450 engine rebuild

[phillipjohnw]

Hey y'all,

I'm getting ready to tear down my gs450 and basically start building it from the ground up again. This time however I was going to attempt to rebuild the engine from the crankcase up. I had heard that gs500 cylinders and pistons will drop straight in along with either reusing the 450 top end or a gr650 top end. I've been looking through all the builds and searching every forum on the interweb, however every thread seems to end with the op boring out the cylinders or resleeving them. I'm a good wrench turner, but I don't have the tools or money for any major machine work. So my question is thus. Will the aforesaid parts bolt together without machine work? Has it been done? And any other questions, comments, cripes, or complaints?

Phil

[jeffasaurus2]

I'd be interested to know a little more about this as well if anyone has any info!

[wally]

I'd like to tag along as well, but only if you post plenty of pics!

[Mekanix]

Did you check the wiki yet ?
If there isn anything in there, lll add a bit for that.

Easyest way to go is to get these parts:

Gs500:
cylinders
Camshafts
pistons
gaskets
tensioner
Slot cam sprocket
Gs450 head.

You would have to deal with clearances and use the proper gaskets to get the right deck height. You could use a combination of gaskets or get custom ones made.

Then get the cams dialed in again because they will be off by up to 8 degrees.

[Big Rich]

Ha! I recently stumbled on a free GS500 motor and came here to search out this very info. Great timing......

[pete]

I'm going to tune in... keen to follow this if you do it for sure.

I have lots of pic's in my Photobucket of my 450 engine rebuild but Photobucket's broken at the moment for me so I can't get the link...

Edit: Rebuild link http://s594.photobucket.com/user/sta...Rebuild?page=1

[phillipjohnw]

Wow, that was fast.

Mechanix I think I followed one of your builds or a build thread that you commented on a lot on gstwins or some other forum. What wiki are you talking about? I'll have to check it out.

Everyone else thanks for the support. I'll understand if you don't follow though. This will be a brutally slow project due to lack of free time, funds, and parts. I just got stationed in Hawaii and there aren't any bike graveyard's to pick through. As for pictures, I'll try to take them but I'm unreliable at best.

[Mekanix]

Here: in rhis section.


http:// http://www.thegsresources.com/_forum/showthread.php?t=205995

[phillipjohnw]

Mekanix, I think I'll be relying on your seemingly infinite knowledge of the twins platform. Do you know if there is any extensive machining or special work that would need to go into using a gr650 top end? If I continue to use my 450 top why would I need to adjust the cams so they aren't 8° off?

I'm still debating on what to do with the rest of the build, suggestions are welcome. I do want to stay away from the cafe style that everyone and their brother does, also its the dreaded L model.

[Mekanix]

You could use the gr head and pistons but not the block.

You could adjust the cams and set them for the powerband you like . As long as the valves don't hit the piston you could get away with it as it is but the performance might not be what you want.

The E styling looks peetty good. Not sure what you could do with the L. Mine Is an L and I like it just the way it is

[phillipjohnw]

If I just left the cams how they are what would that do to the powerband? I'm assuming it would shift it either higher or lower in the rpm range, which way I don't know.

Assuming valve clearances aren't an issue, would I be able to use stock 650 or 500 cams in my 450 head? Would that offer any advantage or just hassle? Go ahead and tell me if I'm barking up the wrong tree. I tend to throw out crazy ideas without putting much thought into them.

I think I'm going to try and retrofit a 500 ignition, coils, and cdi because my coils just fried trying to start it tonight. They were already on their last leg last spring.

[Mekanix]

Gs500 cams seem to have the best lift and duration. Gr cams have 0.010 more lift but much less duration.

By making the cam timing later you get more top end but you loose bottom and mid.
The gs450 - 650 cams all drop in. They fit the same.

You can swap over the whole ignition system. There's info in the wiki for that. Thec timimg is a little different. The advance curve happens a little later.

Keep asking questions :-)

[phillipjohnw]

I'm not sure what other questions I have right now. I'm still in the process of extricating the engine from the bike and looking for parts on ebay/forums. Reading up on as much as I can, some things seem counter intuitive until they're explained. I'm pretty much settled on using 500 cylinders, pistons, and now cams with the 450 top and bottom. I might try and find a base/head gasket combination that would give me a slightly higher cr, but honestly that seems like a lot of work. The only other questions I have are which direction I want to take the bike. I wouldn't mind a nimble cafe with an upgraded suspension (new frontend and swingarm), but I love the look of old school hardtails.

I did see a totally badass 450 build somewhere by scottychop that I would love to try and emulate, but its definitely out of my tool level.

[phillipjohnw]

Cruising through the ebay tonight found two deals. 500 cylinders, piston, and tensioner for a little under $50. They need cleaned up a bit, but other than that they looked good. Also a set of 500 cams for $35, which looked in great shape from the pictures. Now I really need to get the motor all the way out of the frame. Stupid job keeping me from making progress.

[pete]

I hear ya'... do your best to get details and pic's along the way though.