From: BONG@slacvm.slac.stanford.edu (Eric Bong)
Subject: Re: FZR engine transplant
Followup-To: rec.motorcycles.racing
Organization: SLAC
Date: Mon, 28 Dec 1992 17:05:12 GMT

In article <1992Dec23.020806.23090@rchland.ibm.com>,
essbaum@rchland.vnet.ibm.com (Alexander Essbaum) wrote:
> 
> In article <BONG-221292143211@kfp-slac-mac.slac.stanford.edu>, BONG@slacvm.slac.stanford.edu (Eric Bong) 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?

> |>   You can put a 1000 cc motor in a 750 frame of the same year.........

> |> The 750 and the 1000 motors do share the same case castings........

> |> a 1987 FZR 750 motor has a six speed gear box,.........

> |> the 1987 1000 has a five speed gear box..........

> yes, i was also wondering about the transmissions.  i'd like to keep the
> 6 speed.  what are the chances i can get the 6 speed into the 1000 case? :)

  I have no idea if the machining done on the cases to fit the 5 speed is
identical to the machining for the 6 speed. You would have to tear down
both motors and try to swap transmissions to find out. (Anybody out there
done this?) If the machining is diferent, you may be able to do additional
machining on the 1000 cases or machine spacers to install the 6 speed. If
it's not a straight swap, it will probably be expensive.

> |>   I question your motivations for modifying a perfectly good motorcycle.
> 
> only if it's cheaper to get a used 1000 than to rebuild the 750 (it's
> currently got (at least) a spun bearing.

  Oh, now it comes clear. Spun bearing. Well the only reason I know
anything
about the 750 internals is that I blew the installation of a new clutch 
basket. I bent the oil pump gear, which later broke, starving the motor of
oil.
I smoked the top end and all the plain bearings. It took me a long time to 
get the motor back together.

  A spun bearing may mean damaged crank journals. You may have to replace
or
recondition the crank. The Yamaha manual says replace the crank if the
journals
are damaged. Yamaha does not sell oversize bearings. So reconditioning the 
crank would be dificult. You would have to find a place that would weld up
the
journals and grind them back down to size. It gives you a good excuse to 
purchase an after-market billet-crank and after-market rods.

  You may be able to get a 1000 motor for a decent price. Check American
Roadracing
or your local club racing newsletter. Of course you will have to eventually

rebuid your 750 motor. You own a rare machine. The collector value is
severely
diminished if you don't have the origional motor in the frame. You could
put in
a 1000 motor, then re-build the 750 at your leisure. I strongly suggest
making up a
spreadsheet and pricing out all your options before you start to rebuild
your motor.
You can then plan a financial strategy to accomplish your performance
goals.

Have fun,

Eric Bong   DoD # 0270
1986 FZ 750
1987 FZR 750 RT (not exactly stock)
--------------------------------------------------------------
Disclaimer:
The opinions expressed in this posting are my own, and
not necessarily those of the Stanford Linear Accelerator 
Center, Stanford University, or the US Department of Energy.