Starting problems

Information relating to the Matchless G3 or AJS Model 16 350cc Heavyweight
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Re: Starting problems

Postby clive » Mon Dec 10, 2018 11:13 am

mikeydpippin wrote:Thanks I keep going back to the timing..
I loosened mag cog on crank shaft (I turned rear wheel forwards (in gear) until both valves open, and piston at tdc (pushrods spinning) set A/R open with wedge against springs tdc marked with pencil, then I marked a line 1/2” above previous line and turned rear wheel BACKWARDS till top marked levelled with plug hole.
Then turned the auto advance ANTI-CLOCKWISE (towards the rear wheel) until points started to open.
Carefully replaced cog.
Exactly as instructions...
Please tell me book is wrong 🤲


Your procedure sounds right to me but given my recent performance I wouldn't trust my opinion :headbang:
clive
if it ain't broke don't fix

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Re: Starting problems

Postby Rob Harknett » Mon Dec 10, 2018 1:33 pm

clive wrote:
mikeydpippin wrote:Thanks I keep going back to the timing..
I loosened mag cog on crank shaft (I turned rear wheel forwards (in gear) until both valves open, and piston at tdc (pushrods spinning) set A/R open with wedge against springs tdc marked with pencil, then I marked a line 1/2” above previous line and turned rear wheel BACKWARDS till top marked levelled with plug hole.
Then turned the auto advance ANTI-CLOCKWISE (towards the rear wheel) until points started to open.
Carefully replaced cog.
Exactly as instructions...
Please tell me book is wrong 🤲


Your procedure sounds right to me but given my recent performance I wouldn't trust my opinion :headbang:


Not quite right in my book, after setting the piston, next set the points just about to open with the A/R loose So you are just turning the mag shaft only when setting the points, having just set the piston also. Now you are ready to push the A/R jammed fully advanced onto the tappered mag shaft, finally tightening the fixing blot. Check the points are still just about to open. When fitting the A/R it often moves the shaft altering where the points should be. Finale check, turn the back wheel until the piston is set, watching that this is correct when the points are about to open. You are now assured piston and points are set correctly. Remove the jammed A/R wedge. You now have the A/R fully retarded so the bike should start first kick with no kick back and spitting.

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Re: Starting problems

Postby SPRIDDLER » Mon Dec 10, 2018 3:02 pm

Rob Harknett wrote:........with the A/R loose So you are just turning the mag shaft only when setting the points,


Whether you loosen the cam sprocket or the mag sprocket the end result would be the same.
I and most of my chums loosen the lower (driving) sprocket as we find it's less free to move inadvertently than the mag sprocket. The mag axle, having little turning resistance can 'flip'. Once set I give the lower sprocket a smart tap to set it on the axle taper. It isn't necessary to wind the sprocket nut up with gorilla force as it only has to turn the relatively free-running mag but if it's not tight enough the timing can slip when the engine backfires due to the sudden reversing of direction.
I poke badgers with spoons.

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Re: Starting problems

Postby ajscomboman » Mon Dec 10, 2018 3:06 pm

SPRIDDLER wrote:
Rob Harknett wrote:........with the A/R loose So you are just turning the mag shaft only when setting the points,


Whether you loosen the cam sprocket or the mag sprocket the end result would be the same.
I and most of my chums loosen the lower (driving) sprocket as we find it's less free to move inadvertently than the mag sprocket. The mag axle, having little turning resistance can 'flip'. Once set I give the lower sprocket a smart tap to set it on the axle taper. It isn't necessary to wind the sprocket nut up with gorilla force as it only has to turn the relatively free-running mag but if it's not tight enough the timing can slip when the engine backfires due to the sudden reversing of direction.


100% Nev, it's the best way to set the timing, using the method in the book is old hat.

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Re: Starting problems

Postby mikeydpippin » Mon Dec 10, 2018 5:10 pm

Used easy start in carb nothing, so has to be magneto, tried spinning by hand and I got a weak spark but a spark.
Refitted magneto and reset again for the umpteenth time and....
It started and ran really sweet, wot have I done?.
Stopped it tried to start again and it wouldn’t start, so removed plug, dry and smidgen of black soot on it, cleaned plug and away she went again.
(Have now used the colurtune and got a nice blue spark)
The only thing I did differently was as Mick suggested and turn wheel past the 1/2” btdc mark and set, other than that I’ve done nothing different in the past 4 days.
Or maybe the mag is playing up.
Thanks again for all the advise.

I believe there is an answer for this problem, reading Groilys attachment I reckon I had the cam refitted the wrong way and causing negative spark as seen with the pencil test, as soon as I took the cam off and replaced it luckily I put it on the right way.
Last edited by mikeydpippin on Mon Dec 10, 2018 10:42 pm, edited 4 times in total.
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Re: Starting problems

Postby Rob Harknett » Mon Dec 10, 2018 5:32 pm

ajscomboman wrote:
SPRIDDLER wrote:
Rob Harknett wrote:........with the A/R loose So you are just turning the mag shaft only when setting the points,


Whether you loosen the cam sprocket or the mag sprocket the end result would be the same.
I and most of my chums loosen the lower (driving) sprocket as we find it's less free to move inadvertently than the mag sprocket. The mag axle, having little turning resistance can 'flip'. Once set I give the lower sprocket a smart tap to set it on the axle taper. It isn't necessary to wind the sprocket nut up with gorilla force as it only has to turn the relatively free-running mag but if it's not tight enough the timing can slip when the engine backfires due to the sudden reversing of direction.


100% Nev, it's the best way to set the timing, using the method in the book is old hat.


There is something to be said about loosening the cam sprocket Rob / Nev. I can understand it will not allow so much free movement so the points go out of position. Back in the mid 50's when I first had a 55 G3LS we only had the book to go by. No mates with know how then, as they were 16 year old new comers like me. Also no internet or forums. So I still use the old hat way, which also applies if you remove the A/R unit for any reason or replace the chain. In this case, I believe the A/R unit had been removed.

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Re: Starting problems

Postby 56G80S » Tue Dec 11, 2018 12:04 pm

So maybe Groily had it right anyway?

I was puzzled by both valves open as I thought TDC was both valves closed. I always use the version described by Rob Swift, always worked for me. But I have in my youth (20) snapped the little stud off the camwheel.

And I usually check the points first thing, not only for gap but for condition.

Smart arse, next time I do this I'll be on the Forum with failure to start probs.

Still swear by the BrightSpark solid state capacitor but do need to prep the spare as I bought two not realising just how good they are.

Johnny B

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