Here is my written instructions for the cam chain tensioner and valve adjustment incase someone wants to print it out for their shop.
First, for safety, unhook the battery and make sure the key is out and ignition off!Cam chain tensioner: warm the engine up if you can. About 3 minutes worth. Remove the plugs for easy engine rotation. Take the left side cover off. The circular one next to the gear shifter that says Yamaha. Just the round cover though, not the whole side cover. In there you will see your stator/rotor assembly. When you look at it and make note of a couple things. Think of it as a clock. At 3 o'clock is a little oval looking black thing on TCI engines. That is the "pick-up". At 5 O'clock is the timing plate. This tells you what, where, and when your engine is and fires. The "T" means TDC or Top Dead Center which means the piston is all the way up. Look through the spark plug hole and you can see the top of the piston. The rotor (the big round, brown metal piece) spins. The 17mm nut in the middle will turn it and the engine. On the rotor there is a little timing mark/line. When this mark is on "T" it's at TDC. Get it so far? The big silver/ grey piece that covers the rotor, and has the "pick-up" on it, is the “stator". At 8 O'clock are your "brushes" Use a 17mm socket to turn the engine counter-clockwise and counter-clockwise only! So if you are looking at the stator/rotor turn the engine counter-clockwise. When you do this watch how the engine turns and goes to TDC and also notice how the timing mark/line wants to pass by the "T" mark. If it does, do not rotate the engine back, go back around. A wrench might work better until you get a feel for it. You need to do this for 2 reasons. 1) to keep the cam chain tight on the cam chain guide. 2) for the valve adjustment later. If you want, hand push the kick starter and you can see how the engine turns. It makes this a whole lot easier when the plugs are out, which takes the compression out of the equation. Got it? Ok, cam chain tensioner. It's the big acorn nut cap below the carbs. Know what I mean? Remove the cap. You'll see the threaded body and a little 10mm nut in the middle. In the center of the nut is a little pin. Now, turn the engine, use the kicker if you want. The little pin will go in and out. Or not.
Touch the inside of the 10mm nut you'll feel it. This "pin", per manual, should be flush with the nut. I like it to move just a bit. About 1mm in/out. I do this to make sure it's not too tight. To tighten or loosen simply turn the nut. Tightening the nut will make more of the pin protrude, lossening will decrease the amount of protrusion. You must loosen the 27mm lock nut before attempting to tighten/loosen the adjuster. You might need to use a socket to get some leverage. Just turn it a little at a time and re-check. Flush or moving just a bit. No more that 1mm. Ok? Turn the engine over a few times and watch it.
That's it. Then put the acorn nut cap on and tighten it down. Just firm, don't crank it tight. Also, check the O-ring in the cap. It goes in the cap, in the groove. make sure it's pliable and there.
It's good to check this when the engine is warm, BUT the next step is the valves and they need to be "cold" adjusted.
Valves:
The engine needs to be cold for this adjustment!You need to set the engine at TDC for the specific side, and valve, you are working on. DO NOT set the engine at TDC and adjust all 4 valves. If you are adjusting the left side valves, then the left piston needs to be set at TDC. Right side valves, right side piston needsto be at TDC.!! You will need feeler gauges for this.
Be sure to check the manual for your specific year and model for proper valve clearences! Make sure you have the next size up as well. When you check the valves the correct size will fit and just drag, but the next size up should not fit at all.
Ok, the engine should be cold. So, you adjusted the cam chain tensioner first.
Now, plugs are out, you know how to rotate the engine counter clockwise. Take the tappet inspection covers off of the top of the engine. There are 4 of them. Not the round covers right above the spark plugs, but the ones on either side. The ones on the front of the engine, above the exhaust pipe is the exhaust valves. The ones above the carb boots are the intake/inlet. Try not to damage the gaskets, if they have them. You will see a rubber O-ring in the cover. They are on the later models and should be enough, but I use a gasket as well. The covers are a little tough to get off. Don't beat them, but use something thin to kind of pry them off gingerly. The carb boot vacuum barbs get in the way too. Do not damage the rubber plug over them. They need to be on when the engine is running or it will cause a severe air leak.
Rotate the engine around a few times and watch the valves work. Here's what you need to look for to be on TDC for the correct valve. Adjust one valve at a time, one side at a time! .
The engine timing mark needs to be on "T". Remember if it goes past to go around again, not back. Every time you put the mark on "T", get it to be at the same place each time. I usually get it directly over the "T".
Watch the valves. When the engine is at TDC for the side you are adjusting the valves will work like this as you rotate the engine. Exhaust valve will open, so the rocker arm will push the valve down into the head, compressing the valve spring, opening the valve. The piston will be moving up. Then the exhaust will start to close and the intake will begin to open. The piston is going back down now, pulling air/fuel from the carbs into the cylinder. Then when the intake valve is closed the piston is at the bottom moving back up. Both valves will be closed. This is the compression stroke. Once you see the intake valve close, stop turning the rotor and prepare to set the rotor mark on the "T".
Now move to the rotor and slowly turn it counter-clockwise until the mark aligns with the "T". You can look into the spark plug hole and you will see the top of the piston. So, exhaust opens/piston going up, intake opens/piston going down, both valves closed/piston going up and you slowly set the mark on the "T" and you can see the piston in the spark plug hole, then the engine is at TDC. When the piston is at TDC and ready for valve clearance check, the rockers will not be touching the valves and the feeler gauges will fit between the "tappet" (square head screw in the lock nut in the rocker) and the valve stem.
Try this first to get an understanding of how it works.
We'll start with the intake valve on the left side cylinder. Now that you have the piston at TDC for the left cylinder, slide the correct feeler gauge between the tappet and the valve stem. It should just drag. Not loose and you shouldn't have to force it. Then, if it just drags, try the next size up. It should not fit. It's called a "Go, No-go". Correct "Goes", next size up "No-go". If the next size up fits the valve tappet is loose. If the correct doesn't fit, it's too tight. To adjust them you use a 10mm wrench and loosen the lock nut, turning the tappet tight or loose. The lock nut holds the tappet in place. So, if you adjust it so the clearance (lash) is correct, you need to lock down the nut so it doesn't move. When you tighten the nut, don't crank it because the tappet will turn a little. You want it tight, but not killed. Over-tightening it can also stretch the tappet and actually cause it to widen the gap. Then it's too loose. The best way to do it is to put the box end of the wrench on the lock-nut, then put the tappet adjustment tool on the tappet. Now, holding the tappet firmly, unlock the nut. This will keep the tappet from turning. Use this same procedure when tightening the lock-nut. If you just turn the nut the tappet will move. (Note: I use the hex head tappets form Mike's XS. They are much easier to adjust.) You can put the feeler gauge between the tappet and tighten/loosen the tappet until you get the correct clearence "feel". The correct gauge should go and the next size up should not. Then tighten the lock-nut. After you tighten the lock-nut re-check the clearence. It can be off even after you did this. This is a pain and you will want to throw stuff and cuss. It's either a bit too much or not enough, a pain, ugh, but it has to be done. Walk away if needed. Once the correct gauge fits, but the next size doesn't and the nut is tightened you wll want to rotate the engine around. Just like the way you set it to TDC. Exhaust open, exhaust closes, intake opens, both closed TDC, mark right on "T". now check it again. The "lash" clearance will probably be off. Don't flip out. It happens to me every damn time. Think about it this way. If that happens on one rotation, imagine what will happen to the engine if you don't set them correctly. Adjust it again. Good goes, next size up doesn't, hold the screw and tighten the nut, rotate the engine around and re-check. Do this until it is set correctly!!
A pain? Yes, but it needs to be done correctly.
Each valve has to go thru this cycle. Do not just get it TDC, mark on "T" and set all four valves. Each one has to go thru the rotation setting cycle!!!, each time you adjust each valve. Believe me. Once you do it a couple times you can do it in your sleep.
Re-read this a couple times if needed and watch how the engine works.
When you have adjusted each valve individually using the rotation setting method and each valve is correct with the Go- No-go put the covers back on and you're done.
