This is part two of our KTM 4-stroke top-end piston and ring replacement. In our last video, during disassembly, we discovered we needed a new sleeve, and we sent it off to L.A. Sleeve. They were able to get it back to us good as new. We’re going to install a
Wiseco piston, and the first thing we’re gonna do is
check our ring end gap. Throw a little oil in there, and then you install the ring and push it down with the piston so it’s down a bit into the cylinder. And then on this particular machine, it should measure 13 thousandths. This measurement is critical because as your engine heats up and your rings heat up, you want to make sure there’s room for them to expand so they don’t ruin the cylinder. Now we’re moving on to the oil scraper rings. And this is a spring separator. You want to make sure that the end doesn’t overlap on that. The smaller thin rings actually sit on top up the ring expander. It hold them out. This is where most of the mistakes are made when installing rings on 4-strokes, so take care to make sure it looks very similar to this. Now we’re moving on to the upper ring. It goes on fairly simple. On our circlips, you want to make sure that you install these by twisting and compressing, not by bending. I like to seat the one side. Make sure it clips in there solid. You’re going to oil up the piston again. Get our pin started. Set it on the rod and push it the rest of the way through. I use a paper towel to make sure I don’t
drop the ring down in the motor. And once again, we’re putting this in by rotating it instead of bending it and compressing it. Here I’ve got… putting the base gasket on. And once again, the cylinder goes on. Take your time. Feed you cam chain, your cam guides up through. Now we’re just resting the cylinder under its own weight on the piston. I’m using my fingers to actually compress the rings. Very carefully push them through the tapered edge in the cylinder. Take your time with this step. Now we’ve got the piston in. We’re sliding our cam chains. Tighten them up. Here’s our head that we’ve had Faction MX recondition. They cut the valve seat and bead blasted it so looks good as new. We’ve also replaced our valves, and please refer to our valve replacement video for those instructions. Now we’ve just put our two locating dowels in, and we’re going to set our head gasket on top of the cylinder. Notice the piston is at top dead center, and it’s going to make it a lot easier
to find top dead center on the crank here in a minute. Now we’re setting the head on, pulling our cam chain through. Line it up, and then our head bolts with washers. We’re going to tighten those down. And for this motor, it’s 30-35 foot-pounds. Always refer to your service manual for these important specifications. There’s the three bolts that go in from the underside that need to be reinstalled. And now we’re going to find top dead center on the crank. So you remove this Alan bolt, the lockdown bolt. Remove the copper washer off of it, and reinstall the bolt. The bolt has a tapered edge on it, so it makes finding the notch in the crank little easier. And what I’m doing is I’m just rotating the engine back and forth and actually feeling for the notch. Once you get it to top dead center, we can move on to the cam. We’re lubing up the lobes, and we’re setting the cam in with the lobes, generally down for right now. There’s a collar on the end by the water pump that needs to go into a groove. These alignment marks need to be horizontal with the top of the head. We’re putting our cam chain on, taking our wires that we’ve had holding it, putting them out. We’re using our new master link that we got from KTM. We’re putting it on. And we’re going to use our chain riveting tool to swage the ends of the cam chain. We’ve also put paper towels back in, so, once again, we don’t drop anything down on the bottom. This tool makes it pretty slick, makes it so it’s a secure master link. Now we’re going to ready the valve cover. Put a little silicone, a little sealant on there — carefully — you don’t want to get too much. You want to make sure it’s evenly coated on both sides, both surfaces. We’re going to slide the valve cover on. Pull up the lifters a little bit. Make sure there’s no binding. It should all sit flush. You’re going to install the bolts. They are at… eight foot-pounds is what this machine calls for. Now we’re on to the cam chain adjuster. We’ve removed the bolt and the spring so we can reset the adjuster. We’ll mount it on the cylinder and tighten it down. Then we’ll give the adjuster a little head start, release it, and then we’ll put the spring and the
tension bolt in. This holds your cam chain tight. It’s automatic. Now we’re on to the water pump cover. And as you can see, we’re using a new gasket from our Tusk top-end gasket kit. Put those on… once again, about eight foot-pounds. Now we’re going to adjust our valves. We’re going back off our justers. And on this model, it’s calling for between four and five thousandths. So we need our feeler gauge. And you want to just slide it underneath, just so there’s slight resistance. And you have your screwdriver actually on your tappet, and hold it in place while you tighten it with a wrench. Move to the other side. And put your tappet cover back on. Now that our valves are adjusted, we can release the lockdown bolt by putting our washer back in. Now we’re reinstalling our oil supply line. Make sure and get the copper washer underneath… and on top. Tighten those both down. Put our ignition cover back on. Tighten it down. Connect it. We’re going to install our carburetor. Make sure it engages in both the intake boots. Tighten them down. Here, we’re reassembling our decompression lever, checking our play in the cable. We don’t want it too tight. Here, we’re tightening our spark plug, putting our cap on. Now we’re putting our throttle cables on, feeding them through the cam. We’re checking our cable play… tightening everything down. Put the cover on it… crankcase breather hose… shifter… head pipe and our shock… silencer… radiators and our radiator hoses. Slide the tank and seat on. We’re adding fluids here. We need to make sure to remove this air purge bolt. This allows both radiators to fill up evenly. Tighten the bolt back down Add the engine oil. And you’re ready to go ride. Make sure and refer to your service manual for proper break-in procedures.