Types of big bore kits for 850, 902cc?

Y

Yetiman

Joined

Feb 27, 2011

Messages

31

• Mar 25, 2011

• #1

When I bought my 73 norton the PO told me it was a 902cc with a 11.5 to 1 compression head. I'm having a hard time find any info on a 902cc kit. Anyone have any clue, and also what are the other big bore sizes offered for a 850?
Cheers

 

T

Tintin

Joined

Mar 12, 2009

Messages

607

• Mar 25, 2011

• #2

Yetiman said:

When I bought my 73 norton the PO told me it was a 902cc with a 11.5 to 1 compression head. I'm having a hard time find any info on a 902cc kit.

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Well, the magic no here is 920 so it might be that you or the PO simply got the numbers wrong. 920cc is what you get when you use an 81mm piston and probably all of the usual subjects offer(ed) this conversion. Exactly 902cc would mean and odd bore size in the region 80.3mm.


Tim

 

Y

Yetiman

Joined

Feb 27, 2011

Messages

31

• Mar 25, 2011

• #3

I kinda thought he had the numbers backwards, I even asked him twice and he still said 902cc. I had a feeling it was a odd number Thanks for the input

 

montelatici

Joined

Aug 26, 2009

Messages

280

• Mar 25, 2011

• #4

Why oh why? If you want to go faster than any Norton Commando will ever go, it is cheaper to buy a used 600cc Japanese sport bike.

 

Y

Yetiman

Joined

Feb 27, 2011

Messages

31

• Mar 25, 2011

• #5

Hey I just bought it that way. I've never owned a jap bike and i'm sure I never will

 

V

Vulin

Joined

May 17, 2009

Messages

170

• Mar 26, 2011

• #6

what part of SC PA? Im over in lancaster.

 

Y

Yetiman

Joined

Feb 27, 2011

Messages

31

• Mar 26, 2011

• #7

I'm in york city, right off 83

 

Hobot

Joined

Oct 19, 2005

Messages

18,978

• Mar 28, 2011

• #8

Why oh why? If you want to go faster than any Norton Commando will ever go, it is cheaper to buy a used 600cc Japanese sport bike.

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Because the delivery is so so much nicer on a big ole twin which can by pumped up easy enough to give them 600 4bangers a hard time till over 130 mph. The more leaning involved the more the moderns power don't matter.

 

M

myjota

Joined

Mar 15, 2010

Messages

115

• Mar 29, 2011

• #9

why not measure the combustion chamber size and multiply by say 10 (for 10:1 compression ratio cause I doubt 11.5:1 would be any good todays petrol) to get an approximation of each cylinder size then multiply by 2 to get capacity, then you should know what size the engine is.
902 should have 45.1cc in each @ 10:1 or 39.2cc @ 11.5:1
920 should have 46cc in each @ 10:1 or 40cc @ 11.5:1