fzr/yzf head swap question...

[match417]

So i was digging through ebay..found a cometic head gasket for a YZF600, but it says it's for a 94 - 99??? This sparked my question about the coolant passages between the head and block lining up. Yamaha designed this, and Yamaha also designed my 3sgte head. Between the 2nd gen and 3rd gen 3sgte's, the coolant passages are different, and if people want to mate up the head with the block the you have to drill out the block a little bit so the coolant passages line up with each other. Is the same true between the FZR and YZF head/block? Would this head gasket (below) work on 89 - 99 FZR's and 95 - 07 YZF's? There aren't any YZF's made in 94 anyway.

http://cgi.ebay.com/ebaymotors/YAMAHA-Y ... ccessories

[reelrazor]

Bore-and therefore the gasket-is different between the FZR and YZF.

The actual bore opening on a YZF will be larger than an FZR

[the_finch]

Bore-and therefore the gasket-is different between the FZR and YZF.

The actual bore opening on a YZF will be larger than an FZR

When looking into a 660 conversion, you'll find that while the FZR600 and the YZF600 have the same size motor, they have completely different power outputs. The FZR is basically a long-stroke FZR400 motor (generating alot or torque) and the YZF motor has a 2-3mm shorter stroke and a larger cylinder bore. Same cc's, but the YZF has the capacity to rev alot higher and spin up quicker, making more horsepower, with a slight sacrifice in torque.

The gobs or torque our bikes put out, BTW, is what makes them so much fun to ride for being such a (comparatively) old bike.

[match417]

yeah, but it's mainly just a power curve difference between the two bikes. I haven't compared dyno sheets, but the difference in design would give the YZF quicker throttle response than the FZR. Comparing actual horsepower, the FZR has 2 less HP than the YZF at 11,500 RPM. Has anyone taken a YZF block and put the FZR crank/rods w/ YZF pistons? That gives you a more oversquare or "longer stroke" crank with the larger pistons from the YZF in the YZF block. Or!! Find the tiniest turbo you could possibly find and throw it on! That would be awesome! That with a mini I/C..I would do it, in fact I've always thought about doing it to the FZR. I would want a lower compression ratio though, speaking of that, someone was saying that our bikes don't actually have a c/r of 12:1, it's more like 10:1 or something. Anyone know anything else about that? Why would they false advertise c/r if that's true?

[the_finch]

yeah, but it's mainly just a power curve difference between the two bikes. I haven't compared dyno sheets, but the difference in design would give the YZF quicker throttle response than the FZR. Comparing actual horsepower, the FZR has 2 less HP than the YZF at 11,500 RPM. Has anyone taken a YZF block and put the FZR crank/rods w/ YZF pistons? That gives you a more oversquare or "longer stroke" crank with the larger pistons from the YZF in the YZF block. Or!! Find the tiniest turbo you could possibly find and throw it on! That would be awesome! That with a mini I/C..I would do it, in fact I've always thought about doing it to the FZR. I would want a lower compression ratio though, speaking of that, someone was saying that our bikes don't actually have a c/r of 12:1, it's more like 10:1 or something. Anyone know anything else about that? Why would they false advertise c/r if that's true?

People have taken the FZR motors and added the YZF cylinders and pistons. It comes out to approx 660cc, which is the 660 kit people refer to (and I think a member named Dru from Australia actually has built).

The recipe goes something like this:
Take 1 complete FZR600 motor
Remove the following parts and replace with YZF pieces:
Cylinders
Pistons
Connecting Rods
Head
Cooling Tubes
Carb Boots
Carbs
You'll also need to sort the ignition (most people use Ignitech, but you might be able to get the YZF ignition to work) and a new cylinder base gasket spacer
You'd probably also need to sort the cooling system to deal with the extra heat, but some people don't have a problem with it.

For more info see the 660 conversion thread:
viewtopic.php?f=30&t=1199

If I were in your position with that YZF600 you want to pick up, I'd get it and go ahead and do the 660 conversion.