G3 won't start

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SPRIDDLER
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Re: G3 won't start

Post by SPRIDDLER »

Beefheart wrote: Fri Jul 15, 2022 5:44 pm I've checked the timing so many times I could do it in my sleep .......
Is it still on the right stroke? A couple of times after I've checked my own work a pal comes along, peers over my shoulder and makes me feel a plonker when he he points out a basic error that I've overlooked. :oops:
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Which taken at the flood............'
Beefheart
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Re: G3 won't start

Post by Beefheart »

Thanks both for your help l did the ht lead to head, big spark ht lead to mag body 3000+ ohms. So not the mag I also put the old carb back on it is well worn and leaky but did work, no change. So probably not the carb. Now I may be leaving myself open to ridicule here but here goes, because I can't cover the bellmouth properly with my hand I held a piece of paper over it while kicking it over it's definitely pushing out not sucking in as I originally thought . Also it doesn't seems a little too easy to kick over with the plug in.Maybe some investigation of the valves required. If this sounds like I'm flailing around it's because I am
SPRIDDLER
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Re: G3 won't start

Post by SPRIDDLER »

Beefheart wrote: Mon Jul 25, 2022 3:56 pm ......because I can't cover the bellmouth properly with my hand I held a piece of paper over it while kicking it over it's definitely pushing out not sucking in as I originally thought . Also it doesn't seems a little too easy to kick over with the plug in.
That's a useful observation, Colin. All these things are a process of methodical checking, no matter how 'off the wall' the checks may seem.
If it seems to be blowing out of the carb and not sucking in and the compression seems down you need to take off the rocker box side cover and check that the inlet valve is moving and not stuck open (it does happen). if it is stuck open its rocker and the pushrod will be sloppy and free to be moved up and down. It could well account for not getting any reaction when you put petrol in the plug hole.
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Beefheart
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Re: G3 won't start

Post by Beefheart »

At last!! she runs. As you suggested Neville I backed off the inlet pushrod and the compression was back, although it had spun freely with both valves closed (strange). In the meantime I had taken the carb to a mates workshop and given it a high pressure blow through. Reassembled and away she went. Very tempted to buy a compressor. The pushrod issue bothers me a little something keep an eye on. Thanks to you all for your help.
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jackstringer
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Re: G3 won't start

Post by jackstringer »

Beefheart wrote: Sun Jul 31, 2022 1:35 pm At last!! she runs. As you suggested Neville I backed off the inlet pushrod and the compression was back, although it had spun freely with both valves closed (strange). In the meantime I had taken the carb to a mates workshop and given it a high pressure blow through. Reassembled and away she went. Very tempted to buy a compressor. The pushrod issue bothers me a little something keep an eye on. Thanks to you all for your help.
Conga Rats.

Alternative to a compressor is the cans of compressed air for the computer.
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dave16mct
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Re: G3 won't start

Post by dave16mct »

Or carb cleaner.
g80csp11
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Re: G3 won't start

Post by g80csp11 »

just a thought aluminium heads were introduced in 1951 I think , and its possible for valve seat to come loose giving symptoms of loss of compression , and sometimes it resets and will run
Is yours aluminium ? , if so can you feel a step anywhere between seat and head ?

this could explain the tappet clearance changing
Beefheart
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Re: G3 won't start

Post by Beefheart »

I didn't know about that but fortunately I took the head off to check the valves and springs all was well. Aerosol cans sound a more wallet friendly option.
RL
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Re: G3 won't start

Post by RL »

I had the same problem on a 55 16MS after quite a long lay off, the bike started okay then stopped, it didn't kick back but went with a big bang in the exhaust/silencer. I checked initially for a spark at the plug this being okay I then checked and re-timed the timing, drained the fuel and replaced with fresh still no go. After a few days I decided to have another try and on checking the spark at the plug, while there was quite an healthy spark at the electrode I noticed there was also a spark from the plug body so I fitted a new Champion N4C plug and it started 2nd kick.
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jackstringer
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Re: G3 won't start

Post by jackstringer »

My dad took mine to work the other day. It stopped half way up a hill. By the time the "engineers" at his work had poked it there was no spark and the battery was flat. I tried the emergency start but that failed. A charge of the battery and a new plug an all is well again. Thing to remember is do the cheap fixes first then work up. As I have said before, tbeg reason why we ask daft questions is becuase we have had daft things go wrong to ourselves.
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