How to true a stroker crank?

Will'smotobikes19

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Joined
Apr 9, 2018
Messages
1,864
If I can remove the crank from the case half I tapped it in (without heating or cooling anything yeah IK smart) I want to see if I can true or balance the crankshaft. The piston is 47.799mm so I'ts a big bore and its a 3mm stroker crank. I think I've seen people using like a stand thing or a lathe and a dial indicator. I have neither. I don't really want to take it to a motorcycle shop. I feel dumb not heating the case and putting the crank in the freezer. I don't know if hitting the crank can make it more untrue but it is only connected by the pin for the rod. I have everything I need to put this engine together except the back 2 studs which are 75mm. The stock ones were bent and crappy. I just want this thing to run. The wires ripped off the magneto too but I can try to fix that. I found my soldering iron.
 


crassius

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Joined
Jul 23, 2012
Messages
4,572
chucking it up in a drill press might sound like a good idea, but if it falls out, you won't like it

a half inch drill clamped into your vise should be able to hold the weigh horizontally and turning by hand should give you an idea of how close it is to true
 

Street Ryderz

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Oct 14, 2016
Messages
3,723
As you can see in the video above the stand and dial indicator will be nessesary to do this job but that's cheap in comparison to having a shop do it,around here crank service is 180 bucks so If your going to seriously be messing around with these engines it a pay you back ten fold investment IMO anyway.The process is not hard to do just takes some patience and commen sence,setup like anything makes a big difference though if you rig it so it's all nice and square,pre load the indicator then set zero so that every thing is exactly the same each time it's checked your good to go! once you done it and if the balance is good it will make a noticable differance in the life span of parts and ride quality.
 
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