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How to: 2006 WR250F valve inspection

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What you will need:

5mm allen wrench

8mm socket

10mm socket

17mm socket

flat head screw driver

5/8" swivel plug socket

gasket seal

feeler gauges

pen and paper

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Start by removing the radiator shrouds, seat, and fuel tank.

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Remove the vent hoses and plug wire, then tape a plastic bag around the frame to prevent debris from falling into the motor.

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Remove the spark plug. Remove the valve cover to expose the cams. At this point you will need to go to the left side of the bike, and remove the inspection plug and crankcase plug. Put the bike in neutral , and use the 17 millimeter socket to rotate the crank so that the top dead center mark is aligned through the inspection hole.

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Check the cam lobes now . The exhaust cam should be sitting at the 10 o'clock mark and the intake cam should be sitting at the 2 o'clock mark when looking at the bike from the left side.

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I printed the service specs for the valves and created a date chart at the bottom to write in the specs and the date that they were checked.

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Using the feeler gauges, check the 3 intake valves & 2 exhaust valves to confirm that they are within spec.

Intake tolerance = .10mm-.15mm

Exhaust tolerance = .17mm-.22mm

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If they are out of spec you will have to remove the cams, and re-shim in order to get them within the proper spec. I was fortunate enough not to have to do this at this service interval.

It's a good idea to write the measurements down regardless of whether or not they are out of spec. This way the next time you do a valve check you have a reference point to start by.

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If everything is within intolerance you are good to go, and can now begin reassembly. Start by putting the valve cover back on. A small dab of gasket seal in each corner where the lobe protrudes should serve you well and prevent leaks from the valve cover gasket.

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After you have completed reinstallation of the valve cover, remove the plastic bag and reinstall the remaining parts.

Reinstall or replace the plug. I usually just replace mine at this interval.

Now you are ready to ride!

Edited by mill152
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Awesome work, I love seeing people put in the effort to make these and help out other riders. 👍

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Thanks guys! It's a simple task and will save the life of a motor. Not to mention that dealerships charge, IMO an unreasonable amount to do this. Spend half an hour, save some $$$, extend the life of your motor, and learn something you will always be able to use. Perfect!

Due to the fact that I am on the low end limit for tolerance, I will re-shim and update this "how to" thread when I return from my upcoming trip.

Edited by mill152

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Nice post. I like that piece of paper with the screen shot of the tolerances and the recording chart built in! I will be stealing that idea 😉

This is also the same procedure for the yz250f's and the tolerances you post are the same as well.

meWR and seven you should really look at those valves before you even ride a bike you dont have the history of! It's quick, easy and if you bend a valve youre going to hate yourself for having to fork out up to $800 for a new head, maybe even a cylinder and a piston! Just my 2cents tho.

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This is also the same procedure for the yz250f's and the tolerances you post are the same as well.

Sweet! Didn't know if the tolerances were the same or not, but I'll change the title to reflect.

Never mind....for some reason I am unable to edit the title or delete this comment. Guess I'll just leave it here :D

Edited by mill152

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What does "shimming" mean?

Each valve has a shim of different thickness that holds the lifter within the desired distance from the cam lobe. There are no adjustments you can make to the cam, so you have to shim the valves to keep them in spec.

These are shims:

3522f.jpg

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Still have not checked mine. Time to do it as I plan to ride the bike more this year. Thx for all the good info.

 

I read that one result of not having the valves in the tolerance range is hard starts. Mine starts every time very well, cold or hot.

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Just bit the bullet and checked the valves, and I have a few questions. First of all, on top of what @mill152 shared at the top of this thread, I did remove the top engine bracket

 

   ValveCover 006 Engine Bracket.jpg

 

Everything wast pretty easy actually, I wish I had the balls to do this earlier. Tightening the cover back to spec was guess work as I could not squeeze in the torque wrench, but I think I have that 10Nm dialed in by hand quite well. One thing I want to mention is the type of feeler gauge that will work. I had two, but unfortunately the one with more options was too wide to be useful. Pic highlight the useable one

 

ValveCover 028 Feeler Gauge.jpg

 

As for measurement, I could only use the gauge that provided 0.05, 0.1, 0.15, 0,2 etc. My findings:

 

Exhaust: I could slide in the 0.15, I could not 0.2. So I seem to be good here. (0.17-0.22 recommended)

 

Intake: I could insert the 0.05 in all three, 0.1 in one. So two valves are between 0.05 and 0.1, one is between 0.1 and 0.15. (0.1-0.15 recommended)

 

Is it an issue if two have slightly less than suggested gap? I did run the bike like this all last year.

Edited by meWR250f

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Well the issue is that means they are wearing out. I would have put the shim in there to make them be in spec, then re-checked them periodically to see if they are closing up again and how fast. Usually it will still start/run even if theyre just slightly tight, but eventually there may be no or very little gap and it will become increasingly difficult to start. Either way, if you shim them or dont you need to continue checking on them to keep tabs on any further movement outside of the spec range.

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Well, sounds like I have to take it apart again and learn the entire process. Not a bid deal thinking that dealer asked for between 2-3hours of labour, at 90$/h to check/adjust. Do that every 10 hours and....

 

When you put the chain tensioner back on, how do you know that the chain has not moved it's position on the bottom sprocket? I assume the chain tensioner is just removed, without messing around with it's adjustment.

 

Anyway, found this step-by-step how-to, it's very well done:

 

http://forum.dirtrider.com/discussion/6595328/valve-adjust-procedure-for-yz250fyz400f426f450f/p1

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Just checked mine cause when I bought it the guy told me they were good and I didn't believe him. Thank god they are on the money. Peace of mind is awesome. The oil is brand new and clear and the battery is new and now it's time to ride.

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