190mech gave me some information about finding the stroke of a crank when it's not installed, so I made up a graphic. (When installed you can measure piston travel from BDC to TDC or TDC to BDC.) Not all cranks seem to have their advertised stroke or maybe you just aren't sure what you've got on the shelf. Either way, a few measurements and this formula will let you check stroke.
stroke = (z - (x + y)) * 2
where; x = main shaft radius (Measure main shaft outside diameter and divide by 2.)
y = crank pin radius (Measure crank pin outside diameter and divide by 2.)
z = distance from the top of the crank pin to the bottom of the main shaft
What you're doing is finding the center to center distance from crank pin to main shaft, which is 1/2 of the stroke or the radius, and multiplying it by 2 to find the working diameter of the crank which is the stroke.
You could even do this with a bearing installed on the main shaft if necessary.
Last Edit: Feb 21, 2019 12:41:02 GMT -5 by 90GTVert
Brent Smoking section, please.
Senna1Rossi: Ah, gotcha! Thanks, Fox. Does everyone see the Shoutbox, or just the people who you choose?
Feb 16, 2016 12:39:35 GMT -5
Fox: Anyone who is logged in can see it but it's down at the bottom so most have either chosen to ignore it or haven't discovered it yet.
Feb 16, 2016 18:42:39 GMT -5
Deleted: Wow, I just found this. I feel smart now, ha ha.
Feb 27, 2016 19:24:24 GMT -5
Silar: Ahh.. New feature for a new riding season! YAY!
Mar 16, 2016 17:12:34 GMT -5
Silar: Apparently this still is not being used much. hmm..
Mar 17, 2016 13:55:04 GMT -5
180°off: Anyone want to buy a Yamaha 2t that needs a complete rebuild?
Mar 27, 2016 16:00:19 GMT -5
larryhobman: What is the leanest jet size you would try on a 47mm setup, 60cc stock head with a A9 cam
Apr 2, 2016 20:17:30 GMT -5
Senna1Rossi: Thanks renagade281!
May 23, 2016 14:59:12 GMT -5
Fox: I don't really know how to say this but straight. I am Dave's Girlfriend Kellilee and bluntly and VERY SADLY he passed away early Tuesday morning. I know he would want ya all to know this. Thank You Brent for befriending my love he was very happy on here!
Jun 18, 2016 16:26:04 GMT -5
Fox: www.gofundme.com/29mgf6b8 I hope it is ok to pass on his gofundme page link. If not you will un-post it I'm sure. Thanks again all!!
Jun 18, 2016 16:31:18 GMT -5