Bridgestone Motorcycle Parts Discussion Board

Bridgestone Tech Talk => How To => Topic started by: wardie on May 01, 2016, 07:17:27 PM

Title: 90 cylinder swap on a 60?
Post by: wardie 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?
Title: Re: 90 cylinder swap on a 60?
Post by: mqtsteve 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
Title: Re: 90 cylinder swap on a 60?
Post by: slawsonb 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
Title: Re: 90 cylinder swap on a 60?
Post by: disc_valve 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