1974 GT 750 loss of power

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Roger Ackery
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Joined: Wed Jul 20, 2011 3:40 am
Location: Sydney NSW Australia

Re: 1974 GT 750 loss of power

Post by Roger Ackery »

8-)
canaletto5 wrote:Also worth checking the exhaust pipes aren't clogged with carbon.
+1 with Kev on checking those pipes,my A model suffered the same symptoms, compression was 125psi on all 3, My left cylinder exhaust was totally blocked,fitted Delkevic's to fix the problem :shock: :?:
Cheers.
Roger
GT750A.
Tino996
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Joined: Wed Jan 10, 2018 6:41 pm
Location: gatwick

Re: 1974 GT 750 loss of power

Post by Tino996 »

Update. Upon further inspection, there is no spark to the centre plug, looking at it again, the plug still looks brand new! I have swapped plug caps and plugs around, and they work on L & R. So I presume it’s the centre coil? The coils seem to be powered from the regulator, which, as the other 2 coils are working, must be ok? I also swapped the condensers around, no joy! So maybe a new set of coils?..
Martyn
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canaletto5
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Joined: Tue Jul 23, 2013 8:43 pm
Location: Derbyshire

Re: 1974 GT 750 loss of power

Post by canaletto5 »

Hi Martyn

Individual coils can fail. It may be the HT lead needs replacing. If it is a beige coloured coil then the lead can be unscrewed after removing the gungy seal around it. You can then screw a new length of HT lead in. If it is a grey coil then it is a bu*ger to repair. Then it may be worth getting a replacement coil. Kev
Roger Ackery
Posts: 3693
Joined: Wed Jul 20, 2011 3:40 am
Location: Sydney NSW Australia

Re: 1974 GT 750 loss of power

Post by Roger Ackery »

How is the timing,have you disturbed the points in any way,wiring etc, :(
Cheers.
Roger
GT750A.
Tino996
Posts: 19
Joined: Wed Jan 10, 2018 6:41 pm
Location: gatwick

Re: 1974 GT 750 loss of power

Post by Tino996 »

Thanks guys, checked the timing manually, points seem to open when they should. I tried to unscrew the HT lead from the offending coil, but it wouldn’t budge, just stretched a lot! There is definitely power getting to the coils, so looks like ebay for a replacement.
Thanks again for your help and suggestions chaps
Tino996
Posts: 19
Joined: Wed Jan 10, 2018 6:41 pm
Location: gatwick

Re: 1974 GT 750 loss of power

Post by Tino996 »

Update 2..The problem is fixed .. I bought a set of used coils from eBay, Bingo.. either it was the centre coil or HT lead was breaking down, so whichever it was, has sorted the bike, it flies along now. Happy boy.. Thanks again chaps for getting me on the right path.. Brilliant..
Cheers all
Martyn.
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canaletto5
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Joined: Tue Jul 23, 2013 8:43 pm
Location: Derbyshire

Re: 1974 GT 750 loss of power

Post by canaletto5 »

Nice one :)
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