2002 3MB cylinder bore size.
-
So I measured the cylinder bore with a vernier calliper. (I know you need a bore gauge for accurate measuring) but i wanted a rough estimate to see if the previous owner oversized the bore so ik what piston kit size to order.
My measurements are from 55.63mm to 55.73mm but the std bore size for my year (2002 reg as a 2003) is 56mm should i order the 56mm kit or the 56.50mm kit and then have the cylinder bored to the piston size. -
All depends why reboring it, if the cylinder measures size you say then never been rebored. The cylinder on your year although called 56mm is actualy 55.95mm, if the cylinder is not damaged then just get it honed. If honing the cylinder then this piston is what you need.
https://www.ebay.co.uk/itm/Yamaha-DTR125-DT125-R-DTR-125-56-25mm-Bore-Namura-Piston-Kit/292513505226?hash=item441b29dfca:g:jyEAAOSwwbdWQwnAWhatever size piston you buy whoever is reboring it will bore and hone to match what piston you supply. The best reboring is done by Karl at KPM as had them do a
few and also by PJME. Karl charges £30 for a bore and hone with return postage at £10-16 postage depending on courier and insurance required.
He will also fully port your cylinder for £100, just have to tell him what your after like more midrange etc or more mid and topend like a YZ.
http://www.kpmotosolutions.com/
