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MK11 Concentrics??


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VOC Member
Hello all.
What are the general thoughts on MK11 Amal concentrics? I am thinking of putting one on the solo Comet, an upgrade maybe from the old original. 8:1 comp. but fairly standard other than that.


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VOC Member
Mk ones have a tickler and choke slide. MK11s have a cold start device and no tickler. I have a pair on a twin and they do start it well enough but I much prefer the Mk ones that I've had on the Knight for decades. They start with just a three second tickle on the front, and I never use the airslides. As you tickle you can feel that there is petrol under the float. I have used 930Ls and even a 930R on Comets with no problems. My oversized Comet uses a Mikuni and I really miss the tickler. If there is any failure in the fuel supply you can kick for hours without success. If you run out of fuel while riding and don't hit reserve quickly enough there is no way to tell when the fuel is through. I assume that as the floats rise they reduce and slow the flow and it is hard to tell when it is worth tryint ot restart. I envisage the same problem with MK11s. With the Mk one you can hold the float down and feel it fill. If you do manage to flood a warm engine, it only takes a couple of kicks with open valve lifter to clear it.

If anyone has a Mk one 1034L that is not in use I'd like to buy it for my Comet


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VOC Member
Used the Mk2 on the racer because of the regs but if I swap out the monoblock on the road bike (its getting old) I will get a mikuni. I dont have a lot of time for the MK1 or 2.


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VOC Member

Type in "concentrics" in the search box and there is a wealth of info. Martyn did several posts with lots of technical information.


roy the mechanic

Well Known and Active Forum Website User
VOC Member
I run mk2's on my rap, starts well, goes well. The guys with mikunis like them, I guess you pays your money and make your choice.

Kansas Bad Man

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Non-VOC Member
I ran 34 mm Mikunis on my look alike shadow with Weber cams and 7.3 pistons at Bonneville, I have a timing slip of 127 plus MPH ,it had a 3.27 lightning gear and wouldn't pull top gear at a adjusted altitude of over 6000 ft. Sonny rode the bike, the run was made in 3rd gear, with indexed sparkplugs.:D
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