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Discussion Starter #1
Hi all,

I'm have a 1954 T100 with a 500 pre unit engine, currently running with dual Amal 930 carbs. I'd like to convert into single carb and would like some advice on what carb to run, aswell as finding a single carb intake. The bike is a rigid frame chopper with a belt kit and dry clutch, other than that I think I'm running a pretty much stock setup.
 

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That’s a splayed intake cylinder head, made for twin carburettors. There isn’t a manifold made to mount a single carburettor on that.

If it is still a 500, 926 Concentrics or one inch Monoblocs are likely to perform better those 930s.
 

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If it is still a 500,
:agree - 30 mm. carbs. are normally fitted to 650's; btw, R300 and L301 were normally supplied by Amal direct to dealers with 'average'-size jets, slide 'n' needle - the idea was a dealer could fit it/them to a bike and at least start it to make any final carburation tweaks.

The Concentrics fitted to mid-'67-on unit 500's - both single- and twin-carb. - were/are 626's, the smallest 900 body is a 928; the 'equivalent' Monoblocs are 1" and 1-1/16".

Hth.

Regards,
 

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Discussion Starter #4
Thanks for your replies!

If I were to stick with dual carbs, would Wassel carbs be an alternative?

I found a dealer close to me that can hook me up with a couple of Wassel carbs, supposedly made as a refined version of the classic Amals. Does anyone know anything about them? You both mentioned going down in size. The ones I've found are brand new 26mm. What do you think?
 

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Discussion Starter #6
Noted. Would a new set of Amal 626/300 Premier Concentrics be a good choice for my 500 pre unit?
 

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Hi,

Would a new set of Amal 626/300 Premier Concentrics be a good choice for my 500 pre unit?
R300 and L301 were normally supplied by Amal direct to dealers with 'average'-size jets, slide 'n' needle - the idea was a dealer could fit it/them to a bike and at least start it to make any final carburation tweaks.
Hth.

Regards,
 

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Hi all,

I'm have a 1954 T100 with a 500 pre unit engine, currently running with dual Amal 930 carbs. I'd like to convert into single carb and would like some advice on what carb to run, aswell as finding a single carb intake. The bike is a rigid frame chopper with a belt kit and dry clutch, other than that I think I'm running a pretty much stock setup.
I had a 1973 T100P ex police bike, back in the day and they were single carb, if that's any help.

Sent from my SM-G950F using Tapatalk
 

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Hi MrLantz, Wassell carbs were developed at a time Amal were very hard to come by. A few users have been happy with Wassell, but the overall majority have nothing but problems. Wassell replacement parts are said to fit Amal. In real life Wassell carb parts work really bad. Very poor tolerances. I most strongly recommend DO NOT BUY Wassell.

Many that purchase Wassell end up getting Amal Premier & Premiers work good. So after days of fiddling they buy Amal & end up spending double!

Amal sells direct (to USA anyway). You can email Amal & I've found them easy to work with. They will build carb to your exact spec including tops & banjos, slides, jets etc. at no extra cost.

Buying from parts sellers you may or may not get what you want. You have to know what you want before ordering. The 500 guys on this forum can advise on that.

On an aside Velocity stacks tend to be problematic, especially with screens. Can have large effect on mixture. Plus kick back through carb can be fire hazard. Plus the wear of carb slide/bore as well internal motor parts is real concern. Brake dust from cars that gets sucked in is very abrasive, not to mention sand. Velocity stacks are for the track only. The original wire/ gauze filters are still made & available. Avoid paper elements as they don't work well long term.

The exhaust system will effect mixture also. Again seek advise what would be best for your bike set up. Amal jets are not that costly, but slides are. So if at all possible, you want to get the slides right the first time.

I've left you with more questions, but at least you know about Wassell carbs.

Good photos of bike & details of motor set up will allow the 500 experts to give you detailed info that will put you on a good path. I see a belt drive so you could have many mods inside motor as well.
Don
 

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Discussion Starter #10
Hi MrLantz, Wassell carbs were developed at a time Amal were very hard to come by. A few users have been happy with Wassell, but the overall majority have nothing but problems. Wassell replacement parts are said to fit Amal. In real life Wassell carb parts work really bad. Very poor tolerances. I most strongly recommend DO NOT BUY Wassell.

Many that purchase Wassell end up getting Amal Premier & Premiers work good. So after days of fiddling they buy Amal & end up spending double!

Amal sells direct (to USA anyway). You can email Amal & I've found them easy to work with. They will build carb to your exact spec including tops & banjos, slides, jets etc. at no extra cost.

Buying from parts sellers you may or may not get what you want. You have to know what you want before ordering. The 500 guys on this forum can advise on that.

On an aside Velocity stacks tend to be problematic, especially with screens. Can have large effect on mixture. Plus kick back through carb can be fire hazard. Plus the wear of carb slide/bore as well internal motor parts is real concern. Brake dust from cars that gets sucked in is very abrasive, not to mention sand. Velocity stacks are for the track only. The original wire/ gauze filters are still made & available. Avoid paper elements as they don't work well long term.

The exhaust system will effect mixture also. Again seek advise what would be best for your bike set up. Amal jets are not that costly, but slides are. So if at all possible, you want to get the slides right the first time.

I've left you with more questions, but at least you know about Wassell carbs.

Good photos of bike & details of motor set up will allow the 500 experts to give you detailed info that will put you on a good path. I see a belt drive so you could have many mods inside motor as well.
Don
Thanks for a great reply Don!

I'll take your advice and will be ordering a set of Amal Premiers. Now I'm just a bit unsure what size to go for. You have recommended 626's IF it's still a 500. I have no reason to believe otherwise, but then again I can't be sure.

I really don't want to pay up for premiers to later realize I need bigger ones. I'm pretty sure the 930's I'm running today are too big, I've rebuilt and re-jetted them enough but I'm still not happy with how they're running. So I'd be happy to order a set of Premier 626/300's, but I mean there are also 627's and 928's available...

What to do?
 

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MrLantz, Was thinking about you. I really don't have the experience to give an answer. Out of curiosity what is your compression hot? What mufflers are you running?

A year ago now I rode an over carbed T140. Started fine. Ran fine, but was odd. Sort of wanted to bog at times my bike didn't. Rolling on throttle on slower curves didn't pull as I felt it should. The bike had hot megacycle cams. Boyer ignition. Timing 38b. Original owner installed 10.5 pistons. Pinged violently on 91 octane our best fuel. Ok on 110 leaded race gas. Then removed 10.5 & installed 8.6 or 7.9 pistons, couldn't be sure which. Pistons were new, but not fitted to bore & very loose as was bored for 10.5. .
With lower compression, Bike was ridable, but pistons loose in bores & rattled bad. New owner put a few hundred miles on bike like this. Then was afraid of rattles. I evaluated bike & determined needed pistons to properly fit bores.

Back to carbs, had 32mm Amal. I don't know if from Norton or not. I think Norton carbs have different spray tube?? I didn't check. Riding bike & heat soaking motor mixture felt correct. High rpm pulled very strong, did not 8 stroke. Lower RPM was sluggish compared to other T140 I've ridden.

I've found on cars over carbing makes them run the same. Under carbing runs good, but full throttle is doesn't reach its power potential. Basically like your not giving it full throttle even though you are.

I was hoping some of the 500cc guys that have a lot of riding experience will advise from their experience.

Might want to ask on BritBike forum as there are 500 enthusiasts there also. But they'll need to know ignition, air filter/velocity stack, exhaust/mufflers type also.
Don
 

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I have worked on 500 twins and tuned them. I do not consider myself an expert by any stretch of the imagination. If it were mine , I would fit a pair of 26 mm Premiers to it and call it a good investment. The road racing bikes of that era used 28 mm carbs with a little loss of carb response, IF you were racing the bike and keeping the revs up. On the street , the 26 mm carbs will run great and have better response. A single carb set- up on a splayed intake , if you can find one, will not run as well. I have a ‘67 . Someone had put a single 30 mm carb on it when I got It. I changed that to a 28 mm . Carbs can be too big.
 

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Discussion Starter #13
Thanks for your replies!

I have now ordered a set of 26mm Premiers and hope for the best.
 
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