carb problem

fraserreid

Forum User
Non-VOC Member
Real trouble with my new Mark 2 concentric on my 1951 comet. Jets are 190 and 105 with a number 3 slide, needle set to mid pos (have tried top and bottom) Cannot get it to run low end, spits back through carb and into exhaust. Ran ok on old carb so timimg etc is fine.

This usually denotes weak mixture but setup is correct to VOC spares guys, they are looking into it but I also wanted to poll the masses !

Regards

Fraser
 
Last edited:

sidmadrid

Well Known and Active Forum User
VOC Member
Bought one a while ago and they had ommited to drill the idle jet.
Took me a day or two to sus it out. sid
 

fraserreid

Forum User
Non-VOC Member
Thnaks for the advice, checked 3 jets.
Main is 190 and clear. needle is 106 and clear. Then the only other one I could find is numbers 25 in the float base. It has a larger hole in the top (where screwdrivewr slot is) than at the bottom. Is this ok ? and is their another jet I haven't found ?

Regards

Fraser
 

Comet Rider

Well Known and Active Forum User
VOC Member
Mk2's

Hi Fraser,

There should be 2 small jets screwed into the body of the carb inside the float chamber, First is the fuel enrichment (choke) and the other is the pilot jet. Try speaking to the guys at surrey cycles as they are most helpfull, and have exploded drawings which help a lot

Neil
 

fraserreid

Forum User
Non-VOC Member
good news

Their was damage to the small brass tube between body and float chamber. It was loose and damaged on the "fitted" end. Manufacturer said "not their issue" VOC spares were very good, had a 28mm one on the shelf, exchanged mine for that and it runs well. Thanks to VOC spares, especially for help to a newbie ! still a ****** to start though, any tips ?
 

Hugo Myatt

Well Known and Active Forum User
VOC Member
Hi Fraser
I have two Comets. One with the original carb that starts easily with just a wiff of throttle. The other has a Mk 11 concentric 28mm. This one needs a much bigger handful (1/4 to a 1/3) to get it going even with full choke from cold. I don't know if this is typical.
 
R

robinlw

Guest
Thanks all for most useful info on Mk 2 Concentrics as I have a pair to sort on a twin which has proved difficult to carburate correctly. Plus I've just bought a largely std Comet with a very worn 276 & wondering whether to try to get it bored & resleeved.
 

fraserreid

Forum User
Non-VOC Member
carb issue

I was told it would cost over £200 to get my old carb sorted so I bought the new 28mm Amal MII concentric one.

Starting problem fixed now. I attached the choke cable to the "cold start" slide, she starts first kick. RESULT.

Still learning !

now the dynamo, then all done.
 
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