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Oh the horros! (siezed bike)

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Here's the story guys.

I got my frame powdercoated about a month ago. (My garage for pics of you wanna see) and since the frame was out, and my engine was sitting in the garage, I figured it'd be a good idea to check the valves. Checked the valves and they were within spec. Put the cover back on and waited for my frame.

So I put the bike together (before flushing the oil tank with about 5 quarts of oil) and put it together. Ever since then it has been a little harder to kick over, and the decomp harder to push in.

1.4 hours later I changed the oil. Came out pitch black! :D At time went on it got harder and harder to kick over. My coolant temps went form normally around 140 to 170, and thats even using Engine Ice :eek:

So another 1.4 hours went by, changed the oil. Pitch black again and still harder to crank over. The bike ran great though and nothing felt wrong.

Well I guess I learned my lesson on Sunday. Did 4 laps on the track and was still going, riding behind my brother. It was fun. Came around the corner and had no power, felt like a 80. Went off the jump, landed, a second later the back tire locks up. Pull in the clutch and it rolls (thank god) Coolant temp was 170, oil was between add and full marks. Tried kicking it over, kickstarter moved 1/4" and didn't more anymore. :D:D

So I took the cams out today. No discoloration on the cams or the valve buckets. On order is going a be a 03 cam so I have the Auto Deomp.

I'm guessing that it's the piston that siezed. Reason for siezing is that the oil isn't getting to where it should (the piston) and as a result, higher coolant temps, and eventually, a sieze.

So tomorrow hopefully I'm pulling off the head to see what I'm faced with. Question is with 50 hours on the bike, is it really nesecary to do the bottom end? If there is freeplay in the crank and connecting rod I definately will (well, the dealer will for me, I ain't splitting cases) but if there is no freeplay, should I touch the bottom end?

So far, he're's my list to change:

Piston (Wiesco Hi-Comp piston)

Rings

Hone the cylender if possible, if not either resleeve or get a new one

piston to connecting rod bearings

Piston clips

Main rod for the piston to connecting rod

Gaskets

Timing Chain

03 exhaust cam

Shim job on the valves

Any Ness. copper washers and o-rings

Valves have never been shimmed so I will not replace them, just a shim job. How does the list look. Anyhting else I should add?

Also, has anyone done a timing chain change. I have the service manual on me and can't seem to find the section to change it. I'm assuming that I would have to split the cases or something of that nature correct?

Well anyways, let the work begin. I still ahve a long way to go. If it was jsut a rebuild it would be that bad, but since I have to search for what's causing the blockage, let the games begin...

-Phill

01 YZ250F, 50 original hours...

PS: The engine will turn over, but it will only turn over through the crank bolt and it is very hard to turn over. No tight spots so that somewhat rules out bearings....

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Man.. sorry to hear that! I can't really answer about your questions on the bottom end, but I can tell you that you don't need to split the cases to change the timing chain. You do need to pull the flywheel/mag off to get the old chain off and the new one on... super easy tho.

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I wonder if you pinched the oil line running from the frame to the case. At least something seems to be blocking oil flow, or the pump itself may be shot. Pull the frame screen and check it.

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So far, he're's my list to change:

Piston (Wiesco Hi-Comp piston)

Rings

Hone the cylender if possible, if not either resleeve or get a new one

piston to connecting rod bearings

Piston clips

Main rod for the piston to connecting rod

If you are going to replace all of those parts, why don't you look into a 262 bore kit. It comes with a new cylinder, piston and rings. Just a thought

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I would split the cases and check the bearings in case some sand or something got in the bottom end. Also I would check all the oil passages for blockage...something caused this seizure and you need to remedy the problem before you reassemble.

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Well, I race. I dunno, boring is just not for me...

YZ250F rider, I thought the same thing, but then I figured, well, then the tranny would be shot as well. The tranny shifts perfect, and the cams and the valves are looking good, just whatever it is down there (crank bearings or the piston) is not getting enough oilflow. I'm thinking it's something to do with a orfice inside the motor itself. How exactly would I check the oil pump?

That's a relief on the timing chain. I'm assuming then all I need to do is pull the left crankcase cover off when I get down the the piston correct?

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I found the Oil pump removal page. 4-65 to 4-69. Looks like a pain in the ass, but you gotta do what you gotta do...

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Well, I race. I dunno, boring is just not for me...

YZ250F rider, I thought the same thing, but then I figured, well, then the tranny would be shot as well. The tranny shifts perfect, and the cams and the valves are looking good, just whatever it is down there (crank bearings or the piston) is not getting enough oilflow. I'm thinking it's something to do with a orfice inside the motor itself. How exactly would I check the oil pump?

That's a relief on the timing chain. I'm assuming then all I need to do is pull the left crankcase cover off when I get down the the piston correct?

You also need to pull the magneto and the chain guides off. It's not a big deal though. Just make sure when you reassemble you check for oil pressure. Look in your manual, it tells you how to do this.

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I found the Oil pump removal page. 4-65 to 4-69. Looks like a pain in the ass, but you gotta do what you gotta do...

It's really not that bad of a job...You might as well replace the pump. It's only $60 from the TT store. Check that oil pump rotor also.

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It's really not that bad of a job...You might as well replace the pump. It's only $60 from the TT store. Check that oil pump rotor also.

Yeah, sounds like a plan to change the oil pump. Now I gotta get a clutch boss tool as well!

I'll do the timing chain. I'll look more into it.

-Phill

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250Thumpher

Just a thought, but since you said this happened after you had the frame powder coated maybe there was some sand/grit in the oil tank part of the frame? That would explain the dirty oil. How clean was it when you reassembled it...even though they masked it off doesn't mean any sand/grit found it's way inside.

Bill

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Well, what I did is filled up the tank full till i couldn't no more. Did that 3 times and didn't look like anything came out the last timeI did it.

My brother (who also got his done) had plugs machined to thread into the dipstick threads and sreen threads. Then the vent tube was capped off, and the return line was capped off.

We'll see in a couple days when I pull the cylender off.

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Yeah, sounds like a plan to change the oil pump. Now I gotta get a clutch boss tool as well!

I'll do the timing chain. I'll look more into it.

-Phill

You done need that tool. I've had my clutch out several times with out using the tool. I use an impact gun to get the nut off. To torque the nut on reassembly with the motor in the bike and the drive chain hooked up I just step on the rear brake to hold the clutch. You can do this to remove the nit also.

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OH THE HORROR!

Well guys, I pulled off the Valve head. The oil lines didn't seem clogged (Doesn't matter about the upper lines now) Even the bolts when I took off the head, had "grease" on the end of it more than oil.

So I cranked it over and the walls still looked new! Honing marks still in it. So I cranked it to TDC, then cranked it over again to TDC. Still hard. Took the 8mm off to pull the cylender. Clid it up, and I found the little monster bastard that ruined my engine.

Connecting rod main bearing (bearing that connects the rod to the crank). Around the bearing is red. The piston will move, and the crankshaft will spin, but the connecting rod bearing won't budge.

Sooooo, the motor itself is off the the dealer to get the cases split. :D:D I'll have the stealership split the cases and change the connecting rod bearing and the crank bearings. Not to mention the oil pump. Basically have them do the bottom end. I'll deal with the piston and all of that. Last thing I will do in a bike is split the cases.

-Phill

Pics tonight

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Sorry, to hear about the bottom end going south. Just food for thought, since you have the top end off, check your cam chain guides, cam chain tensioner to make sure it moves freely and take a close look at your valves. I had to replace all of my valves on my 02.

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They're on the borderline of becomming out of spec. Plus when I change my cams the value may differ. I'll know when I install the cams.

Why not hsim the valves? I have the motor apart.

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When they reassemble the bottom, make sure they dont set up the clearance for the Crank/rod bearing too tight. Its best to set the tolerance a wee bit on the loose side. Might as well put in a new cam chain as well.

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