AJS & Matchless Owners Club

hi all.... i have fitted an air filter to my 1961 ajs model 18 500cc and have been pondering on wither i should

have changed the jets in the carb ?? the filter i have fitted (to me ) seems quiet free flowing

(https://www.feked.com/air-filter-conica ... ew-on.html)

if i do change the jets in the carb should i go bigger jet or smaller jet ????

also i noticed the bike when on over run i get the occasional popping back fire in the exhaust unless i keep

the throttle open very slightly could this be due to the exhaust front pipe at the cyl head not being sealed or down mixture related

regards colin

Hello, Colin.
I have had the same filter on my 1961 G80 for the last couple of years and have had no cause to change the carb settings - the old girl runs just the same and just as economically as it always has over the 20-odd years Ive had her.
The popping in the exhaust is due to an air leak (it doesnt need much of one), possibly at the head but mine was due to a less than snug joint between the pipe and silencer that the clamp wouldnt take up. I shimmed it with some very thin stainless sheet I had, though a strip of beer can wouldve done just as well.

I envy your location. The Arbroath Smokey is truly the food of Gods. I've ridden up there more than once for that pleasure

Steve

Hi Steve thank you for your quick reply
As you said there is no noticeable difference in performance that I can notice but there is always a doubt in my mind as to causing damage in side the engine. I will rest at ease now
Your are right about the smokey is a delicous.

just an update on the popping through the exhaust .......... i took the whole exhaust off this afternoon and found that the clamp for the silencer was slack so i have sealed and tightened the clamps and bolts ...... i will find out if the popping has stopped next time out

colin

smokiewazhere wrote:Hi Steve thank you for your quick reply
As you said there is no noticeable difference in performance that I can notice but there is always a doubt in my mind as to causing damage in side the engine. I will rest at ease now
Your are right about the smokey is a delicous.

You can sleep easy as the addition of the filter will cause the carburation to be tad richer which in theory, whilst it may reduce power output slightly, will make the engine run a little cooler which is not going to harm it.

I had to shim the joint front pipe to silencer as suggested - although my front pipe and silencer are less than pretty. they won't be replaced until they're holed.

Johnny B

Hi Colin.

I've only just seen your question. I have a 1960 AJS 18 and late last year I fitted a screw-on conical filter. It didn't seem to make any difference to the performance or the carburetion. However concerned by the reference in the handbook that a smaller main jet should be fitted I purchased a smaller jet. The original jet was 300, the book recommended 290 but I could only get a 280 so I fitted the 280. The result was more power, smoother and slightly reduced fuel consumption. I'm very pleased to have changed it.

David

hi David

i to have just seen your post and thank you for your input .... i have not looked at what size the jet is next time i strip the carb i will have a look and if it is bigger than 300 i will change for a 290 if i can get one.

thank you

regards colin