Carbs for my '74 850 Commando

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bertscommando850

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Hey guys - I'm looking for a pair of rebuilt carbs for my 1974 850 Commando. Or a rebuild kit. Anyone know what size my carbs are? Or how to properly id them? I've seen a few sets on EBAY - I dont know enough to purchase a pair. I have a manual on my NORTON - and there is a section on the carb - It looks very simple to rebuild these carbs. - I believe i could do it. I just dont know "little tricks of the trade" so to speak. Any advice?

1. How do i Id my carbs?
2. What kind do i have?
3. Is it a simple enough to rebuild myself?
4. Where is the best place to get the best rebuild kit?
5. I would entertainpurchasing a set of carbs that have been built right and tested.
6. Thanks all - You guys are great.
 
bertscommando850 said:
1. How do i Id my carbs?
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Look for numbers on a raised pad on the right hand side of each carb body. Note that one carb should be a left handed unit and the other, right handed.


bertscommando850 said:
2. What kind do i have?
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What you would normally expect to find on a '74 Commando would be two 932 (932 = 32 mm) Amal "Concentric" Mk1 carbs. Either L932/30 and R932/29 for a MkII model, or R932/33 and R932/34 for a MkIIA.




bertscommando850 said:
4. Where is the best place to get the best rebuild kit?
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Without saying where in the world you live, it makes it difficult to answer, but genuine Amal parts ultimately come from the manufacturers, "The AMAL Carburetter Company" (Burlen Fuel Systems).

Having the worn carbs sleeved is often regarded as a preferable option to buying complete new carbs.
The Bushman's website has some good carb information: http://www.jba.bc.ca/Bushmans%20Carb%20Tuning.html
 
Unless you're an originality fetishist, go to a single Mikuni VM34 carb with appropriate manifold and fittings available from various sources. Better fuel consumption, nice steady reliable idle and ease of tuning. You will be impressed.
 
Fullauto said:
Unless you're an originality fetishist, go to a single Mikuni VM34 carb with appropriate manifold and fittings available from various sources. Better fuel consumption, nice steady reliable idle and ease of tuning. You will be impressed.
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...but as with so many things in life, it's just not the same if you don't get the chance to tickle 'er first :)

I find the concentrics to be part of the period experience but I've given up modifying and now accept the old clunker for what it is.
 
Hmm. Foreplay for Commandos. Never thought of it that way before. Seriously, it's like having an outside toilet. Why would ya?
 
Single 34mm Mikuni. Good mid range - loses out on top end - don't kid yourself.
Dual 34mm Mikuni, Great top end - loses midrange. Front wheel won't dance in second gear accel.
Original Amals just work best and worth the slight extra effort to maintain. Mine are sleeved now and have always done new needles and needle jets every 4000 miles. Pretty painless. Good blast-off power everywhere as intended.
This is my experience with '72 Combat anyway but each person has their own priorities.
 
hi batrider,

As another combat rider, I agree. Sleeved Amals are my preference. If I had an 850, I probably would go single Mikuni.

fullauto,

Was going to ask about the fuel economy of a Mikuni. Does Australia measure in US gallons, Imperial gallons or liters of "gasoline"? :D My sleeved Amals are getting 50-60mpg US gallons.
 
An outside loo in western Oz has gotta be better than one in Yorkshire, UK, once you have checked for spiders and snakes :(
I have an 850, and have standard amals. I bought new from RGM...many folk say the originals were better (That means mine must be really bad!!!) They work great at the moment, but only have 3500 miles on them. Depends on what you are after...
Reliability...Mikuni....originality, reasonable performance, period experience, amals (2 of em)....If you want more then log onto CNW website and see what Matt does with Kleins etc...I can only afford to look.
If you go for amals then get them re-sleeved and use brass or chrome slides to cut down on future wear. (I have heard chrome ones bits break off... :( )
 
79x100 wrote;
...but as with so many things in life, it's just not the same if you don't get the chance to tickle 'er first
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I took my Norton to my new workplace last week, and one of my collegues came out to "hear" me off. Sat astride the bike, I leant over and began to tickle the carbs one at a time. "What's that that you're doing?" he asked. Ah modern bikers, they just don't know what they're missing! :lol:
 
Funny you should ask about fuel consumption, illf8td, I recall getting 45mpg (Imperial that is) at best out of my 850 Mk2 with standard Amals. I get 55mpg (Imperial) at worst with my current Mikuni VM34. My mate Ralph here has a MK3 with Amals and he doesn't believe that I can get 150 miles out of my Roadster tank. He gets not a lot more than 110 miles. He won't call me a liar but he just doesn't believe me. If anybody got 55 to 60 miles to the US gallon with twin Amals I wouldn't call you a liar, but.............................I've never seen anything like it before and I would have to see it to believe it.
Another thing about Amals, I don't recall them staying in tune for more than a few hundred miles.
What's changed with Amals?
 
I've been using the little 30 mm PWK copies this year and when they work they are very good. The copies are not really ready to go out of the box with some quality issues.
I've been waiting to hear how the big ones GP has work out. They are huge but I bet they are well made.
I have 28 mm Mikunis on my Chang and those work very well, I'd be interested to see how they worked on a Norton. I thought they might be a bit small for a 750 but George said to give them a try and I'm pleased I did, very good mid range.
 
Fullauto said:
Funny you should ask about fuel consumption, illf8td, I recall getting 45mpg (Imperial that is) at best out of my 850 Mk2 with standard Amals. I get 55mpg (Imperial) at worst with my current Mikuni VM34. My mate Ralph here has a MK3 with Amals and he doesn't believe that I can get 150 miles out of my Roadster tank. He gets not a lot more than 110 miles. He won't call me a liar but he just doesn't believe me. If anybody got 55 to 60 miles to the US gallon with twin Amals I wouldn't call you a liar, but.............................I've never seen anything like it before and I would have to see it to believe it.
Another thing about Amals, I don't recall them staying in tune for more than a few hundred miles.
What's changed with Amals?
Click to expand...

I heard that! :D You're right, Ken, I wouldn't call you a liar..I reckon you could get 55US mpg out of a twin-amalled commando--- if you babied it. If we go for a run with the clunkers and putter aong at 75-80 km/hr, my fuel consumption is brilliant. If I flog it at 120 km/hr into a strong headwind on the highway, only just over 40mpg. Get that same wind behind me, over 60. It really is down to how much throttle you are using , once they are tuned correctly. I personally have no issues either way, I've ridden a couple of single-Mikuni'd commandos that were very smooth, but, for now, I'm happy with my Amals , which have only done 10, 000 miles, bought new. When the bodies are starting to rattle and I can't keep them in tune for an acceptable length of time, I'll review the situation
 
I just put NEW amal 930s on my 71. after 33+ seasons, years of messing with original carbs and a single amal solution , this is the best so far. The exhaust note is so tight and perfect its quite inspiring, particularly through the dustall decibels. to ride a bike that looks, sounds and idles like new makes it fun again. at 200 USD per its not cheap, but it sure works well. question will be how well will they wear.
 
The factory supplied Amals on my MKII 850 get 55-60 mpg (US) unless I'm really beating on it. The plugs are a light tan color and I'm thrilled with the performance. They've been sleeved once about 15000 miles ago.

Besides the inevitable slide wear, the biggest issue I've had with them for 35 years is the occaisional clogging of the pilot jet. Every Brit Iron owner needs a #78 drill bit and a can of Gumout in the workshop.
 
maylar said:
Besides the inevitable slide wear, the biggest issue I've had with them for 35 years is the occaisional clogging of the pilot jet. Every Brit Iron owner needs a #78 drill bit and a can of Gumout in the workshop.
Click to expand...

Or move the pilot jet back to where they were suppose to be.
 
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