1957 M16 not running properly

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Re: 1957 M16 not running properly

Postby Plugsnpoints » Tue Nov 13, 2018 9:52 am

It definitely didn't have one to start with when I bought it a month ago! That's why I didn't know it was missing. It's an unknown still. I hope to have it running sweetly by the end of the week! Motorbikes and women cause me no end of grief! :D

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Re: 1957 M16 not running properly

Postby SPRIDDLER » Tue Nov 13, 2018 10:08 am

Plugsnpoints wrote: Motorbikes and women cause me no end of grief! :D

Good luck.
As one of my girlfriends said: "If it's got tyres or t*sticles it's bound to be trouble".
Last edited by SPRIDDLER on Tue Nov 13, 2018 11:17 am, edited 1 time in total.
I poke badgers with spoons.

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Re: 1957 M16 not running properly

Postby Rob Harknett » Tue Nov 13, 2018 10:39 am

Bikes do go without a main jet. I recall Jampot rally at Oakhampton Devon years ago. My little AJS 1936 250 started running awful. Not sure if it was 2 or 8 stroking, certainly did not run like a 4 stroke. Until you opened the throttle then it flew. As revs dropped going up hill back to the rally site two up, it almost died. Took the nut off the bottom of the mixing chamber and the main jet fell out. Not only that, I found the carb just hanging on the studs, nuts were only hanging by a couple of threads. I had to wonder if someone had been trying to nic its unusual, horizontal mixing chamber carb, while the bike was parked in town.

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Re: 1957 M16 not running properly

Postby 1608 » Tue Nov 13, 2018 4:19 pm

Anal carbs and nuts falling off, whatever next :rofl:

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Re: 1957 M16 not running properly

Postby Plugsnpoints » Tue Nov 13, 2018 5:41 pm

1608 wrote:Anal carbs and nuts falling off, whatever next :rofl:
The anal carb is a race version of the oral carburettor...

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Re: 1957 M16 not running properly

Postby Plugsnpoints » Fri Nov 16, 2018 7:08 pm

This is starting to get to me now! :o



The ignition timing is spot on (1/2" before TDC fully advanced), a new set of points (15 thou gap), condenser and plug. The HT lead is good and coil connections good.

The carb has been stripped, cleaned, blown out, it has new fibre washers. new float seat and new float needle. The main jet (correct one) is now installed. The mixture screw is 1 1/2 turns out.

I give it a little tickle and away it goes.


It pops and bangs but still won't rev. It dies when I open the throttle. It pops and bangs with the odd flame out of the exhaust.



Has anyone got any more ideas please? The advance retard unit is free but looks worn. Are these still available?

There's bags of compression


Thanks in advance (excuse the pun!)

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Re: 1957 M16 not running properly

Postby clanger9 » Fri Nov 16, 2018 8:19 pm

Flame from exhaust = way too rich.

It's hard to determine the cause. If the float level is right, there is maybe something wrong with the metering needle. It does have needle fitted, yes? And it's on the middle notch?
1966 AJS Model 14 250 CSR "cafe racer"
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Re: 1957 M16 not running properly

Postby Plugsnpoints » Fri Nov 16, 2018 8:37 pm

Hi. yes the needle is on the middle notch. I have checked it but will make sure tomorrow. Thanks :)

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Re: 1957 M16 not running properly

Postby clive » Fri Nov 16, 2018 10:16 pm

Look at the magneto chain tension. If it is too tight the unit will not advance/retard. Try turning the unit whilst the engine is stopped. It should advance and then snap back. If it does not it is probably the chain too tight. It does need a fair bit of play. Unfortunately the pins holding the bob weights do wear. The club sells the return springs.
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Re: 1957 M16 not running properly

Postby Plugsnpoints » Fri Nov 16, 2018 10:33 pm

clive wrote:Look at the magneto chain tension. If it is too tight the unit will not advance/retard. Try turning the unit whilst the engine is stopped. It should advance and then snap back. If it does not it is probably the chain too tight. It does need a fair bit of play. Unfortunately the pins holding the bob weights do wear. The club sells the return springs.

Thanks Clive, it's a later points and coil model though.

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