reepicheep
Member
- Apr 3, 2009
- 670
- 2
Well, my 11 year old has pretty much outgrown the KX-60, not so much because of the bike, but because of it's wheels. We ride woods at Big Rock near Maysville KY, and that 14 inch front wheel on the 60 is just killing him on long rocky hill climbs.
I found an advertised 1999 KX-80 (which from the VIN is actually a 1998-KX80) with a bad crank and top end issues (had some new parts with the bike). That gives a nice upgrade over the KX-60, disc front and back brakes, KIPS valve, a carb with an air mixture screw (finally!), upside down front forks, 17" front wheel, looks like a really nice bit of kit.
I got it for $400... cheap, but it needs crank for sure, and likely top end work, and had no title (just bill of sale). So probably a pretty fair deal for both me and the seller at the end of the day. I kinda wanted a project bike to rebuild with the kid anyway... I want him to be the one kid on the planet when his generation grows up that won't go all wobbly kneed at the thought of fixing something.
So now the fun part begins... rebuilding my own broken stuff stinks, but buying other peoples broken stuff cheap and fixing it makes me feel great for some reason. Not rational I know, but as hobbies go, it's a pretty cheap one. :)
First, the crank. I'm seeing some great looking Wiseco crank kits on ebay for $130 or so. Stupid cheap (IMHO), as it comes with a new crank and complete bottom end bearing and seal kit. So that's kind of a no brainer, unless somebody here knows something I don't. Anbody have any experience with these?
Now the trickier question. The bike was probably bought new in 1999, ridden for two years, then the piston (predictably to everyone but the original owner) let go. That first owner then let the bike sit for... just about forever, then traded it to the second owner for a mountain bike.
Since the thing sat for so long, and probably because the second owner didn't split the cases and de-shrapnel everything, the crank was toast. Sticking in spots, excessive up and down play, and excessive side play.
Unfortunately, he dropped $100 (or whatever) on a brand new .020 over wiseco piston, and just slapped it in there. The second owner also said they had the bore replated. They put it together, ran it briefly (it would not stay running), and came to terms with the state of their crank. Then they parked it until I bought it.
So here I sit with the slightly damaged top end. There is scoring on the cylinder that you can just barely feel with a fingernail, but it starts pretty low... maybe 80% of the way down before you get to the ports in the cylinder wall.
The piston has some light damage. The skirt is lightly scuffed (from the bad crank no doubt), there is a little chip on the crown (not bad, maybe a quarter way down to the ring), and one end of the wrist pin hole looks like it was flared out a bit by some sort of impact (maybe the wrist pin came out and got jammed on a port or something).
They dropped the $100 for that Wiseco and $whatever for the plating, so I'm not out anything. But I have that piston and cylinder.
So I have two choices at this point...
1) Do the new bottom end, put the existing "slightly abused" piston in the existing "slightly abused" cylinder, run it for a few hours, then tear it down and see how it looks. Obviously, tearing down the top end on a KX-80 to check it is laughably easy. In fact I might even make the 11 year old do it while I observe silently. So that "extra work" is almost a plus.
2) Take the head and cylinder and ship it to Eric Gorr and let him do the magic he did on my KDX-200 (now 225). So for $400, it gets bored to a 100cc, nicisil plated, and comes back with new piston and piston parts. But try and use the stock 80 carb and exhaust but rejet appropriately to make it decent in the woods.
3) Take the head and cylinder and ship it to Eric Gorr and let him do the magic he did on my KDX-200 (now 225). So for $400, it gets bored to a 100cc, nicisil plated, and comes back with new piston and piston parts. Then buy new carb and exhaust parts to match the new 100cc motor.
Were it just option 2, I'd ship it to Eric tomorrow. A KX-80 chassis with a 100cc big bore kit with a low end or "mo-betta" porting would be a killer woods bike for a talented 11 year old rider. The kids woods bike (KDX) Kawasaki never built. :(
My only concern that makes me think I would end up at #3 is that the increased displacement would start some sort of financial death spiral. If I go to the 100cc cylinder, do I then need the new bigger carb? And do I need the new exhaust? It has a stock pipe on it now, which includes a nice beefy header and nice aluminum silencer, so I wouldn't mind sticking with that. Unless it's stupid loud, in which case I'll need an FMF regardless.
At the end of the day, a $400 bike with a $400 top end and a $125 bottom end and $100 in carb and $200 in pipe isn't a horrible deal for a really well dialed in woods bike (under $1300). And that's worst case.
But even better would be a $400 bike with a $125 crank and everything else using "parts on hand". The 60 had enough power for Jack already, so an 80 with a Kips valve and a carb I can actually dial in (air fuel screw) is plenty for the next 3 years at least.
And maybe the best is a $400 bike with a $400 top end and $125 crank, but still stock carb and exhaust. $925 for a great woods bike with stupid good midrange, even if peak HP isn't quite what would be achievable with the finely tuned 100cc carb and exhaust.
Any thoughts and experience from people that have been down this road?
I found an advertised 1999 KX-80 (which from the VIN is actually a 1998-KX80) with a bad crank and top end issues (had some new parts with the bike). That gives a nice upgrade over the KX-60, disc front and back brakes, KIPS valve, a carb with an air mixture screw (finally!), upside down front forks, 17" front wheel, looks like a really nice bit of kit.
I got it for $400... cheap, but it needs crank for sure, and likely top end work, and had no title (just bill of sale). So probably a pretty fair deal for both me and the seller at the end of the day. I kinda wanted a project bike to rebuild with the kid anyway... I want him to be the one kid on the planet when his generation grows up that won't go all wobbly kneed at the thought of fixing something.
So now the fun part begins... rebuilding my own broken stuff stinks, but buying other peoples broken stuff cheap and fixing it makes me feel great for some reason. Not rational I know, but as hobbies go, it's a pretty cheap one. :)
First, the crank. I'm seeing some great looking Wiseco crank kits on ebay for $130 or so. Stupid cheap (IMHO), as it comes with a new crank and complete bottom end bearing and seal kit. So that's kind of a no brainer, unless somebody here knows something I don't. Anbody have any experience with these?
Now the trickier question. The bike was probably bought new in 1999, ridden for two years, then the piston (predictably to everyone but the original owner) let go. That first owner then let the bike sit for... just about forever, then traded it to the second owner for a mountain bike.
Since the thing sat for so long, and probably because the second owner didn't split the cases and de-shrapnel everything, the crank was toast. Sticking in spots, excessive up and down play, and excessive side play.
Unfortunately, he dropped $100 (or whatever) on a brand new .020 over wiseco piston, and just slapped it in there. The second owner also said they had the bore replated. They put it together, ran it briefly (it would not stay running), and came to terms with the state of their crank. Then they parked it until I bought it.
So here I sit with the slightly damaged top end. There is scoring on the cylinder that you can just barely feel with a fingernail, but it starts pretty low... maybe 80% of the way down before you get to the ports in the cylinder wall.
The piston has some light damage. The skirt is lightly scuffed (from the bad crank no doubt), there is a little chip on the crown (not bad, maybe a quarter way down to the ring), and one end of the wrist pin hole looks like it was flared out a bit by some sort of impact (maybe the wrist pin came out and got jammed on a port or something).
They dropped the $100 for that Wiseco and $whatever for the plating, so I'm not out anything. But I have that piston and cylinder.
So I have two choices at this point...
1) Do the new bottom end, put the existing "slightly abused" piston in the existing "slightly abused" cylinder, run it for a few hours, then tear it down and see how it looks. Obviously, tearing down the top end on a KX-80 to check it is laughably easy. In fact I might even make the 11 year old do it while I observe silently. So that "extra work" is almost a plus.
2) Take the head and cylinder and ship it to Eric Gorr and let him do the magic he did on my KDX-200 (now 225). So for $400, it gets bored to a 100cc, nicisil plated, and comes back with new piston and piston parts. But try and use the stock 80 carb and exhaust but rejet appropriately to make it decent in the woods.
3) Take the head and cylinder and ship it to Eric Gorr and let him do the magic he did on my KDX-200 (now 225). So for $400, it gets bored to a 100cc, nicisil plated, and comes back with new piston and piston parts. Then buy new carb and exhaust parts to match the new 100cc motor.
Were it just option 2, I'd ship it to Eric tomorrow. A KX-80 chassis with a 100cc big bore kit with a low end or "mo-betta" porting would be a killer woods bike for a talented 11 year old rider. The kids woods bike (KDX) Kawasaki never built. :(
My only concern that makes me think I would end up at #3 is that the increased displacement would start some sort of financial death spiral. If I go to the 100cc cylinder, do I then need the new bigger carb? And do I need the new exhaust? It has a stock pipe on it now, which includes a nice beefy header and nice aluminum silencer, so I wouldn't mind sticking with that. Unless it's stupid loud, in which case I'll need an FMF regardless.
At the end of the day, a $400 bike with a $400 top end and a $125 bottom end and $100 in carb and $200 in pipe isn't a horrible deal for a really well dialed in woods bike (under $1300). And that's worst case.
But even better would be a $400 bike with a $125 crank and everything else using "parts on hand". The 60 had enough power for Jack already, so an 80 with a Kips valve and a carb I can actually dial in (air fuel screw) is plenty for the next 3 years at least.
And maybe the best is a $400 bike with a $400 top end and $125 crank, but still stock carb and exhaust. $925 for a great woods bike with stupid good midrange, even if peak HP isn't quite what would be achievable with the finely tuned 100cc carb and exhaust.
Any thoughts and experience from people that have been down this road?