Maintenance & Technical > KX500 Original
Fixing problems with new (old) bike. - Running
motopunk:
--- Quote from: MeanGreenMachine on September 21, 2013, 07:58:11 AM ---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
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the blue 43mm kayaba forks came in 91.. you have the 1990 41mm kayaba fork without rebound-adjusting, that were also used on the european 89 kx250 and 500s ...i think it could also be revalved , but you can update your bike with the blue 43mm forks or the later 46mm forks (97-2004) in any case you need the rigt clamps to the fork that you bolt in.
MeanGreenMachine:
While I'm playing the crankshaft rebuild waiting game, I've been doing some reading about rods... It looks like Hot Rods should be avoided? I looked around on Motosport.com and I don't think you can get the OEM rod anymore... What's my best choice? Vesrah? Pro-X (had a hard time finding one but think they may still be around)?
Crankworks is a Hot Rods distributor so I imagine I'll have to call and expressly insist on not using one if that's the case...
Motorrad:
--- Quote from: MeanGreenMachine on October 02, 2013, 02:13:56 PM ---While I'm playing the crankshaft rebuild waiting game, I've been doing some reading about rods... It looks like Hot Rods should be avoided? I looked around on Motosport.com and I don't think you can get the OEM rod anymore... What's my best choice? Vesrah? Pro-X (had a hard time finding one but think they may still be around)?
Crankworks is a Hot Rods distributor so I imagine I'll have to call and expressly insist on not using one if that's the case...
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can still get stock rods from Kawi. after oem.. id run vesrah....
avoid hotrods... seriously....
sandblaster:
--- Quote from: MeanGreenMachine on September 21, 2013, 07:58:11 AM ---How do you know when your pivot bearings are going bad? Slop?
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...
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Before I remove the swing arm assembly and shock from the frame, I put the bike on a stand and move the swing arm around.
If it is tight with no slop in any direction, then I disassemble and inspect each bearing.
If the bearing are smooth and not gritty and the inserts are shiny then I grease them up and go.
If I find any slop or gritty bearings or the bearings fall apart I replace everything..
On the rollers, if they aren't too worn and spin freely, just make sure that the surface isn't checked.
If the surface is smooth, run em.
Chain slider... as long as it's not allowing the chain to eat the front of the swing arm then it's usable... But if it's getting thin, I'd replace it to be safe.
Chain guide... as long as it's not allowing the chain to eat the mounting bolts then it's still usable... But if it's getting thin, I'd replace it to be safe.
MeanGreenMachine:
Well guys, after all the time, money, and painstaking work, it looks like I just trashed my shiny balanced, rebuilt crank. Look for a possible basket case for sale composed of all brand new unused top shelf parts for less than half of new cost...
I used the heat/freeze method, placing smoking hot sockets fresh out of the toaster oven on the bearings, but noticed that it wasn't really heating the bearing inner race up so I ended up assisting it with a heat gun until the bearings started to be a little hard to turn from the inner race expanding. I put sealant on one case half, grabbed the crank from the freezer, and wiped the journals with solvent, put a little bit of Loctite bearing retaining compound in there and after a quick reheat on the bearing with the heat gun, I dropped it in till it stopped.
It wasn't until I put the other half on that I noticed a slight gap. I gave the crank a smack with a rubber hammer, and started lightly tightening down the bolts. The crank was frozen and wouldn't turn. Closer inspection revealed that the crank didn't seat all the way down, and when I tightened the bolts, it bent the crank. I ended up pulling the ignition side case half back off, and noticed that the crank now has very visible runout after being bent. The crank is now bent beyond usefulness and frozen in the clutch side case half with no way to remove it short of pressing it out, which would undoubtedly destroy my nice new main bearings.
I really have to stop and decide on whether to just scrap the bike before I take anymore losses on this train wreck.
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