2002 CR125 Build *Complete*

Good call, most seem to be pretty smooth now, with exception of the bigger countershaft bearing. I may need to give it a few taps to make sure it's fully seated.

@arvid
I don't quite have that much dry ice but I'm planning to heat the case with my heat gun, and put some dry ice in/on the bearing itself before getting at it with the bearing puller.

Thanks bud, you bet I've been watching your YZ as well!

This morning's plan worked out pretty well. Heated the case a bit and froze the bearing and pulled it with the rental tool.

Success! And recovery from my idiocy last night.



Luckily my eBay bearing worked here for the clutch lifter. Got it in by freezing it with the dry ice and using an 8mm Allen socket adapter as the guide and bearing driver. Drove it in with a 6" 3/8" drive extension.


Here's the end result witht he main and countershaft bearings in all the right places.



Crank is in!


Transmission is in!



Gaskets and all the seals are in!


Side note: if using the Wrench Rabbit engine rebuild kit, you'll get a spare set of water pump gaskets and oil/water seals. Was scratching my head trying to figure out why I had some duplicates. I also oiled up the transmission lightly just because it was so dry. I made sure to oil up the main bearings with my premix oil.

Driving the left crankcase on:


There's a bottom end folks:


Everything rotates quite smoothly so far. Engine is looking really fresh. I wire wheeled all the bolt heads for the engine case bolts, got rid of all the grim eon them especially toward the exhaust. I'll trim up the gaskets tomorrow and continue with the engine.

I bet it'll be a huge upgrade over the dog it was before.

Went to start putting in the rest of the components today and saw this.



I guess it's time to split the cases again and see what's going on.

Good thing I saved my cardboard drawing for the case bolts...almost threw it out yesterday.


I started getting the cases apart but noticed that the front wasn't coming up, even with mallet taps. So I re-oriented the splitter.



After that the back stopped coming up evenly but tapping with the mallet did it.


Of course this happened.


Hello darkness my old friend...


Yup, there's a gap alright.


Why won't you cooperate?

I actually gave it a couple good whacks with my hammer (and an aluminum block in between). No luck unfortunately, it sounded like it was going straight to metal.

It turns out that a washer that didn't belong had found its way onto the main shaft, and by sealing the crankcases together the main shaft had started to press the bearing out.



The weird thing is I was positive I checked this while assembling it the first time.


This was the (ghetto) setup. I didn't want to pull the crank back out. You can see that the bearing is now seated correctly.,


With that sorted out I threw everything back in and pulled the cases together.

This was my 'solution' for the torn gasket from earlier. I'm hoping it holds, I don't have time for a new gasket to come in.

Figured if I can't dazzle you guys with quantity, I can at least go for quality! I'm really going hard trying to finish the bike lately. I have an impending move to another state and should've had this done a while ago.

Found the spot where that washer from before was supposed to go!


I got to work on the rest of the parts that fit into the right crankcase cover.


I'm used to Yamaha's service manuals and I've got to say Honda's manuals are absolutely terrible in comparison. The level of detail, advice/notes, drawings, and photos they provide is just all around weak. This section took a little while to trace out, and I ended referencing Partzilla more than once. Torque specs are all over the place in the manual too.

One thing to note though that I couldn't figure out. The manual states to position the drum center in a gear other than neutral, but doesn't state how to tell. Anyone else here know? Everything went together, but I'm really not sure what position the pawls on the drum shifter should be. I'm hoping I have a working transmission at the end of all this!

Temporarily installed my clutch basket so I could tighten the primary drive gear bolt. I think some oil got in the cavity in the crankshaft because this was tough. Oil is generally incompressible...


So I guess I confirmed that the washer is aluminum. I couldn't get to the torque spec of 64Nm yet.


After a couple attempts of that, I ended up doing this. Hoping that the combination of the washer and the socket extension would prevent damage to either by sharing the load.


Finally got it tightened down to the spec. This is the aftermath.

Out with the old, in with the new.


Check this out. I always had a hard time starting off in 1st on this bike, it was super rough and jerked like crazy. I found out why during my teardown.


I first worked on getting out the starter gear. A couple taps with the socket/hammer combo didn't work, so i heated up the basket and it came right out. It's already partially out in this photo.


I then went and center punched the rivets on the clutch basket for the outer idler gear.


Drilled a small pilot first.


First one off successfully


Then went to the bigger bit on the rest. At this point I was noticing I wasn't totally centered.


So I opted to use the angle grinder instead. Made easy work of it.


This is what we're dealing with here.


Next up, installing the starter gear into the new basket. Hopefully tomorrow.

Tried to freeze the starter gear with liquid nitrogen to get it into the clutch basket without having to press it. It didn't seem to work due to some burrs on the edges of the teeth cut into the aluminum basket. I ended up putting it under the scope and lightly filing the edges down with a tiny file.

Pouring the nitrogen.


This is how it boils after something that's not -200C is put into it.


The end result.


I had the whole thing set up on a press, just in case.


Of course, even the frozen gear wouldn't drop right in after heating the basket.


So I ended up just using the press to get it in anyway.


Success


Got some shavings from the basket. Oh well.

Thanks!

I realized my previous post was missing some stuff.

The frozen gear:


The nitrogen boiling:
https://i.imgur.com/Ov1OS78.gifv

With the starter gear ready to go, I got going on the drive gear.

Nice and tight:


So I guess I can't peen the backside of the bolt as instructed.


So I did the bolt head!


I started getting my new clutch plates all nice and oiled.


Again, the largely inadequate Honda manual didn't cover this part well at all. I hope I timed the power valve and governor correctly.


Slowly getting the right crankcase cover on.


I used my old inner hub, it looked pretty good still.


Here's the whole thing so far.

New clutch plates, springs, and pressure plate are in.


Cleaned up the flyheel/stator from the rust and dust that was in them. Cleaned up the wire harness as well.


Also re-sanded and sort of polished the Honda logo on the clutch cover. From when it was sand blasted and painted the texture was pretty rough. You can't really tell from the photos but the logo looks a bit better.



The motor.



Literally have no idea if I did the ignition timing correctly. I don't have a strobe or a running motor to check.

Cleaned up the power valve assembly.


Got it back in the cylinder after scrubbing the whole cylinder with soapy water.


OEM size piston installed.


Ring end gap all good.


All installed and torqued down. The head was just put on as a dust cover temporarily.


This is Moto Tassinari's way of cutting the rubber tabs off the insulator. I put tape on the sealing interfaces in an attempt to protect them...which didn't work.



So after almost ruining the part, I ended up doing the other side with an xacto blade. I cleaned up both sides as well as I could, and lightly sanded the damage from the hacksaw.



Not sure how the sealing surface on my exhaust joint was this damaged, but I hand sanded it for 30 minutes or so and got here.



I also spent some time getting all the carbon deposits out of it with a dremel wire wheel attachment on my big drill.


This is my solution to Honda's crappy exhaust seal design. The smaller O-ring makes both fit nice and tight into the pipe ID.


All ready to go.



Hoping this is the last time I have to gut the bike (at least for a long time).

Motor's in.


Here's what one of the engine mount bolts looked like, and then my attempt cleaning it up.



Forgot that I ordered a 120 link chain.


Ignition cover on and clutch cable in.


Seriously it's the little things.



Full side pictures



I then had to temporarily put the plastics back on for the long weekend because I went out to visit family and wanted to clear up space in the garage. It's looking pretty good!

Started doing work on the carb I bought off eBay. It's a 38mm Keihin PWK Air Striker off a 1999 CR250. It came with a 5.5 slide, 42 pilot, 190 main and R13 needle. I read a couple forums all over the internet for some jetting recommendations, but unfortunately I think I've got too many different mods to really know what the perfect jetting would be right off the bat.


A really good resource is Motocross Hideout though unfortunately its linked photos don't seem to work anymore.

Fortunately Keihin stuck to the same jetting architecture and I was able to use some spare jets I had from my FCR carb on my 250F as a starting point. Can you tell which ones were used?


Since I didn't have an R14 needle on hand as the link recommends, I went down to the 4th clip to make it richer. I'm assuming R13 is leaner than R14 but really have no idea. It'll be a good amount of trial and error. I went to a 48 pilot and 178 main as well.


I polished up the slide, just for fun.


I'm still waiting for my easy adjust idle and air mixture screws to come in from the UK. Unfortunately I ran out of the nice new vent hose and had to re-use one of the old ones. A little more bling on the way!


The 38mm carb is a tight fit in the 36mm insulator but not all that bad really.



I decided to route the vent hoses differently than the original setup to try and clean up the setup as well as minimize the length. I'm not sure yet how I feel about the polished case saver. I'm torn between leaving it as is to match the polished pipe on the other side or grit blasting it to give it a nice matte finish.


It's definitely a tight fit with the shock spring right there.


I thought I had a bad radiator hose set, and one of the ones given to me was too short.


It turned out I needed to swap locations with the one going between the radiators at the bottom. That was still pretty short for the job but it worked.


You can also see all the electronics are wired in and the kick starter is installed.

I cleaned up the top engine mounts with some maroon scotch brite.

Appreciate the concerns here, note that I've been working to finish this build ASAP due to an impending move to another state and don't have time to wait for parts any longer at the moment. RTV itself is designed to form a seal, and in the case of that gasket should hold up just as well as Yamabond does on their case interfaces. I haven't noticed any leakage yet.

The insulator issue was just caused by me following Moto Tassinari's recommendations on how to saw the rubber tabs off. Rest assured I'm planning on getting a new one and re-cutting it after I'm done with the final build photos.

I got the full wrench rabbit rebuild kit last year when I was sourcing parts. It was an economical solution to having all the new parts I needed in one package, and I had been watching a lot of Jay Clark's builds where he uses Hot Rods and this kit in general. I figured if it worked for them it'll work for me. Fortunately I'm not the fastest rider so I don't really abuse my motors or rev them out all that much. I'd like to think it'll last.

The gear jammer, as in, jamming an aluminum washer in the gears, is the recommended method I've seen from lots of how-tos.

Hope this helps with the concerns and doesn't discourage you about the build too much!

Thanks man! Hard to get a read on this thread since nobody really comments.

I had to put a washer under one of the bolts that mounts the rear brake master cylinder, tightening it (just finger tight) was unfortunately cracking the guard a bit.


Kind of hard to see, but I noticed when putting the pipe on that it was hitting this non-OEM bolt I was using on the power valve cover. I was able to find one that was much lower profile luckily. Don't know where the OEM philips bolt went, or if I ever had it.


Bike is nearly done except for some final touches now.



I'd like to take the plastic off the tires and really get a good look at the bike, but I'm planning on taking some proper photos in some nice scenery with the DSLR in about 2 weeks so it'll have to wait. Hoping to actually start the bike this weekend and get a short video.

I got some quick daytime shots in today. With a couple minor things left to come in the mail, I'm getting closer to getting the proper photos.

I was able to make the gas tank cover fit after opening up the mounting holes.


Some temporary detail shots. The bike sat for so long I need to clean up the dust and some graphics residue before I take the real photos.









Full bike shots. Sorry about the sun in one of the pictures, I didn't notice it until I copied the photos to my computer.

My quick adjust screws for the carb came in super fast from the UK. Looks like the idle adjust will be harder to use than expected, it interferes with my fuel line.


Also got the adhesive velcro as @ledger recommended. Hoping this thing sticks!


I spent a little more time this weekend cleaning up the cables and zip ties. I'm waiting on a front disc guard to come in the mail - hopefully next week. For some reason I always feel like Hondas should have disc guards, looks weird without.

Thanks for the comments guys! I'm pretty happy with how it turned out. I got my new hour meter in (gotta be at 0.0 hours of course). The disc cover was missing the mounting hardware so that should be in tomorrow.

In the meantime, here's a short clip of me starting the bike. I was pretty nervous going into it but luckily it seemed to run ok for a bit. My neighbors would get cranky if I ran it for too long so I'll have to bring it to a more secluded area to run it for longer and seat the rings.

I'm thinking the smokey exhaust is just because it was cold and I had a lot of premix oil all over the piston/crank/cylinder that needs to be exhausted. I'm not thinking one of the seals is bad/off...yet.