Author Topic: 90 cylinder swap on a 60?  (Read 1990 times)

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wardie

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90 cylinder swap on a 60?
« on: May 01, 2016, 07:17:27 PM »
If I purchased cylinder, base gasket, piston and rings plus head is it an easy swap to fit onto a 60 motor?

Looking to upgrade thought if I could swap a 90 top end that would the  easiest. Anyone can share factual info on this swap?

Offline mqtsteve

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Re: 90 cylinder swap on a 60?
« Reply #1 on: May 02, 2016, 07:17:00 AM »
Hey wardie,
I'm not sure, but I think the 60 and 90 have different cylinder stud patterns.  The 90 cylinder is bigger and has different studs.  Cylinder stud (p/n 2121-5000) and head stud (p/n 1126-5000).  I don't think it would be an easy swap?  Some other members may have a concrete answer?  Good luck! Steve
Steve S.
4/1966 BS90 Sport(o.i.), 5/1966 BS90 Sport(o.i.),
1965 BS90 Trail, 1965 BS90 Mountain

Offline slawsonb

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Re: 90 cylinder swap on a 60?
« Reply #2 on: May 02, 2016, 11:21:40 AM »
No experience here, but just  makes me wonder how the big end and crank bearings would stand up to the additional displacement (force)...If its even possible. ???
...bert

Offline disc_valve

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Re: 90 cylinder swap on a 60?
« Reply #3 on: May 03, 2016, 09:04:43 AM »
Sorry, Wardie, that swap is not on. The 60 Sport is a bored-out 50Sport, and the 50 Sport engine castings are all around 20% smaller in dimension that the 90 motor. The 90 cylinder spigot is too big to fit the  hole in the 60 crankcase, and the 90 Sport gudgeon pin is too large to fir in the 60 con rod.

Graham

 


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