Cam Chain Tensioner Extenders Installation

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From experience, some personal insights on cam chain tensioners.

Although almost everyone who has checked or extended cam chain tensioners has done so with minimal problems, I don't think the potential for problems should be under-estimated. Things can go wrong very easily, as they did for me. If they do and you are lucky, you'll only need to pull the engine, take off the rocker cover and rocker case, re-time the chain, and put everything back together again. Figure 40 man-hours plus gaskets, etc. And hope you live relatively close to Mac. If you're not lucky, it could be catastrophic engine damage. It's not clear if the valves can contact the pistons in our bikes.

The things to avoid are:
1) Don't ever loosen the screws holding the tensioner body to the the jug and then retighten them. When you loosen the screws, the tensioner will extend. When you re-tighten them, the tensioner can't retract, and will therefore overtighten the chain. The tensioner must be removed and reset if the screws are loosened.
2) If you remove the cap to check the tensioner, don't accidently push the rod into the body further than the spring automatically has pushed it in. Otherwise, you will again overtighten the chain.
3) If you remove the tensioner, make sure the rod is fully retracted when you are re-inserting it. Don't accidently push it in while you are inserting it. However, once it is inserted and fully seated, gently push it in until it contacts the guide so that any slack in the chain is taken up, preventing any chance of the chain slipping. Don't push it in too hard though or you risk overtightening the chain.
4) Don't remove a tensioner without first insuring that the related cylinder is at top dead center on the compression stroke. Otherwise, an open valve can close under the pressure of its spring, spinning the camshaft and slipping the timing. Important to note that there is absolutely nothing that prevents the chain from slipping on the gear other than gravity and friction, neither of which are guarantees in this situation.
5) After the extenders are added, I would recommend spinning the engine several times by hand to insure that everything is working correctly before spinning the starter. This is easy to do if you followed step 4 above by pulling the left side cover and removing the cap over the timing marks and the nut on the end of crankshaft. Insure the crank is spun counter-clockwise, or you risk upsetting the timing.

Note: If you loosen a tensioner and there is a lot of pressure pushing it out, then the valves are open and the chain is under tension. Same applies if you are putting a tensioner back in, and you have to push hard to get it in. If that happens, do nothing to disturb that chain while the tensioner is out, or you risk slipping the chain. Get the tensioner back in as quickly as you can. Better yet, follow step 4 above. If you hear a short whirring noise and the tensioner then goes back in easily, the chain has slipped and you will need to pull the engine to reset it.

Note: Although it isn't foolproof, there is a way to determine if the valve timing may have slipped by removing the spark plug tubes. If you do, you can see the very bottom of the camshaft gear. You will need a bright light, and a small mirror is helpful. If you spin the engine by hand, you will see the following marks appear at the bottom of the gear: an F or an R (front or rear jug) with a line and a paint mark, an F or an R, and a line. You will also see an F and R appear in the timing window. Spin the engine until the F appears in the timing window. Then look for the F on the bottom of the gear for the front jug. Don't confuse the F for the F with the line and paint mark. If you don't see it, spin the engine until the F appears again in the timing window. You should then see the F on the bottom of the gear. If you don't see it either time, you may have a problem. It should appear every other spin of the crank. When you see it, the piston should be at TDC exhaust. When you don't, the piston should be at TDC compression. Do the same for the rear cylinder, but look for an R instead of an F.

Note: All the above applies to a 2008 Nomad 1600. Not sure how it relates to 1500's.
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Tom Maziarz (tomm)
Kawanow #00766
2008 Kawasaki Nomad (Black)
1978 Suzuki GS750EC
1974 Honda CB360T