blood and oil mix surprisingly well

my track bike is getting a little lovin'. she's a 2001 GSX-R750 with almost exactly 25,000 miles on her. the last 2500 have been exclusively at above 8000rpm. i'm careful to change the oil frequently, and i diligently warm her up before hitting the tarmac WFO, but she's been smoking a little bit, and maybe feeling a little tired in the top gears, pushing the air aside at over 150mph. since i bought a compression tester to troubleshoot my friend Joel's Yamaha R6, i figured it would be wise to check mine, as well. a healthy sportbike engine should push 170-180psi. my old girl could only manage 110. time for a teardown!

since i was into the transmission last spring (um, twice...), it was a matter of maybe thirty minutes to drop the engine out of the frame, and get it on the bench. (i had popped off the valve cover to check clearances.) i am fortunate to have a clean, well lit, heated space to do the work in. that won't keep me from putting barriers to efficiency in my own way, though!

this thing has got to come down to its very core, as low compression indicates piston ring wear. the pistons are pretty much in the dead center of the mass pictured here.

i love to take shit apart! i'm of the school that logically unbolts components, keeping fasteners together but avoiding anything so time-consuming as bagging & labeling. when i was younger, i would throw all the bolts into a single box, and then would just depend on quick wits and common sense to ascertain where they should go during reassembly. i'm not so carefree these days, but i don't really have the patience for baggies.

pull the cam chain tensioner, cams & cylinder head. pull clutch cover, clutch assembly, starter cover, starter, starter clutch & idle gear, cam chain guides, cam chain drive sprocket & cam chain. spin it around & pull the stator cover & stator, as well as the water pump. flip the lump over & pull the oil pan. let oil drain in this pan, conveniently placed such that i will drop one or more bolts in 3 inches of oil. because i am an idiot. and Murphy is one of my dearest friends.

in the matter of another 45 minutes or so (disassembly is a false indicator of how quickly i'll be able to get this thing back together), the engine is down to the cases, ready for the heavy artillery. at this point, the "lower third" of the case has to come off for removal of the transmission. there are six allen head bolts with fairly high torque that need to be removed from the area behind the cylinders. none of them are very accessible, and the motor wants to spin around the torque applied in the amount necessary to break the bolts loose. this is a surefire recipe for some amount of body fluid leakage. i'll use one elbow to prevent counter-rotation while using two hands on a ratchet with allen-head socket, and five of the six bolts break loose at around 35-40 ft-lbs, in a nice, controlled manner.

the sixth bolt is a bit more stubborn, so the motor is trying to lift off the bench in addition to spinning, so i clamp it down to the bench with my other elbow, and then around 50 or 60 ft-lbs, this bolt goes CRACK! and suddenly spins free, but the sudden force reversal pops the ratchet mechanism into a neutral state, and the side of my thumb impacts the machined mounting surface at a few hundred feet per second. the damage is fairly minor, and as i already implied, somewhat expected. it still smarts, and i chew off the rolled up bit of epidermis before the anesthetic adrenaline burst wears off.

 i tried a couple band-aids, but they don't stick to oil & it's a funny spot to try to keep a band-aid on for any length of time anyway. lucky for me i'm a good clotter. a few moments of direct pressure & i'm back to business. oh, but look! during my fumbling with the sixth fastener, i must have jostled the cardboard enough to knock the timing chain off the bench. and wouldja look where it landed! it was while cleaning this up with my dominant left hand that i noticed the oil & blood mixing. the blood seemed rather oleophilic, to tell the truth; as if, had i mixed it thoroughly, it may have catalyzed into some new type of epoxy or perhaps some previously undiscovered biofuel...

anyway, flip the lump back over & remove the dozen or so smaller bolts from the other side (of varying lengths, but i'm fairly certain i can figure out where they go back using my superior cognitive powers). use a soft-faced hammer to pop the lower case off, set it to one side. pull out the transmission input and output shafts, complete, since i already fixed them, and lay them in a clean plastic bin together. next, remove the eleven 6mm bolts from the crankcase halves, and then the ten 8mm bolts that comprise the main bearing web. these are also very tight, so i manage to scuff the back of my right hand while further juggling the lump during this operation.

tap, tap, tap again with the soft hammer, and there we go! cases are split, and the crank is ready for the final step in disassembly - the connecting rod big ends. find the right tool for this - a "twelve point" 10mm socket, as specified in the manual. i suppose if one doesn't know what this is, or can't figure it out by looking at the star-shaped bolt heads, he has no business disassembling an engine to this point.

these bolts are also very tight, but i'm able to at least push the wrench handle thru the axis of rotation & minimize the squirming. what's left hasn't got very much mass to resist my application of torque, so it takes patience & a well-considered initial lever position to ease the process. once the bolts are loose & nearly out, a little tapping disengages the bearing caps, and the pistons slide down (up) to the bottom (top) of their respective bores. lift out the crank & set it aside after checking the bearing journals for unusual wear.

it's amazing how small the power-producing core of this engine is. it is not any longer than my forearm, and weighs maybe 30 lbs with the considerable mass of the crank, yet is capable of producing 120-ish horsepower in stock tune. i notice some normal 25k wear on the rod bearings, as well as the two main bearings on the cam-chain end of the crank. i need to order rod bearings, crank main bearings, piston rings, a new cam chain, and a gasket kit, including a new head gasket with ~.020" tighter squish - about $500 worth of parts - to put the old girl back together. it amounts to about two cents per mile, to restore this engine to better than factory spec.

down to parts in under two hours. i so get off on this stuff.