GS 550 crank question

[Guest]

I have a GS 550 that I have been working on for a short time, and currently have the head and cylinders off, a friend of mine was over to visit (drink my beer) and was looking at the motor and noticed the way the rods were sitting that #2 and #3 rods were at different heights. I always thought that 2 and 3 were on the same throw, and like for 1 and 4. does this mean that the crank is twisted, or is it like this by design?

[lhanscom]

Sounds twisted to me, they should be at the same height.

[focus frenzy]

bad, very bad, that is the first and biggest indicator of a twisted crank.
does #1 and #4 line up?

[kent]

No, #1 and #4 are around a .125 difference at about the center of the stroke, it appears that the twist could be in the center journal where the timing sprocket is, is this usually where they twist? and also, is the crank junk or is this something that can be repaired

[Guy]

If your crank is a built up assembly, and it's slipped and twisted, it's an awkward enough job to have it pulled apart and pressed into register again, but it's an almost impossible job to get it properly balanced afterwards. Might be cheaper to buy a secondhand bottom end with a good crank. I wouldn't have thought a 550 would make enough HP to twist the crank. Also if it's out of register by as much as you reckon, there would be severe vibration. How many of those beers did youse drink?

[kent]

Yea, I think I'll look for a new crank, I pulled the crank out today and it looks to be about a 15-20 degree twist through the center on the chain sprocket thingy, and I only consumed about three beers, after that my eyechrometer starts to get foggy.

[jimcor]

There are quite a few 550 parts bikes, at least one is offering free parts, on the Parts For Sale section of the forum. Course I don't know if shipping charges would make it worth your while or not.