Posts Tagged ‘cylinder removal’

This post is a continuation of this thread. 

Having removed the heads as described in this post we are ready to inspect the barrels and remove them if necessary.  Here too you can either roll the bike while in gear or use the started to roll the motor over so you can inspect the wall of the cylinders.  In my case I was surprised to find I could still see cross hatching from the honing stones!  Nice.  However, since I haven’t been in to this motor before I wanted to shake the rods and look at the piston skirts and flywheels.  So I decided to remove the cylinders regardless of the condition of the cylinder walls.

The front cylinder is different than the back and cannot be interchanged.  Typically the front jug casting number will be an even number while the rear is an odd number.  In my case these castings are 16568-78 in the front and 16587-78A in the rear.  The numbers not being of the same revision tells me that (at least) the rear cylinder has been blown up and replaced. 

Each cylinder is held in place with 4 base bolts and triangular base washers.  Roll the motor over until the pistons are bottom dead center.  Loosen and remove the nuts from each cylinder.  Carefully free the cylinder from the base.  Be sure that you don’t let the piston fall to the front or rear when it comes free from the cylinder.  I then roll the motor over to the point the piston on the front cylinder is being pulled down into the engine case.  I place a socket extension through the piston wrist pin and then very carefully roll the motor over until the extension is resting on the case’s base gasket surface.  This way when you pull up on the rear cylinder you will not accidentally pull the piston down risking damage to the piston.  Once secured, remove the rear cyclinder in the same manner as the front.

That’s pretty much got us to where it time to see the local machine shop to spec your cylinders and ring end gaps to see if you need to bore and replace pistons or not.  In my case I found what appears to be a brand new piston in the rear and one with only a small amount of carbon on the front.  All of the observations going to support my initial theory about this bike.  The winner blew it up, fixed it and sold it.  Cool so long as there is no hidden damage deeper inside.

With the guts exposed I got the check out the nice set of S&S rods and fly wheels making up the guts of my bike.  Examination of the serial numbers on the flywheels reveals a 4.5 inch stroke (2SL trailing in the serial number) making this baby a 93 incher as I suspected in the beginning.  I don’t have a tool for measuring the bore of the cylinder very accurately but I do see .090 on the rear piston.  .090?  Seems like a LOT over.  Can’t see what the front says due to carbon.  Definitely has to be accurately measured and put in balance it isn’t.

3/3/2010 update:  From what I can find on the net it seems that the pistons are S&S stroker pistons and they seem to be measured against a stock 74 c.i. cylinder.  When using the 74 as the baseline then an 80 c.i. cylinder is  already .060 over (according to S&S’s spec sheets.)  Therefore, my .090 pistons are really .030 over the stock 80 c.i. bore.  I like that a lot better than thinking my cylinders are bored to .090!

Now I know what’s in there and that the rods feel pretty damn good.  Machine shop here we come.