Maintenance & Technical > KX500 Original
Fixing problems with new (old) bike. - Running
MeanGreenMachine:
Ok, I finally got some images of the work so far... Won't need 1000 words if I can just show you guys!
Bike torn down:
The Barrel:
Cracks in the usual places:
Peeling:
Piston. It doesn't look all that worn.
KIPS Parts, one valve is broken:
This part broke off, but continued to hold the valve to a degree
Scored a transmission from a 1991 from eBay:
Old shaft on the bottom for comparison
Close up of the galled section
ID of the new gear, the old one was galled badly on the edges
Output shaft looks ok, the output splines on the old one were trashed
It came with a 1/2-13 bolt in it, Permacoiled back down to 1/2-20.
Fumoto F101 drain valve installed. It's totally shielded by my skidplate, otherwise not a good idea. I intend to install it with Loctite red, and torqued firmly. Hopefully it stays.
I machined the cross slots for more complete oil drainage.
MeanGreenMachine:
A short video of the fit (if you could call it that) of the main bearing on the power take off side of the crank:
http://img825.imageshack.us/img825/738/ibfyjzxmcqiwvpmrhrzfpm.mp4
I plan to send it out to Crankworks, and have them build it back up, resize, rebuild/replace rod, and balance it. I'm going to use bearing retaining compound at least on the PTO side in hopes of this not happening again...
MeanGreenMachine:
Well, the cylinder and new Wiseco piston are out to US Chome. I'm gonna have the piston coated at the time time, as I'm a big fan of the black polymer coating when it comes to anti scuffing/seizing and (hopefully) taking up a little bit of that big clearance needed for this piston. Once it comes back, I gotta pack the piston back in a box with the crank this time, and get that sent out to Crankworks... In the meanwhile I'm trying to get everything else done.
This weekend, I used some classic, grade AAA s**tkicker engineering to make a soda blasting rig to clean the engine cases. Turns out it works quite well to clean the cases, and even better on the frame (right down to discovering more cracks the previous owner hid when he painted the frame... Ass): Uploaded with ImageShack.com
Uploaded with ImageShack.com
Uploaded with ImageShack.com
BTW The fine baking soda flows at too great a rate (at least with this gun) if you just drop the siphon hose in the box and go to town, so the valve was added to bypass some air to thin out the mix. You could go nuts with a pressurized feed system or something using air/vibration that fluidizes the mix of soda/air going to the gun, but I didn't have time. You still have to shake the container and/or stick a finger over/block the valve once in awhile to create a vacuum pulse to dislodge clumps, but it works well enough to get the job done if you're patient enough. Baking soda is available at Wal-Mart at 2 bucks per 4 lb box. It took 4 boxes to do the cases and the frame... Pretty cheap.
After blasting, I fixed and welded up the broken front exhaust mount (closest to where the pipe hooks up to the cylinder), re welded one of the foot pegs, and the rear gas tank bracket that had cracks. I'll give it another blast to clean/roughen, then paint the frame. I was going to powder coat, but figured that if more cracks develop, I can repair it as I go and simply repaint. I guess I'm going for a good practical, rideable bike, since I'm sure I have a few falls and get offs coning in my future!
MeanGreenMachine:
Ok guys, so I have the front half of the bike put back together and am basically waiting for my cylinder and piston to come back so I can ship the crank (with the piston) for rebuild/balance. I have a couple questions I wanted to ask.
I've cleaned and washed the rear swing arm carefully, and wasn't able to notice grittiness or slop on any of the pivot bearings by hand. Obviously, 60HP worth of 2 stroke insanity is going to beat on it much harder than I ever could. How do you know when your pivot bearings are going bad? Slop?
This is probably putting the cart before the horse, but I was also wondering about forks too. I was reading that the early years have blue colored front forks that can be revalved to work adequately. But after going over to OEM-Cycle, it looks like the 1990 bikes have a special size fork for this year only. Can these be revalved? Can 1991+ "blue" forks bolt in or do you need a later year triple clamp? Should I just ride it, and save up to install KX450F forks, triple clamps, and custom stem (I could make the stem if I knew the dimensions)?
Lastly, how worn is worn when it comes to your chain guides? The 2 rollers that bolt onto the frame look fine, no play, no roller wear, but the rubber chain guide that goes around the front of the swing arm has some grooves in it, and the aluminum and nylon guide in the rear looks halfway worn through...
The nylon sides of the chain guide a
MeanGreenMachine:
Finally got the cylinder back from US Chrome... Having done some boring/honing work on Nikasil cylinders myself, I can definitely say that they did a beautiful job welding up the cracks, plating, and honing it. They even welded up the worn exhaust spring loops for me as I had requested. I had the piston coated at the same time... It's not as beautifully masked and applied as a factory coated piston (has a couple drips on the crown and the bottom of the skirts) though it should get the job done fine anyways.
I ended up using the Motorrad freeze/heat/bearing retaining compound method to install the bearings into the cases today. I took all of the bearings out of the package, and carefully wiped the OD clean with solvent, placed them in zip lock bags, and put them in the freezer overnight. I installed the crank seals with a light smear of case sealant, and put the case halves in the oven at 275 and let sit until hot. I took each bearing out, wiped the OD with paper towel to remove frost, wiped quickly with a light smear of Loctite 609, then quickly installed in the bore by hand, being careful not to get it in the races, or let it run down into seals, etc. I had a panic moment when one bearing stuck in it's bore and was beginning to expand, but managed to place the old bearing over it, and using a socket, drive it into the bore with a couple good smacks.
The crank and piston are on the way to Crankworks... Once it's back, it'll be time to try the hot socket on bearing inner race/freeze the crank trick.
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