1991 CR250R

[Tejasmud]

I figured that I would create a thread on the things I do and have done to this machine. It was restored from the ground up back in 2011.

Here is a quick overview of the initial build.

Putting her back together with powder coated frame. All new bearings in steering stem, swing arm, linkage, and wheels.


Engine before rebuild.


Cracked cylinder skirt, and ended up having this one sleeved.


Tearing it down.






Cases after bead blast and clear coat.


Bearings, seals, gaskets, connecting rod, and covers..


Crank rebuild.


Truing the "tin can crank" required making some split ring collets to keep from damaging the tin cases on the crank webs. Was able to get crank trued in to 0.0003" runout, which is pretty good.


After getting the cases back together..


Ended up like this after the build....


Have done a few other things over the last few years...

One off rear brake clevis.


PMP sprocket on the rear 14t - 51t final drive on the initial build, since have switched over to a Renthal/RK set-up 14t - 49t to help on keeping momentum and less engine drag.


Suspension was done this last year..
Rear shock rebuild. This is a 1989 CR500 Showa shock. Assuming previous owner needed a heavier rate spring, which made the rear to stiff.


Ended up keeping the stock valving, just re-sprung, new head seal, o-rings, nut, piston ring, bladder, bladder cap, and new retaining rings.


The forks had been revalved already and had the lowest rate OE springs. Re-sprung, seals, bushings, o-rings, ect...

Other than a sub-frame and new powercore silencer after a rear fender landing, the bike has run without a glitch since.

Here it sat last weekend at the track after 50hrs of run time.



So, time to do the top end. Easy part is tearing it down...



Piston rings were just over the limit by 0.002" on the ring gap. This was a ProX piston, and just went back with the same. Same as a stock piston. ART.


Cylinder was cleaned up and inspected. All within specification still.

[Tejasmud]

Reeds still in great shape on the Boyesen Rad Valve.


Power valves serviced. Chamfering and polishing the valves really kept the carbon build-up to a minimum...


Cylinder ready to put back on...


Picked up a blue silicon hose kit off ebay, which some of the hoses were too short, however working on getting this resolved with the seller. Only need one hose to fix me up, and hopefully they will correct their kits so that others who buy them don't go through the same thing. The kit was $32.40 shipped not really much to complain about.


Up grading to a new PWK Air Striker off a 2000 CR250R also. The PW worked great, and have never had a problem with it. Just need something to tinker with, and if it will give me the low to mid response I keep reading about, it will be worth it.


So, this is how she sits today.


Rear suspension is still tight, however time to do the rear linkage and swing arm service on her too.


Picked up a rear linkage in great shape off ebay. $25, The original connecting rod/wishbone has a gouge in it from the shock bolt wearing into it. The rear bearings were all shot initially, and the slop allowed the bolt head to rub.


Anyhow, should be able to break it in and tune the PWK this weekend..

Oh, and it always seems I have extra nuts and bolts left over???


E

[dogger315]

Real nice resto, Tejasmud. Also enjoyed the detailed write up of the "journey"
so far.

The '91s are overlooked by many, but are iconic models that bring back
memories of the Stanton and Bayle days.

From the pictures of your tear down, it looks like you have the engine dialed
in. It also doesn't hurt to get a rebuild after 50 hours - I wish everyone took
that good of care of their CRs. Also, love the custom billet brake clevis.

You're probably not going to notice any improvement in low to mid power from
a simple carb swap. Since you have your PJ jetted correctly, the PWK is going
to provide a little better throttle response and be easier to keep jetted correctly
over time. It's still a nice upgrade over the PJ. If you're looking for more on
the bottom, try a shorty silencer.

Look forward to updates.

dogger

[Tejasmud]

Thanks Dogger. It took a while to get this bike into the current condition. Quiet a few $ are in it as well, as I'm sure you can relate. I hate to say it, >$5000 last time I tallied up before suspension. The way I look at it, I can buy a brand new bike for $8000+ and know nothing about it, or I can restore a classic bike for $8000+, know everything there is to know about it. Plus the cool factor is greater.. I have a bit more to go with the rims/spokes and possibly hubs eventually.

I was able to break the top-end in and get the PWK dialed in yesterday.

42 pilot, air screw set at 1.25 turns
Needle in the 3 position
170 main

The throttle response is much better low to mid over the PJ. I was actually impressed with it. I have been looking for a Shorty, and actually running a Power Core at the moment. Have run a Turbine Core on it before. The power on the bottom is actually great with the gnarly pipe with power core and boyesen rad valve set-up. It pulls like a tractor offroad trail riding with the stock 14t-51t final drive, and allows me to run a 14t-49t on the on an SX style track without much loss in power. The PWK has removed the periodic hesitation in the throttle response mid gear. Say coming out of a corner and hitting a double is much easier.

I like it.. Not as effortless as a 4-stroke per say. I always joke with a buddy of mine telling him, "I'll have this 2-stroke powering like a 4-stroke." haha...

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[Tejasmud]

Since it had been raining here in N.Texas over the last few months every flippin weekend, it seemed like a good time to do maintenance on the ’91.

It started out with just some front wheel and rear suspension bearings, and the project list just grew from there as always…. Hahaha…

So, serviced front wheel bearings with new spacers then decided on new fasteners for the axel caps.



Well, then the front caliper looked to need servicing, so tore it down, soda blasted, satin clear coated, new pins, pads, seals, springs, and bolting.





All that looked great, but the fork protectors were screaming help.
This is where the exercise on attempting to match aftermarket plastic colors began… Not much of a choice on this older machine given OE parts are long gone…

Started with new fork protectors and decals w/new fasteners, then the red was too red on the decals and didn’t match the flash red. So, I decided to match the fenders best I could with UFO (Red 1) to the decals.





Close, however the tank, still (Flash Red), didn’t match. Luck of the draw, I was able to pick up a Clarke oversize tank with larger cap, which was close in color, more of a “fighting red,” for $75 off the bay.





Of course all new OE fasteners were desired. Tank bolted right up except the shroud bolt centers were about 3/8” closer as opposed to the OE tank. A little filing was needed. Again, the wonderful world of aftermarket plastics…

Also was able to modify an Acerbis mud flap to work. Found that the flap from Moose (Cycra) will not fit. The holes are predrilled and not offset.



Anyway, here is the result.





Looking into a red and black gripper seat cover, or possibly might go with blue.
Eventually the wheels and hubs, which from the look of it a conversion on the front suspension may be the way to go to get past the ’90-’91 hub.

Time to ride it, and quit wrenching on it.... lol

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[doohanfan]

don't forget trampas parker world champ on the mighty 91 cr! quick question. do you think the front half of the swingarm is painted ive been looking at mine and it looks like its a frosty silver maybe? and another question did you sleeve because it couldn't be repaired mines cracked almost in the exact spot as yours. I have genuine top end kit and aurum plating a local mob in Brisbane says he can fix it for me but my question is will it most likely fail again! I don't want another damaged bottom end! its how I bought the bike and bloody good crankcases are like hens teeth. ive got a sleeved jug but it looks like the last guy installed it with a house brick!! mines currently at 2500+ and still resides in a 5 draw faux leather tall boy in the master bedroom.

[Tejasmud]

Originally Posted by doohanfan

quick question. do you think the front half of the swingarm is painted ive been looking at mine and it looks like its a frosty silver maybe?

The center part of the swing arm is a casting, having a rough surface with ejection marks, the rest is extruded tube for the most part. After welding it is anodized. Unless yours has been actually painted, the difference is just the metal and surface finish. Many times people will polish the smoother tube portion. If this has also been done, the contrast will appear even more different. I could see it looking like it was painted if this was done..

Originally Posted by doohanfan

and another question did you sleeve because it couldn't be repaired mines cracked almost in the exact spot as yours.

I sleeved the cylinder for a number of reasons. Time to repair and the ability to increase the bore size in the future were the main two.

Originally Posted by doohanfan

I have genuine top end kit and aurum plating a local mob in Brisbane says he can fix it for me but my question is will it most likely fail again!

Really depends on who does the work. I'm not familiar with aurum plating, obviously, however best rule of thumb, "If the business does a lot of motorcycle cylinders there is good reason." They are good at it. Taking a cylinder to "Machine Shop Jenkins," usually isn't a very good idea. No matter how awesome their dad's set of tools are.. Just examples of who does the work, and will it fail or not fail.. I've seen repairs done and they hold up. PowerSeal here in the States does good work.

Originally Posted by doohanfan

I don't want another damaged bottom end! its how I bought the bike and bloody good crankcases are like hens teeth. ive got a sleeved jug but it looks like the last guy installed it with a house brick!! mines currently at 2500+ and still resides in a 5 draw faux leather tall boy in the master bedroom.

I hear you on finding certain parts for older bikes. Not to mention what some people actually think they the part is worth.. Unbelievable!..



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[dogger315]

Nice refresh! Looks to be ready for another season in the dirt.

A new seat cover will definitely set it off. There's more than one company
selling repro seat covers complete with the correct graphics. You might
even be able to get it in the shade of Red you are switching to if you are
interested in going that route.

I don't think most people realize the 91 was the last of the Flash Red CRs
(albeit a more Reddish Orange than the earlier versions). So you decided
to change colors to match the available graphics?

dogger

[Tejasmud]

Originally Posted by dogger315

Nice refresh! Looks to be ready for another season in the dirt.

A new seat cover will definitely set it off. There's more than one company
selling repro seat covers complete with the correct graphics. You might
even be able to get it in the shade of Red you are switching to if you are
interested in going that route.

I don't think most people realize the 91 was the last of the Flash Red CRs
(albeit a more Reddish Orange than the earlier versions). So you decided
to change colors to match the available graphics?

dogger

Thanks! Yes, ready for another season in the dirt. Been really wet here though, and not ready to commit to the mud just yet...

Sourcing a repro seat cover with the splash, Flash Red plastics, and even the splash swing arm and shroud graphics can be found without too much effort. Just never been much of a fan of the splash graphics. Anything other than that almost has to be custom these days.

It started with the red in the newer graphics on the fork guards.... I think subliminally, it was just a way for me to justify changing the original Flash Red plastics... hahaha....



E

[doohanfan]

thanks for the answers mate, i'm almost ready to start putting it back together. I didn't think it was painted but I might give mine a whisp on the scratches. mines never been off until I got it. its still got the inked stamped number on the inside of the swing arm. going to chat with the plater Friday Im worried only because his wife is his secretary/translator! but he does only bikes, on his own. closes the shop for 1 hour for lunch, I love that! no affiliation with any brand or race team? im a backer of the straight shooting, little guy so I'l decide after a bit of a chit chat. also i found some pics from the previous owner, i'll try to put one up here if you don't mind? iv'e not done one yet so ill see if I can do it. but tell me what you think of it. I paid for it off the pics alone knowing it needed full rebuild. because they are just a rare bike compared to 92 up and 89 down. most people don't even know what year it is, another reason why I like them.