GS450 Crank in GS500

[kidsixteen]

Hey guys,
I have a GS500 engine with a rod knock that needs a bottom end rebuild.

According to my research on this site and others the crank dimensions between the 80+ GS450 and the 89+ GS500 are the same as the entire bottom ends are easily interchangeable. Are the crankshafts themselves completely interchangeable as well?

Since the GS450 rotating assemblies are significantly cheaper than GS500 units (~$100 vs $300) I'd love to be able to throw a 450 crank in there and use the money I'm saving for other parts.

Knowing that the cranks are dimensionally similar, are there any major differences between the two that would prevent me from using the cheaper 450 crank?

Thanks for the help!

[Nessism]

You might want to ask this question over at GStwins... http://gstwins.com/gsboard/
There are a number of twin lovers around here, but I've never seen a thread here about this kind of info.

[kidsixteen]

I did. I'm a regular over there. I just know there's more knowledge of the GS4XX engines over here than over there. Couldn't hurt to ask on both sides.

[Guest]

That's a really good question actually, and aside from having both physically side by side to compare I'm not sure how you could tell?

If you want I can shoot you a photo of the crankshaft spec's page from the factory repro manual but that's probably the best help I can give...

[kidsixteen]

Looks like the part numbers interchange.. gonna assume it'll work and buy one. We'll see!

[7981GS]

I learned something new today. Thank you.
Would it also go to reason that the 450 crank is a drop in for a 400/425?

Daniel

[Nessism]

I learned something new today. Thank you.
Would it also go to reason that the 450 crank is a drop in for a 400/425?

Daniel

400/425 use a roller bearing crank. 450/500 are plain bearing.

One possible issue with the larger stroke crank is crankcase clearance. Please report back on how it goes.

[7981GS]

400/425 use a roller bearing crank. 450/500 are plain bearing.

One possible issue with the larger stroke crank is crankcase clearance

I realize all of that.
Thanks for your help.

Daniel

[Guest]

Wow they really did use the same crankshaft (with revisions) from the '80 450's right through to the 2009 500's

That's really handy to know...

400/425 use a roller bearing crank. 450/500 are plain bearing.

One possible issue with the larger stroke crank is crankcase clearance. Please report back on how it goes.

Ed I thought there were two types of 400's, the 2 valve with plain bearing and 4 valve with roller bearings? Or maybe it's the other way around?

Either way the crank's still different...

[Big Rich]

For those that may be interested, there is a guy called Burning1 is making a track bike with a GS450 motor on GSTwins. Smart guy, has been doing a lot of research.

http://gstwins.com/gsboard/index.php?topic=57916.0

I know it's not entirely relevant to this thread, but it's a good read for those that are curious.

[kidsixteen]

I learned something new today. Thank you.
Would it also go to reason that the 450 crank is a drop in for a 400/425?

Daniel

Not even close. The two cranks are significantly different. If I could use a 425 bottom end I probably would, but the 500 jugs and head won't fit w/ that case anyway. Wouldn't make sense. But damn, roller bearings and a kick starter would be AWESOME.

[7981GS]

For those that may be interested, there is a guy called Burning1 is making a track bike with a GS450 motor on GSTwins. Smart guy, has been doing a lot of research.

http://gstwins.com/gsboard/index.php?topic=57916.0

I know it's not entirely relevant to this thread, but it's a good read for those that are curious.

Thanks for the link! TONS of info there.

Daniel

[Guest]

I haven't read that thread through yet but if he does what he's planning that things gonna haul!

I may have to go join that forum again... I was a member many years ago until I found the GSR...