Advice on an RD 250 build

[sprouty115]

A little more progress today -

- Pistons, gaskets, seals and a bolt kit (for the cases - they were a mess!) all on order. Shopped around a little, got bored of trying to juggle the numbers in a spreadsheet six different ways and just ended up splitting the order between HVC Cycle and Economy Cycle.

- Pulled the gear shafts out and started to pull the forks and drum but it looks like there are no seals to worry about in those so I stopped.



- Cleaned up everything. All looked good, even the neutral switch assembly.



- Trying to sort out how to de-grease/clean the cases. Went to the auto-parts store but everything looked pretty toxic so I bought some Simple Green. But...the truth is, it doesn't really cut it for something like this. Need to do some further investigating. If anyone has any suggestions, I'll take them.

Also need a few miscellaneous screws in either cap or Phillips head. Will have to find an online source that sells in small quantities.

[anonny]

Simple Green with scotchbrights should get the cases pretty spanky.

[markjenn]

Soda blasting seems to be the way the professionals do it, but you'd need to find a professional. If you do go with media blasting, you want to use something that will clean off completely. I've heard ultrasound in a solvent bath is great, but I've never found anybody with the equipment near me. Most of us use the shade-tree approach of an escalating series of solvents/cleaners (Simple Green is pretty low on this scale) and various abrasive pads like scotchbrite. Work hard enough and you can do a reasonable job and what's left typically looks good as patina. I've heard using steel wool on alum is considered a no-no, but it works great on steel parts.

- Mark

[sprouty115]

Thanks guys, I think you're right, I'll give it another go with the Simple Green. Now that I know I don't have to pull out the drum and shift forks I really don't want any abrasive material getting in there.

BTW, heard back from Lyn at Vintage Specialties - the crank is junk. It was so far out that he couldn't even get it close. Fortunately he has a rebuilt unit already to go. So for the regular cost of the rebuild plus a core fee it should be on it's way back to me shortly.

Also was doing some more reading on different forums of rebuilds trying figure out all the little tricks that don't show up in the Hayne's manual. It's seems like a pretty simple engine but like everything, you need to be organized and not tear into it blindly, e.g. I'm really glad I didn't attempt to diasassemble the oil pump before I did some poking around!

[markjenn]

Originally Posted by sp115

Thanks guys, I think you're right, I'll give it another go with the Simple Green.

I'd definitely feel free to escalate to a good industrial de-greaser.

- Mark

[sprouty115]

Yeah, after an hour with the Simple Green I gave up. Ten minutes with auto engine degreaser and I was nearly done.
Of course once I started cleaning I couldn't stop so I ended up pulling the shift forks and drum.




And of course once I cleaned all the sludge and residue I got to a better look at the bottom of the crankcase just below the counterbalance/webs.
Looks like grenade went off in there at some point...




Tonight I'll clean the top case and then dry assemble it. Then I'll see what I get for the bearing journal diameters.

I also did a little more research and found out that those little indentations aren't supposed to be in the journals. I assumed they were when I first pulled it apart, but in actuality the "pips" on the bearings are supposed to sit in the machined openings in the front where the cases meet. Thank god for the interwebs.

You know it's funny, but as you work on a bike this old you can't help but wonder about what kind of life it had. Everytime you take a part off and clean it and inspect it you learn a little more about it and the people who owned it. And in that respect this bike seems pretty unusual. Because it seems like most everything is in one of two conditions: either perfectly functional but with a a little bit of dirt and grime or completely beat to shit by abuse and lack of mechanical skills.

Truthfully if I didn't have such a soft-spot for these bikes, and if the rest of the bike was in the typical rusted-mess condition they are usually in, I'd have passed it on or parted it. Unfortunately(?) the more I dig in the more I'm enjoying it and I really want to see this looking good again.

[sprouty115]

Got my new "rotor" and stator today:

My stuff on the left, new stuff on the right...




It looks like the seller sent me the electrical system for an RD200. It don't believe they are interchangeable. He sounded like a OK guy, so I don't expect an issue, but it is sort of a pain in the ass.

[stainlesscycle]

Originally Posted by sp115

Got my new "rotor" and stator today:
ight="598" alt="Rotors 1">

It looks like the seller sent me the electrical system for an RD200. It don't believe they are interchangeable. He sounded like a OK guy, so I don't expect an issue, but it is sort of a pain in the ass.

yeah it's an electric start setup - you don't want it.

[sprouty115]

Pretty much done with the disassembly. The only issue I had was one stripped screw on the tach-drive retaining plate. Unfortunately as I was trying to get it out the tip of the impact driver bit cracked into a bunch of small pieces which left me with a stripped head and a bunch of hardened tool steel embedded in it. I took my time with a carbide bit and eventually got the screw out, but I decided the next day I didn't like the look of the remaining thread. So I made up a jig and put a Helicoil in. Much better and probably even stronger.


Helicoil

The cylinders are out being done, but other than that parts are rolling in.

- Gaskets, seals, bolts, and the oil pump rebuilding kit, are all in
- The crank is on it's way back.
- I have a new rotor coming.

The only thing left to order is a clutch holding tool, fuel, oil, and oil-tank hose.

One thing i did the other night was take apart and clean and inspect the reed cages. Every thing looked dirty but OK. Then I noticed one set of reeds was slightly raised off the cage. Doesn't look normal, so I need to pull it off and flip it over to see if it's the reeds or the reed block.


Reeds

[sprouty115]

Crank is in along with a very clean rotor, courtesy of Lyn Garland at Vintage Specialties.

Delivered with a smile by the mailman..

New crank and rotor

[stainlesscycle]

Originally Posted by sp115

Doesn't look normal, so I need to pull it off and flip it over to see if it's the reeds or the reed block.

shouldn't be the reed block. flip em over and see if they seal.

[sprouty115]

Yup, got up early this morning, flipped the reeds over and everything is sitting flat. Can't wait for the weekend to start some assembly!

[sprouty115]

Got some time to get back to it yesterday. Went from this:

photo (10)

To this:

image

Pretty straightforward assembly. Probably took about an hour and a half. And everything went really smoothly except for one thing - the shift-rod seal installation. I had picked up a tip from a UK 2-stroke site that suggested not to install the seal in the case but instead put the shift rod through the case and then work the seal over the rod.

Turned out to be good advice, because the seal includes a small circular spring that wants to pop off as you slide the seal over the splines - which it did repeatedly, though eventually I got past the splines. But that was as far as I got because as soon as the seal hit the cut-out for the cir-clip it jammed. I tried gently poking at it for about 15 minutes before I gave up. Eventually I tried wrapping a piece of electrical tape over the cir-clip slot, and then sliding the seal on. That worked perfectly and after it was in, I just slid the tape out.

Seal is in, tape pulled back out:


image (1)

Next up: clutch assembly and rotor/stator while waiting for the cylinders to arrive.

[dave0]

Good time to make sure it shifts through the gears.

Looking good!

[sprouty115]

Originally Posted by dave0

Good time to make sure it shifts through the gears.

Looking good!

Sorry, somehow missed this, but yeah, grabbed the shift lever and everything seemed ok!

So despite competing projects I did make some progress: the clutch went on without much issue. Figuring out how to torque the primary drive nut and clutch nut was interesting though. Lots of suggestions to block-up the connecting rod and shove a penny between gears. I thought about it a bit and decided after spending all that money on the crank I couldn't bring myself to do it. Sucked it up and bought a clutch-holding tool and with a little help from my son got everything torqued to spec with no drama. That means the clutch side is pretty much done except for the oil pump.

The electrical side also still requires some work as there are lots of screws with wonky heads and a worn-out points cam that needs to be replaced. I also have to see if the brushes are OK (one is significantly shorter than the other) and then checkout the points themselves.

Some pics...

Clutch-side and my new shiny tool

clutch

I hate messed-up screw heads

Points

Chewed up points cam.

Points cam

Brushes - need to figure out if the length difference is normal, or at least how close to worn out the short one is.

Brushes 2

Also got a nice package today.

Cyclinders

Hone looks great and everything cleaned up nicely.

image (3)

They even chamfered the edges of the ports.

Ports


Should be have some time this weekend to keep things rolling.