Engine

Engine Rebuild #9 (Piston Ring Installation)

Ok, now we’re installing the five piston rings on the JE pistons that are part of the 836cc upgrade kit.  Again, instead of going to the 3rd over (.75 cm) above the factor setting piston, I upgraded to 836cc.  I had to bore the cylinders and buy new pistons anyway, so it made sense to just increase the power when everything was open.  Also, the quality of these and the Wiesco pistons looked far superior than the ones available on Ebay that are the same size.  CB750 Supply has some kits available if you don’t want to go to the larger bore pistons.   Another great option seems to be the thermally coated ones from CycleX.  To save some money and get more performance, I went with the Stage 1 Kit from Dynoman.  Highly recommend them for their customer service and quality.

When getting started, you’ll first have to determine what sides of the pistons are the front and which are the back.  The  larger valve (intake) will match with the largest cut out at the top of the pistons.  There are two pistons whose smaller cut out (exhaust) tilt left and two that till right.  Use the head as a guide to match the offsets with he correct pistons.  When you look at the pistons from back to front, there should be two inward facing triangles if you use the exhaust cut outs as lines.  I explain it here in the video:

For the JE pistons (part number 144539), there are five rings (in order from top to bottom):

  • Upper Compression Ring
  • Lower Compression Ring
  • Upper Oil Ring
  • Oil Ring Spacer
  • Lower Oil Ring

Start from the bottom and work your way to the top.  Match the ring gaps per the instructions that come in the kit.  This will maintain the best compression as you use the motorcycle.

Ok, next step is to install the pistons onto the motorcycle and keep the upper end build up going.

UPDATE:

Found this on the Dynoman website.  Complete instructions for the JE 836cc pistons.  Would have been great to find this prior to working on these.  Luckily I figured most of it out.  I don’t know why Dynoman doesn’t just print one of these out and throw them into the kit.

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