing a pair of used carbs on used manifolds, I'd check that gasket surface for flatness. Put a piece of very fine wet/dry sandpaper on a flat piece of glass (or metal surface plate), then a drop of oil; gently rub the gasket surface across the abrasive paper. You'll be able to see the high spots because they're shiny. Repeat this until the shiny surface is even across the gasket surface. Repeat this for the carb to manifold gasket surface (remove the o-ring before you place it on the abrasive paper, the reassemble with a new o-ring. The manifold-to-head gasket is also a heat insulator -- they tend to pack down after they're used so I always put new ones in on a carb installation, too. (I check and flatten the float bowl gasket surfaces on used carbs, too.) Tightening the carbs to the manifolds (and manifolds to the head) is important to prevent air leaks and also -- if the carb is pulled too tightly, it will warp the body and cause the slide to stick. Overtightening the float bowls can cause fuel leaks and sometimes binds the float so that it sticks and doesn't - ummm - float. What you're doing in the video looks careful and correct to me (I agree with Tim that first loose assembly then alternately setting the final tightness is good). I love twin Amals (I've never used anything else on my Production Racer - although I did try a set of 34mm Amals that a flat tracker had on his Nortons -- the power is incredible but it's hard to fit them in the space and dial in manifolds) but I'll be the first to agree that they have to be set perfectly in all ways, otherwise, they're "ornery". In my opinion, putting a single carb on a Commando is like cutting one leg off a race horse.
That's great advice and is exactly what we do to older Amals thats been in service for a long time or in unknown condition but these were new Premiers and were just put on prior to this tear down and rebuild so we didn't feel it was necessary for that at this time.
@@jessesvintagegarage765 Not to take up a lot of your bandwidth, but it would seem likely to be of assistance to your subscribers to note that "modern" gasoline fuels with ethanol play havoc on motorcycle carburetor parts, both from the corrosive effects of ethanol and also its tendency to attract water out of a humid atmosphere and mix it with fuel. This applies to most carburetors - even those cast in aluminum like Premiers and Mikunis - but it seems especially bad with classic-carbs like original Concentrics (which are cast in less-stable zinc "pot metal". Effects of this are shown especially in the idle circuits of the carburetors which can be blocked by the corroded bit of metal within the drilled passages. Best wishes, Jesse, thanks for the useful and helpful videos.
Loved my 1973 Norton 850 Commando Roadster, It was the last British bike i owned. bought it in '74 almost new, Came with a Mukuni Carb which Idled too high no matter how it was jetted / tuned, had decent low end grunt but zero pulling power from 50mph on, no starting probs but exhaust sounded so tinny with the Mukuni carb, even with Dunstall pipes & muffs, Put dual Amals back on and it & it could breathe again, had a nice throaty exhaust note with original carbs& Dunstalls. and i always liked the tickler/primer feature on the old Amal carbs. Whitworth, Metric & SAE has always been a problem. I replaced most the Norton hardware & isolastic mounts with grade 8 & nylox as well as replacing all philips & flat head hardware with allen heads on most the old daily riders Had quite a few different bikes in the 60's, As well as a few American bikes, '38 Knucklehead, '53 Panhead & 46 Indian Chief, which were the very first street bikes i ever bought when i turned 16,Those old bikes could be had in decent running condition for $200-$300 back then, they were the vintage cruisers of their day and sadly most were chopped by idiots in the late 60's, along with a 53 BMW r 250 single & an odd Moto Guzzi. When i was 17 i got British bike fever, as older affordable Brit bikes were like the sport bikes of their day. Had a Matchless, AJS & BSA thumpers, BSA a-10 vertical twin, Early Norton 500 mongrol- hill climber turned street legal mad max machine made from various years & model Norton parts. a Velocette & a few other odd british makes mostly pre & post war up to the early 60's makes & models, If i had to choose a favorite blast from my past It would be the Triumph 200cc Tiger/ Mountain Cubs, i Had 2 of those fine little thumpers, one set up one for trials riding & off road and one set up as a cafe/sport & distance touring bike with a larger Triumph 500 petrol tank & some vintage panniers.. Rode that touring cub from LA to Vancouver Canada many times on PCH. In the 80's i Rode a 1st generation '79 GL1000 goldwing JDM model with a leading link forks my daily rider for for 12 years, put nearly 400k on that bike, wore it out and found another just like it & put 200k on that one. I am in my 70's now & dealing with old age physical failures, so small scooters fill my speed needs these days. My very last street bike was 10 years ago a '99 Hayabusa, a crazy sport touring death wish on 2 wheels. Rode it somewhat conservatively for a few months, and called it a good life after riding about 1.5m miles in 60 years without any serious incidents or accidents, so now i am back to to my scooter roots with a 1964 honda trail 55. manual 4 speed & hand clutch, my soul survivor. Amazing scoot gets 150++ mpg and climbs most anything it's aimed at.
Amazing stuff
@@jessesvintagegarage765 Yep. that's a story of a two-wheeled life well lived.
Most people installed the single Mikunis because the original Amal Concentrics were worn out. The pulse of the intake beats the Amal slide oval and it starts shipping air around the slide. Once this happens it is impossible to set the idle. The single Mikuni has it's own issues. Cable routing is very important. We had a few of them stick open. It happened to me on a customer's bike and it is the only wheelie I have ever pulled on a Norton. I am running sleeved Amals on my '74 850 and they work great.
Yessir, sleeved Amals with anodized slides are a revolution in Amal carburetor performance.
@@brucebear1 It's what I have but I didn't install them. The PO did that.
I had a 34mm flat-slide mikuni single carb on mine when i wanted to get rid of the worn original Concentrics back in 1998.
Easy starting, perfect idle, less vibration but absolutely no grunt from 3000revs up.
Then i invested in a set of new concentrics and boy what a difference.
But as you mentioned, concentrics wear rapidly and after about 25000km you either have to bin or sleeve them.
I am now on my third set of concentrics in 22 years 😅
@@stefansikora5183 It's the horrable pot metal slides that Amal uses. If you look at a Mikuni carb the slides are brass (heavy) and chrome plated (very hard). The sleeved Amals with anodized slides are the answer.
Rubbish. The mixture knows where it's going. It's going to low pressure created by the piston down cycle. It's not going to look for an alternate path. The idle is adjustable with loose slides.
Keep up the good work guys, your content is very, very good. Huh I didn't know the mikunis were Japanese.
The reason people did a mukini swap cause the Amals wore out in the bore. To be fair to Amal the Brit bike industry wanted their carb made to a price so the material used isn't the greatest. An article published by n Classic Motorcycle Magazine in the 80s covered this when they interviewed the general manager of Amal as they were gearing up for an expected revival of the British industry. He said when the cb450 came out they told the manufacturers they ( Amal) could do a cv carb for Brit bikes but no the carb was built to a price.
Thanks for sharing this
Looks like a pain getting those carbs on. I love my 1964 Triumph TR6 because it's only got one Amal 930. I can take it off and put it back on in less than 5 minutes. Those Norton's do seem like great bikes though.
It's all in the technique and having the right tools. (BTW I've owned 3 1/2 Commandos but I've always felt that the 500cc single carb TR6 Triumphs - or "Trophy" models - were about the perfect motorcycle, lightweight, good handling, easy to work on, "enough" power.
@@brucebear1 I have both a 1974 Norton with twin carbs and a 1966 Triumph T100 with a single Amal Monobloc. I much prefer the single carb set up. It's just so simple.
@@JR-bj3uf Yessir, I understand that principle and I agree that that's a valid choice for any rider that prefers it. But one of my favorite things about riding an 850 Commando is when you pass about 110 Mph, you're tucked in behind the fairing, the telephone poles are coming past like fence posts, and the engine is still winding faster and faster.
*My* choice is twin carbs - not saying anyone has to make that same choice or agree with me, but that's what I want.
@@brucebear1 I prefer the twin Amals on my Norton.
I owned 2 commandos and the amals were rubbish,worn out after a few miles. So i wonder that they went back to this scrap
The problem with all the Amals was that both the slide and carburetor body was made out of the same soft materials that gauled up and wore down in fairly low milage and now the new anodized cnc billet aluminum slides completely cure the wear problem. All of our brit bikes have Amals with anodized slides and stay up floats. The only exception to that is the trident as they are smaller and more expensive and hard to find but it will get them fairly soon
Rubbish. I have Amals with 40K on them and I don't know about this soft metal problem. Maybe put the spring in straight and wear would be minimum.
bodge up merchants
Just before NVT's sad demise the experimental department fitted an 850 Interstate with an SU carburettor with special rubber mounting. I seem to remember it improved MPG significantly. That would be a possible English single-carb option. I also remember a British tuning house putting twin 36mm amals in conjunction with an SS camshaft which gave an 130mph top end.
I'm gonna leave a comment , so stay tuned.😂
That's how to Ben's a flange. I won't be asking these guys to work on my bike.
Dumb move, Now you will learn why the Mikuni was on there!
I have nothing against mikuni carbs but this mikuni was put on because we didn't have a good set of Amals and a friend had that mikuni setup so I used it but never really cared for it truthfully just didn't start first/second kick like it should have and I liked how all my other bikes worked with good sets of Amals on them, that and I really like how the Amals look on my bikes also. Just my opinion on this.
My 750 has a mikuni and pretty well starts first kick
I can under stand the chap wanting to keep his bike original. My carbs are worn on my commando making balancing difficult so I am considering a single set up for ease of tuning I'll be staying with Amal though. Tim
When you put a single Mikuni on a Norton Commando it loses the acceleration, the big torque and that beautiful grunt sound coming through those peashooters. Big mistake putting on the single Mikuni. It's cheaper to rebuild the Amals than to put on the Mikuni. Buying the Amal Premiers is the way to go if you don't trust your Amal rebuild learning curve. Getting the Amals back on gets you the grunt factor back. Just know that ethanol gas is the enemy of the Amal's idle circuitry and passages.
@@robertturnbull2903Yeah but with a single Mikuni it just doesn't go after it starts.
Stay tooned here
That's how to bend a flange. So I can't spell.
If your referring to the tightening of the intake manifold allen bolts? I was using a factory cut down allen wrench that is only 3" long. Those bolts need tightened to 8 ft lbs and it's impossible to use a torque wrench on them and yes I used a wrench to help lever past the tight areas and obstacles but I did not tighten it any more than what I felt was 8 ft lbs.
I'm sorry if you thought it looked like I was tightening them down as tight as possible but I can assure you that was not the case. Its gotta be around 8 ft lb no more, ( do not over tighten and you can't leave it loose )
@@jessesvintagegarage765 thanks for your reply. You pulled one side down to the required torque then pulled the second one, that makes a gap on the second half of the flange. You should pull them down as evenly as possible. It is a fiddly job. I generally fit one carb as you did, then with the second carb at a bit of an angle screw in the Allen screw finger tight then fit the second screw tightening evenly. I also like to set the cables and slides of the bike so I can see down the chokes . Tim.
@@jessesvintagegarage765 If I were installing a pair of used carbs on used manifolds, I'd check that gasket surface for flatness. Put a piece of very fine wet/dry sandpaper on a flat piece of glass (or metal surface plate), then a drop of oil; gently rub the gasket surface across the abrasive paper. You'll be able to see the high spots because they're shiny. Repeat this until the shiny surface is even across the gasket surface. Repeat this for the carb to manifold gasket surface (remove the o-ring before you place it on the abrasive paper, the reassemble with a new o-ring. The manifold-to-head gasket is also a heat insulator -- they tend to pack down after they're used so I always put new ones in on a carb installation, too.
(I check and flatten the float bowl gasket surfaces on used carbs, too.)
Tightening the carbs to the manifolds (and manifolds to the head) is important to prevent air leaks and also -- if the carb is pulled too tightly, it will warp the body and cause the slide to stick. Overtightening the float bowls can cause fuel leaks and sometimes binds the float so that it sticks and doesn't - ummm - float.
What you're doing in the video looks careful and correct to me (I agree with Tim that first loose assembly then alternately setting the final tightness is good).
I love twin Amals (I've never used anything else on my Production Racer - although I did try a set of 34mm Amals that a flat tracker had on his Nortons -- the power is incredible but it's hard to fit them in the space and dial in manifolds) but I'll be the first to agree that they have to be set perfectly in all ways, otherwise, they're "ornery". In my opinion, putting a single carb on a Commando is like cutting one leg off a race horse.
That's great advice and is exactly what we do to older Amals thats been in service for a long time or in unknown condition but these were new Premiers and were just put on prior to this tear down and rebuild so we didn't feel it was necessary for that at this time.
@@jessesvintagegarage765 Not to take up a lot of your bandwidth, but it would seem likely to be of assistance to your subscribers to note that "modern" gasoline fuels with ethanol play havoc on motorcycle carburetor parts, both from the corrosive effects of ethanol and also its tendency to attract water out of a humid atmosphere and mix it with fuel.
This applies to most carburetors - even those cast in aluminum like Premiers and Mikunis - but it seems especially bad with classic-carbs like original Concentrics (which are cast in less-stable zinc "pot metal". Effects of this are shown especially in the idle circuits of the carburetors which can be blocked by the corroded bit of metal within the drilled passages.
Best wishes, Jesse, thanks for the useful and helpful videos.
painfully slow to watch... is this the first time they worked with real tools