What would you do? 900 swap or 750 motor work?

[cyrus buelton]

I've currently got a 1999 750 with FCR's, leo pipes, etc.

I really am not much of a fan of my S4r as I prefer the 2v motor. So I will probably sell that.

But I'd like some more power, so here is the question:

900 motor swap with a 944 kit installed?


or

take it to my mechanic and have him do engine work that will upgrade the 750 to a 795 which yields about 87hp at the rear wheel (I will link to his page if you want to see the dyno chart).



Bueller?

[Triple J]

900 motor swap for sure. 

[cyrus buelton]

900 motor swap for sure. 

a 944cc with short manifolds peaks at 87.9hp (from his website, on his dyno)

I am not too picky about a dry vs wet.


Just looking for more mid-range which the 750 would give and the 944 would give more top end, which I have very little interest in.

[Monsterlover]

900 swap ftw.

It will make more power everywhere

Plus you'll get a 6th gear (750's are 5 spd right?)

[cyrus buelton]

900 swap ftw.

It will make more power everywhere

Plus you'll get a 6th gear (750's are 5 spd right?)

Yeah, it would get an extra gear.


How would it make more power when they have equal HP, with the 944 making 8 more lbs of torque? That noticeable?

[Triple J]

What's the torque comparison betwen the two? I suspect the 900 has quite a bit more.

Anyway...I just like the 900 engine.  

[Triple J]

Also...87 hp at the rear wheel seems like a lot for a bored 750. My 1000DS motor (stock, but with full exhaust and open air box) doesn't put that much out. 

[Spidey]

944 kit, definitely.  Those 944 engines feel really good.  The dyno numbers aren't going to tell you too much about how it'll feel on the street.  I don't know about that specific 750 kit, but the couple of hopped up  750s I've ridden just don't match the 944 kit. 

Honestly, though, unless you're in love with your 750, I'm not sure I'd mess around with the $ in doing a motor swap with a 750.  I'd just buy a more modern air-cooled Duc with FI.  For the price of the engine plus the cost of your 750, you're already in the range of a FI 900 or an earlier 1000. 

[Monsterlover]

Yeah, it would get an extra gear.

How would it make more power when they have equal HP, with the 944 making 8 more lbs of torque? That noticeable?

Torque peak at different revs could yield the same hp number.

ie

80ft/lb @ 7000 rpm = 106hp

or

90ft/lb @ 6185 rpm = 106hp

Look at the torque curve more than the Hp curve.  HP is just a number derived by multiplying torque and the rpm it's made at and dividing by 5252.

The two numbers that change everything (including the riding experience) are torque produced and the rpm it's produced at.

Sure the 900 will make more top end than the 750, it displaces more and can efficiently burn more fuel in the upper range.

Because of that it will do better in the mid range as well.

I googled and didn't really see much in the way of dyno charts for 900's and 750's (let alone with big bore kits)  They have to be out there.

[Duck-Stew]

Got $ to spend, 944.  More power EVERYWHERE.  Mid-range, upper end, 6th gear, dry-clutch, timing belts are cheaper, etc...

Trying to do it on the cheap:  Drop-in 11:1 Ferracci pistons (or Pistal, or whomever) in your existing barrels and top it off with either 695 or 800 heads.  Same manifolds, so same carbs, same exhaust manifold location and you can do it IN the frame.

[cyrus buelton]

Also...87 hp at the rear wheel seems like a lot for a bored 750. My 1000DS motor (stock, but with full exhaust and open air box) doesn't put that much out. 

My bad........84.98 and 59fp torque (the line I looked at was when he dumped in some race fuel)


Here is a link to his dyno result along with the mods:

http://www.hordpower.com/gallery/album07/795ssIgnition?full=1


(side note about JD: when Pegram raced with the 749 punched to an 848....they spoke with JD as he already had done the punch out for Mark Hatten)


Monsterlover - go to www.hordpower.com, click on "dyno charts" on the left and then select "ducati"

These are all done on a dyno in his garage (yes, he has a Dyno 250), which he built last year. Previously he had a shop, but built one behind his house to be closer.

Got $ to spend, 944.  More power EVERYWHERE.  Mid-range, upper end, 6th gear, dry-clutch, timing belts are cheaper, etc...

Trying to do it on the cheap:  Drop-in 11:1 Ferracci pistons (or Pistal, or whomever) in your existing barrels and top it off with either 695 or 800 heads.  Same manifolds, so same carbs, same exhaust manifold location and you can do it IN the frame.

Was trying to do it cheaper vs more expensive.

obviously throw on about a grand just for the motor........

[Monsterlover]

A couple other things to consider when thinking of the 900 upgrade would be the 5.5" rear wheel, and the sprocket carrier that goes with it.

Just went through this making a 750ss into a 900ss

[Duck-Stew]

A couple other things to consider when thinking of the 900 upgrade would be the 5.5" rear wheel, and the sprocket carrier that goes with it.

Just went through this making a 750ss into a 900ss

The wheel swap is optional BTW.

[Monsterlover]

Well, that is true.

I use the bike for the track and wanted the larger contact patch you get from a 180 over the 160.

For a street bike I don't think it would matter unless you rode knee down all over the place

[Triple J]

My bad........84.98 and 59fp torque (the line I looked at was when he dumped in some race fuel)


Here is a link to his dyno result along with the mods:

http://www.hordpower.com/gallery/album07/795ssIgnition?full=1

Makes sense now...that's quite a bit of work to the engine.