1967 G15 MKII carb question

Rob Harknett · Post by **Rob Harknett** » Tue Oct 30, 2012 9:40 am

Check the link I first gave Rick.
389 carbs are not always the left. They are left & right, so check out full numbers the 389 l/h & r/h carbs, fload chamber types also differ. The 1967 model year started production Sept 1st 1966, The new 1967 models would had been ready for the 1966 London motor cycle show at arround the end of Oct 1966, From that date the 1967 was available. So a 1967 Matchless could had been purchased from about Nov 1st onwwards.

Rob Harknett · Post by **Rob Harknett** » Tue Oct 30, 2012 10:00 am

Rick I believe it was 1966 the carb was 389/241 left hand, from then on the 389's were left hand carbs. 689/241 was right hand side ( seems then the prefix number changed, prior to that the 3 surfix numbers changed to determin L & R. the difference between 389/241 and 689/241 is, the 689 had the float bowl on the opposite side. The carbs did also fit the Atlas at the same time they were used for Matchless. Some internal parts differed. e.g. Matchless had 360 main jet Atlas 420 main jet. I have not checked my own library for this info, its quicker to look in the archives. So you can check for yourself I've made no typing errors here

John Donne · Post by **John Donne** » Tue Oct 30, 2012 10:08 am

The Amal Monobloc and the Concentric are a totally different carb. The twin Norton monoblocs have different adjusting screws for both the mixture and the throttle stops. Both of the adjusters were oppossite each other and not pointing outwards, on all the Monobloc variations of the G15/N15. The mixture adjuster had a hexigon head on it for the adjustment, and the throttle stop screws also had a different head. The G15 used a dirivative of the Atlas engine, as the drive side was machined different to the standard Atlas casting to take the alloy primary chaincase. If you tried to fit a stock Atlas engine in to the G15 frame, the drive side would need to be modified to accept the alloy primary chaincase. The Amal Concentric was the solution to the carb adjustment problem. I have got the twin Monoblocs on my Atlas Scrambler chopped type, and my 1966 Norton N15CS has the left and right hand type,, and i have the correct type of adjusting screws fitted, and i do not have any problems with the mixture adjustments.

oldandmatchless · Post by **oldandmatchless** » Tue Oct 30, 2012 4:11 pm

Thanks for all the great responses to my question.

Looks like the carbs I have will work (as they were 750 Atlas carbs), but that I may have the wrong slide stop (idle) screws.

I am going to contact several of the better known suppliers of Hybrid/Norton parts to see if I can source different stop screws. Other than that, I may have to modify my stop screw heads for clearance.

Thank you!

Rick

Rob Harknett · Post by **Rob Harknett** » Tue Oct 30, 2012 5:00 pm

Or perhaps try Amal Rick.
http://www.amalcarb.co.uk/

John Donne · Post by **John Donne** » Tue Oct 30, 2012 8:27 pm

The Monobloc throttle stop screws that were fitted to these carbs do not have the larger adjusting heads on them, but a slimed down head so that the adjustment can be made. You merely have to order the correct adjusting screws of the slimed down variaty.