2002 KDX/CR Hybrid build

[sixstringsteve]

Mike does top-notch work, and he really took his time to make sure everything was right.

As you can see, he does killer work:

Here are the new front motor mounts.

I learned a lot from him today. And now it's nice to know I've got a guy who can weld aluminum for me, and who can help me with any weird exhaust bends/cuts/welds that I may need. I highly recommend Mike for any aluminum welding needs you may have.

 

[sixstringsteve]

With it all in, I have about 1/4" clearance all around the head.

Motor installed. Finally.

Well, I met my goal of having the motor installed by the 4th of july. I realized that two of the nuts holding the head on are stripped, so I need to resolve that issue. Anyone have any ideas? Can i buy the studs and replace them?

I also lost all the needle bearings out of one of the rear susp linkages, so i need to order a new cage bearing. Then I should slowly start putting it all together.

 

[Rot Box]

First off Holy crap that looks good! That was nice of Mike to help--quality work that's for sure :greg: Looks like you'll have to remove the motor to do a topend, but that won't be too bad.

Second I would buy new nuts and/or studs through the dealer. I had a friend build a CR like my 84 for the Baja and he used parts store nuts. After one short ride they worked loose... They were flanged on the bottom like stock and torqued to spec. Really strange I know but I wouldn't take chances here :-\

I'm glued to the screen

 

[sixstringsteve]

I hope I don't have to remove the motor to do a top-end, it BARELY fits in there. I guess if I remove the head it'll come out easier.

I'll see if I can get some head studs in there soon. that'll set me back a few days, but I want to do it right. I also need some cage bearings for the rear suspension linkage, then it'll be back to playing tetris trying to make the pipe, radiator, tank, and rear shock all fit in there.

 

[MattL]

Rick lent me his 43/64ths drill bit today, and it worked out perfectly.

I got the swingarm bolt, swingarm, and rear motor mount installed. That's a milestone. I had to trim the swingarm bushing just a bit more. I'd guess I ended up with 45-46mm for each bushing.

I cant tell from the pictures, but what is the bushing made of? From pictures it doesnt look like there is much in there between the motor and the swing arm. What I am wondering is,or making sure of is that the pivot point is not metal on metal.

 

[sixstringsteve]

The bushing doesn't roate, it has a cage bearing around it, so the bushing stays put, and the swingarm rotates around the bushing. The bushings are wide enough to prevent the swingarm from contacting the motor.

It's the same setup as the CR.

 

[MattL]

Gotcha.

 

[jevyguy]

Very Cool. Subscribed!

 

[sixstringsteve]

I got the forks on at lunch today. I'm not sure how tight to get the spanner nut. It's snug, but not cheater-bar tight.

And I looked all over for the head studs, head nuts, and swingarm cage bearings, but nobody had 'em in stock. I figured I'd call RMEATVMV just to check, and sure enough, they had everything I needed. I never thought to call them for OEM parts. So i should have all my replacement parts here tomorrow. Then I can get crackin on putting it all back together.

I still need a chain and front sprocket, then I should be set.

 

[rholbrook]

Caleb is your friend for ALL parts.

 

[sixstringsteve]

I should always go to Caleb first, then work my way back from there if he can't get it.

 

[sixstringsteve]

Caleb is your friend for ALL parts.

I'm quickly learning this. Even though it was only 7 bolts, I should have gone through Caleb for 'em.

 

[Rot Box]

How did the head stay and linkage bearings look when you pulled them down? Besides the rear shock they are typically the most neglected part on a dirtbike

 

[sixstringsteve]

This bike was hardly ridden. I'd guess about 20 hours tops. I didn't take apart all the linkage bearings, but every single bearing I have touched has been bone dry. The headset is now lubed up nicely, and the rear swingarm bearings are nice and lubed. I'll have to re-pack the linkage bearings when I get to that step.

 

[sixstringsteve]

Didn't get a ton done tonight, but that's ok.

I got the front forks/bars mounted, and I pulled the head.

I have no clue how I'm going to get those 3 stripped head studs out. They're soaking in PB right now. I wonder if I'm going to have to weld some nuts to them and back 'em out with a wrench. Anyone have any great ideas?

The above pic shows a rough idea of where the c/s sprocket is in relation to the swingarm pivot bolt. I think it'll be fine.

I'm still unsure what to do about the radiators. THe CR radiators are about 130% bigger (1" taller and 1" wider) than the KDX rads. In order for the CR rads to clear the KDX head, they'll need to be raised 1/2".

Or I could go with the KDX radiator, which would simpler since I have more room to work with them. I'd just need to make mounts to bolt it up. I wonder how the plastics would line up with a smaller radiator.

I'm also toying with the idea of making some radiator supports/guards since they seem like the first thing to break when the bike goes down.

I test-fit the tank and it'll fit fine. The airbox looks good too, but I didn't have the subframe in. The exhaust looks like it'll be good as well.

 

[Rot Box]

I'm sure you did, but I thought I'd mention to tighten the large nut on the upper triple clamp before you tighten the fork pinch bolts. I've seen people do it vise versa and its not pretty

I overheated my old KDX once and cracked the jug $$$ I didn't feel like it should have had a problem given the circumstances, but it happened and it sucked. I'm sure stock radiators are fine, but if you can make it work I'd use the large radiators. Guards would be a great idea and not terribly difficult to make. Unfortunately the rads stick out like a sore thumb on the CR's :-\

It'll be interesting to see how the air boot designed for a case reed motor aligns with the cylinder reed motor's carburetor. If you run into trouble I've seen people use 97-01 air boots (these years had the aluminum frame and the reeds in the cylinder not in the engine case like the 02-07's) to better align with the carb. Does that make sense?

 

[Unimog]

I have no clue how I'm going to get those 3 stripped head studs out. They're soaking in PB right now. I wonder if I'm going to have to weld some nuts to them and back 'em out with a wrench. Anyone have any great ideas?

I didn't see what they look like, but I have a set of metric stud sockets you could borrow.

 

[sixstringsteve]

I'm sure you did, but I thought I'd mention to tighten the large nut on the upper triple clamp before you tighten the fork pinch bolts. I've seen people do it vise versa and its not pretty

Fortunately I did tighten that down prior to the pinch bolts. And I made sure each fork leg was raised the same amount. Thanks for the tip.

I overheated my old KDX once and cracked the jug $$$ I didn't feel like it should have had a problem given the circumstances, but it happened and it sucked. I'm sure stock radiators are fine, but if you can make it work I'd use the large radiators. Guards would be a great idea and not terribly difficult to make. Unfortunately the rads stick out like a sore thumb on the CR's :-\

How did you overheat it? I think you've convinced me to use the CR rads, but I'm going to have to have them modified so the flow is the same as the KDX, but I think it's going to be worth it in the long run. It's just going to suck if I break 'em, cuz I'll have to get each radiator custom built each time.

It'll be interesting to see how the air boot designed for a case reed motor aligns with the cylinder reed motor's carburetor. If you run into trouble I've seen people use 97-01 air boots (these years had the aluminum frame and the reeds in the cylinder not in the engine case like the 02-07's) to better align with the carb. Does that make sense?

I have no clue what a reed is or what a cage is, so this is all greek to me. I'm told that if I just make an adapter plate out of aluminum it should work, but who knows.

 

[Rot Box]

I have no clue what a reed is or what a cage is, so this is all greek to me. I'm told that if I just make an adapter plate out of aluminum it should work, but who knows.

If you look at the KDX motor the reeds/reed valve is an internal one way valve made of epoxy or carbon fiber "reeds" between the intake manifold (the rubber part that clamps to the front of the carb) and the cylinder. If you compare the CR125 motor with the KDX motor you'll see that the reeds bolt into the bottom end of the motor on the CR but on the KDX they bolt into the actual cylinder. There are several reasons for the different placement, often but not always a case reed motor will produce more topend horsepower where a cylinder reed motor will produce more bottom end power/torque. Either way a cylinder reed motor positions the carburetor higher than a case reed motor. If you're carb sits too high, and doesn't line up with the air filter boot there are options out there to make it work


Slow speed technical riding with a lot of RPM's is what made my KDX overheat. Again likely my fault, but more cooling the better on a trail bike.

 

[sixstringsteve]

I didn't see what they look like, but I have a set of metric stud sockets you could borrow.

Thanks for the offer unimog. I ordered new studs yesterday, I just need to pull my current studs out now, which is proving to be harder than I thought.