Engine siezed today (99 xr250)

Today My cousin and I went out riding today, trail riding. The idea was to get a few hours of riding in and come home before the heat.

Well 10 miles into the trip my cousin is on a kdx i'm on the xr. He wants to go play on the main track there so i pull off the road and shut down the bike in some shade. He comes out, time to ride again, flip out the kick started and it doesn't budge an inch. I figure the kick starter is fux0red so i go to bump start it, NO DICE. It just locks the rear tire, the engine has siezed.

Oil is repsol non-synthetic, 1 ride old, new filter. Bike has oil. Bike didn't smoke, started this morning with 2 kicks and ran like a top until i turned it off in front of the track to wait for my cousin.

So question is, &%$#@! has just happened and why?

How much will it cost to fix?



any chance youi gota bad needle valve and flooded the engine- and the engine is hydraulic'd

pull the plug and see what happens

pulled the plug and it still doesn't crank :thumbsup:

could be that when you shut down the cam chain parted, that would explain the no oil smoke and bike had a fresh oil change. (not oil related) When a cam chain breaks valves contact the piston crown and thus the engine will not turn over. Also a ring may have broke but that would have smoked prior to shut down. Most likely a broken camchain.

Top end rebuild is easy to do. Replace all that you can afford while there, as a minimum, NEW gaskets, piston rings, camchain and valves & seals. Good time for a big bore kit if you are interested. Price your parts at bikebandit.com as an example to give you and idea of costs.

Take the cams and spark plug out (or pull the head) and see if it will turn over. This will let the valves come all the way up and never hit the piston, and you can visually see if any valves are broken or bent (badly) and stuck open. If it turns over, the valve train seized and you'll also need to check the piston for damage. If it doesn't turn over, the piston or bottom end seized.

A bit of work, but it seems like it'd be worth knowing what died in there.

A broken timing chain with no engine damage is about $15 for the part and a couple hours of wrenching to fix. A piston seizure isn't too bad - a few $hundred and waiting on the shop to do any cylinder work. Having to split the cases for a bottom end problem costs a bit more - mostly for labor. Valvetrain repairs can run from a few $hundred to around $1200 for a complete top-end rebuild. Replace the piston/rings/etc. if the piston has valve impact damage.

Best of luck with this.

if the cam chain siezed and did no damage ( i dont see how it could considering it broke when the bike was off, you're thinking 15 bucks?

How do i find out what's broken? How do i get to the cam chain?

I just realized that you didn't mention if the bike rolls in neutral or with the clutch pulled. (just checking on where it's seized)

Timing chain inspection:

Pull the valve cover off, look at the chain. Having a manual is almost a "must" at this point. You'll at least need the torque specs to put things back together correctly. The manual has great info on how to take the head and cylinder apart and how to inspect each piece.

The timing chain itself won't seize; it's not that strong. I'd be surprised if the timing chain broke with the engine off, but if it did as the other rider posted, then yes, a new chain is about $15. If it fell into the bottom-end, it might have jammed the crank which may be a good thing. You can fish it out and look in there with a flashlight to see if the crank sprocket or anything else is damaged. While you're in there, look for a broken chain adjuster or guide. Maybe something bent or broke off in a position that's keeping the engine from turning. You'll need to do some wrenching and and re-adjusting your cam timing to get the bike running again, as long as there isn't any piston or valve damage.

My personal guess is you have a piston seizure from overheating. That still isn't too bad as far as failures go, and saves the hassle of valve work. If it's that, you can handle the tear-down and assembly in your garage without any exotic tools. I'd have a shop bore/hone the cylinder as necessary as it's generally a better finish than one done by hand.

I suppose it comes down to how comfortable you are working on your bike, or if it would be better to hand it over to a shop and get an estimate. Many places will give you credit for the tear-down if you have them do the repairs.

I really dont think the bike overheated. It was probably in the low 70's, and the bike had been cooled down for 10 minutes and then i started it up, drove to the track (<1 min) and turned it off. I turned it off with the kill switch. After that it was no more.

Took the head off, or whatever it's called the very top of the engine.

The bike turns freely now, everything looks relatively clean. Any ideas? Cam chain is beautiful.

Maybe your kick starter jammed up and was locking the engine somehow.

Examine your valves and see if the top of the piston has been hit by a valve.

If not, put it back together and start it up.

FIXED! Thanks to all for the suggestions.

It was quite simple. I pulled the head and the kick starter spun. So i payed attention to everything, cam chain looked good, then i noticed the cam was kind of moving up and down, hmmm. I looked around and discovered a nut had wedged itself right under the cam and when it went around was touching the cam and causing it to lift. With the head on this would make it stop.

Guess where the nut came from?

THAT's RIGHT THE VALVE ADJUSTMENT NUT!!!! color me embarrassed.

Lesson learned.

Shit... how tight are they supposed to be? I just got done adjusting mine last night and put in a new plug and it seemed to have helped it a WHOLE lot... but I didn't torque the locknuts, just tightened them with a boxed wrench, pretty tight... but they were very tight to begin with, I used a socket.

??? should I make sure they're real tight?

yeah i dunno, i thought i wrenched them on pretty good. sigh.

Good for you NO damage is the best result you could hope for.

Its hard to remember to always use a torque wrench !!!

Even I get lazy sometimes and pay for it later.

Woot! Nice catch! :thumbsup:

FIXED! Thanks to all for the suggestions.

It was quite simple. I pulled the head and the kick starter spun. So i payed attention to everything, cam chain looked good, then i noticed the cam was kind of moving up and down, hmmm. I looked around and discovered a nut had wedged itself right under the cam and when it went around was touching the cam and causing it to lift. With the head on this would make it stop.

Guess where the nut came from?

THAT's RIGHT THE VALVE ADJUSTMENT NUT!!!! color me embarrassed.

Lesson learned.

Done the same thing where's it come off... or gotten very lose twice, both times it was tight. Usually ticks like mad when that happens though.

Whenever I do my valves I'm amazed at the torque that the lock nuts take. I'm not sure I'd have the confidence or the feel to torque them enough by hand.

A cheap clicker torque wrench is a big help for doing your valves. I bought mine for about 60-70 bucks. It's taiwanese, and certified to within 4%, complete with a small certificate that shows that some dude at the factory tested it at several torque levels, and what it actually was putting out.

Not the best, and you can go cheaper on a beam-type torque wrench, but I really have no confidence in those.


i have a torque wrench, i just dont use it or like it very much...

Maybe i'll start using it now, what is the torque spec for that nut?

Davidl9999,I agree on your breakfast of champions,although mine is coffee and hydrocodone 10-650,old army break to the L-4 lower back.But back to the moto stuff,Im not in any way shinning any negetive light on Cleoents problem,but,Ive put 8000 miles on my 99 XR250,since being in Panama using castrol semi syn 20w50 and changing at nmt 400 miles,and the only problem ive had was getting caught in a monsoon type of rain forest rain,and the engine started to sputter,It never died completly I did not walk!got home and put some silicone around the top of my plug wire and black taped up the I-cat,and that done it,the problem was the I-cat was touching the frame,I reached down and touched it with the motor running and felt a tingle,it produces so much spark that with water added into the equation,it was shorting to the frame,but its an after thought now.even in Panama type heat,my temp gauge has never gone over 250-275,but at my age,I may not push my motor as hard as the kids do,also keep in mind that its a 250 4-stroke,so I dont ride it like its a race bike.But dam its fun to weave in and out of grid locked traffic and get to my destination way faster than driving my suv or F150,and finding a parking spot is a breeze.I hope cleoents finds his problem to be a simple one.

Has any of your guy's bikes been hard to start after checking the valves and adjusting? Not as in the number of kicks but just, hard to kick?

Oh and in my manual, I dont think it lists a torque for the valve locknut...

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