Other engine possibilities...

[Rollin668]

Has anyone every heard of mounting other motors in the GS frame?
So far I've heard mention of fitting an xr650 engine or a Yamaha 660 engine... anyone?

Think the idea would be great to try out but just wondering if this is done with "relative" ease...

Thanks...

Rolly

[Lars]

I don't think they have more power than the GS engine and it's a 1 cylinder engine, they wear more quickly.

[werase643]

what would be the advantage....

the GS chassis is NOT the greatest chassis ever built(note  either is the RS250 below, but it has a SSSA with the chain on the right side)

If I had a KEWL engine....which I do...KTM DUKE II(640cc and 50+HP and 6 speed trans)
I would find a HONDA RS250 GP chassis to install it into....which I havent...

soooooooo
want a good deal on a KTM engine to install into a GS?

[Blueknyt]

just to help your search for an engine, the GS450 shares same platform, same crank, and trany GEARS, output shaft has different offset for drive sprocket. crack open your engine, see whats wrong exactly, grab a 450 engine and gut it for what you need,   i would say use the whole bottom end, just change the sproket, but the shift drum is setup for diffrent pattern of shifting, so, unless you had resets on with linkage,  you would have to shift 1 up 5 down.

[Rollin668]

Man, this little series of conversation disappeared quickly... anyway... still looking into options for another GS motor.

just to ease my tension - anyone know where to locate a stock RUNNING AND COMPLETE gs450 or 500 motor???

Thanks...


Rolly

[scratch]

I have an aquantance at work whose brother has a running GS450 that he is looking to unload for an undisclosed $ (I'll let you and him talk).

[werase643]

I do believe the head of the 450 is different.....
something about header/frame interference

[Blueknyt]

yes, the CChamber is bigger for lower compression, the valves are same size, the intake ports are wider apart, and the exhaust ports are angled out. HOWEVER, im belive if you did want to use a 450 head, i believe you have enough room tobend the tubes sharply enough to clear the frame. the bore size is abit smaller. but figure he could Vamp the lower end from the 450 for the 500
.   let me look, i might have another crank&rod assembly in a box, but you would have to/and recomend,  new bearings be installed while you have it apart..

[Lars]

Hmmz, if it's a 450 and it has lower compression it would make noticably less power.  Are the ports angled in such a way you need a 2-2 exhaust system?

[Rollin668]

Anyone have any experience with the EX500 motor?
I'm told of a racer who has mounted an ex500 motor in the GS frame with success...

What do you think?


Rolly

[Gisser]

Hmmz, if it's a 450 and it has lower compression it would make noticably less power. Are the ports angled in such a way you need a 2-2 exhaust system?

GS450 and 500 both run 9:1 c/r.  It's been reported that the 500 head will work atop the 450 engine with a couple minor mods.  Doing it vice-versa will require some welding around the combustion chamber.  In other words, forget it.

Aftermarket pipes for the 450 are 2-into-1.

[Blueknyt]

the 450 may have same Comp ratio, but the chamber itself is deeper, i have 2 of both sitting on my bench,  the 450 piston might have a higher dome as the valve relief is deeper, the 450 and 500 cams apear to be identical, all marks  are same, but i would have to check with a dial indicator to be sure. Valves are the same, springs are the same from what i can see, dont have a tester though. the GS450 brestbones are narrow and come down between the pipes, , the GS500 has the perimeter frame and the breast bones come down on outside of pipes, the 500 cyl/pistons/and head combo on 450 would work, but you would have to customise the exhaust header, the 450 exhhust crossover is under and behind the engine(just got done choping one up) i still think one could showhorn  a GS650 twin or a yamaha XS650 twin inplace, hmmm fun.

[Gisser]

the 500 cyl/pistons/and head combo on 450 would work, but you would have to customise the exhaust header

Of course, the solution here is to just use the GS500 frame.  But, I was referring to transplanting the 500 head onto the 450 engine, not swapping complete top ends.  It's been done.

i still think one could showhorn a GS650 twin

No doubt, because one of the design goals for the GR650 mill was compact dimensions.  Unfortunately, peak power wasn't a priority and it's performance lags behind the GS500.  But, I'd go for the added displacement just for midrange grins.

[werase643]

I have 2 650 engines......
$100 for the pair...what I paid
one is torn down

come get them
located in central NC   W-S