from 750ie to 800 stroked

[Ageispolis]

How hard can I expect it to be to get more horsepower out of this motor, being that it is the 2001 750 fuel injected model with limited performance part availability? I am reading and looking at what seems to be the possibility of stroking this motor with a 916 crank.

On the 800:
-The intake/exhaust valve diameters are 2mm/3mm larger.
-the stroke is 66m as opposed to the 750's 61.5mm
-bore is same
-the inlet timing and exhaust timing are 19/60 and 57/24 as opposed to the 750's 12/70 and 56/25
-the duration is 3 shorter on 800 intake and same for both on exhaust.
-valve lift is 10.8/10.3 compared to 750 - 9.35/8.5

changes from 750 to the 800 are:

-New crank – 66mm stroke (same as 916, 996 engines)
-New pistons – shorter compression height, same bore as 750
-900 size valves
-Camshaft timing and lift revised
-Camshaft design revised – 2 bearings instead of 3, not interchangeable, except 620 (?)
-Head design revised – as per cam changes, LH cam end cap revised
-6 Speed gearbox fitted – from 400 engines with sprung damper in clutch drive
-Same exhaust headers and mufflers fitted on 800SS/Sport as the old 900 and 1000 models. The 750SS/Sport used a smaller diameter header with the same size stamped x-over, muffler pipes and mufflers as the 900 – M models have always used the same 40mm sized headers and mufflers on all 600/750/900.


off of: http://www.moto-one.com.au/performan...p2vmodels.html

I could just swap a 800 or 900, but it is more fun to take the engine I have and make it better. It is even better if I could do this with stock parts off of other bikes. If anyone knows anything about this, or any resources to point me to, please do. This and a 6 speed tranny swap with dry clutch setup and I'm set.

[Brewmaster]

I approached Bruce Meyers about this same topic. He looked at me and said "don't be stupid, just buy a 800 motor and plug it in." Basically it (the 800) will make more power stock than what you will most likely get from doing all those things on the 750. Bottom line ($$$$ that is) it seems that the 800 is a better choice. I was/am considering this for my race bike. This is only due to the rules allowing up to 805cc for the classes I race. A 900 would throw me into a different class which would be even harder to be competitive with.


That said you could probably find a 900 cheaper (and more plentiful) and up the ante even further!

[Ageispolis]

Yeah, I thought of putting in a 900, but I like the idea more of taking my current engine, and pushing that further. With the low availability for parts for the IEs, I was considering ts an option. I guess maybe a 900 swap is easier.

[Guy Pike]

As I'm sure you know, Bruce built class winning motors of displacements near 800cc from 750's before the 800's came out. I have considerable seat time on one of these gems. If he thinks an 800 is the way to go, I trust cousin Brucie above anyone on the matter.

[blade625]

795 HC kit from BCM, send your heads to Bruce for porting, he can re-flash your ecu also. Should make right at 80rwhp. He'll lighten your flywheel for like 80 bucks also.

6 speed is an easy swap, while you have the cases apart, you can send your crank to Ben Fox [along with your new pistons, etc.] and he can balance it [lighten it too, if you like] Lots of fun stuff you can do, if you like to work on it.

Dry clutch is not too difficult, slipper would require some special parts. I have the drawings for the custom hub nut, and a re-machined 160005 bearing to allow you to move the o-ring further down the input shaft [to seal it beyond the splines] which is probably the hardest part.
I refuse to give up on my 750SS, although I must admit...I look across the shop at my S2R800 sometimes...and think about cannibalizing it for a racebike