18s carb

REDWARDS · Post by **REDWARDS** » Sat Aug 02, 2008 2:25 pm

My 1952 18s has a monobloc carb, which has seen better days, so I was thinking of treating myself to a brand new pre monobloc to suit the bike, the spare list quotes a 89B-1AK for the carb spec, how does this equate to 274/ 276 type specs.

paul knapp · Post by **paul knapp** » Sat Aug 02, 2008 4:14 pm

Ron, the 274, 275 and 276 series carburettors have internal bore diameters smaller than the required 1-3/32" bore you require for your 500cc . The 289 series covers your bore requirement.
274 series- 25/32" Dia.
275 series- ...up to 7/8" Dia.
276 series- ...up to 1-1/16" Dia.
289 series- ...up to 1-3/16'Dia.

The 1AK will give you a separate float chamber with a 3 Deg. angle.

Paul

REDWARDS · Post by **REDWARDS** » Tue Aug 05, 2008 3:58 pm

Cheers Paul,

Any idea where I can get one , the club doesn't stock them.

Ron

RogerJ · Post by **RogerJ** » Tue Aug 05, 2008 4:06 pm

Ron,

Try http://www.surreycycles.com/ or http://www.hitchcocksmotorcycles.com/ or even http://www.amalcarb.co.uk/

REDWARDS · Post by **REDWARDS** » Wed Aug 06, 2008 1:29 pm

I have tried the 3 places Roger suggested with no luck, it seems the 89 series are no longer made, what would be a good alternative to use,

paul knapp · Post by **paul knapp** » Wed Aug 06, 2008 2:15 pm

Ron, I would be looking at a 276 with the biggest bore in that series which is 1 1/16" , only a 1/32" smaller than you require. I doubt you would feel the difference if you are only using the bike for general riding where you are not going to ride it full throttle. That is my personal view, others may have a more informative assessment.

Paul

REDWARDS · Post by **REDWARDS** » Wed Aug 06, 2008 6:43 pm

Thanks for the advice Paul, if I used a 276 would I still use the same jet size recommended for the 289.

paul knapp · Post by **paul knapp** » Thu Aug 07, 2008 5:07 pm

Ron, I can't answer that, maybe one of the Amal stockist may be of some assistance, otherwise it may be just trial and error.