G3L Carb. setting

John B. · Post by **John B.** » Sat May 28, 2011 4:38 pm

Just about to commission my G3L. It came with a 624 concentric carb. fitted. Has anyone set one of these up for this model? Jets, slide ect. It runs, but not happy, seems to rich. Should be possible to get it it right. Don,t want to waste dosh on new bits that are miles out.

iandusud · Post by **iandusud** » Sun May 29, 2011 5:50 pm

Burlen fuel systems recommend when fitting a concentric in the place of a monobloc to fit a main jet 20% smaller and leave all other settings as per the monobloc. According to F. Neill the monobloc settings are 220 main jet, 3 1/2 cutaway, 30 pilot jet, 106 needle jet, needle on central notch. So you should probably use a 180 main jet.

Ian

John B. · Post by **John B.** » Sun May 29, 2011 11:28 pm

Thanks Ian, I'll give that a whirl. Sounds as if my main jet is much too large!! J.B.

laxy · Post by **laxy** » Mon May 30, 2011 1:54 pm

but what about the size of the carb bore? that carb came off another bike so its not just a case of fitting the correct jets etc

John B. · Post by **John B.** » Mon May 30, 2011 11:37 pm

Hi Laxy, Its a 624 which without going back out to the workshop is I think 1" or 1 1/16". Have downloaded tuns of Amal Conc. stuff this afternoon and may have the wrong needle in the bowl! Float should come .080" below bowl edge . Mine is well above!!!! Will post if problem solved. J.B.

iandusud · Post by **iandusud** » Tue May 31, 2011 8:36 am

Hi John,

The float height adjustment is done by heating the float bowl (in boiling water is ideal, but you can use a heat gun or a blow torch) and then tapping the float valve seat. To move the seat up, ie to lower the float height, you need to make a suitable size drift easily made from an oild nail of the right diameter. Raising the height invovles tapping the seat down. It's a bit fiddly but you'll get there in the end.

BTW there seems to be a lot contradictory advice on the internet as to what the ideal float height should be. I think Amal recommend that the float shoule be level with the float bowl, others suggest the 0.080" that you quote. You takes you pick...

Ian

John B. · Post by **John B.** » Tue May 31, 2011 8:30 pm

Laxy, I,m a silly billy that 624 Conc. is of course 24mm like what it sez on the tin. Thats just under 1" which matches the inlet well. Ian,I have done the float height and it has made a hell of a difference. Almost got a tickover now. Got other problems now with it, going to start a new thread. JB.