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Old 05-12-17, 08:55 PM   #1
Rookesy
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Default Help needed with a JAP 5 please.

Gents,
I have a JAP 5 that was on a generator and I cannot get it to start. I did the usual checks - petrol was getting through and it had a good spark etc.
I took the head off to check the timing and this is what I found - https://youtu.be/CPa3q9jR68Y .
The timing for the piston seems to be 180 degrees out with the valves opening at the wrong times. Can anyone help please as to how to change it over to run correctly? I think once that is sorted the mag should just slot in with the correct timing. Thanks in anticipation
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Old 05-12-17, 09:10 PM   #2
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Looks right to me. Assuming the exhaust valve is closest to the camera?
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Old 05-12-17, 09:23 PM   #3
air-cooled
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Rotate the mag shaft 180 degrees and put it back on the engine.

Phillip
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Old 05-12-17, 11:46 PM   #4
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I agree with Phillip.

Last edited by 1956ld1; 05-12-17 at 11:46 PM. Reason: mistake
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Old 06-12-17, 05:03 PM   #5
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Default looks fine!

As someone else has said....if the exhaust valve is the slightly larger valve head, nearest the camera, these seem to be operating in correct sequence with the piston movement.

Can you get at the drive gearing from the crankshaft to camshaft? There should be timing marks on these which should align when correct timing!
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Old 06-12-17, 05:41 PM   #6
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Quote:
Originally Posted by 1956ld1 View Post
I agree with Phillip.
Doesn't the Wico A magneto have an "idle" spark? Certainly sound like the impulse clicking every TDC, so I don't think turning the mag will make any difference.
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Old 06-12-17, 06:19 PM   #7
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The larger valve is always the inlet, even on these industrial engines, and if the magneto is running at engine speed, then as Charles says, changing it by 180 degrees won't make any difference.

Just out of interest, the Ruston 6AP magneto also runs at engine speed.

Peter
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Old 06-12-17, 06:40 PM   #8
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Have you got the correct specification of magneto to suit the engine? Are you turning it in the correct direction?

Dan
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Old 06-12-17, 06:54 PM   #9
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Quote:
Originally Posted by Appletop View Post
Looks right to me. Assuming the exhaust valve is closest to the camera?
What am i missing here Rob, i'd have said its correct if the closer valve was the inlet.
Suck, squeeze, bang, exhaust and repeat.

Neil.
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Old 06-12-17, 07:17 PM   #10
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'Fraid not - go and watch an engine; exhaust immediately before inlet.

MP
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