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DRZBigB

Overheated, and now has No Compression :(

15 posts in this topic

Well - first trip to the desert with my Cousin's 2003 WR450F, and after riding 10 miles in the soft sand, his bike stopped running - just bogged down and died...

There was smoke coming from the breather hose that goes to the valve cover.

After a quick inspection - I immediately noticed that there was no radiator cap and that his radiator was EMPTY!!!!

SO... What is the most likely thing that happed? I'm assuming something with the valves, or cams..

Any help is appreciated - my cousin is REALLY bummed, and I'm probably going to be the one that ends up fixing it!

Where should I start - just check the valves?

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Tear off the top end to inspect and if oil smells horrible bottom end may be hurt also. Judging from the description of ten miles in soft sand then bogged and died the engine is hurt, maybe toasted. Good luck.

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Sounds like it is probably time for a new head, kind of hard to say though. All we have to go in is that it over heated. Start tearing it down and see what it looks like in there.

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Sounds like it is probably time for a new head, kind of hard to say though. All we have to go in is that it over heated. Start tearing it down and see what it looks like in there.

That's really it. untill you get in there you just will not know. I would be prepared to re-build the topend and split the cases and inspect all parts. If the oil was really burnt the you could have issues with the clutch, grears ect..ect..

if it was me I would find a shop I trusted and have them go through the entire motor. Have them give me an itimized list of issues and parts. then based on cost decide if I wanted to repair it my self or have them do it

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Any sign of leaking around the head gasket area? If not, maybe you just cooked the rings.

Pop out the sparkplug and pour a teaspoon of oil into the cylinder and spin the engine over a few times to coat the rings and cylinder with oil. Pop the plug back in and kick it over to see if the compression has improved. If compression returns it's possible that you may just need new rings, followed by possible piston and cylinder depending on the damage.

It's also possible that the heat simply baked the oil off of the cylinder walls, causing you to lose compression. The WR's seem very suceptible to this. I've flooded mine a few times and the result was fuel washed the cylinder walls down causing zero compression. I poured a bit of oil into the cylinder, compression returned to normal, and the bike started and ran perfecrly normally with no ill effects. You may not need to tear down at all.

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At this point you need a complete inspection to gather information about the engine so YOU and Your COUSIN can make a few decisions.

I would start with tear down and inspection of the cylinder head , cylinder and piston. The results of that inspection will lead to information necessary to make decisions on whether or not you will need to split the cases.

We do feel your pain. we would like to help. we can be more helpfull with more information from you. YOU have some work to do, Please keep us informed along the way and we will help you save money any way we can.

Now get to work!

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One more thing!

Start by reading the service manual. If you do not have one you can download one from the Sticky at the top of the forum.

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Well - first trip to the desert with my Cousin's 2003 WR450F, and after riding 10 miles in the soft sand, his bike stopped running - just bogged down and died...

There was smoke coming from the breather hose that goes to the valve cover.

After a quick inspection - I immediately noticed that there was no radiator cap and that his radiator was EMPTY!!!!

SO... What is the most likely thing that happed? I'm assuming something with the valves, or cams..

Any help is appreciated - my cousin is REALLY bummed, and I'm probably going to be the one that ends up fixing it!

Where should I start - just check the valves?

Maannnn...that hurts...As bad as it may sound, you probably need to buy another bike for your boy and salvage the one you burnt. If you burnt it up and you try to rebuild...you may always have troubles due to the fatigue and warp and all of that throughout the drivetrain. You do have to dig into it but if it just bogged down like that man........ it pretty much melted

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It's worth giving Frostbites idea a try before anything else, also drain the oil & check it's condition & if there is anything that comes out with it. In the end you'll probably have to strip her down.

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I really appreciate everything!!! I gotta tear into it and crank it over and see if its really cooked or was just hot..

I'll post pictures and stuff when I get it apart!

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