Burnt My Crank Up

[toofast4uu]

Fella's,

I tore my motor down tonite. Turns out that my crank seized up, and then threw out the piston a little bit.

Here's the good news,

1) My cylinder isn't scored, it's already at .50 and I can still go to .80 if needed...I'll leave that to the machine shop.

2) I have a spare crank!

Bad news: I have never switched out a crank before!

Is this something that a backyard mechanic should try? Do I need to press the cases together or need special tools for? (Besides the flywheel puller) If i split the cases, are all my gears going to come flying out?

I heard stories about the bearing spinning on the cases, but is this true? on two strokes?

What do you think?

And does anyone recommend a good shop?

[CronicArt]

Originally posted by christiangiorda@Oct 18 2004, 10:32 PM
Fella's,

I tore my motor down tonite. Turns out that my crank seized up, and then threw out the piston a little bit.

Here's the good news,

1) My cylinder isn't scored, it's already at .50 and I can still go to .80 if needed...I'll leave that to the machine shop.

2) I have a spare crank!

Bad news: I have never switched out a crank before!

Is this something that a backyard mechanic should try? Do I need to press the cases together or need special tools for? (Besides the flywheel puller) If i split the cases, are all my gears going to come flying out?

I heard stories about the bearing spinning on the cases, but is this true? on two strokes?

What do you think?

And does anyone recommend a good shop?
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The first thing I always but is a shop manual for what ever bike it is. They have everything you ned to know. If you are really unsure find a reputable place to do it for you. I can't recomend any shop since I do my own work and never had any experiance with one. Sorry bro.

[rpyfz450]

If you have a clean place to work, you should have no problems. Sometimes splitting the cases can be difficult with the sealant they use. Make sure you don't pry on any mating surfaces.

When you say the piston got thrown out, what did you mean by that?

Oh yeah... if you would like a second set of eyes & hands for the task, let me know.

I prefer OEM service manuals for tasks like these.

Without a manual its crazy to get into this stuff and the parts list doesnt really show that much, but it doesnt look to be anything special or overly difficult etc.

Sorry to hear it was worse than just the piston, but it did seem like there was some more serious damage etc.

Also if you do need an extra set of hands or just ears to listen to whats up etc you know how to contact me.

May as well stroke that bad boy while your at it

[Insane250r]

when i had my crank and rod rebuilt my shop had to press the crank back together and the case halfs. you can seperate them yourself though. If you got a manual i wouldnt be to afraid to split the cases. just take your time and read the book if you cant see how it goes together.

[toofast4uu]

OK, thanks for the info guys!

I was reading my shop manual this morning. And I also read over "Macdizzy's" Blaster rebuild late last night. It looks like I can do it myself, for the most part!

I have a spare "Stroker" crank to use.

Kurt, do you have a flywheel puller? If so, could I borrow it, or maybe you could bring it over one night?

When I drop off the cylinder and head to my local shop (Rauseo Cycles), I'm going to talk to them about the time and costs involved with putting it back to together. If they're reasonable (like 2 hours), I think I might let the pro's do it. Let's see how the disassembly goes, and I'll take it from there.

(Kurt, to answer your question about the piston, the shim or race on the inner crankshaft broke apart, and the shavings went up into the piston. I don't know how, but the piston is a little nicked up, but the cylinder is as clean as could be! (I'm still going to get it mic'ed to and bored to at least .60, because I did have a little piston slap, and it think it might be slightly out of round)

Looks like we're going to have some fun with this now!

Originally posted by christiangiorda@Oct 19 2004, 10:48 AM
Looks like we're going to have some fun with this now!
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And I thought I was the only one who really enjoyed this stuff.


If kurt doesnt have the puller let me know cause I think I may, but I have a few of them so we would have to measure it or something to be sure its the right one.

So what will the total cc's be with the stroker and new bore? Got to love a good stroker