Hitchcocks Forum

Hi,

I have recently inherited a 1956 500 twin from my uncle that was last taxed and run around 1966/67. I am completely new to the Classic bike scene and restoration. The bike is fairly messy but I have been able to carry out some initial cleaning and rebuilding and the engine starts albeit poorly and runs roughly. I have bought the various manuals from Hitchcocks and have the original books that the bike came with. The bike is now pretty much entire. We found the Amal 276 Pre Monobloc carb in pieces under the floorboards in the pantry of my uncle's house! I have cleaned and rebuilt the carb with new gaskets and ,to me, it all seems sound. I have also replaced the engine top end gaskets - drained the old oil out an replaced the filter.

The bike is fitted with a Lucas MN2L Magneto and from what I can see I am getting a reasonable spark on both cylinders after making up new HT leads and checking the points gaps etc. I suspect that the ignition timing is out as the bike backfires into the carb when running.I have changed the plugs to NGK B6HS which I understand are an equivalent to the Champion L7s it came with.

I would be so grateful for any guidance on checking and setting the timing on this bike. I have read about removing the timing cover and checking the magneto sprocket etc. I just don't get it at present though. I can see the prescribed TDC measurement in the manuals - is this when the points should be closing or opening? Am I being optimistic hoping that the non-reconditioned magneto will work after all these years? The bike was in a cool garage and covered.

Any help or advice most welcome.

Best regards

Hi Colin P...........First let me welcome you to the group and as you are new to all this then it should prove to be "Interesting", one way or the other --LoL !!......

So, just to start you off then} Ignition timing is set when POINTS OPEN.........If you can post some photos please ??-----Try this}.... https://imgbb.com/ .... and select "HTML Full linked" when prompted....Others will be along soon with a more detailed reply, no doubt...Cheers !!

Hi Colin, welcome and a nice bike to find! I suspect the spitting back in the carb is to do with the carb body to slide fitting being too loose. This is caused by wear on the sliding surfaces and results in too much air being passed leading to weak mixture, hence the spitting. You might improve matters by fitting a new slide (available from Hitchcocks in the Amal carb section) but in my experience the body of the carb will also be worn and just a new slide may not improve the running enough for reasonable riding. The good news is that new carb bodies are available now and not particularly expensive. In the past before new ones were being made I had to get one of these carbs bored and sleeved with brass, an excellent repair which worked very well. Whereabouts are you? I could look at it if you're not far away, I'm near Silverstone.

REgards, Mark

Thank you both for the replies - all noted. I shall try and post some photos.