GS550/650.

[imago]

Does anyone know if the heads are the same or interchangeable between the 550 and 650? Failing that, anyone know if the port spacing is the same at the head (not the rubbers)?

[wraith]

You can put the hole 650 top end on the 550 bottom end, done it twice 

Once the 650 barrels went straight on the 550 bottom end then on the later one I had to open the 550 crankcase a bit for the 650 barrels  

So I'd say yes the 650 head will fit the 550.

I've also used the 650 katana carbs on a 550 with a CV head but I don't know if the port spacing is the same, as just used the 550 rubbers.

[imago]

I was moving some stuff and uncovered the XN85 plenum that's been sitting on a shelf since forever. So I was pondering using it on a 550 or 650 as I reckon a middleweight turbo would be pretty cool.

With modern injectors, electronics and turbo it'd be quite nippy too. Obviously stuffing an oil cooled motor in would get similar gains, but where's the fun in that? 

[wraith]

The XN85 was a interesting bike but compared to the gpz750 turbo it was well short on power. 

With a good turbo on it etc it would be good fun, go for it  you know you're going to be getting bored when you have finished the one you're doing 

[imago]

33 minutes ago, wraith said:

The XN85 was a interesting bike but compared to the gpz750 turbo it was well short on power. 

With a good turbo on it etc it would be good fun, go for it  you know you're going to be getting bored when you have finished the one you're doing 

I haven't touched that for weeks, then there's the 'throwback build' that I want to get on with. Maybe I should get those done before I start dreaming up new stuff. 

[wraith]

Start the mid wight one started, then when you get bord of one you have another two to play with