From: BONG@slacvm.slac.stanford.edu (Eric Bong)
Subject: Re: FZR engine transplant
Followup-To: rec.motorcycles.racing
Organization: SLAC
Date: Tue, 22 Dec 1992 23:19:10 GMT

In article <Bzns4r.3wK@bailgate.gpsemi.com>,
martin_s@sn4608.oldham.gpsemi.com (Martin Shelley) wrote:
> 
> In article <1992Dec21.095706.21177@hemlock.cray.com>, tbb@sumac02.cray.com (Todd Blachowiak) writes:
> |> 
> |> (Alexander Essbaum) writes:
> |> > does anyone know how hard it might be to put an FZR1000 motor into an
> |> > FZR750 frame?  my manual kinda implies that a 1000cc motor of the same
> |> > year would mount ok in a 750 frame (the 750 is from 1988).  do 750's
> |> > and 1000's share the same block dimensions?
> |> > 
> 
> I don't know about the FZR 750 but there was an article in Performance Bikes
> (a British Motorbike mag) about a guy who put an FZR1000 engine into an OW01
> frame.
> 
> (this might be the FZR750 but I don't think so. I think the OW01 is the
>  FZR750R. Confused - I sure as hell am.)

  Yes, the OWO1 is an FZR 750 (depends on year). The 1987 & '88 were the
FZR 750 RT. From 1989 on the bike changed to FZR 750 OWO1. Prior to '89
the cylinders were canted forward 45 degrees. From '89 on the cylinders
are more upright. The FZR 1000 motors are the same as far as forward tilt
verses year.

  You can put a 1000 cc motor in a 750 frame of the same year. I don't know
about fitting a motor from a diferent year. The 750 and the 1000 motors
do share the same case castings. However, there may be internal machining
differences. For example: a 1987 FZR 750 motor has a six speed gear box,
a two lobe oil pump and an external oil cooler where the 1987 1000 has a
five speed gear box,a single lobe oil pump and no oil cooler. There may
be machining diferances to accomodate the differing gear boxes, oil pumps
and oil cooler fitment. I've never checked though.

  I question your motivations for modifying a perfectly good motorcycle.
The '88 FZR 750 will out power most bikes on the road in stock trim. With
a high quality pipe and jet kit it will run well against most new sport
bikes, certainly the ZX7 (Maybe not the ZX7R or the water-cooled GSXR).
Put cams, a racing ignition box, two ring pistons and slide type carbs
on and most new bikes couldn't catch you (depends heavily on rider skill).
Plus you loose a gear going to a 1000 motor. I love the six speed.

  There are alternatives to shoving a 1000 motor into the 750 frame besides
building a roadrace motor. The stud spacing on the '87 & '88 750 and 1000
cylinder banks are the same. you can fit a 1000cc top end on a 750 case.
This would bump the 750 up to 912cc. Take care in fitting the base gasket.
The 750 gasket is .030 paper and the 1000 in .012 metal. Make sure the
piston doesn't top out. Cosworth makes a 912 kit for the 750, retaining the
750 head. The same care must be taken to keep the cylinder from toping out
plus you may need to modify a 1000 cc head gasket to allow sufficient water
flow. Both options retain the 6 speed 750 gear box.

  Your origional question (Alexander) was how hard would it be to fit a
1000 motor in a 750 frame. Of course that depends on your mechanical
aptitude. It can be done. It would probably take me 12 to 16 hours of
labor if I didn't do any performance modifications to the 1000 motor.
And I would need assistance lowering the 750 motor and raising the 1000
motor (it's a expensive when you drop them).

  No matter what Stephan says, it's dificult to tune the CV carbs to 
engine mods on the FZRs. Maybe it's easier if you're racing, and use
only full throttle. You have to tune all carb ranges on the street. It
takes many iterations and there is always some compromise.

Have fun with your FZR. I think they imported less than 200 in 1988.

Eric Bong   DoD # 0270
1986 FZ 750
1987 FZR 750 RT (not exactly stock)
Newsgroups: rec.motorcycles.racing