Well, it looks like Ofreen will beat me! (Congrats, good job!).
I have 138,000 (and change) miles on my 750K2, which is 83,000 (and change) miles from 1980 when I took it down and bored it to .025mm oversize, replaced the cam chain and tensioner, and cleaned and lapped the valves. Around 1998 or so I installed a new set of fiber clutch plates, about 80k total miles on them at that time. In 2006 I took the top end off to hemi the head for an article I wrote here, hand-cleaned and lapped the valves, replaced the bottom cylinder gasket and therefore installed new .25mm rings on the pistons, and stuck them back in. At that time I also opened the bottom to Plastigage the bearings and found all to be .0022" or less, so just put it all back together as it was, with new gaskets and O-rings. That's all the 'rebuild' maintenance this 750 engine has ever seen, and it has NOT led an easy life under me.
Ofreen has over 140k on his bike! Way cool!
But, I don't wish to ride with an oily right leg this year, due to the hailstorm on July 14, 2011, which drove pea-sized hail at over 200 MPH into our city for about 14 minutes: the devastation was something to behold, and it even cracked the cam cover gasket on my engine when it packed ice stones 4" thick onto the fins (it was facing the storm's incoming path). Since I have to pull the engine to replace the gasket, I'm gonna revive my old buddy, too.
Will bring pix along: at this moment I have spent the first 2 hours to pull the engine out and remove the top end so I can take the cylinders in to have the fins welded back on (it broke 2 off on the same side as the oil leak). I have a set of nice 0.5mm pistons for it, but there is a .003" deep scratch in one cylinder, so I will have to go up to 0.75mm to ensure it will clean out. Drat: I really wanted to go thru all 4 "steps" with my engine. Oh, well...
Another wonderful member here found me a VERY young tranny from a K3 (6k miles), so I will miss the 3 extra Neutrals I now have once this is over: I kinda got used to selecting Neutral any time I wanted to...but I suppose all good things must end?
Terry from AUS sent me a cam that has so few miles on it that the Parkerizing is still there on the lobes: mine has lost .028" of lift on all 4 center lobes, and about .016" on the outer ones over these miles. Not a bad lifetime! So, it will get a new sprocket and chain (from the F2 engines) and some nice K4 rocker towers I found at a junkyard (16k miles), but with free-floating rocker shafts instead of the locked-down ones.
Two of the intake valves show some small leakage at higher engine speeds, but all 4 exhausts still show a perfect seal. Pix to come. That's just impressive, as the valves and guides are still OEM, and mine is a K1 engine with the pointy, seal-less Stellite exhaust guides (intakes are Stellite, too, but with the seals). After I measure the wear I'll post it here for posterity's sake.
At least I can say that my K2 bested my mentor's record: his K0 sandcast went 87k miles (although it was in just 5 years) before he rebuilt it - in 1974 (are you out there, Chambo?)
On hand are: new rod and crank bearings in the next size down, new tranny complete, new primary chains and tensioner, NOS Honda pistons in 0.75mm oversize (with 1-piece oil rings, like before), Honda piston pins, new steel clutch plates this time (maybe I'll get fiber ones, too), slightly used "410" cam chain from an F2 engine that died very young but stayed oily inside, new cam chain tensioner parts, new(er) rocker shafts (might make my own for this one, too), terrific cam with full New Factory K1 lift specs (7.8mm inlet), and about 4 different kinds of aluminum polishing compounds that I don't know how to use yet.
Also on the slate: will attempt to make some bronze fork sliders for the front forks, as mine are quite loose now. This chassis has the early-style forks, so these are a wear part and can be replaced, just can't be obtained now? I think it might be time for some new wheel bearings, as these were installed at about 60k miles and were never re-lubed since 1996. I found some sintered bronze-asbestos (take that, DC...) brake pucks that I'll use, and have a line on some similar rear shoes, if I can get them.
I might even finish the jig for my lathe and bore the ID on these Timken steering head bearing kits I bought in 2009, so I can install a set in mine again.
Will start with the pix tomorrow: the cylinders are already at the shop.
