classic motorcycle forum

Motorcycle Discussions => British Bikes => Topic started by: bsa_man on July 19, 2009, 10:51:47 AM

Title: B31 Overheating?
Post by: bsa_man on July 19, 2009, 10:51:47 AM

Hi.  I have a 1947 BSA B31 and I've just recently rebuilt the engine and started running it for short periods while I keep an eye on it.  I'm finding that although it runs smoothly, in my opinion it is starting to overheat.  What adjustments on  the carb (amal 276 type) etc do I make to try and rectify this problem?  Many thanks, Glenn

Title: Re: B31 Overheating?
Post by: Goldie on July 19, 2009, 09:53:07 PM

Have you checked the ignition timing, running it too far retarded will cause it to over heat

Title: Re: B31 Overheating?
Post by: bsa_man on July 20, 2009, 12:51:19 AM

Hi there, no I haven't checked that but I hopefully will get a chance to tomorrow evening.  

Title: Re: B31 Overheating?
Post by: Goldy on July 20, 2009, 04:12:13 PM

Just to state the obvious, when you say you are running it for short periods, you do mean riding not just running stationery, when it will overheat.  As Goldie says check the ignition timing. If that's ok look at the spark plug. If it is very pale in colour or in severe cases, burnt, then the mixture is too weak. It can be made rich by screwing in the air screw (to reduce the air) If this is not enough then raise the needle by one notch ( to allow more fuel).
All the best.