Author Topic: 88mm barrel with 70mm stroke anyone?  (Read 539 times)

Offline jacksonracingcomau

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88mm barrel with 70mm stroke anyone?
« on: May 09, 2020, 08:06:17 AM »
Specifically
Has anyone turned down nikasil barrels for short stroke crank?
88mm x 70mm is true 850cc, someone must have done this way back when

Online Turin

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Re: 88mm barrel with 70mm stroke anyone?
« Reply #1 on: May 09, 2020, 09:17:05 AM »
Someone has had to have installed a set of those big bore gilardonis on an ambassador or V7sport.

Other than the pushrod tunnel, wouldn't these work?
http://www.mgcycle.com/index.php?main_page=product_info&cPath=68_129&products_id=5307
2000 Quota 1100 es
1997 Daytona RS
1987 LeMans SE Dave's Cycle Racer
1974 850-T Sport
1969 A-series Ambassador
1996 Triumph Daytona 1200
1991 Ducati 907ie ( Paso )
1982 Alfa Romeo GTV6 Balocco SE 3.0

Offline Roy gardner

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Re: 88mm barrel with 70mm stroke anyone?
« Reply #2 on: May 09, 2020, 04:05:21 PM »
I have a pair of 88mm VW pistons which were once destined for use in a Guzzi motor. They are about 4.5mm too tall for a 78mm crank, they were used with 4 or 5mm spacers under the barrels. As pistons go, they are horrible,steel struts in them make them heavy and they have flat tops and wide rings.
Look into MGNOC Tips books, VW pistons were used in Guzzi's in the '70s. There may be some good quality racing VW pistons which would do the job?
MGNOC L112
1973  850 GT (sold 1979)
1974  160 Stornello (bought new 1978)
1972 V7 Sport, (bought 1979, still running strong)
1977 Convert (bought 2009)
1974  850T (ComposT, pawned to buy Vincent parts!
1985? LM 1000 (saved from a savage, has become hotrod Convert)

Offline jacksonracingcomau

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Re: 88mm barrel with 70mm stroke anyone?
« Reply #3 on: May 09, 2020, 08:26:56 PM »
Achieving with oe barrels sleeved with liner is one way but to use new kit Turin links to is obviously cheaper and nikasil better anyway. i have neither oe barrels nor pistons, missing when bike bought
Any early loopy’s (700 or 750 ) or 750 Tonti wiith gilardoni 88mm kits out there ?
Deck height/ squish setting is the real question, head gasket notsomuch

Wildgoose Chase Moto Guzzi

Re: 88mm barrel with 70mm stroke anyone?
« Reply #3 on: May 09, 2020, 08:26:56 PM »

Offline mtiberio

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Re: 88mm barrel with 70mm stroke anyone?
« Reply #4 on: May 10, 2020, 06:42:42 AM »
I had a race motor which I got from John Hoffman in Georgia. It was perhaps an old Reno Leoni motor. It had a short stroke V-7 Sport crank and some 88 or 89mm pistons. It ran quite well, lots of fun. Not the same power as my 90x78 motor, but was easier to ride.

Offline 5154guzzi

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Re: 88mm barrel with 70mm stroke anyone?
« Reply #5 on: May 10, 2020, 10:05:14 AM »
About 25 years ago I installed a pair of 88mm VW forged pistons in my V7 Sport, using a set of Ambo cylinders with cast sleeves.  They worked well enough, but the flat top piston lowered the dynamic compression too much with the Sport Cam , even with the increase in displacement.  No power gain,  the pistons need some dome.   I don't remember needing any spacers, the deck height was pretty spot on.  Someday, I`ll put the stock pistons back in along with nickisil plated cylinders.

 


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