Topic: 67mm bore Moto-Archeology, Edit:removing rusted pistons.

[Don R]

  Hopefully I corrected my multiple errors in mm sizes.

 I deleted my first post and started over. This stuck and rusty motor had been covered outdoors for a bit before I got it, it matches a frame that I also have.
  I pulled the cylinder and noticed it was packed with silicone from the bottom indicating it has been re- sleeved.  The bore appears to be 66.5, the OD of the lower sleeve is 70mm, the wall thickness at the bottom of the sleeve appears to be 1.4 to 1.5 mm. The top case didn't need to be bored. I'm guessing it's a stepped sleeve like the 860 kit that CycleX sells.
  After an overnight soak in rust remover, three of the pistons pressed right out. No names in the pin relief area. They are soaking so the underside of the dome might reveal an Alcoa logo or whatever. The rods are RC modified stockers with smoothed beams. they are numbered for cylinder X1-X2, etc.  and say RC on every rod and cap.
  I believe this is the motor that had the really short valve springs with thick shims under them and is likely the source of the RC315 cam that my brother had. One of the retainers was perilously close to pulling a keeper through. 
  I'm soaking the cylinder again and cleaning everything, hoping the last piston comes out and the cylinder can be bored to a useful size. Due to the thin sleeve bottoms, that might not be likely.

[denward17]

Don, what will you have to do, put in new sleeves?

[Don R]

Don, what will you have to do, put in new sleeves?

 Possibly, for now I'll likely swap the entire guts from another engine into these cases and then decide what to do with the high-performance goodies. I've been threatening to do the 6 hour drive to CycleX with a trunk full of stuff.
 
 Edit: it's a Henry Abe 900 kit. I guess I need a better caliper or need to learn to use one.

[Don R]

 Dynoman has a 906 kit that's 67.5mm that is advertised as a clean-up size for the 890 motor. Does this sound right? .5mm is around .020" that would clean up an approx. .010" of rust, not a lot.

[Don R]

   After soaking overnight in vinegar and then again in Evaporust, I heated the entire cylinder with oxy/acetylene and couldn't get the piston to move using reasonable force and heat in the press. I used all of the usual penetrating oil products and beeswax last. After the heating and pressing didn't work I turned the cylinder over and tapped the bottom of the piston with a brass drift, accidentally causing the sleeve to start to come out. I figured good and removed it.
 Next, I planned to heat the sleeve directly in the press but after setting it up I gave the piston a push and it started moving down. (I think the beeswax worked).
  So, to answer my own question the OD of the sleeve is 74mm through the cylinder, The tail that hangs in the case is reduced to 70mm and the bore is 67mm.  If it isn't pitted too badly the Dynoman (edit) 67.5mm 906 kit should work. I'll clean it as good as I can and run the hone through it to further check it.

[grcamna2]

   After soaking overnight in vinegar and then again in Evaporust, I heated the entire cylinder with oxy/acetylene and couldn't get the piston to move using reasonable force and heat in the press. I used all of the usual penetrating oil products and beeswax last. After the heating and pressing didn't work I turned the cylinder over and tapped the bottom of the piston with a brass drift, accidentally causing the sleeve to start to come out. I figured good and removed it.
 Next, I planned to heat the sleeve directly in the press but after setting it up I gave the piston a push and it started moving down. (I think the beeswax worked).
  So, to answer my own question the OD of the sleeve is 74mm through the cylinder, The tail that hangs in the case is reduced to 70mm and the bore is 67mm.  If it isn't pitted too badly the Dynoman 70.5mm 906 kit should work. I'll clean it as good as I can and run the hone through it to further check it.

I hope the rust pitting inside the sleeves is minimal;do you know if a 'pointy' inside micrometer exists? 
 I ask because it could measure across the cylinder/s and sit inside the rust pits,to see just how much it would need to be bored-out.

[Don R]

  My local machine shops aren't on my favorite's list, one ruined a crankshaft and the other lost a set of rods for a VW my brother was building. I'll run my hone through it first just to see how it looks and get a professional opinion.

[Tracksnblades1]

   The tail that hangs in the case is reduced to 70mm and the bore is 67mm.  If it isn't pitted too badly the Dynoman 70.5mm 906 kit should work.

Is the 70mm ID or OD…?
How’s the 70.5mm going to work with the 70mmm?

I’m not visualizing something right….

[Don R]

  Thanks for catching that, I made an error, several actually. In spite of my early incorrect attempt at measuring the bore, the bore is 67, the dynoman piston set is 67.5. The OD of the sleeve is 74 in the cylinder and reduces to 70 at the bottom. Right now, the bottom of the sleeve is 1.4 to 1.5mm thick, the .5mm overbore would remove .25mm from the bottom of the sleeve.
  I was wondering how thick the sleeves are in the cylinder and hopeful the sleeves may be strong enough to be used with the reduced bottom and another bore job.
  I have another set of 72mm pistons and a cylinder that needs CycleX's expertise but honestly, it might be a better choice to just start on a new/old cylinder.
  A nice, slightly modified 81 gs1100e just fell into my lap for less than the cost of a big CC Honda motors parts and machine work, the only reason to build the 750 is because you love old Hondas.

[PeWe]

CycleX stepped sleeve is 74.2mm OD inside the cylinder.
EDIT: ID 64.0mm.

Good for 67.0 mm pistons 890cc.
67.5mm give thin sleeve into case but freqently used.

I have a cylinder with those sleeves, Dynoman 890cc pistons.
Sleeve/cylinder must be sealed. O-ring + sealer. My cylinder got Wurth black RTV only. Will hopefully stay oil weep free.

CycleX next step for sleeves, 74.5mm not stepped. Top case need to be milled.
EDIT: ID 69.0 mm
Perfect for 70 mm pistons, 970cc. My K6 has that.
Cylinder need to get a wider milled hole for sleeves at bottom for o-ring and sealer.
My shop milled a 1.25mm wide groove around sleeve, ca 6mm deep. (OD 77.0mm)

If not, oil weep thru the air vent 1-2, 3-4.

CycleX sold those 2 types of  sleeves for a good price a few years ago. $129US for a set of 4.
So I had to order both sets

[grcamna2]

The lower part of those sleeves are too thin.

[Don R]

  Good information thanks, I have early and late cylinders and new 812 and 836 wiseco piston sets that I nabbed cheap off of ebay. I was thinking of having some work done locally but the best bet is to go see Ken. He can make the best of what I have to work with.
  The lower part of these sleeves is as designed, I'd defer to the experts before proceeding.