i have seen later m20 and m21 bikes with a long alloy spacer on the barrel to carb,i am on a 1940 and the barrel studs are short,i was going to make a tufnol spacer 1/4 thick to insulate the carb a little but have been told side valves run very hot,how were they originally?thanks arthur.

Hi Arthur..A 1/4" Tufnol spacer is ideal for your M20. The sidevalves do run warm and insulating the carb eliminates fuel vapourisation problems. The longer cast alloy spacer used on the M21 was there to increase the length of the inlet tract which improves low to mid range 'pull'..at least theoretically. Even with the spacer fitted however, tract length is well below the optimum....Ian

thank you Ian,thought it was the way to go,but the chap who told me has a m21 with sidecar and said they were all like that,still realy impressed with speed of responce on this forum!and help,off to look at andy tierans web site.thanks again.

The only way a monobloc will clear the generator is to use a long spacer.

Hello All,

Does anyone know the part number for the spacer? I have 66-127 as the part number for a flange gasket, but I don't know if this one is the extra thick one for insulation.

thanks again all

Kevin

Hi Kevin & others,
try looking at this place,
it looks like they have nicely made up tufnol spacers,
I'm thinking they fit an M20

I read your post the other day abt the work your doing,I bought my m20 last summer and will be doing much of the same u are doing.
U mentioned having your Mag rebuilt at a good place, somewhere on our side of pond.

where would that be? and what do they charge?


http://www.hitchcocksmotorcycles.com/hints-tips-mk1-concentric

tnx Patrick

email (option): pwegelin@moog.com

Hey Patrick, thanks for the reply on that carb spacer. I'll order up a couple. I believe my buddy's 16 H could use one too.

That shop is Doug Wood in Boyertown Penn. A freind of mine with local repair shop was sending out another mag and I piggybacked my order on his.

Kevin

Ed Strain is your man in the US for magneto rebuilding... does them all Splitdorf, Bosch, Lucas, etc... He does not have a website, but do a search for magneto repairs and his name will come up many times on many sites, all recommending him.

Give him a call and let him know your needs. He does great work: my magneto rebuild came to $250.

ED STRAIN MAGNETO REPAIR 727-521-1597.
ED STRAIN
6555 44TH ST. N. #2006
PINELLAS PARK, FL 33781
TEL: (800) 266-1623
TEL: (813) 521-1597







JDE

email (option): teladelujo@msn.com