Wildgoose Chase Moto Guzzi

General Category => General Discussion => Topic started by: jacksonracingcomau on May 09, 2020, 08:06:17 AM

Title: 88mm barrel with 70mm stroke anyone?
Post by: jacksonracingcomau 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
Title: Re: 88mm barrel with 70mm stroke anyone?
Post by: Turin 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 (http://www.mgcycle.com/index.php?main_page=product_info&cPath=68_129&products_id=5307)
Title: Re: 88mm barrel with 70mm stroke anyone?
Post by: Roy gardner 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?
Title: Re: 88mm barrel with 70mm stroke anyone?
Post by: jacksonracingcomau 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
Title: Re: 88mm barrel with 70mm stroke anyone?
Post by: mtiberio 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.
Title: Re: 88mm barrel with 70mm stroke anyone?
Post by: 5154guzzi 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.