Topic: 750 into a 650 frame

[1981cb650c]

I want to build an engine for my '81 650 custom. It seems that I might be able to fit a 750 in the frame. when I pulled my engine I noticed that honda used spacers to make the transmission wide enough for the frame and the front mounts could easily be modified to fit almost anything. Has anyone attempted this before? could someone tell me how wide the engine is mount-to-mount at the front and rear and the distance between front and rear mounts so I could measure up my frame? I am looking at a 750 upgrade do to the serious lack of parts for these 650's. they say with patience and perseverence you can piss a hole through solid rock, I want to know if this is possible or just way too much work (the engine swap, not the hole in the rock thing) -Dave

[merc2dogs]

 I've seen the sohc 750 stuffed into a little mustang frame, so if all the measurements agree I'd say it's feasable.
  As you say with patience and perseverance.

  But then I also replaced a Fiat 850 spyder engine trans and rear suspension with a Toronado big block V8 trans and front suspension. wasn't realy driveable, but it was a rush. punch the gas and you felt like the ball on a pinball table when the plunger hits it.

ken. 

[bryanj]

Dont forget you need to get the engine at the correct angle for oiling and mount an external oil tank wityh lines--total rewire as the generator is different Etc. Etc. Not forgettting use of gas axe and welder just to get it in there!

[bill440cars]

 I've seen the sohc 750 stuffed into a little mustang frame, so if all the measurements agree I'd say it's feasable.
  As you say with patience and perseverance.

  But then I also replaced a Fiat 850 spyder engine trans and rear suspension with a Toronado big block V8 trans and front suspension. wasn't realy driveable, but it was a rush. punch the gas and you felt like the ball on a pinball table when the plunger hits it.

ken. 

     Hey Ken,
           I'll bet that Tornado "Big Block" did provide a rush! I knew of a guy who dropped a Blown 350 Chevy in an MG Midget and that was a monster!

                                                           Later on, Bill

[eurban]

This question comes up now and again on this forum.  The cylinder and head on the 750 tilt a good bit farther forward than the more upright 500/550/650s.  There is really no way you are going to fit a 750 engine into the 500/550/650 frame unless are ready to significantly cut up your frame and reinvent.  You would also need to find a place to mount the oil tank.  Basically this is not a practical mod.

[Geeto67]

as long as you are going the custom route, why not a modern motor like a cbr600 or something? I have an fzr600 motor on my workshop bench right now and I can say the thing is tiny comapred to the GS750 and cb750 DOHC motor that sits next to it. modern motors tend to be smaller all around with way more hp.