Starting trouble

[tippi11]

Good morning,
First of all: SPRIDDLER, thanks a lot for your info and comments. I agree that this engine could be a mix of different years/components (I had to take it "buy like is" from the previous owner without info about history or works carried out in the past).

Regarding magneto: it is placed in front of the barrel, no auto A/R, no lever for advance/retard, just a pure Lucas SR1 ant-clockwise.

Proceeding as per your suggestions, here are my "test results":
1. Plug is not wet
2. There is a spark (plug with 2mm gap), it is hard for me to say if it is strong blue, because I cant compare the appearance with another magneto performance. But I presume this spark would be good enough to fire my Enfield engine, for example.
3. The teaspoon method provides no result, no response from engine

Since 1. and 3. results are contrary, my confusion is almost perfect.

To make the overall situation even more frustrating, I observed that oil dribbles out from the crank case breather. I hope this is “only” wet sumping (long standstill) and doesn't affect starting.
At this stage I am totally lost; how to proceed, please help …
Regards, Peter

[clive]

Peter, not managed to keep up with all this thread but immediate thoughts. Plug gap should be about 18 thou of an inch. I make that 0.45 mm, a 2mm gap seems huge or was that only to test not under compression? [my maths may be a bit out?. If I am right it may well not spark under compression.
If the engine has wet sumped it would indeed affect starting as it slows the rotation of the crank and may be preventing the magneto getting sufficient turning moment to spark well. Finally an SR1 without auto A/R may be causing problems as some bikes like a good bit of retard to start, some dont mind if they are on full advance. Most need a bit of retard when starting from cold. I assume you have timed to 7/16 or 1/2 (depending on who you read) before TDC. You might try retarding the timing a bit to see if you can get it started. If so I would suggest you need an A/R unit or and N1 mag and manual A/R depending on which magneto cover you have.

[SPRIDDLER]

Thanks Peter. It helps a lot to be informed of results, (whether they are positive or negative).
(Clive, my suggestion to open the plug gap to 2mm was purely to test the strength of the spark. Rightly or not, for the past 50 or so years I have always set points at 0.025" (6mm) without a thought - a hangover from my motoring days I guess.
Peter. It's a strange situation that there is no result at all from adding the petrol to the cylinder via the spark plug hole. Either the plug is not sparkling or it is sparkling at the wrong time relative the piston/valves positions (that is to say it should spark on the compression stroke, as you already know). It is worth checking the condition of the HT lead from mag to plug and also that the slip ring and carbon pick-up and its spring are good as the plug may spark in open air but fail when under compression or the spark may be taking a path to Earth via the cylinder before it gets to the plug. Clean the slip ring with methylated spirits or petrol on a piece of non-fluffy rag but not with your finger down the hole or when you turn the mag you may get an electrical shock! (Apologies for such basic advice ).
As Clive has said, maybe retarding the timing may help. In case there is any doubt here is a note I posted many years ago on how to determine which way to set the handlebar lever:

Singles only
The points gap can be set regardless of the A/R setting but the timing must be set on full advance.
If the A/R control cable enters the mag on the right of the mag body (when viewed from the points side) full advance is with the cable under tension - i.e. when pulled tight.
If it enters on the left - i.e on the frame downtube side, full advance is when the cable is relaxed.
That is to say that since the points turn clockwise (viewed from the points side) the points backplate has to rotate anti-clockwise to advance the ignition.

[Mick D]

Hi

Clive's correct, an engine that has wet sumped will be more difficult to start, drain the sump before going any further, then.

Remove the plug and dry it off, check it is still sparking and re-fit.

Get an aerosol of Easy Start or similar, spray the recommended quantity into the carburettor throat and try to start the engine - this approach should coax the engine to fire if nothing else. If it doesn't fire you can rule out fuel as the cause.

Another approach would be to get some fit mates to push you as fast as possible down the road and try 'bump starting' the bike, this will spin the magneto much faster and give you a chance to vary the throttle opening - buy them a bier when it fires.

Spriddler - My 1961 Matchless has a duplex frame and is a G3

Regards Mick

[SPRIDDLER]

Spriddler - My 1961 Matchless has a duplex frame and is a G3

Regards Mick

1961 is too modern for me, Mick

SPRIDDLER: Model is late G3 swinging arm, duplex front frame variant, engine number is 56/16MS28374.
Regards, Peter

In Peter's posts he referred to a G3 with manual A/R but no year given and I assumed he had a 40's G3.
My reply was largely referring in general to Peter's comment that the engine is marked: '56 AJS 16MS, so at least the bottom half of the engine is neither a Matchless nor a 'G3' engine, not that there's any difference in practical terms. Of course it could have a Matchless frame and logo on the tank but fitted with an Ajay engine, but I think Peter recently said he doesn't have any documents relating to its past.

Another approach would be to get some fit mates to push you as fast as possible down the road and try 'bump starting' the bike, ..

Well Mick, I never expected you of all purists and with your experience to suggest anything so vulgar as trying to start it by pushing it down the road. At the very least I would have expected you to recommend a mag and carb overhaul and a complete strip and rebuild

[56G80S]

Can't work out an SR1 without A/R.

Photos would be a help as Spookey says, even if:

"I am unsure that one can identify the dots (thanks to my camera)"

From memory, the article referenced sets out a method ignoring the dots and timing using the cam lobes just to get a start. Even poor pictures will help more than stacks of words.

Stick with it, we'll get there.

Trying to do too many things all at once not the best route.

Johnny B

Johnny B

[tippi11]

Okay gentlemen, thank you very much.
Needless to say that, meanwhile, I dont trust any involved component. Therefore I will conscientiously follow your hints.
Regards, Peter

[Dixter]

Hi Peter: I share your frustration. Lets press on. To "fire: we need compression, spark, and fuel.

1. I'm confidant you followed the directions in the link I sent. "Lining up the Dots". and we should have compression and the valves timed correctly.

2. I'd not worry too much about a drip or two of oil dripping from the crankcase breather. However, if as stated earlier: If this engine has a crankcase flooded with engine oil, starting will be extremely difficult. Your next task should be to remove the drain plug on the engine crankcase and drain any oil inside the sump. Next, check the oil tank and ensure you have a liter +/- in the tank.

3. I'm also not too concerned about the carburetor.. at this time. You poured fuel into the cylinder. I'd like to see this bike fire, kick back, or give some indication that the compression + spark are occurring.... at the same time! So now, I'm focused on ignition timing.

4. One last question.. Does your SR-1 magneto have one of these attached?

images-12.jpeg

5. I can 'coach' you on how to set the spark or ignition timing, and happy to do so, but I'd gain a great deal of insight if you could briefly walk me thru how you time this motorcycle.

I'll await your report.

Ciao, DC


Keep the Faith, Baby!

61hwTNohtWL._AC_UL320_SR312,320_.jpg

[clive]

Regarding magneto: it is placed in front of the barrel, no auto A/R, no lever for advance/retard, just a pure Lucas SR1 ant-clockwise.
Regards, Peter

Spriddler I suggested 18 thou gap for the plug as this is probably the smallest gap that produces a reasonable spark from a poor magneto although I have always shut down a new plug from the 25 thou gap it comes with, rarely using a feeler guage and just doing it from eye so its not that critical with a good mag.

This set up with an SR1 and no A/R, manual or auto, is in my view always going to prove difficult to start. What we hope Peter can do is get back to his experience on page one of the thread where the engine was at least occasionally making a bang!

[SPRIDDLER]

This set up with an SR1 and no A/R, manual or auto, is in my view always going to prove difficult to start. What we hope Peter can do is get back to his experience on page one of the thread where the engine was at least occasionally making a bang!

Oh, dear! It wasn't clear to me until Peter's post yesterday that the mag has no A/R facility of any sort. Yes, that will be tricky to set up. Besides which, since the timing will be fixed it'll always run either too far retarded or be somewhat too advanced for relaxed starting.