Engine timing

Hey everyone, this is my first post on the forum so I just wanted to introduce myself. My name is Chris and im an 18 year old from the Boston area in MA. Now that thats cleared up, my real reason for posting.

I have a 1981 kz1100 that was running great until one day when I started it, and the cylinder head got a hole blown out of it. Turns out one of the cam lobes nailed right through it however the damage doesn't go past the head. So, I got a used head, pulled the damaged one off, and now I just need to do a few things before reassembly and hopefully a running classic bike.

I would like to adjust the valves on the new head while its on the bench; i've read all posts about it and have a manual but still don't know the procedure, any tips would be appreciated. Next, I'm at a point where I have a new head, and my engine is stripped down to the block. I plan on replacing the head gasket obviously, but should I go for valve stem seals and anything else while im in here?

finally engine timing. I pulled the side cover exposing the crank bolt to turn the engine over but I can't see the timing marks. I also don't quite understand the procedure on how to time the engine using the cam sprockets and timing marks. (I've done this before on a 4 stroke yamaha 225 dirtbike but this is harder). It also looks pretty tough to get the timing chain onto the sprockets while doing so.. Is it as hard as it looks? And just in case I mess up is this an interference motor?

Sorry for the lengthy post I just have alot of questions and I'm dying to get this project going. Thanks everyone for your time, this forum looks impressive.

Post edited by: 81kz1100, at: 2007/01/03 11:13

Howdy... Let's see... you want to know about:
1. valve / cam timing
2. valve adjustment
3. cylinder head tips

Let's talk the last item first as it is the easiest. Get or build a valve spring compressor and disassemble the head. Replace the valve stem oil seals and lap the valves. Check for play in the guides by putting a valve in after disassembly and see if it will wiggle. When you have the head apart, clean the combustion chamber with a wire brush wheel on a drill (fine brush). The valve stem oil seals will need replacing.

To adjust valve timing, make sure you have the exhaust cam first. Then rotate the engine using the 17mm nut on the crank end under the points cover so that the mark on the engine case aligns with mark above the T for the 1.4 (one and four) cylinder. Pull the hyvo chain out towards the front as much as possible as it tends to bunch on the crank sprocket. Slip the exh cam in and align the EXH mark towards the front of the bike so that it aligns on the valve cover gasket mating surface. The notch in the exh cam should be on the right and visible since you will be working from that side. The notch should be pointing to the front. Pull the chain out and stick the INT cam in... notch should be on your side again. Point the IN (intake) line at the rear of the bike at the rear valve cover gasket mating surface. Now, you need to get this right so try and follow... it is easier to show that tell but I am trying... on the exh cam, there is a line next to the EX pointing at the front at the gasket mating surface. The CAM CHAIN PIN next to the line is counted as ZERO (0)... start counting from that pin with the next pin as one and count to 44. Move the intake cam so that the line from the IN will line up with this 44th pin. It helps to use a Sharpie and mark every 10th pin. Recount a couple times. I will attach a pic of what it is supposed to look like at the bottom. Torque the cam cap bolts to 12 ft/lbs.

Valve timing is critical because if you don't get it right, you will end up bending the valves in your new cylinder head. It would be pretty hard to check clearances and adjust before reassembly. I suggest you wait till you get the head on. Once you do, roll the engine to TDC for 1 & 4. Only one of them will be at actual TDC and that is the valve on the exh side and intake side that has the lobe pointing DIRECTLY away from the bucket. Measure the clearance using a metric feeler guage. Sears/Craftsman sells them with gauges that are thin enough (down to .051mm). Roll the crank over 360 degrees and do the other exh and intake cams. Measure the other clearance... etc. Once you have all the measurements, you can read how to adjust the valves in a how-to article I wrote for the 903/1015cc engines on my web site. The procedure is the same for the J motor.

Wiredgeorge,
Thanks for the response, in my manual it attempts to explain the 44th pin however it made no sense to me. Now I understand how that whole deal works. So there are actually timing marks near the crank bolt huh? The dimly lit garage must not have helped with seeing those.I think this bike will run, just finished cleaning the carbs and they really weren't dirty. Thanks alot for the help.

PS If I finish it I'm going to post pictures and maybe take a video to show.

Do what you like but here's the bottom line on the head.

While it's certainly easy on your bank account to just lap the valves in and install new valve seals, it's not the best way to go about it.

A proper valve job is the real solution.

Also, it's not very common at all for a stock motor to do what yours did. You need to investigate what happened to cause the desctruction of the head.

In all my years of working on KZ's, I have yet to see a stock cammed motor do what yours did...