Recently picked up a 1983 Gs450E for 180$
was wondering if the complete topend form a gr650 templer would work on a Gs450 bottom end
anyone on here done this?

i'm pulling this out of old knowledge oms-crs there is a difference in the cylinder oil drainback from the head down to the cases...  i always wanted to put the canadian 400 8 valve head on a 500.... for better top end breathing.... but the exhaust was in direct line of the down tubes.

This has been done before, look up "GS527 Beast" on YouTube.
There is the oil drainback sealing problem where the match of the GR head to the GS500 cylinders is very slim, very thin overlap of the two in that one area, so not ideal but works, may start seeping in time.

The bigger issue is that the 450 has a short stroke, & the GR has a VERY LONG stroke, so using the GR head & pistons results in something slightly above 7:1 compression ratio... TBC


My 1st post here.... If it ever goes through!!!
Does it ALWAYS ask you for a confusing blurred captcha interpretation & a bunch of motorcycle questions where it does not accept the correct answers? Like the first year the GS (was) introduced in the US? It was officially June 1976 they were first manufactured, 1977 model year, but there were also 230 or so 1976 m.y. "GS750A" dealer/promo test ride models only available to generate interest in the upcoming GS product line. The darn thing won't accept  EITHER correct answer! 1977, 1976, or 76 or 77!!!!!
Also,spark plug, spark plugs, ignition coil, or ignition coils ARE correct answers for "what produces the electrical arc responsible for combustion in the engine?" It won't accept ANY!!!!
Also it only accepts incorrect answers for "what do the airbox and fuel lines connect to?"
Carburetors is the only correct answer, it only accepts carburetor - the correct answer for a Hardley-Ableson or a Suzuki GN400, but NOT a GS twin!!!
And the petcock controls fuel or gasoline, but it only accepts GAS as the answer..  my knowledge sharing may be severely limited on this forum if this doesn't stop!!!!!
These darn things are gonna kill me by not accepting correct answers!!!!!
I hope this is only a hazing thing here, not a forever verification thing...being smarter than the computer, but being shut down 19 times out of 20... holy geez.

Also, you may want to contact BorisH on the GS Resources forum. He had some custom CP/Carillo pistons made for GR650 combustion chambers & GS400/425 crankshaft stroke. He was willing to give out the order number to have them replicated, but you would need to alter the piston pin size, with a 450 bottom end, to 18mm, possibly check/change the compression height, & possibly add a few cc's volume to the domes to make up for the GS450/500 crank's shorter stroke in the compression ratio department.

Rich Graver, a WERA official & unbeatable semi-retired GS twin racer (probably on here I'd imagine, was once on the GS Resources - WERA90EX?, but definitely on the WERA forum) also has had custom batches of these exact pistons made up, as well as 76, 77, or 78mm pistons to punch a 450 or 500 out to 540-something cc's.

I'm on here for a little extra info sharing and assistance on my GS twins - building up a 77 GS400B & 79 GS425E into track bikes, race bikes, canyon carvers. 425 top ends - one with Wiseco K844 750 pistons for 449cc 10.5:1, the other with old NOS MTC Engineering 920cc GS750/850 pistons for 10.4:1 & 489cc. GR650 cams for both, although one set may sent to Web Camshafts for a serious performance grind due to the competition I will be up against if trying to run it in most WERA classes (Vintage 4 bump up, or Clubman).

Welcome to the forum Chuck! Sounds like you have a wealth of information and experience from which we would all benefit 

I think I've tuned up my GS as far as I can go with minor mods.  Any advice for head work?

PS dealing with the stupid questions is a rite of passage here.  If I remember correctly, it's "sparkplug" as one word for that question.

THANKS!
The captchas seem to be getting a little less blurred out, & the very finicky "correct" answers are becoming more predictable as to which correct or often  incorrect variation is what the server is looking for... What a p.i.t.a.!!!

For head work, I really should be learning my own porting techniques by now, but I rely on "Rapid Ray" Rains aka "Suzuki Ray" for head work, and also could recommend the father & son team at Rockdale Cycles in Conyers, Georgia.
I'm too particular to do any serious head porting without flow bench results, and I don't currently foresee myself buying a flow bench, so there you have it...

650 Tempter head/pistons on GS500 cylinder on GS450 bottom end:
https://youtu.be/tQEVHd1cSyw