AJS & Matchless Owners Club

Hi all, Just got my 1956 16MS running again after rebuilding the engine.

Some oil leaks to chase and general setting up to do, but I'm really pleased that it starts so readily and the oil returns to the tank almost immediately in a strong pulse.

I couldn't resist taking it out into the lane where I live and giving it a very short run to warm it up and work through the gears [I've never ridden this bike since retrieving it from a barn]. I was very pleased to get the wind in my hair [well it grows out of my ears anyway] and sample the riding experience if only for a short while.

I have one question for the collective:- when coming to an uphill section and giving it a little more throttle to "power up the gradient" the engine hesitates, stutters and won't have it - changing down a gear works and restores the revs but the momentum is lost. What might be a likely cause?

Not a desperate issue as yet as I've still got a bit to do before a legit road run is in the offing but I'd be grateful for any pointers.

Best Regards
John

sounds like carburation a mile out . have you rebuilt the complete engine inc rebore . did it work before
what carb is fitted , sometimes the main needle circlip can break and when refitted

It may be ignition is retarded, try giving it more advance when giving it more throttle.

Rob C

robcurrie wrote:It may be ignition is retarded, try giving it more advance when giving it more throttle.

Rob C

Could be difficult, 1956 would have an auto advance unit.

DM2 wrote:

robcurrie wrote:It may be ignition is retarded, try giving it more advance when giving it more throttle.

Rob C

Could be difficult, 1956 would have an auto advance unit.

...then check if the auto advance is working.
Rob C

robcurrie wrote:

DM2 wrote:

robcurrie wrote:It may be ignition is retarded, try giving it more advance when giving it more throttle.

Rob C

Could be difficult, 1956 would have an auto advance unit.

...then check if the auto advance is working.
Rob C

and and make sure it's been set properly.

When setting the ignition the auto advance must be jammed open so that timing is at full advance.

It may be worth checking that AR unit is working. If OK re check the ignition timing. Gap points first, remember to jam open the AR unit fully advanced, before timing the ignition. Maybe you forgot to do that? I use bits of wooden clothes pegs to jam the AR open.

Thank you for the response folks - much appreciated.

Carburation struck a chord because I didn't know what groove the throttle needle was in. Turns out it was in the top one - so I raised it to the third [of four] from the top which I read somewhere in a search of the forum. I have the maintenance manual but which groove isn't specified. I also found that the pilot jet mixture screw makes the mixture richer by screwing it in whereas I had assumed the opposite.

I haven't checked the main jet yet.

I took the tank off to get at the carb innards and took the opportunity to take off the rocker box and check the cylinder head bolts as there seemed to be an oil leak coming from there.

I have just recently replaced the condenser and spark plug and at the same time set the points gap and checked the faces of the contacts.

With the bike back together it started first time so I had another short run. It was better but still faltered a bit trying to accelerate up hill.

As far as timing goes, I set the valve timing and mag timing before I put the barrel back on ( I used 1/2" BTDC ). I did jam the arms of the AR mechanism open to do the timing [and remembered to take the wedge out afterwards]. The ARM needed quite a bit of cleaning and lubrication to get it working freely. The pivot on one of the arms is worn which made the mechanism stick before returning to the retracted position but until I get a new one I reckoned the vibration of the engine would take care of the sticking point. I went through several cycles of tightening the mag chain to get satisfactory tension while still keeping the ARM operating freely.

I used tissue paper to determine the just opening point of the contact breakers though there is possibly room for more accuracy there - so that and the main jet are next on the list.

The bike still starts very easily on the first kick and revs freely which is very pleasing.

Thanks again for your suggestions.

John

If there is an air leak between carb flange and spacer or spacer and head you will experience power loss on hills such as you describe John. Surfaces should be flat (try a pane of glass etc to test) and if necessary cleaned up with fine emery. My new spacer needed this treatment and carb flange though I assume you have a monobloc and O ring seal?