classic motorcycle forum

Motorcycle Discussions => British Bikes => Topic started by: GJM_T120 on August 21, 2006, 04:13:09 PM

Title: 1971 Commando carb problem
Post by: GJM_T120 on August 21, 2006, 04:13:09 PM

My 1971 Commando has always apparently run very lean. Even when warmed up, she has to be left partially choked. I changed the needle settings and this helped some.

Suddenly it became about impossible to start. I could use starting spray but it would run about 3 sec and then seemed to be starving for fule. I took the carbs apart and the only thing that looked wrong was the needles had some sort of fouling about 1/2 way up - it looked like carbon. I got the fouling off by gently rubbing with steel wool and she runs ok but still needs priming with either starting spray or squirting some gaso into the intake.

I am pretty sure all jets and passages are clear and the float setting is about spec.

The carbs are AMAL 930'2

The bike has a Boyer ign.

Any ideas??
Title: Re: 1971 Commando carb problem
Post by: lsdt on August 23, 2006, 01:25:28 AM
Before pulling the carbs to bits try a new pair of plugs, if that works and if the problem returns try a hotter pair or try advancing your ignition. Could be dry fouling. (crap modern petrol with funny aditives) There is a reason why the choke helps but I forgotten why.