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Old 01-22-2012, 11:26 AM   #6
Tosh Togo
Beastly Adventurer
Joined: Nov 2010
Oddometer: 1,594
Originally Posted by Bloodweiser View Post
Super new to 2 strokes.
I'm working on an RD400 with 11,xxx miles and a squeaky crank.
Split the cases yesterday and could use some input on direction.

First: is it common practice to replace everything?
I mean, should I plan on replacing rods and pins as well as bearings and seals? What about the labyrinth seal?

Standard re-build on a 2-stroke crankshaft is a full rod kit (big and little-end bearings), + seals and thrust washers as needed. If you HAVE to pull the crank apart and install new seals, it's best to freshen everything else up while you're in there.

PS- due to the little-appreciated fact that the metal will deform permanently, every time that you press apart and re-assemble a rolling-element crankshaft, the press-fits get weaker. There's a limit on how many times you can do it before scrapping the crank components....and it ain't very many.

Originally Posted by Bloodweiser View Post
Second: I'm really interested in figuring out how to do this.
I'll need a press I know,
has anyone had experience with the 6-ton or 12-ton press from HF?
Yes. I've seen people who had a big press but not enough skill destroy crankshaft parts. Works every time.

Originally Posted by Bloodweiser View Post
But if a press was all I needed, I'd probably would have bought one already.
V-blocks are damn expensive though.
Cheapest I've seen is about $150. Any recommendations here?
See preceding reply.

Originally Posted by Bloodweiser View Post
Third: Since my cases are split horizontally,
why can't I measure runout by placing the crank in the bottom case
and true it like that?
Not a good idea. You can try that, but there's no guarantee that the bearing saddles in the cases are dead-flat the way that properly set up V-blocks and a dial gauge are. Crank-rebuilding is not an easy game to learn, especially when you don't have the right equipment and have even less knowledge about the task itself.

While there's no doubt that you've already got a BFH for final crank-truing, the other tools needed to do it the right way will cost far more than the job itself.

Ship it out to someone who does it for a living. You might seek help from anyone who services snowmobiles.

btw- did you by any chance leak-test the engine before tearing things apart?.
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