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#146246 - 08/04/08 4:16 am Amal Carb - replace, rebuild or switch to Mikuni?  
Joined: Feb 2006
Posts: 1,095
Matthew in TO Offline
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Matthew in TO  Offline
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Toronto, Ontario, Canada
Now that my battery/electrical issue is solved, it's time to solve my last (thus far) challenge on my 1969/70 Triumph T100S. Whenever I stop at a light, stop sign, or anywhere in traffic, there is a strong chance that when I change into first from neutral (or release the clutch if remaining in first) and re-open the throttle to pull away that I will hear a splut and the engine dies. It's at the exact moment when the throttle is just opening. It happens about once in every 10-20 stops. To avoid getting run over at a stoplight, I keep the engine running at about 2,500 rpm when stopped to ensure that it will not cough out and die. The restarting process is near dreadful in traffic, as I must re-tickle the carb to flood it or it won't start. Only once this weekend I was able to restart the bike without tickling the carb, as this was after a long run at over 110 kph and the engine was hot.

It's got nothing to do with my electrics, as even when stalled the head light is as bright as ever, and after I tickle the carb as above the bike will start with the light on or off.

So, I'd have to think that my carb is worn out. Based on the "new" AMAL concentrics out there for sale, and the quality of rebuilds of original Amals, and the apparently better Mikunis, which would you go with? I'd like to keep the cost to below $200 if possible.


1970 Triumph T100S (1969 T100S motor)
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#146247 - 08/04/08 4:30 am Re: Amal Carb - replace, rebuild or switch to Mikuni?  
Joined: Apr 2006
Posts: 176
Colin_In_Ottawa Offline
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Posts: 176
Ottawa Canada
Hi Matt - I just sold my T100. I had put a JRC carb on it last winter. After getting a few early bugs worked out I was happy. The bike idled sooo nice and started every time from cold in 2 kicks. Just make sure you get it with the stronger return spring and hopefully, unlike mine, it won't have the float adjustment so out of whack that it won't run. But for under $200, it gives the AMAL a run for it's money.


*******************************
70 Bonnie
70 T100s Bobber
07 Bonnie
10 Tbird
#146248 - 08/04/08 5:05 am Re: Amal Carb - replace, rebuild or switch to Mikuni?  
Joined: Feb 2006
Posts: 1,095
Matthew in TO Offline
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Matthew in TO  Offline
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Toronto, Ontario, Canada
Thanks Colin. I'll check out JRC.

Did you replace the T100 with something else, or do you have a few more Brit bikes in the shed?


1970 Triumph T100S (1969 T100S motor)
#146249 - 08/04/08 8:25 am Re: Amal Carb - replace, rebuild or switch to Mikuni?  
Joined: Oct 2004
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Tiger Offline
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Melbourne Australia
The spit back off idle/stall is typical of a worn AMAL, IME you could possibly cure it by fitting a new slide but that will wear out in maybe 2000 miles.
Amals can be fixed and if done properly are a great carb.


1969 TR6R
7.62 x 51 is not a maths puzzle.
#146250 - 08/04/08 11:31 am Re: Amal Carb - replace, rebuild or switch to Mikuni?  
Joined: Nov 2007
Posts: 219
sawtooth Offline
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New York
As a learned friend once said to me.."if you can't tune/fix the AMAL then forget Mikunis"

I've heard that JRC/PWK/Keihin are a "decent" replacement carb...the local chopper guys use them on their 650's chops.

IMO they do not "look" right on late model Triumphs...they looked small on my T140E

#146251 - 08/04/08 3:26 pm Re: Amal Carb - replace, rebuild or switch to Mikuni?  
Joined: Oct 2007
Posts: 93
Buster Conrod Offline
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uniontown, pa, usa
I had similar problems years ago and also considered going to a Mikuni. I got a new AMAL carb body and slide and everything worked fine and still does. No choke, never need one.

The problem is not that you have an AMAL, the problem is that it's OLD! An AMAL is about as simple as a carb gets. The only thing I would do differently is to get the bowl with the removable drain plug on the bottom. Great for getting undesirable stuff out of the carb bowl and I think you can even change main jets through it, am I right?


1970 TR6R Dry Frame Silver and Blue, Prettiest bike ever....
#146252 - 08/04/08 4:55 pm Re: Amal Carb - replace, rebuild or switch to Mikuni?  
Joined: Feb 2007
Posts: 197
bsatrinor Offline
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staten island NYC
even if you buy a new AMAL 28---you will still have junk-----------the pwk-jrc are flange type bolt on replacements----- -- the mikuni is a problem with adapters and rubber hoses and funny size jets-- go witrh the jrc-you wont be sorry your bike will be apleasure to ride------i used a pwk 28 on my bsa B25t----runs perfect

#146253 - 08/04/08 6:33 pm Re: Amal Carb - replace, rebuild or switch to Mikuni?  
Joined: Feb 2008
Posts: 163
dale karger Offline
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dale karger  Offline
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pennsylvania, usa
I am most likely going with Mikunis because I am get a little engine work done and the guy doing it uses them with excellant results. Yes, you are most likely going to have to get an adapter..perhaps not. There is a guy in Niagra Falls ( usa ) that sells Miks and he can help you. Just If you do use these carbs get a air filter that will let it breath. The small pancake one I understand are too restrictive. No sense putting on a new carb only to have it struggle for air.


76 T140V
79 Honda CB 650
79 Yamaha 175 Enduro
68 Chevy Impala Convert
- - - - - - - - - - - - - - - - -
#146254 - 08/04/08 7:22 pm Re: Amal Carb - replace, rebuild or switch to Mikuni?  
Joined: Apr 2006
Posts: 206
Clanger Offline
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Clanger  Offline
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Posts: 206
Northants
I've run very worn AMAL carbs, still do in fact. But the fact that you need to tickle *when warm* seems to me that you have a problem with fuel level in the float chamber.

Maybe worth checking before you shell out? Maybe experiment with going even a little higher than recommended to see what happens. You may have to adjust other settings to get the rest of the range right, but I think it'd be worth trying to fix the stall problem first.

Also make sure you put in new plugs and gap them *exactly* right. Lightly fouled plugs can sometimes run right everywhere except idle, (more a problem on mag systems really, but maybe worth a mention)

#146255 - 08/04/08 8:31 pm Re: Amal Carb - replace, rebuild or switch to Mikuni?  
Joined: Mar 2006
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Gunk Offline
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43.34 (4320') | -79.81 (-794...
I would repair the Amals.
I ordered a pair of JRC's and while I was waiting I rebuilt my old, worn-out, Amals and they run like new.
I'm not afraid of switching, the money was already spent.
But I'm glad just the same, since the Amals are the original deal and they work like new.
Now I'm getting a new chrome chain guard... and a paint job I think.

Gunk


"he who laughs fast, laughs first"~Gunk
#146256 - 08/04/08 10:24 pm Re: Amal Carb - replace, rebuild or switch to Mikuni?  
Joined: Nov 2004
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az-idea Offline
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Posts: 976
palo alto,ca.
..stumbles an dies coming on to throttle off Idle 1]..easy to start when after long run n'still hot 2]..classic signs for[possibly]too lean pilot,or air screw just an 1\8th or a 1\4 out too lean for said pilot..?..

#146257 - 08/04/08 11:53 pm Re: Amal Carb - replace, rebuild or switch to Mikuni?  
Joined: Mar 2005
Posts: 460
Jethro Offline
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Jethro  Offline
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Posts: 460
Cincinnati, Oh
I am often surprised at comments regarding Mikunis... I've run a set of VM34's on my 71 650 for three years. Still original set, and they run GREAT! Starts second kick cold, first kick warm. Great gas mileage, good pubs on them for tuning, good parts availability. VERY tunable. I did splurge and buy and adaptor set from SUDCO, and it was expensive, but it LOOKS great, and works terrific. If you need, I'll post my "specs" on it, i/e main jet, etc..

#146258 - 08/05/08 1:27 am Re: Amal Carb - replace, rebuild or switch to Mikuni?  
Joined: Jun 2006
Posts: 331
2twins Offline
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Maryland, USA
I fixed the exact same symptoms in my '71 T100C by adjustment of float level. Ratty old 626 single carb. Runs fine, no stalling anymore. As I recall, I lowered float level. Gas too high in float caused over rich condition at initial throttle opening, bike would stumble and stall.
Coincidentally (not), no more sooty plugs. How do your plugs look?


Woody 2Twins
#146259 - 08/05/08 2:19 am Re: Amal Carb - replace, rebuild or switch to Mikuni?  
Joined: Feb 2006
Posts: 1,095
Matthew in TO Offline
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Matthew in TO  Offline
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Toronto, Ontario, Canada
Quote:
Originally posted by Buster Conrod:
The only thing I would do differently is to get the bowl with the removable drain plug on the bottom.
My AMAL has that now, I thought they all did. It used to leak a lot until I installed a good fibre/plastic washer.


1970 Triumph T100S (1969 T100S motor)
#146260 - 08/05/08 2:22 am Re: Amal Carb - replace, rebuild or switch to Mikuni?  
Joined: Feb 2006
Posts: 1,095
Matthew in TO Offline
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Matthew in TO  Offline
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Toronto, Ontario, Canada
Quote:
Originally posted by 2twins:
I fixed the exact same symptoms in my '71 T100C by adjustment of float level. Ratty old 626 single carb. Runs fine, no stalling anymore. As I recall, I lowered float level. Gas too high in float caused over rich condition at initial throttle opening, bike would stumble and stall.
Coincidentally (not), no more sooty plugs. How do your plugs look?
This is completely new territory for me. How do I adjust the float level?


1970 Triumph T100S (1969 T100S motor)
#146261 - 08/05/08 4:01 am Re: Amal Carb - replace, rebuild or switch to Mikuni?  
Joined: Sep 2007
Posts: 1,562
Roadwarrior Offline
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El Dorado, California
There is a link in one of the threads to the AMAL troubleshooting manual. I set mine to .080 from the top of the bowl. Heat the bowl in hot water, and then raise or lower the needle seat by tapping lightly on the underside of the seat until you get what you need. Bending the float tabs does nothing as it is memory plastic. Do a search on AMAL Concentric, and I am sure you can find the link to the manual. I printed mine out, then forgot the thread. If you are running a 626, you should consider upgrading to a 928 or a 930. Nothing wrong with Amals.


Bob


73 Triumph T140 Main Ride
70 Bonnie
67 BSA West Coast Hornet

56 Chevy

Who are the brain police?



#146262 - 08/05/08 4:11 am Re: Amal Carb - replace, rebuild or switch to Mikuni?  
Joined: Sep 2007
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Roadwarrior Offline
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El Dorado, California
I couldn't find the link, but found this. Should help.

http://www.hitchcocksmotorcycles.com/amal/mk1_conc_ht.html


Bob


73 Triumph T140 Main Ride
70 Bonnie
67 BSA West Coast Hornet

56 Chevy

Who are the brain police?



#146263 - 08/05/08 4:13 am Re: Amal Carb - replace, rebuild or switch to Mikuni?  
Joined: Jul 2007
Posts: 253
RHall-HCV Offline
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Posts: 253
Charlotte NC
JETHRO, I AM INTERESTED IN YOUR JET SETUP FOR THE VM34. CAN YOU GIVE ME ALL THE JET SIZES AND THE SPRAY BAR AND NEEDLE COMBO NUMBERS. IM RUNNING THEM ON A 750 TRACKMASTER STREETTRACKER AND ITS REALLY GOOD NOW BUT WOULD ALWAYS LIKE TO TRY OTHER THINGS. THANKS.


ROB HALL
HCV MOTORSPORTS
#146264 - 08/05/08 11:17 am Re: Amal Carb - replace, rebuild or switch to Mikuni?  
Joined: Mar 2006
Posts: 50
victortrry Offline
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victortrry  Offline
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Posts: 50
Sydney Australia
Hi Matthew.
Instead of replacing the amals, which are a really simple carby I was able to purchase the carby bodies which had been turned to accept mikuni brass slides.
Although there is no provision for chokes in the mikuni slides it doesn't appear to be a problem.
The bike goes perfectly now idles well.
Victor
1970 A65 Firebird
1970 TR6

#146265 - 08/05/08 12:53 pm Re: Amal Carb - replace, rebuild or switch to Mikuni?  
Joined: Oct 2004
Posts: 4,429
Tiger Offline
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Tiger  Offline
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Posts: 4,429
Melbourne Australia
That conversion is a winner, I have a single 930 bored for and fitted with with a VM Mik slide, brilliant economy and at 12K miles it has been faultless.

Jeff "Sidevalve" Skillen [Maitland] who would have done your conversion ran out of Mik slides a long while back and is manufacturing his own out of hard anodised alloy bar, amazing stuff that a sharp file cannot mark.

He also trues the carb bore perpendicular to the mounting flange which can be grossly inaccurate in all, but particularly late production, bodies.

$AU100.00 ea approx which compares well with $AU130.00 for a new AMAL body and $AU30.00 for a slide which will last 2000 miles.

I have posted in detail about these conversions in the past.

BTW Victorry, the Mik slides are either hard chromed brass or some other yellow coating [not hard anodise] on alloy.


1969 TR6R
7.62 x 51 is not a maths puzzle.
#146266 - 08/05/08 10:24 pm Re: Amal Carb - replace, rebuild or switch to Mikuni?  
Joined: Jun 2006
Posts: 331
2twins Offline
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2twins  Offline
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Maryland, USA
Quote:
Originally posted by Matthew in TO:
This is completely new territory for me. How do I adjust the float level?
Start with a look at the AMAL Carb tuning info, attached as a "sticky" at the beginning of the British Bikes in General board. I bet some info is there. A quick search of "float level" suggests that some classic threads may have diappeared, with some different approachs according to RFW, JH and others; too bad they are gone.
Basic idea is gently heat the bowl, and tap the float needle seat to raise and lower. Use care not to damage the float needle seat. I heated the bowl by dunking the bowl in boiling water for a bit, then used the blunt end of a 1/8" drill bit as a drift to gently tap. I'll probably get flamed for using tool steel on brass, but I got away with it. I had to try a number of times to get it to spec, it moves easily with the bowl warmed. One generally accepted target spec is to have the top of the float travel to .080" below the rim. Different theories are out there as to how to measure this; either holding the needle down in the seat, or flipping the bowl upside down while holding the pivot secure.
Keep in mind that the target is the actual fuel level. The standard I went by came from Healy's guidance, based on the actual fuel level of .170" to .240" from the top of the bowl; I set mine around .21 as I recall. To measure this I rigged up a bit of clear tubing coming of the base of the carb (you said you have a drain plug, right?), then checking the fuel level in the clear tubing held next to the carb body with the carb fully assembled.

As usual, methods described are my shade tree mechanic's methods, and not always endorsed by the pros....


Woody 2Twins
#146267 - 08/05/08 11:03 pm Re: Amal Carb - replace, rebuild or switch to Mikuni?  
Joined: Jun 2006
Posts: 331
2twins Offline
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2twins  Offline
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Maryland, USA
Here's a link with how-to info and illustrations:
http://www.jba.bc.ca/Bushmans%20Carb%20Tuning.html


Woody 2Twins
#146268 - 08/05/08 11:34 pm Re: Amal Carb - replace, rebuild or switch to Mikuni?  
Joined: Jun 2006
Posts: 331
2twins Offline
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2twins  Offline
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Maryland, USA
-and the summary of my earlier experience is in an old thread on the Triumph board, use the search function and plug in this topic: "AMAL Float Level, Adventures of an Amateur"
And if you want to see my mess from the beginning, search this one: "Triumph Bulletin Board New carb set up T100C "

Seems like I started out thinking I needed a new carb back in '06, until these folks gave me an education.


Woody 2Twins
#146269 - 08/05/08 11:47 pm Re: Amal Carb - replace, rebuild or switch to Mikuni?  
Joined: Feb 2006
Posts: 635
Ginge Offline
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Ginge  Offline
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Qld, Aust and Otago,NZ
Matthew

I agree totally. Even with a brand new AMAL on the same bike as yours, mine did the same as yours until I tweaked the float level and reset the pilot.

It's lovely sitting at the lights with hands off the throttle.....confident that she won't die.

Money saved.


Ginge
#223865 - 11/17/08 1:54 am Re: Amal Carb - replace, rebuild or switch to Mikuni? [Re: Tiger]  
Joined: Feb 2006
Posts: 1,095
Matthew in TO Offline
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Matthew in TO  Offline
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Toronto, Ontario, Canada
Well, I took the carb off my bike today, and the sleeve looks to be quite pitted and worn. I'm planning to send it to http://www.amalsleeve.com/ for a rebuild, since their price is better than a new carb, and I've heard that the new AMAL carbs have the exact same quick wearing engineering challenges as the originals, while the rebuilt carbs have better sleeves and build quality.

I've decided against the Mikuni or other carbs, since I want the original look.

Does anyone have a review of or comments about http://www.amalsleeve.com/? I know they advertise on this site, but feel free to msg me if you prefer. They seem to do good work, per their website.


1970 Triumph T100S (1969 T100S motor)
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