Actual cc of the 850?

[Bonzo]

My logbook says 828cc but I see some say it's an 829cc.

Which is it?

 

[baz]

My logbook says 828cc but I see some say it's an 829cc.

Which is it?

828.88 I believe

 

[Fast Eddie]

All depends on your rounding up.

If you use 3.141 it comes out at 828.723cc… which should be called 829.

If you use 3.14159 it comes out at 828.878cc… even closer to 829.

So IMHO, correctly rounded, it should be called an 829cc.

It was robbed of a claimed 1cc by lazy rounding up !!

 

[Bonzo]

 

[SteveBorland]

Depends on the oversize really

 

[concours]

All depends on your rounding up.

If you use 3.141 it comes out at 828.723cc… which should be called 829.

If you use 3.14159 it comes out at 828.878cc… even closer to 829.

So IMHO, correctly rounded, it should be called an 829cc.

It was robbed of a claimed 1cc by lazy rounding up !!

But then given back with side cover badges, like Robin Hood

 

[worntorn]

In hot humid weather my 850 feels like an 828.
On a cool crisp fall day it pulls harder, more like an 829.

Glen

 

[Dan1950]

Depends on the oversize really

At . 020 over its 839.678993965254

 

[Fast Eddie]

At . 020 over its 839.678993965255

Approx …

 

[worntorn]

On the right day that would pull like an 840

 

[Matchless]

If you really want an 850 just bore it to +0.040" . (850.547) The extra performance will blow your mind!

 

[Dan1950]

If you really want an 850 just bore it to +0.040" . (850.547) The extra performance will blow your mind!

I once bored an A65 . 080 over and fit it with 10.5:1 pistons and a head from a flat tracker.

That bike was insane but you didn't want to venture far from home as things would fall off at the most inopportune times.

 

[L.A.B.]

When new, an 850 should have been somewhere between minimum A bore grade and maximum B grade so 828.88 - 829.42cc.

 

[Matchless]

When new, an 850 should have been somewhere between minimum A bore grade and maximum B grade so 828.88 - 829.42cc.

Would be fun to have some side panel transfers made up with that.

 

[Torontonian]

If you really want an 850 just bore it to +0.040" . (850.547) The extra performance will blow your mind!

Both of my 850's are on .040 rebore.
Let the power flow.

 

[Mart UK]

Mine too. Is there a step beyond 0.040?

 

[L.A.B.]

Mine too. Is there a step beyond 0.040?

+0.060"

 

[Mart UK]

+0.060"

Should see me out then .

 

[L.A.B.]

Then +0.080"

Engine

Engine

www.rgmnorton.co.uk

920cc

920 COMPREHENSIVE CONVERSION KIT

KIT COMPRISES OF:050016 - 920 CYLINDER LINER X2050163 - 920 PISTONS (COMPLETE WITH RINGS & CIRCLIPS) X2050207 - 920 GUDGEON PINS X2920HG - 920 COPPER HEAD GASKET050150 - 920 GOLD DECALS X2 (ALSO SILVER ON PART NUMBER 050149, BLACK ON PART NUMBER 050148 AND RED ON PART NUMBER 050151) PLEASE STATE

www.rgmnorton.co.uk

920+0.020"

920 PISTON KIT +20

RGM NORTON 050164

www.rgmnorton.co.uk

 

[Mart UK]

Not expecting to last that long. I'll let my sons know.