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1100 heads on an 850 Breva or Griso.

Calijackalbob

Calijackalbob

Cruisin' Guzzisti
Joined
Aug 5, 2015
Messages
125
Location
Australia
I recently sold an 8V 1200 Griso and miss it so much I WANT TO REPLACE IT.

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I just found an 850 Griso for sale at a great price. I am sure I would be happy with it's 75 horsepower. 75 Horses is all my Bellagio had, and it was more than enough. (My Bella below, after a V7 style makeover.)

P 20180413 161348

I currently have a 750 Breva with a mere 55 horsepower. It is slow but tons of fun. I don't think an 850 would disappoint after owning the Bellagio or the Breva, but if can be upgraded, why not?
(My Breva below, after a V7 style makeover.)

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Anyway.... I have heard the only difference between the 850 and the 1100 is the heads. I would love to hear if anyone has turned their 850 Breva or Griso into an 1100 with a head swap. Was it worth it? Did it cost much? Did the gains in horsepower/speed justify the work/expense involved?

Looking forward to hearing from y'all.
Bob.
 
Bore and Stoke is different. As Steve said the stroke is shorter on the 850s . 1100s are 92 X 80mm and the 850s are 92 X 66mm so a head change won't have any impact.
 
Bore is the same as the 1100, stroke is shorter. The heads are the same except the inner spark plug hole is blocked off with a plug.
Stock I think you would notice the difference between an 850 and the Bellagio because of the single spark. It is a simple fix to add the second plug with the biggest challenge being mapping. Good fun when you're finished tho.
 
Apart from all the above in needing new heads, barrels and pistons, the crank balance will be thrown off also.
The 850 bottom end and 1100 heads and barrels setup on the Bellagio has a custom balance setup, and along with that the pumping ratio in the lower crankcase will be thrown off to hell resulting in the condenser being overwhelmed at high RPM.
Chris.
 
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