M20 Concentric Settings

iandusud · Post by **iandusud** » Thu Nov 18, 2010 5:03 pm

Hi folks. I'm working on a 1957 M20 fitted with a 928 Concentric. Can anyone please give the correct settings.

Thanks, Ian

Don Madden · Post by **Don Madden** » Thu Nov 18, 2010 6:13 pm

As far as I know the G9/M20 were never fitted with concentric carbs, certainly not in 1957, about 10yrs before they were introduced. The later Triumph 500cc T100 single carb engines were fitted with 628/8 concentrics with 180 main, .106 needle jet, needle position 2, slide 4, & fixed, pressed in idle jet. Since the engines are somewhat similar these settings should get you close. Note that needle, needle jet & jet holder were upgraded soon after the concentric was introduced & you could have a mixed bag. The upgrade is strongly recommended. Contact Amal for the correct upgrade kit. Cheers, Don. Edited by - Don Madden on 18 Nov 2010 6:14:43 PM

iandusud · Post by **iandusud** » Thu Nov 18, 2010 6:38 pm

Thanks Don. Those look like good ballpark figures. I was thinking that there must be folk here who have replaced monoblocs with concentrics. Hopefully someone will pipe up.

Cheers, Ian

laxy · Post by **laxy** » Thu Nov 18, 2010 7:50 pm

Hello Ian, Surrey Cycles tel. 01483 272328 supplied me with a new mk1 concentric for my 31csr,I just told them what bike it was for and they jetted it all up and sent it to me all ready to fit.Perhaps if you ring them they may advise you?