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Discussion Starter #1
I currently am running a set of MK II carbs and can not get them enough, i have tried everything, except changing the needle, needle jet and slide. The carb guy a spoke with recommended changing out the slides which runs around $200, just wondering if these are a good carb worth investing in or should i be looking at Monoblocs or MK I's, Interestingly enough i saw on ebay last night a flat slide carb that looks like the mk II's, anybody had any experience with these?

Thanks,

Jason
 

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You could always go with a fresh set from Sudco. They are basically a bolt on deal. We just put a set on a 78 750 Bonne at work, and they brought it to life.
 

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I like my Mikuni setup from MAP on my 69 TR666... Its basicly the same Sudco setup that Copper is talking about...But it comes with a shortend manifold.. But i will admit I had to change the needle and shave the slide a little... She rides like a raped ape now... FUCK AMELS!!!!
 

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I gotta say the same, but it goes both ways too. The Amals are either good or they are a total chunck of shit. I've had both good and bad luck with both Amals, and Mik's. It's just getting them dialed in and finding a good one to begin with is usually the hard part.
 

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Discussion Starter #5
Thanks guys, has anyone else had any experience with Amals? Would changing the slides have that much affect on leaning out the bottom end?
 

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F.U.Jay said:
I like my Mikuni setup from MAP on my 69 TR666... Its basicly the same Sudco setup that Copper is talking about...But it comes with a shortend manifold.. But i will admit I had to change the needle and shave the slide a little... She rides like a raped ape now... FUCK AMELS!!!!
What ever dude !!! Amals rule you just have to be smarter then them .
 

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Im running 932's. I know 930 are preferred, but this what I have. Mine run fat on the low end as well, but come on strong on the mid and top end hense the 932. The Amals will start my Trump and idle it when it is cold so I'm not complaining to much. I have also heard that Trump motors are sensative to header length. The shorter the pipe the more top end and longer for bottom. I'm running drag length with no baffle. I would like more bottom end since this is the power band I ride in for cruising, but this is my set up for now. If I was going to buy new carbs, I would buy amal's. I would also buy brand new. It seems all the used ones are junk and that is why they can be had for so cheap.
 

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Discussion Starter #8
My Mk II's are new, but i was wondering if spending money on slides will lean it out or if i should spend the money on 930 concentric's?
 

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Discussion Starter #9
So now i am totally confused, One guy i talked to said slides, the next guy says mains, Any idea's? my mains seem to be spot on, top runs great, pulls hard, will reducing them help rid my bike of the low end richness?
 

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76tri said:
Thanks guys, has anyone else had any experience with Amals? Would changing the slides have that much affect on leaning out the bottom end?
If you're problems are low down, rejet and reduce the cut away, I prefer Mikunis they are easier to set up and balance.

Frenchie
 

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Trumpnut said:
What ever dude !!! Amals rule you just have to be smarter then them .
Then I guess im a TOTAL dumb ass,,,Mine was such a bitch,,,Ran lean as shit no matter what I did,,,Plus the fuel valve stuck all the time,to the point I had to keep a tiny screw driver to dig it out of the body...gas would dribble like a drunk on NEW YEARS EVE....

Nice ink,,,, I'll stick with the Mik,,, and maybe go get a bigger tattoo also JK
 

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76tri said:
So now i am totally confused, One guy i talked to said slides, the next guy says mains, Any idea's? my mains seem to be spot on, top runs great, pulls hard, will reducing them help rid my bike of the low end richness?
ok, I was confused when you first posted : "... MK II carbs and can not get them enough," but I see now, wet at low-end.

also note most input here so far is re Concentric experience vs mikuni, the Mk II is a superior carb to Both.

just going by your (local) advise, $200 for just new slides seems extreme; also have you moved the needle lower into the jet (clip higher position) to lean it ??

and I am recalling a persistent plug-wetting problem some time back on my '79 T140D with a boyer, I had to carry spare plugs everywhere. Take a close look at the starter plunger/enrichner/cold-start circuit, especially if they are still linked together off of one lever, OR if you have non-stock rubber runners.

but if you have Mk II's on an earlier than mid-'78-up it is not stock.

anyway, my rich condition was caused by worn cold-start plungers, but still ran great mid & top due to the Boyer.

I checked early in the week & they had nothing listed, but I'll keep
checking, Dennis Kirk has an ebay store that occassionally has a huge stock of Amal parts, pieces, jets etc; recently I bought a brand new pair of 34mm Mk II's for $225. might get lucky and source you some different slides, I'll let you know if they list another batch.

For general ref, here is a good chart/info on Mk II's :









Amal type Mk II


Main jet
Needle jet
Needle type
Needle position
Throttle valve cuttaway
Starter jet​



R2930/1 L2930/2



200
.105 (2928/030)
2C3
2
3
50​




.........................................................................

ok so I cant get the table to line up, you can figger it out.

http://www.t140.com/views/mk2.html

and here is some discussion of setting up Mk II's on Bonneville Specials, like my '79 : http://www.britbike.com/ubb/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=11;t=002226;p=1&r=actu

I do believe you're having the same condition I was, the low-end fouling from leaking starter plungers . DO beware just changing plugs & keeping running tho, that much gas washes past your rings & thins your oil.

.

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Comon problem with the MKII rich on bottom . There is 2 spots for the pilot jet to sit . One is in the float bowl and the othe is in the traditional place on the air filter side of the body . Somtimes when they get rebuilt or built in general they miss putting the plug in place of one of the polit jets . If you remove the float bowl and turn the carb over you should see a small aulim. plug slightly off center and between the main jet and the air box side of the carb if there is a threaded hole you will need to remove the pilot jet from the floatbowl housig and reinstall it there . then use epoxy to plug the hole in the float bowl housing .
If you look at the pics posted you will see the 2 pilot jets although one of them has no hole .
And on Concentrics that run rich on the low end check for a pilot . They say the new amals are bushed but I have found some that arn't ( by milling a brand new one into the idle circut showing no bush installed and sending back to prove a point ) so by installing a pilot jet you can better tune the idle circut ( even if the carb is bushed a pilotjet will lean the bottom out ) . Also check the mixture screws if you are running twin carbs and make sure the tapers match . When the float over flow and the needle sticks that is common to . The needle seats machining is not the best so by taking some tooth paste on a Q-tip you can lap it smooth to a good seal .
 

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F.U.Jay said:
Then I guess im a TOTAL dumb ass,,,Mine was such a bitch,,,Ran lean as shit no matter what I did,,,Plus the fuel valve stuck all the time,to the point I had to keep a tiny screw driver to dig it out of the body...gas would dribble like a drunk on NEW YEARS EVE....

Nice ink,,,, I'll stick with the Mik,,, and maybe go get a bigger tattoo also JK
TOUCHY !!!!:D :D :D
I've seen super lean on bottom before and found most of the time the mixture screw at fault . The taper to short and fat or even better once found a new carb with the idle and mixture screw reversted . And if you know what the idle screw tip looks like you'll understand .
Mikunis are fine carbs but they don't look as cool as a twin AMALS on a old trump
 

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Discussion Starter #15
Thanks guys, I bought my carbs from Denis Kirk via egay, ia hve checked the float levels, and enrichers per the mk II tuning instructions available on the british cycke supply website. Today for shits and giggles i turned the air adjustment screw out 3 turns from the previous 1.5 and the bike ran alot smoother, still a little puff of black off idle, but atleast the chugging was gone. I think new slides will remedy this, but the cost from British cycle is $87 each. They are chrome plated if that makes a difference, MAP sells the for $29.95 so i will probably order from them.


Jason
 

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Discussion Starter #16
I guess i should also note that the needle has been moved to the first position. Looks like i will placing an order tomorrow, new slides, jets and needles. Not much time left in the riding season, so hopefully i can get it tuned before the snow flies.


Jason
 
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