[grant74]

Hi there guys (and gals, of course!)
I'm a newbie to this Yamaha forum and lovin it already! - Wondered if I can ask my fellow Yam owners for some help? I have a 96 (p) Yamaha YZF750R (uk bike) and I love it - just the right height & everything for me - I want more power but can bear to part with the bike and dont really wanna spend fortunes on tuning for very small bhp gains. I've heard that a Thunderace 1000 engine will go "straight in"? I appreciate that this may be mega old news for most of u guys and prob be asked 100 times before - but has anyone actually done this mod? What about things like the following :
Wiring loom
Exhaust manifold
cooling system
Airbox (enough clearance underneath & can u use standard 750 airbox?)
chain / sprocket alignment?
Any frame mods?
can u use standard 750 ecu?

I would love it if you guys can help me out with some sure-footed info on this swap - cos if it is a nice easy swap-over then I'll go for it rather than spending the cash on dynojetting and rolling road tuning etc. I know it'd be quicker / easier to buy a Thunderace but I would really rather keep my beloved 750R. Cheers Eveybody! Stay safe out there!
Grant.

[rf9rider]

It won`t fit straight in, the Ace engine is 10mm higher, so you need either to have the frame spars cut off and rewelded in the right position (easiest way), or make brackets, but then you need to start shaving metal off the head to allow for the thickness of the brackets to allow the sprockets to line up.
The standard Ace airbox won`t fit under the tank (10mm higher) so you`ll need to either mount the tank higher or fit K&N`s or similar, then probably a bit of dyno time to get it set up right.
The ecu`s are different, the 750 allows the engine to rev higher than the Ace, so best to stick with complete Ace electrics.
Everything else is straightforward, rad and headers fit ok.
Sounds a lot of work, but worth the effort.

[grant74]

Thank you so much for ya response mate. i seem to be getting a couple of conflicting bits of advice at the moment. I spoke to another guy from this forum - I emailed him direct - now, he says he has done this conversion. However, since I have a Mk2 yzf750 (95 on?) he said that I would need downpipes, carbs, and thermostat from the ace, and that i could use my ecu. He did point out that this would let the engine rev higher. (Maybe a little self-restraint needed?!)But when I asked about any other mods he never mentioned the frame having to be altered - only that the airbox wont fit and to use K & N's - just like u said. What's your feelings about this? would it make any odds that I have the later adjustable suspension model? (not an SP tho, unfortunately!) - what's your experience with this mod? have you done it yourself or know someone that has? The other guy says he got 140bhp at the back wheel after a bit of dynojetting and setting up - sound about right to you? If so - thats awesome and potentially R1 beating power!! Thank you again for taking the time out to help with my query. Cheers, Grant.

[rf9rider]

Not sure about what he meant by saying you need the downpipes, carbs and thermostat?
You need a complete Ace motor with Ace downpipes, as they are a different size to the 750.
You also need to extend the bottom rad mounts as the Ace downpipes stick out forward about an inch more than the 750 ones.
All YZF750 frames are the same, the rear engine mounts are identical to the Ace, but you will need to alter the front as the Ace motor IS 10mm higher, so the holes will not line up.
I`ve had a few YZF750`s, one with an FZR1000 motor in it, and another had the Ace engine in, never had it dyno`d, but would keep up with the older R1`s and Gsxr`s etc.
I used the complete Ace wiring loom with Ace ecu, didn`t want to over rev the motor by using the YZF750 ecu.
Its definately worth the effort.

[rf9rider]

Just to add, if you want to keep your bike "original", you can rebuild the Ace motor into the YZF750 engine casings, so you keep your engine number, and then who`s to know what the actual cc is?

And the 750 six speed gearbox will also fit both motors, as the Ace has only 5 gears.

All depends on how much work you want to do.

I`ll look to see if i have any pics of the conversion for you.

[rf9rider]

Heres my YZF750 frame with Ace motor, with the frame spars cut off and rewelded 10mm higher.

[rf9rider]

Heres a mates YZF750 frame using brackets, this is harder to do as you need to lose the thickness of the bracket from the side of the head so the sprockets align properly.
If you look closely at the brackets, you can see the actual engine mounting bolts are higher.

[grant74]

wow! thanks a lot for taking the time out to give me more help with this conversion. I see what u mean now I have seen the pics. A brave move to cut the frame but it does look an incredibly neat bit of welding! Its far more involved than I first thought but does sound an exciting proposition - especially when there is 140bhp to be had! Time to get saving those pennies I reckon! Many thanks again - most appreciated - will try and return the favour if ever I can! Cheers mate.

[rf9rider]

No probs.

[Clayman]

rf9rider, on Sep 24 2008, 05:40 AM, said:

Just to add, if you want to keep your bike "original", you can rebuild the Ace motor into the YZF750 engine casings, so you keep your engine number, and then who`s to know what the actual cc is?

Hi
I just joined efter reading this tread, and I have a question about what you say above.
Would cylinder, piston, conrods and head from a fzr1000 or thunderace fit on the yzf750r engine and crankshaft?

A frame mod to make it fit is ok, but is the cylinder swap-able,
or does the case need lots of modifications?

From what you write i guess it works, but i like to keep the 750 crank.

[Bootxjr]

Hello all,
bit new here so I'll take a guess on that if you kept the 750 crank with the 1000 cylinders you'd end up with something like a 900cc. THe reasoning being the 1000 would be a longer stroke crank?

[Clayman]

Bootxjr, on 10 September 2009 - 10:56 AM, said:

Hello all,
bit new here so I'll take a guess on that if you kept the 750 crank with the 1000 cylinders you'd end up with something like a 900cc. THe reasoning being the 1000 would be a longer stroke crank?

Hi
yes, kind of
you would get 824cc, high revs, 6gears, almost same weight.
But most of all, you did something a bit more unusual :-)

But the question remains, can it be done?
rf9rider need to come by this thread again.

[rf9rider]

Clayman, on 16 September 2009 - 08:38 AM, said:

Hi
yes, kind of
you would get 824cc, high revs, 6gears, almost same weight.
But most of all, you did something a bit more unusual :-)

But the question remains, can it be done?
rf9rider need to come by this thread again.

Sorry, i don`t know a lot about using the 750 crank, all i know is the Ace or FZR1000 engine can be built into the YZF750 casings, thus keeping the original engine number.

[Clayman]

rf9rider, on 15 December 2009 - 04:01 AM, said:

Sorry, i don`t know a lot about using the 750 crank, all i know is the Ace or FZR1000 engine can be built into the YZF750 casings, thus keeping the original engine number.

Ok, thanks
hm, i think i will try and put cylinder and pistons from a fzr1000 on my yzf750 engine.
the cylinder should be to high and have to be machined.