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General Category => General Discussion => Topic started by: rjamesohio on October 18, 2020, 09:06:56 AM

Title: Roundhead cranks....
Post by: rjamesohio on October 18, 2020, 09:06:56 AM
Hi all -

I'm moving my feet on my G5 and wondered:

Are the crank throws and pin diameter the same for 1000 CC motors as 850's?

I ask because I have a spun rod journal on my G5 crank and it will likely cost me as much to repair that crank as to possibly source another good crank to use in that engine with new bearings obviously.

Ron
Title: Re: Roundhead cranks....
Post by: guzzisteve on October 18, 2020, 10:01:25 AM
Yes, both 78mm and pin diameter spec is all the same from 700 on. I'm doing a 700 motor now.
Title: Re: Roundhead cranks....
Post by: 1down5up on October 18, 2020, 02:24:19 PM
V7 Sport, 750s 750s3 have cranks with a smaller stroke, and any that were for a loop wont have the threaded hole in the front nose for your alternator rotor bolt.

Title: Re: Roundhead cranks....
Post by: Antietam Classic Cycle on October 18, 2020, 06:23:21 PM
Hi all -

I'm moving my feet on my G5 and wondered:

Are the crank throws and pin diameter the same for 1000 CC motors as 850's?

I ask because I have a spun rod journal on my G5 crank and it will likely cost me as much to repair that crank as to possibly source another good crank to use in that engine with new bearings obviously.

Ron

Convert & G5 cranks are "graded" - ones with a white paint spot are different than those with a blue paint spot. Crankpin diameters:
Blue: 44.008-44.014 mm
White: 44.014-44.020 mm
When checking the balance on the Convert and G5 crank, the weight used is 1.650-1.680 kgs.

850-T crankshaft: crankpin diameter: 43.893-43.994 mm
Balance weight: 1.471-1.601 kgs.

850-T3 crankshaft: crankpin diameters: same as the Convert & G5
Balance weight: 1.586-1.616 kgs.

FWIW, for ~ $125 + shipping, I can have your G5 crank rod journal ground.