im trying to upgrade my m20 to m21 ive bought acrank from dragonfly totaly nackerd so i need to find acrank rebuilderi live near burton on trent does anyone have any reckamendations sorry about the bad spelling thanks martin

email (option): jmwyatt@btinternet.com

I'm not local to you, I'm about 75 miles away if thats any help, do none of the British bike shops near you do them? Whatever you do don't take it to Alpha bearings unless you want it done some time after Christmas!

email (option): davmax@ntlworld.com

thanks dave i thought alpha had gone bust i wont be rebuilding till winter so alphas will be fine im hoping the extra hp will help me tug a sidecar apart from m21 crank and piston i think thats all ineed to do to get a bit more grunt not shure what pinoin to use book says 16 but there is 19 at present 3 teeth seems a big drop cant get above 55 now thanks for your time much appretated martin

email (option): jmwyatt@btinternet.com

Dave's brother here - I've run a postwar ('51) M21 daily with a series of big chairs fitted, currently a Canterbury Carmobile (a treble adult when it came out in '54, a double adult + child by the end of its production run in the 60's), for getting on 120,000 miles now, and have retained the 19 tooth engine sprocket for most of that mileage. Forget dropping down to the 16 tooth it'll just rev more (I tried one for a couple of weeks, try it with an 18 tooth - it'll still pull fine, but then again, I don't see over 50mph very often, but it manages perfectly well enough in modern traffic 'til you start using motorways and faster A roads.
It's probably worth bearing in mind that when the 16 tooth was a factory recommended fitment how often did your average road traffic regularly travel at over 50mph?

Hi martin

I re-geared my WD to a 20T engine sprocket

The result is a less buzzy motor & a more relaxed cruising speed of 50mph

Down side is I use 3rd gear more if in hilly countryside, but it's not a problem for me

In m21 mode which I will like you go to, I'm planning a 21T engine sprocket, should be good for 55mph comfortably

Hope this helps

Jo'b

email (option): Jonnyob1@googlemail.com

email (option): davmax@ntlworld.com

thanks one and all for your good advice mutch appretated martin

email (option): jmwyatt@btinternet.com