Yamaha WR 250 R 2008 Engine Rebuild?

Hello guys I am new to the forum I am from Switzerland and have now bought a WR 250 R. These are quite rare in Switzerland. But it has 80,000km, now I want to know what should I do with the engine completely? She has a problem and after 100km the spark plug is completely rusted and broken.
Hope get some help there are no good German forums. I'm sorry for bad english
Best regards
Nils

Did you fix the sparkplug issue?
I would just ride it, if sounds healthy, and doesn't burn oil

No I haven't fixed it. And what could it be broken cylinder head gasket? Just want to know what is going to break quickly so that if the engine is open it can fix it right away.

exocon wrote:

No I haven't fixed it.  And what could it be broken cylinder head gasket?  Just want to know what is going to break quickly so that if the engine is open it can fix it right away.

Hard to say, rusted and broken in 100km is not good. Can you get parts? If so, if it was my bike I would do a compression check and at the same time look for water signs in the cylinder. If present I would do a complete rebuild with new piston, rings, bearings and inspect all else including transmission and clutch.

If that was the spark plug that came with it, then put a new one in before anything else and run it and recheck the plug. That old plug has an unknown history.

Starpower wrote:

exocon wrote:

No I haven't fixed it.  And what could it be broken cylinder head gasket?  Just want to know what is going to break quickly so that if the engine is open it can fix it right away.

Hard to say, rusted and broken in 100km is not good. Can you get parts? If so, if it was my bike I would do a compression check and at the same time look for water signs in the cylinder. If present I would do a complete rebuild with new piston, rings, bearings and inspect all else including transmission and clutch.

If that was the spark plug that came with it, then put a new one in before anything else and run it and recheck the plug. That old plug has an unknown history.

The spark plug was already new. And then the problem came.
Parts are hard to come by Where do you get your website Parts maybe you can send them to Switzerland? I found one site partzilla it calls Maybe the site ist good?
Could you maybe give me a precise list of what you would change? I've never made Yamaha engines before, but probably not that much of a difference from a Honda CRF 450R.
Do these motors have any construction faults that you can fix right away?

Thank you for the current help and maybe a little more

Get parts from cmsnl.com its in Netherland

No known motor issues with this bike.

Jens Eskildsen wrote:

Get parts from cmsnl.com its in Netherland

No known motor issues with this bike.

Should the crankshaft bearings also be replaced straight or is the crankshaft and bearings of good quality? So even if the tolerance is correct? What about the gearbox? Or clutch?

For a 80‘000km Motor never opened it looks not to bad? What you think guys?

That does look good, especially for the miles. It looks like it may have had a head gasket leak, this would also explain the rusted plug and if it hydro locked it could have broken the plug but does not seem likely.

I would do rings, bearings, gaskets, cylinder hone and valve job. Good to go for another 80K!

A spark plug that's rusty on the outside where the spark plug wrench goes is pretty common. I know that both my 2008 WR250R and 2008 WR250X spark plugs had a fair amount of rust on them on the external steel parts of the plugs.
It's probably just from condensation forming on the bare steel of the plug and time taking it's toll.
If you were able to extract the plug easily once you could get a wrench on it, it's probably no big deal.

Just make sure your spark plug drain hole is always clear so the area can drain and vent as needed. It's just above the exhaust header pipe.

Also, post back when it's up and running and let us know how it went. Always nice to see how a job ends and read what you learned along the way.

Tomorrow I'll look at the other side of the engine. Hope with the same result. I'm still unsure whether to split the engine and replace the bearings

exocon wrote:

I'm still unsure whether to split the engine and replace the bearings

Myself, if time and money were not an issue, I'd disassemble the entire engine and inspect all parts and probably replace the bearings, oil seals, and gaskets since I was already in there.
The cam chain and clutch plates would get replaced, too, and probably a new cam chain tensioner, as well.
I'd feel it would be the perfect time to do so.
I'd treat it as a winter project, take my time, and do it right with the correct parts.
I've done that to many used Yamaha dirt bikes and dual-purpose bikes as a hobby, and come spring I'd use those bikes a lot with confidence.

Have a Yamaha Service Manual and use that as your guide.

Thanks for the answer abr why a new cam chain tensioner? They last forever or not?

exocon wrote:

Thanks for the answer abr why a new cam chain tensioner?  They last forever or not?

Just for peace of mind.
If I were spending the time and money for an overhaul, it would be money well spent.

So people the whole engine is disassembled. It is like new inside for 80,000 km. Will make crankshaft and bearings and new cylinder, as well as clutch. But do I have a question if someone knows whether the WR 250F cylinder fits my bike? Or does someone have experience with the 250cc Athena set for this motorcycle?

The WR250F parts will not fit.
Different bike, entirely.

new parts are here so let begin

Awesome.

Complete all new bearings and crankshaft next new timing chain and cylinder with piston