Bore out, or new engine?

[Poot]

HI all,

I've got an '80 850, and have something in mind for winter (a long ways away, but still dreaming).

I wanted to increase the power on my 850, either by boring it out, or by just bolting on a 1000 motor.


Does anyone know what the max volume I could bore out my engine to, while keeping it rock solid? Also, I'm not really sure of what this would usually cost at a machine shop, so any ballpark figures would be great.


If I'm not mistaken, the 850 block is the same as the 1000, but just not drilled out?



thanks



poot

 

[Einar J Skog]

Hi :lol:

The 850 has a 69mm piston,and stroke length 56.4 mm

The GS1000 has a 70mm piston, and stroke length 64.8 mm

So,if you bore the block out max.,If it is the same as in the GS1000 .
then you get 73.5 mm

Then the volume in the GS850 will be : 73.5 mm X 56.4 mm =956 ccm

And then you must bay pistons If you can get any that fits.

Wiseco 73.5 mm will not fit...
Wrist pin is 16mm in 850
Wristpin is 18 mm in 1000


Best thing to do is to bay a GS1000 engine.....


Einar

GS1000GLX (Wiseco 1100)

 

[SqDancerLynn1]

A GS1000 would be a better choice. gs1100 would be nice too if you can find one

 

[Anonymous]

One thought is that----If you want to get noticable power increases you would most likely have to bore it to the service limit. With the larger engines you could just rebuild the new block to a minimum over bore and then be able to rebuild it again at as later date.