G9 with G11 Barrels
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G9 with G11 Barrels
I have a 1956 G9 which I bought a couple of years ago. The engine and frame numbers match the log book and confirms the engine as a G9. However, there are 7 fins on the barrels. My understanding is that the G9 should have 6 fins whilst the G11 has 7. If this is true, I would like at some stage to revert the engine back to a 500cc G9. Looking at the parts list for 1956 the crankshafts for the G9 and G11 have different numbers, presumably because of balancing. My questions to you noted experts are:-
Would a G9 crankshaft perform okay with G11 pistons? Which I am guessing is my situation.
Is there a way of telling whether the crankshaft is for a G9 or G11 without splitting the crankcase?
If there is a mismatch would there be any long term reliability issues?
Hope someone can help.
Would a G9 crankshaft perform okay with G11 pistons? Which I am guessing is my situation.
Is there a way of telling whether the crankshaft is for a G9 or G11 without splitting the crankcase?
If there is a mismatch would there be any long term reliability issues?
Hope someone can help.
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G9 with G11 Barrels
As you suspect, the crankshafts are the same except for balance. I think the only difference you find will be where the engine vibrates the most. The internal parts are the same, rods, bearings & other parts. The pre-1956 cases , barrels, heads, etc will not fit. You can even put in a generator G12 crankshaft with the 7 fin barrels if you use the 1958 only 650cc pistons, (providing you can find any) & rods. Cheers, Don. Edited by - Don Madden on 03 Oct 2011 11:49:56 PM
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G9 with G11 Barrels
I would guess the 500 barrels would be harder to find considering most would have opted for the larger capacity by then?
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G9 with G11 Barrels
Just an idea-could you sleeve the barrels down to accommodate the 500 pistons if the stroke is the same?
- Samuel
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G9 with G11 Barrels
Thanks for replies. My main concern is that I have a mismatch of crankshaft and pistons which could cause problems. Obviously the factory thought that a mismatch was not a good idea because they went to the trouble of producing separate crankshafts for the G9 and the G11. If it is a case of just more vibes I can put up with that, but if it is going to cause an engine failure then I am concerned about pushing the engine too far.
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G9 with G11 Barrels
Ken, what is your bike like to ride?
If it's a sweet motor, wouldn't it be best left as it is?
If it's a sweet motor, wouldn't it be best left as it is?
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Re: G9 with G11 Barrels
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Last edited by matg80s on Sun Apr 07, 2019 10:37 am, edited 1 time in total.
- dave16mct
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Re: G9 with G11 Barrels
G11 barrells won't fit in these crankcases. 56 on crankcases had a wider throat to accomodate the 600 barrells, 500 barrells then had a thick spigot to fit in the wider throat. The 500 barrells you need have oil grooves on the outside.
Dave.
Dave.
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Re: G9 with G11 Barrels
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Last edited by matg80s on Sun Apr 07, 2019 10:38 am, edited 1 time in total.