Top end question
- Thread starter Tocco
- Start date
If your cylinder is fine then ya you can just put a new piston in it but if its scored then you have to get it bored.
If you are going to change the piston and rings, you at least will need to have it honed. While it is apart it would be a good idea to have the cylinder checked to see if it is out of round at all before putting in a new piston.
The piston and rings need to match the bore of the cylinder. 66mm is stock bore. For what particular reason do you want it to be stock bore? If your cylinder is good you may just need a hone and either new piston and rings or just a hone and new rings, or maybe the next bore up depending on what condition the cylinder is in.. New sleeves can be pressed in as well which will bring you back to stock bore. that can get pricey though.. Stock bore 66mm cylinders can still be had.. at 77psi you definitely have something wrong with the top end. Have you pulled the cylinder off yet? You will in no way know what size piston you will need until you know whats up with the cylinder..
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i'll add...you cannot just look at the condition of the cylinder and see/tell if it's acceptable for just a new piston/rings of the same size.
it must be measured, preferrably by a professional, in multiple places for size and out of roundness to determine if it's ok for the same size, or will need a new over sized piston.
your chances, at 77psi compression, of not needing bored to the next size are slim at best.
it must be measured, preferrably by a professional, in multiple places for size and out of roundness to determine if it's ok for the same size, or will need a new over sized piston.
your chances, at 77psi compression, of not needing bored to the next size are slim at best.
Boring you cylinder wont hurt it, or give you any power gains.
Why dont you want to bore it? going .5mm will not affect anything but what piston goes in it
Why dont you want to bore it? going .5mm will not affect anything but what piston goes in it
