2003 WR250F - New to me. Some basic questions

Hi Everybody


My first post here on TT, been reading lots over the last few days and learning as much as I can, but I still have a few questions.


I just recently bought a 2003 WR250F which needs some TLC, the last owner has owned it for 5 years and said that in the last 3 years he has probably ridden the bike 10 times.

The bike looks OK for the most part, but I want to strip it down to repaint the frame as it has rust showing up in a lot of places, nothing major at the moment, but I can't leave it like that.


I plan on checking the valve clearances, replacing oil & oil filter, flushing the radiators and brake system. Will also strip the rear linkage and check and re-grease everything, I'm pretty sure nothing like this has ever been done to the bike before. And the carb needs a service.


2 things I didn't count on when I bought the bike and only noticed them when I got it home, was the Fuel tank is cracked badly underneath the radiator shroud and although the shocks looked fine when I test drove the bike, when I got it home they were leaking badly, I've never packed a bike into the back of my pick up before and tied it down really hard (Did I blow the shock seals because of this?). I've bought a new shock seal kit to sort this out as well.


I've downloaded the service manual for the bike (The link courtesy of a TT member on one of the threads, thank you) and will carry out all checks and servicing required.


What do I do about the following:


1. Do I pull the head off to check the piston and change the rings? it's seems to run pretty strong, but I have no reference point to compare to, it's been 15 years since I owned a bike and I have never owned an Enduro or Motorcross bike.


2.  I've read that the fuel tank can't be repaired by plastic welding or glueing - I have a lot of experience with fibreglassing and epoxy laminating - Could I possibly cover the entire tank in real Carbon fibre? I live in South Africa and a replacement OEM tank is like $850 and an aftermarket is about $400. I can't find a second hand tank locally and I can't import a 2nd hand tank from Ebay because of our import regulations on 2nd hand parts.


3. If I find a YZF tank for it, do I need to change the seat as well or will the stock one fit in a fashion?


4. What else should I do apart from the basics?


5. Although the exhaust looks standard it is really loud and sounds a bit rattly inside, do I just need to repack it?


I'm not really too worried about trying to get more power right now as I have a lot of learning to do and I'm sure lots of falling to do. I want to keep it as stock as possible, but just bling it up a little. (I will do the throttle stop change though).


Thanks in advance for the assistance!


Pics before I bought it.











I wouldn't think you could wrap the tank sucessfully. Here is my reasoning - you are still going to have problems sealing around the inserts that the shrouds attach to. Of course you could fiberglass over them but you still have to drill a hole for attachment. You could try a stud but I'm still thinking you are going to have problems eventually from flex. The thead I found appears that you need the YZF seat to go with the tank. How much difference there is between the two I don't personally know. I'm assuming when you are saying "shocks" you actually are referring the forks. Yes the seals do start leaking perodically and need replacing. When you tied it down you caused the air that was in the forks to be compressed and build a slight amount of pressure. As it was a constant pressure from being tied down it pushed oil out around the fork seals. You could try popping the dust seals off and trying the "film" trick to see if that will stop them from leaking. Personally I've never tried it but others seem to have success with it and it's worth a try if you don't want to take them apart. Really I would take them apart and service them as they might not have ever been serviced since 03 and new bushings, seals and oil makes them work so much better and you know what you have. Don't know about the silencer - from what I've read the WR's are pretty quiet from the factory so sounds like something is going on that needs attention. I have an 03 YZF and if want me to take any measurements or pictures of the seat or gas tank to help you let me know. Clay

Hi Clay


Thanks for your response. Sorry yes I meant Forks not shocks, gotta get used to all of the correct terminology. I'll pull the forks out and replace the seals etc, always a little scared of doing something I haven't done before, but I guess once I've done it once I'll be good to go. Engines I'm happy with, rebuilt a few racing car engines and 2 stroke outboard engines before so no worry there.


I was actually thinking about wrapping the tank shortly after I posted these questions and was also trying to figure out how I am going to get around the bolt hole problem. Plus adding a layer around the tank is going to change the size of the tank meaning I will probably have problems fitting it as well.

I might have to end up ordering an after market tank like the Clarke 2.8Gallon, I don't want to go too big. But if I manage to find a 2nd hand YZF tank I might just ask you to take some measurements and photos for me. Thanks for the offer.

Don't worry about changing the seals in the forks. Nothing special really needed. Well as I can remember a thin 17mm wrench and something to help you drive in the new seals is about it. Revalving is more involved but what you are doing is pretty simple and straightforward and it sounds like you are very capable of doing it. I'll be happy to provide pics or measurements. I can tell you for sure that a 2003 YZ250F and a 2003 YZ450F share a lot of parts - I know forks, shock, seat and shrouds will swap and it looks like the rear subframe also. Other years may also swap but I have both of these to look at and this might give you some more options for finding what you need. Clay

Edited by nuity5

Your bike looks like it has a YZ rear fender.  The muffler is not stock so it probably needs repacking.  There are some plastic welding kits out there, I've never tried one.  You say the tank is cracked, is it leaking?  Do a leakdown test before you go and pull the head.  

Congrats on the new toy. I replaced my tank with a 3.3 gal clark unit and have not look back. fyi tried the plastic weld and it did not hold. don't know why as it worked well on other things I tried it on. lots of great folks on here and willing to help.best of luck freight

Hey Guys

Thanks for the responses.

Clay thanks for the info, I managed to track down a workshop that works on a lot of WR's and YZF's and they confirmed that I can use the YZF tank and my seat will still fit. :)

flyandryde - yes the tank is cracked right through, the fuel leaks out quickly and it runs right onto the header pipe, EEEK!!

Now that I've taken the tank off I've found 4 other cracks that haven't gone through yet but they also look pretty bad. The plastic in those areas has also gone a funny yellow colour, so I think it's a lost cause.

Thanks Freight, good to hear you are happy with the Clarke tank, I've been eyeballing them already

I think I'm going to bite the bullet and buy a new 2.8 Gallon Clarke tank from the US if I can't find a good second hand tank.

I started to dismantle my bike tonight after work, sheez this things got lotsa parts, hope I remember where to put them all :)

Radiators are bent, right side especially but they don't leak, the previous owner looks like he had just plain water in them, just a funny rusty colour.

Oil filter looks like it was last changed 5 years ago and the oil was black, didn't smell burnt though.

Pulled the carb off as well and the throttle stop has already been changed.

Got the sub frame and airbox off. Tomorrow I'll start to tackle the swing arm and take the motor out. The frame definitely needs repainting, lots of small rust bubbles in all the nooks and crannies.

What is the consensus on repainting the frame, I can respray it myself with a 2k or do I send it for powder coating, I know powder coating is probably stronger but if I paint it I can touch it up myself when it needs it.

I'll take some more pics of the progress tomorrow.



How did you manage to test ride it if it was leaking gas onto the header?    

http://www.colorrite.com/ sells spray paint to match your bike.  It's expensive.  I bought a can and it matches perfectly, good for touch up.  Don't know what you can get where you are.  

I bought the Chinese radiators from ebay, they look and work great and only $85 for the pair.  

How did you manage to test ride it if it was leaking gas onto the header?    

http://www.colorrite.com/ sells spray paint to match your bike.  It's expensive.  I bought a can and it matches perfectly, good for touch up.  Don't know what you can get where you are.  

I bought the Chinese radiators from ebay, they look and work great and only $85 for the pair.  


When it was standing normally and when I rode it the fuel was below the level of the crack so I didn't pick it up. It was only when I pulled the front down when I tied it onto my pick up that the fuel then reached that level. When I arrived at home the fuel was leaking out.The fuel was so old in the tank it actually smelt like plastic, so whether the previous owner knew it had cracked or not I don't know, but I bought it "as is" so I was up the proverbial creek without a paddle. You live and learn.

Was thinking of painting the frame silver to look a bit more like the aluminium frames and match the swingarm better.


Good to hear about the Chinese radiators, I was actually just looking on ebay at them now, my radiators don't leak but they are pretty banged up and bent especially the right side, was thinking of ordering the rads that come with the blue hoses to bling it up a little.


Going to probably order a new 2.8 Gallon Clarke tank from the TT store as I still have a discount code for joining :)  $82 for shipping but it's still cheaper than I can get it here.


I've also decided to check the valve clearances and if all looks OK, I'm going to leave the head alone, no point in spending money if I don't have to, I'm not going to be racing the bike and it didn't smoke at all when I rode it.

Just won a bid on Ebay for a brand new 2.8 Gallon Clarke Tank for $103, so I'm pretty chuffed right now, can't wait for it to get here.

Here is what my bike looks like at the moment

Yamaha WR250F 7.jpg

Cool! That sounds like a good start. My guess on trying to weld the plastic tanks is the gasoline contamination. We've all seen it - the first set of stickers when new will stay on a plastic tank for a while but once they bubble up you're done - any more you put on, unless perforated, will bubble in a very short time. The only explanation I can think of is gasoline is migrating through the plastic. Hope everything keeps working out for you. Clay

Hi Clay.

I wondered why I see older WR's and YZ's with perforated stickers, I just thought it was the old style on those bikes, makes sense though. My bike looks like it stood for a large portion of it's life outside in the elements, the tank was very discoloured in the areas that would receive direct sunlight and all of the corners where it was cracked were very yellow. Apart from the leaking crack it had another 4 deep cracks that would have opened up at the slightest bump. All my life I want to go and ride my bike in the outdoors in a flame retardant suite. It hurt the pocket but at least I can be confident with it now :)


I can't wait to carry on with the rebuild but I've got my brothers outboard engine in pieces waiting for me to complete the rebuild so I need to tackle that first (and sneak in a little bike building along the way:))

Hey Guys


I spent most of the day today stripping the balance of the bike down to pretty much nuts & bolts (apart from the engine), I can now strip the old rusty paint off the frame and make it all pretty again (Oooh shiny).

Lots of old rusty bolts and bent ones need replacing, pretty sure I will be needing a few new bearings for suspension and wheels as well.


I popped the cam cover off tonight and both Intake and Exhaust are running at least 1 tooth out (about 20 degrees After Top Dead centre).

I couldn't check my shim clearances properly as my feeler gauge is too wide for 2 of the intakes (will get a new narrower one tomorrow) but the one intake and both exhausts are out of spec, all well below minimum spec.


Do shim clearances generally tighten up over time? I would have thought they would widen over time?

OK so I got myself a narrow feeler gauge and checked my valve clearances properly, my 2 outer intakes are within spec at 0.10mm or just over, the centre intake valve is less than 0.05mm and both exhausts were 0.15mm so I need to shim them.


When I removed the shims they all have either 184 or 181 on the shims and from what I can pick up on other threads is that these are likely still the original factory fitted shims :D (I hope)

So the 2 exhaust are going to get 180 shims changed from 184 and the centre intake is getting a 170 changed from a 181 as per the manual.

I will do a check at 10 hours to make sure everything stays within spec.


I have another question - the PO didn't do a very good job of regular maintenance and the oil and oil filter looked gastly when I took them out. What's the best way to flush the engine?

My Dad used to flush old dirty engines with a mixture of oil and diesel, run them for 20 minutes or so with all filters in place and then drain it all out again, change filters and put in new oil and after that the oil would stay clean and transparent for many oil services after that. Or is it better to just do the full oil and filter change, ride it for an hour or two and then do another oil and filter change again?




If the shims have 181 or 184 on them those are factory.   If you buy aftermarket shim kits they come 180, 185, 190 etc.  Even Yamaha only lists them every 5 hundredths.  

If the PO was a slacker about maintenance I would change the oil with cheap oil, ride it until it gets hot and change it, maybe doing this a couple times.  I wouldn't put diesel where the oil should be, too much of a risk.  Maybe others have a different opinion or have tried it. 

 Also I would pull the clutch and alternator cover and clean it out, that's where crap accumulates in mine.  Pull the flywheel, you're likely to see a bunch of shit stuck to the stator and rotor. 

Thanks for the advice flyandride, probably safer just to keep oil only in there. Didn't think of the crap accumulating in the clutch and alternator areas. I want to repaint those covers anyway so I'll do it while the engine is still out of the bike.


Got my frame all stripped down and ready for some new paint, wanted to start with the etch primer today but it's raining here so will have to wait till it passes.


Sorry for all the crap in the pic, haven't cleaned my garage in about a year (Just concentrate on the frame :smirk: )



Got my new fuel tank today :banana:


It's a Clarke 2.8 Gallon or 10.6L tank, stock was 10L on my bike.

Ooohh Shiny :D






Out of curiosity - should I start a rebuild thread of my bike instead of posting it on here?

Do guys do and enjoy following a rebuild thread?


I did a 3 1/2 year 100 page plus thread of me building a bass boat from start to finish on one of the boat building forums and it was a hoot :smirk:

Go for it! I'd start a new thread though.

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