Keeping The Valves Fresh

[tigmaster]

For all you four strokers out there, many of you probably over look this. Keeping your valves shimmed properly is a big thing. I know it’s not too fun to get to them, but you should check them often. To get to your valves, you’re going to want to remove your radiator shrouds and gas tank. Not that big of a deal is it? Well now take your valve cover off and the two caps on the stator cover side. Now find a socket that fits the size of the bolt that you can see through the larger cap cover. Turn the engine over with a ratchet on that bolt the same direction you would kick start it. While looking through the smaller cover hole you will see a single mark pass, ignore that. Then you will see one mark pass and right after that another. Line that mark up with the slit cut in the hole. I know I’m sorry I can’t explain better, but you will see what I mean. Now you are ready to check tolerances. Get yourself a set of shims aka feeler gauges. Slip them between the cam lobes and the bucket that they hit. Compare the readings you get with those in your manual or obtained by asking a dealer. Just for reference mine is 0.006-0.008 inches for exhaust and 0.004-0.006 inches. If you can’t fit a shim in there then you should not ride your bike until you buy the correct shim, because valve damage can occur. As long as you can fit a shim in there, you are theoretically able to ride, just try to fix it soon. Now say you’re off. First you need to remove the cam chain tensioner, those two small bolts with a larger one in the middle on the side of your engine. Remove the big one first. Now on your tensioner there is a foot that sticks out. It will go out yet not come back in. look on the side of it for grooves. There will be a device resting on those grooves, pivot it up and push the foot part back into the tensioner device. There now your cam chain tensioner is reset. Ok now you are going to need to remove the cam shafts over the faulty valves. Cams are held on with four bolts usually. Remove the timing chain from the cam, trying to keep it on the other cam not skipping a link or anything. Now you need to pull the bucket off which the cam lobe rides on. These usually have tight tolerances and are oily and I have found that a magnet makes it easy to pull them out. Now usually in the bottom inside of the bucket there will be a shim stuck to it or still on the valve retainer. Remove the shim. Now on the shim there will be a number measurement. Here you now have to use math. Say your tolerances for valve shimming or between 0.006 and 0.008. I would recommend you pick a nice number like 0.007 to shoot for. Now take 0.007 minus the maximum thickness shim you could fit in there. Say I could only get a .002 in there, so 0.007-0.002 = 0.005. Now subtract this from the thickness of the shim. Say I have a 0.125 shim. So 0.125-0.005 = 0.120 So you now go to the dealer and buy this shim size. There you go. Now when putting it back together there is only one important thing, timing. Now on your camshafts there are two marks 90 degrees apart. On the cam in the back of the engine the marks should be pointing up and the other pointing towards the back and lined up with the case. Do the same with the front cam, but the mark should be aligned with the front of the case. Pull the timing chain tight against the bottom crankshaft timing sprocket. Make sure your timing mark still lines up in that small cover hole. Wrap the chain around the exhaust cam making sure to keep the marks lined up the keeping the chain tight wrap it around the intake cam. With the chain tight makes sure all the marks still line up. Check the clearances of the valves again and if good put everything back together and your good. I want to warn you though to be extremely careful with timing or bad stuff happens. Make sure the tension bolts are tight also. He number of times you should shim your valves is very debatable but if you have done it more than 4 times you should consider replacing them. If you shim your valves too often you risk breaking the head off of the valves. So now good luck with this process and let me know if you have any questions.

[JThompson]

Wow thanks that was a good one

[wr250f95]

tdc marks vary from bike to bike.

[tigmaster]

ya but they are usually made very obvious.

[DAVO]

cheers matey i will past the information on 2 my friend

[tigmaster]

no problem