2007 550 Engine Rebuild.

Ok, I bought this bike for quite cheap last year.

It still ran, but was loud.

Main bearing on flywheel side had gave up, which also made the piston eat the liner.

The conrod, appears to be fine, and I feel comfortable putting it back together.

My question is, the crank... I finally got around to measuring it for trueness.

It's 5 thou out, it's spread directly opposite the pin, go figure...

Am I making a bad choice by giving it a squeeze, and trying to get it back to zero?

The hour meter says 72 hours... it ran quite a hard life, I'm friends with the previous owner who bought it with about 20 hours on it. Am I going to regret not changing the rod bearings? Can I do the little end easily?

This engine was open before my friend owned it at 20 hours, there was an NTN race on the flywheel side of the crank, with an SKF bearing in the case.

I'm just not quite sure what I should do at this point, I'm not sure if I'll be keeping the bike or not, it's a bit much for the street, but I barely get to ride as it is. I also don't want someone to buy it, and have the rod bearings implode and ruin all the new bearings, piston, and liner again.

Thanks again for all the help, this forum has been spectacular with the information provided, as well as some of the members here for the trust in the community. Really saved me a ton of money on the project so far.

Which dimension? And why?

Taffy said:

I'd have a go at it. you can undo your work by getting a cold chisel (that is too big for the gap) between the cheeks and knocking them open again.

.005" is close. where are you holding the crank and where are your dial gauges mounted?

Taffy

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I have a stand I made, the bearing races sit on rollers, measuring at the dowel, and just before the threads on the other side, where the key sits.

I have a lathe, I could measure it on centers... but my lathe is 75km away.

I'm assuming either way you measure it works...

gery said:

At least diameter and lenght. I have the same engine as you and looking for conrod replacement.

Click to expand...

Uh, you can feel free to take yours apart, I don't have proper measuring devices to do that. Pretty sure you can find that info on this forum though.

Nope, it's not twisted, just spread.

Does this just happen with lots of high RPM torture? I'm assuming whoever built the crank would make it .000" ?

Thanks bud.

So I should give it a squeeze and put it back together?

Any advice on pinching this crank closer to 0?

I managed to get it to 0.0045" by using a clamp for 24 hours, too worried to over do it.

I've managed to get it down to 0.002" after about 30 mins... for a "loose" pin, it sure doesn't want to move.

It's break time... that's a lot of work over 30 mins trying to get that thing straight.

I've hit the thing hard enough that I thought for sure it would be out the opposite way, but nope, sometimes it doesn't move at all.

Beat it up a bit more... Got it down to 1 thou out, I'll go for 1 thou the opposite way.

Lacking motivation this weekend... Had a really long busy work week, still tired from it.

Sooo... somehow the crank magically went back to 2 thou out...

And it refuses to budge any further.

Maybe I'm just not hitting it hard enough?