Author Topic: Making A Twin  (Read 2780 times)

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Offline Cyberwolf

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Re: Making A Twin
« on: February 14, 2012, 12:32:39 pm »
Hello I am Jims friend in Idaho that is making this engine, Jim asked me about how to realign crankshafts.
I thought I would post this here for all to see.
There are a couple of ways that I know of depending on just how badly tweeked they are tells me which way I want to start.
The first is to use a Milling Machine vise and clamp the counterweigths together to pull them back inline with each other, If the counterweigths are machined round on the rod end when the counterweigth was turned, I clamp them in several places then check with the following method. Sometimes this can work well and little or no other tweeking is needed. This does take a good vice with hardened jaws to do this job.
The other is to put the crank between dead centers in a Lathe and check the run out with an indicator, then decide which way it needs to be moved, then take a brass drift and hammer and tap the counter weight, fairly hard  to align the crank back within specs. This takes some practice and some are very hard to move. Just remove the dail indicator before you start wailing away or you will be buying a new one.
I try to get mine within .0005 or less but there are times they just won't come in any closer than .001 Which is well within specs. Myself I just want them as close as possible for less chance of vibrations and out of balance conditions.
All of these things rob HP and torque. If any one need father info or has questions please feel free to ask.
Richard.

 

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