Well, I've gone and done it. I decided to pick up another neglected, orphan bike to restore and play with for at least a few seasons. I came across a very inexpensive (I'll leave that ambiguous) 1997 CR250R that was calling my name. I knew the top-end was toast, but as with any new project, I had no way to know how far gone things would be until I took it home and unbuttoned the mill.
So, I'll share the bad news, the good news and then ask a few questions while I wait for a manual to arrive.
Looks like the bottom ring decided to eat itself. About 1 inch of it broke off, caught on the main intake port, dug a HUGE scar in the piston, nicked the top of two ports, then spent time salt-and-peppering the top of the piston and the head before exiting the motor.
Here are the pictures of the damage...first, the scar from the ring tearing down the side of the piston...
Then what looks like a seize-point or serious scuff, with more shrapnel damage...
...Here's what the top of the piston ended up as...
...and the matching head "acne"...
Now, here are the pics of the cylinder. The first two are from the underside, looking up the bore. The nicks are obvious.
These two are looking from the top down the bore.
And now...the questions.
First, is the head salvageable? Can that be cleaned up well enough without machine work that will cost more than a new head?
Second, the Cylinder. I was glad to see that there was no scoring or damage to the cylinder walls themselves. However, the damage near those nicks has me fearing. I know I had old iron-bore cylinders with worse damage that were smoothed out by hand, but I''m not sure I can safely pull this off in this case. Is this garage-repairable, or am I going to be forced to weld up, re-plate and bore the cylinder? I know that "the best thing to do would be...", but I'm asking what I can do...not necessarily what I should. Will those damage points, if smoothed, result in rings prematurely hanging/breaking on the next top-end?
Thanks for any input you folks can provide.
By Ryan Turner
So I'm at a bit of a cross roads, I currently own a 06 rm250 and I love it. I also have a 02 kx250 which I'm selling with intent to buy a newer two stroke. I can't afford a newer ktm and the older ones aren't that great and kawasaki never impressed me. so I'm stuck between 06 yz250 and 05 cr250. I've heard the yz and rm after 06 are almost the same bike just the Suzuki handles better and the Yamaha has better suspension. So I'm not sure if I wanna buy carbon copy of my bike with slight differences. That's why I'm interested in a cr250 I heard the 02+ models RC valves are shit garbage but was mostly fixed in the 05-07 models. I ride at a track and at some bogs down the road from me. So from people who have owned both, what would you recommend. I know the cr is known for a hard hitting power band which I enjoy since im an aggressive rider. Should i just see which deal comes my way first.
Like the title says I've recently acquired an 07 CR250. Just got it into a safe state to operate it and the first ride out I realize the suspension is pogo-stick, jack-hammer hard.
My data: Height 6'3" Weight 215, or 225-230 with gear, Slow B rider, hare scramble racer only-NO MX/no jumping, Current springs Forks .46, shock 5.5. I'd like to soften the first 1/2 of the travel to soak up roots, rocks, and sharp edge hits but maintain some firmness with the mid-valve for the last 1/3 of travel.
Here is what I'm looking at right now:
30.1 X 11 shims
14.2 X 5 shims
11.2 X 4 shims
I have not measured the mid-valve stack yet as I was hoping to just be able to modify the base valve first and see how it goes. I don't want to make too many changes at once.
I was thinking about taking out the even numbered shims (28, 26, 24, 22, 18) and placing them under the 14's as a trial. So it would look like this;
30.1 X 11
14.2 X 5
If anyone could offer some assistance with this I would sincerely appreciate it. I have a place local to me that has all the shims in stock so I just need to settle on a corrected stack and then get these back together.
I realize the pivot is the 14.2 and debated on making this a 2 stage stack.
By D Mack
I went into my local shop for some oil and pre-mix. I am doing some work on my 98 CR250. Changing swing arm bearings, wheel bearings, which completely destroyed, possibly the originals. I hadn't gotten into the linkage yet but going by the damage to other bearings I figured they would be shot. I asked the guy to give me a price on the parts while I was there. He quoted me $230 + tax. Needless to say I didn't buy them. I went home and purchased a complete set off amazon for $66, shopping included. I'm all for supporting local business but their price was insane. I don't know how they stay in business with prices like that.
Just opened it up in preparation to get started with jets and needle set up. I am somewhat bewildered by the fact that there are no markings whatsoever on the jets, needle or slide.
I have some misc. Keihin jets kicking around, and they all have the size and some with the Keihin logo stamped on them. Is it that the newer models/parts are no longer marked? Or should I be concerned about the authenticity of the carb manufacturing. (i.e. clone) Everything about it looks authentic, including the box and part numbers.
BTW, intending on putting this on a basically stock 2004 CR250. With FMF Fatty, FMF Shorty muffler, V-force reed cage and a +10 oz. Steahly fw weight.
Running 50/50 91 pump and Sunoco GT260+ at 40:1 Bel-Ray H1-R.
I haven't checked squish yet.
Got tired of fighting with the stock Mikuni. Could never get it right. Close, but not the way that I think it should be.