Starting trouble

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

Post by Dixter »

Hi Peter, those readings are quite low. Conventional wisdom seems be be, an engine needs 90 to 100 PSI to start and run. 6 Bar is 87 PSI. I'm not an engineer and certainly not an authority.

Low compression would surely yield low performance, but I'd expect an explosive charge even at 1 Bar. For grins, I'd re-test, but also move ahead with supplying a correctly timed spark, and keep looking for combustion. We want a bang!

Testing procedures vary, and I'll ask:
A. did you have someone help, either holding the tester on the engine or vigorously kicking over the engine,
B. was the throttle open fully or carburetor removed.
C. Was the tester held tightly in place for 5-7 strokes?

If the compression tester is still on hand, there is great value in injecting 5 - 10 cc of the same engine oil, into the cylinder, rotating the engine 6 - 10 strokes, and re-testing. If a noticeable increase in pressure is observed, the most likely problem is poor sealing on the piston and rings. If not, you may get off light with simply grinding in the valves. This is a quick task, and not much expense.

My sense is a lot of folks are in your court and share your anguish with getting your bike up and running. I know I certainly am.

Best wishes,
DC
Dick Casey
The RideNut
tippi11
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Location: Germany

Re: Starting trouble

Post by tippi11 »

Good morning,

Two things I would like to let you know
-General: I am really impressed by this forum and the reactivity of all of you. Thanks to your help I gathered a real bunch of suggestions and background info. Saying this, I think it is the right time to close this topic. I am not giving up, but based on your support I will concentrate on the ignition timing story (automatic a/r unit) and compression (see also below). It can well be that I have to submit a new topic regarding the auto a/r unit because my manual doesn´t include info about the SR-1 magneto combined with this unit, mounting, adjustment etc. Let me also point out, that I invite you to get or keep in touch with me via email (p.tippkoetter@t-online.de), it is sometimes easier, particularly when it comes to detailed pictures or so.

-Compression:
The last compression test showed readings of 7 bar (101 psi) without and 8 to 9 bar (116 to 130 psi) with oil injected in the plug hole. Assuming the valves are ok, piston and/or pistons rings seem to be worn, at least not optimal. A closer inspection, not done yet, may result in a new piston together with a barrel re-bore!?

Thank you very much.
Regards, Peter
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spookefoote1956
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Location: Wales Innit

Re: Starting trouble

Post by spookefoote1956 »

Tippi, it's always a pleasure to help out. Please do not feel that you are wasting our time. We love this kind of a challenge. Don't cut the thread or we'll never know what happened! However your timing isn't going anywhere without the A/R unit.

Cheers, Chris :beer: :beer:
Hail Joe Lucas ............ Prince of Darkness!
All my bikes are original........ to me!
"Creativity is your intelligence having fun" Albert Einstein
Mick D
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Location: Aberdeenshire

Re: Starting trouble

Post by Mick D »

tippi11 wrote:The last compression test showed readings of 7 bar (101 psi) without and 8 to 9 bar (116 to 130 psi) with oil injected in the plug hole. Assuming the valves are ok, piston and/or pistons rings seem to be worn, at least not optimal. A closer inspection, not done yet, may result in a new piston together with a barrel re-bore!?
Hi

Don't get disheartened and try to keep to a structured diagnostic approach. Your compression issues will not be the reason the engine is not firing and a re-bore and replacement piston won't make it magically fire, just add more delay and expense.

You seem to have sparks, ruled out fuel, the compression is OK, valve timing looks good, Id concentrate on ignition timing.

If you can't get hold of an auto advance unit straight away I'd suggest retarding the ignition a couple of degrees at a time and trying to get the engine to fire, give it up to about 20 degrees and if it still doesn't fire rest the ignition to where you started from and repeat the process but advancing a couple of degrees a time. It's a bit of a scattergun approach but I think you may be doing something wrong when setting the timing, (particularly as you have no auto advance). Once you get it to fire it's a short step to getting it running.

Regards Mick
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spookefoote1956
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Re: Starting trouble

Post by spookefoote1956 »

Hail Joe Lucas ............ Prince of Darkness!
All my bikes are original........ to me!
"Creativity is your intelligence having fun" Albert Einstein
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dave16mct
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Joined: Mon Jan 01, 1990 12:00 am
Location: LANCASHIRE UK

Re: Starting trouble

Post by dave16mct »

No. More like this one on ebay: 223650981970
Dave
Last edited by dave16mct on Sun Sep 22, 2019 4:22 pm, edited 1 time in total.
Mick D
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Joined: Mon Mar 24, 2014 5:44 pm
Location: Aberdeenshire

Re: Starting trouble

Post by Mick D »

Hi

According to the Lucas documentation you need part number 47544.
ATD.png
ATD Subs.png
ATD Applic.png
Another 'outside of the box' thought, do you have the correct 17 tooth magneto and camshaft sprockets?

Regards Mick
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tippi11
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Location: Germany

Re: Starting trouble

Post by tippi11 »

Hello Mick,

Thank you - yes, I have the correct magneto and camshaft sprockets, both 17.

Regards, Peter
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spookefoote1956
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Re: Starting trouble

Post by spookefoote1956 »

[quote="Mick D"]Hi

According to the Lucas documentation you need part number 47544.

Is that the one they used on Vinnys?
Hail Joe Lucas ............ Prince of Darkness!
All my bikes are original........ to me!
"Creativity is your intelligence having fun" Albert Einstein
Mick D
Posts: 2886
Joined: Mon Mar 24, 2014 5:44 pm
Location: Aberdeenshire

Re: Starting trouble

Post by Mick D »

Hi Chris

Nope - the only applications for 47544 are listed in my third snag. That's not to say others won't work though.

Regards Mick
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