2010 TXC 250 Valve Adjustment

COFFEE EDIT: Link to copy of this in the Tech Ref area: http://www.cafehusky.com/threads/2010-txc-250-valve-adjustment.17407/

I've got about 70 hrs and 700 miles on her now. After hydro-locking it in a puddle a few days ago I decided to give the valves a tickle with the feeler gauge since I already had the valve cover off. The owner's manual calls for Exhaust to be .008, Intake .006 (all measurements in inches), rats! A quick call to Tasky's reveals they like .006-.008 on Exhaust and .004-.006 on Intake, I'm still out of luck so....... I now have an excuse to go see the brand new 310, 449 and 511 they have on the floor while I snag a shim.


The above image shows the timing marks for TDC in RED. They need to be positioned horizontal as somewhat depicted by the GREEN arrow. You'll also notice that both intake and exhaust valve lobes will be angled toward the spark plug equally at about 45 deg. as another method of verification. I used the kickstart lever to line it up, just takes light touch with the spark plug removed.




These x-lite motors are shim-under-bucket style, meaning the cams ride directly on the valve buckets instead of the older engine's method of having the sliding "follower" between the cam and the shim. You have to remove the cam and the bucket to get to the shim, which rests right on top of the valve stem. I used a strong magnet to extract the bucket and shim as one. CAUTION: you need to have a rag or something stuffed down the cam chain channel during disassembly and reassembly to prevent an errant shim or bolt or other FOD from falling into that channel and into the netherworld at the bottom end. My tight valve had a 1.65 mm shim. Did the math and determined I either needed a 1.60 or 1.55 so I took both at the dealer's gentle prodding. I tried the 1.55mm first and it brought the valve right to .008, perfect!



Circled in GREEN above is the left hand exhaust lobe with the edge of the bucket barely visible underneath it.

Now for the REAL reason I wanted to post this thread. The 3 socket head bolts circled in RED above are specific to the locations you see them in! The workshop manual is WRONG with the pictures it provides as reference for the Exhaust cam hardware installation! The Intake cam picture is the correct reference for the Exhaust cam. You will notice this yourself if you take note of each of the 6 bolts as you remove them. The 3 M5 bolts NOT circled are interchangeable. I caught this when finger tightening the bolts and found one of them to bottom out before the bolt head was making contact.

The 2 M6 bolts get 88 in/lb's of torque and the 4 M5 bolts got 48 in/lb.

That's about it. I thought the bike was pretty clean before starting this job but the camera makes it look completely filthy. I blew all loose dirt away from around and above the engine area to minimize the amount of crud that might fall into the top end while it was exposed. Hope this helps somebody else along the way.

Nice work Greg !!!

I just need to start stalking all your threads. Great walkthrough and tips!

I also noticed that little spring on the end of the exhaust cam is different on your bike than on mine. Mine is a straight line and yours has a little bend in it. I wonder if that has an effect on anything.

Good contribution, always like to see the tech pics.

Yes, very helpful. Thanks.

All looks good - now time to ride!

Trying to get 'er to start now. Not quite starting but is cranking over like normal. I did put a short burst of WD-40 in the cylinder through the spark plug hole a couple days ago to help displace water and hopefully prevent corrosion while I took my time reassembling things. Wonder if that doused the plug? Timing cam timing was double checked. iBeat doesn't show any failures. Charging the battery for a little bit to go try again.

Jeff, am I the first to try the new style of plug in this bike by any chance? Wasn't sure how to gap it with 2 tangs instead of one. Hmmmm.

It's alive! Just needed a bit more cranking with a charged battery. I think there was still a bit of moisture in the cylinder too. Purrrrrs like a kitten now. Whew

I don't know, to be honest. The workshop manual doesn't have any real clear pictures that show the spring. I believe that whole assembly is the automatic decompression mechanism. The spring holds the little flyweight close to center of rotation until a certain RPM is reached then it moves outward or something like that. I could be way off on that theory, though.

Just curious, was that the first time you checked your valve clearance? The reason I'm asking is that I don't know how often to check my valves on my 2011 310. Manual says after 4 hours initially but after that I would like to know real world time frames and longevity of this motors valves. Thanks!

Yep, first time. Checking earlier would be smarter IMO in case they aren't in spec from the factory.

Ten hrs. on the older motors. Personally I would do the same on the new one's unless specified otherwise.

According to the service manual is 15 -30 hours depending on how hard you ride the bike

Old thread revived....

Reading the workshop manual, they break up checking the clearances and removing the cams into seperate sections leaving me with a question...?

Do you have to remove the alternator cover to expose the 17mm nut on the main crank to move the piston up or down, or can you leave this cover on and just use the old engine in gear and rotate tire?

Seems like removing the cams is easier than my Yamaha's - on those the cam chain actually goes around the cams and so taking out the E and I cams requires a few more steps. This looks fairly straightforward!

Thansk ioneater for the pics! Cheers, JB

I just use the kickstarter, but your method probably works just as well. No need to remove the alternator cover.

Cam removal is quite easy...just be careful with the wimpy little bolts holding the cam covers on as they have been known to lift threads out of the hole. Hopefully all will be in spec and you won't even have to mess with that. I just stripped my KTM backup bike down tonight and it has the cam chain-over-cams setup like your Yamaha. I'm not looking forward to putting it back together!

Thank you sir.

I will try to avoid stripping the threads. Been doing a bit of that on another bike and don't feel like having to by another size heli-coil or timesert kit for a while.

Best of luck with the other bike

45in lb MAX on the 5mm cam cap bolts....even if they are tighter than heck when you take them out.

get a 1/4 torque wrench...no shortcuts!

Yes I had to get the small torq wrench as well. Are you folks using loc tite on theses going back in, considering everything is covered in oil?

Also, these are the same size shims as the recent, older engines?

The X-Lites use 7.48 shims like a Honda CRF 250 or Yamaha YZ250F.