Seattle-ite newbie

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scottychop
Posts: 2
Joined: 04 Sep 2010, 17:00
Location: Seattle, WA

Seattle-ite newbie

Postby scottychop » 05 Sep 2010, 06:29

Hello all,

I actually do not own a GR, and instead am looking for information on parts interchangeable with the motor mods I am planning on my GS450. We have a lively discussion going on over on the GS boards about motor swaps, and the idea of a GR650 transplant has been mulled over. Instead, I am going the route of keeping my bottom end, using GS500 jugs, and GR650 top end for a whopping total of 527cc's of greatness. I have purchased the head and jug, and am actively searching for pistons and rings at a reasonable price. Since I have to have the jugs bored anyway, I may just go with OS pistons. Any thoughts and tidbits you all might possess would be fantastic!

Scott

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vtwin
Posts: 383
Joined: 24 Jan 2007, 04:02
Location: norcal

Postby vtwin » 05 Sep 2010, 15:41

Scotty, there has been mention here that the 650 head will work on a GS500 block and jugs. Guess the 650 has a better head, but a bad bottom end for racing applications at any rate. Good luck and post what you find since it's probably getting harder to find GR650 stuff.

Big R
Posts: 339
Joined: 13 Sep 2008, 11:50
Location: Western PA, US
Contact:

Postby Big R » 05 Sep 2010, 19:04

Hey Scotty, here's the info i found. The 450's and 500's are identical except for the bore of the cylinders (that's where the extra 50 cc's comes from) and the exhaust ports. Everything else is a direct swap.

Now the 450 and 650: the GR650's have about 13mm extra stroke in the crankshaft, 3 more mm bigger pistons than the gs500, a 5 speed tranny, a lower redline (8500 rpm), but also has the angled exhaust ports as the gs450.

I think the crank from the 650 wont fit into the GS450, so the longer stroke wont do you any good. The heads and pistons from a GS500 would probably be the easiest swap for you, except you would have make a custom exhaust.
go big or go home

scottychop
Posts: 2
Joined: 04 Sep 2010, 17:00
Location: Seattle, WA

Great

Postby scottychop » 05 Sep 2010, 19:33

Thanks for the replies. I know it has been done by at least one other person out there. He has nice youtube videos of the bike at idle. He mentions that the trick was to use the 450 bottom end for it's stoutness, the 500 jugs bored out to accept the 650 pistons. And 650 head and cams. He also mentions that the cam chain tensioner is the weak link. I think upgrading to the 500 is the way to go. I've had the good luck to get both a jug from a 500 and top end from a 650 both in decent condition. This is going to be my winter project, and am doing the research now to get the planning phase done with. Any thoughts on compatibility would be great.

Oh, and I have never tried to tackle an engine swap of this magnitude before! I have done pistons, rings, etc...but nothing quite as Frankenstein and am really intriged. Hope you are all willing to look at a lot of pictures and answer a LOT of questions!

Scott

Big R
Posts: 339
Joined: 13 Sep 2008, 11:50
Location: Western PA, US
Contact:

Postby Big R » 06 Sep 2010, 01:32

All the info i got for the conversions was found at GStwins. If you search their site for GR650, GR 650, or Tempter you can find all sorts of stuff.

And FYI: i think the bike is a fj1200 or something...... but is uses the exact same pistons as a gr650.
go big or go home

fletcher0780
Posts: 13
Joined: 26 Jun 2010, 12:46

Postby fletcher0780 » 09 Sep 2010, 14:08

got any pics of your gs?


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