Author Topic: Weight and Hp of a G31 600OHV  (Read 4542 times)

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Offline alexd912

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Weight and Hp of a G31 600OHV
« on: 16 Jul 2009 at 07:10 »
Hi all,

Im about to get y Douglas on the road this week but my insurance company here in Finland needs to know the weight and Hp of the bike as this is how they access the premium.

If anyone out there knows the approx weight and Hp of the G31 then please let me know.

Best regards

Best regards
1930 Douglas G31

Offline Doug

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Re: Weight and Hp of a G31 600OHV
« Reply #1 on: 18 Jul 2009 at 17:07 »

I do not recall seeing a published weight for the F/G31 models. Douglas catalogs (or period road tests) usually only mention the weights of the lightweight models eligible for a reduced road tax/license. An exception was the 1930s big side valves, the T6 given as 295 and the S5/S6 at 304lbs. Hard to say if the F/G31 would be a little more or a little less. Someone is just going to have to weigh their F/G31 and report.

Same goes for horse power. But since the engine is derived from the Dirt Track engine, you can derive the power from the same source. Not that horsepower ratings for the DT are commonly published. I have a copy of a letter from Eddie Withers were he cites from his notebook on the assembly and testing in June 1928 of DT engine EL1250 in the Douglas Experimental department, where all the OHV engines were assembled before being sent out the the assembly department. He did not mention if it was setup with the in.op.20 or the camshaft, but did mention it was setup at 9:1 compression and presumably running 50-50 petrol-benzol fuel as most DTs were at that time. It recorded 26.65hp at 6200 rpm (it was 500cc.) Since the G31 (600cc) is single carburetor, straight petrol, and I hope you do not spin it quite so fast; you should develop significantly less horsepower. If I had to guess I would say in the range of 20-22hp. Definitely not in the Hayabusa insurance category!


Offline eddie

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Re: Weight and Hp of a G31 600OHV
« Reply #2 on: 18 Jul 2009 at 18:18 »
I have seen reports of 27-28BHP for the standard 500 dirt track engine with an increase to 34 BHP for the short stroke motors used in the Dixon Red Devil. With regard to the weight - putting each wheel in turn on a pair of bathroom scales, and then adding the figures together usually gives a reasonably accurate figure for the total weight.