TOPIC:

MediumB wrote: Added. I know the 79 and newer has an auto adjust and nothing is needed. Per Clymer and FSM it would appear I need to run through the entire cam process to ensure I don't detonate the chain, guides or camshaft. Just wanted some fellow confirmation.

If your bike is the type with the chain rub block in the valve cover, removing the valve cover will result in extra slack in the chain and the tensioner will extend. This is a bad thing because when you then go to install the cover later the rub block will press down further on the chain and it will become over tensioned. This is why you should remove the tensioner wedge/spring device from the tensioner before you go to put the cover back on.

The warning does not apply to the 1978 KZ650 B2. That uses a roller chain, and a sprocket system for guiding the cam chain near the valve cover. The warning is for any valve train with an automatic adjuster and Hyvo cam chain which uses rubbing blocks as guides in the valve cover.

I now see we are dealing with two different KZ's.. My replies have only been for the original bike in this thread, the Kz550.

As loudhvx stated the valve cover on the KZ650-B2 can be removed and the gasket replaced without worrying about touching the cam chain tensioner. Ed

I took some photos for the Kz550 cam timing and valve warning page, but it will be some time before I can code it. I'll post some of the raw photos here for illustration.

1st is cyl 1 at TDC of the power stroke.
2nd is cyl 2 at TDC of the power stroke.
3rd is cyl 3 at TDC of the power stroke.
4th is cyl 4 at TDC of the power stroke.

The photos are not presented in firing sequence. Firing sequence would be 1 2 4 3. So that is the order you would see as you rotate the crank from one TDC to the next TDC. (Incidentally, this is basically how all inline-four Kz's would be, with very slight differences in lobe positions, but so slight, they would probably not be discernible in the photos.)

To simplify the manual,
When 1 and 4 are at TDC you are measuring intake clearance.
When 2 and 3 are at TDC you are measuring exhaust clearance.

So expanding to the four possible positions, according to the manual,
With cams in the 1st photo position, you measure intake on 1 and 3.
With cams in the 2nd photo position, you measure exhaust on 2 and 4.
With cams in the 3rd photo position, you measure exhaust on 1 and 3.
With cams in the 4th photo position, you measure intake on 2 and 4.

(Remember these photos are in numerical order, not firing order.)

So, if you follow the text of the manual, explicitly, some lobes will be pointed upward when measuring, and some will be pointed sideways when measuring. None are really pointing exactly away from the valve. (The valves are not vertical.)

I've done it using the manual's method, and using the "pointing away from the valve" method. The results do vary a bit. But if you aim for the middle of the range of clearances you should end up fine.

If I had to recommend one method over another, it would be to follow the FSM, and that includes the instruction on whether to change a shim or not. Don't "aim for the larger end of the clearance".

Perhaps just laziness, but for me it's so easy to just address each valve individually by pointing the cam lobe away and measuring, and not having to align T marks, etc.

Good Fortune!

You don't need the crank at TDC or what have you, you just need both adjacent valves on the base circle at the same time.

BTW, Suzuki GS bikes position their cams the same way as KZ bikes.

Well, that's sort of the question... whether or not to follow the instructions explicitly or just point the cams away from the valves. I've done both, and there is a slight difference, but usually not enough to make a huge difference as long as you are not trying to hit the very top limit of the clearance range (which is a bad idea anyway). The base circle is pretty big, but depending on position, other valves are compressed or not, and that will affect how much the camshaft is deflected, which will affect the measurement.

Following the manual means being at TDC , at least in the 550 manual. If we assume there is no camshaft deflection (either by bending or moving within the bearing), and we assume the base circle is perfectly round (measuring it shows slight imperfections) then the Clymer's instruction will be the same as the FSM. In practice, the results are not exactly the same. The cmashaft does deflect a tiny bit, and the base circles are not perfectly round.

You can't go wrong with measuring the valve clearance with the cam lobe pointed directly away from the cam follower, no matter what engine you have. Any other way is the factory's attempt at saving time in the service department at the dealership, by enabling the technician to check a few valves at a time. You have to be careful, though, as it is very easy to get the measurements wrong if the cam is on the acceleration ramp just off the base circle!

loudhvx wrote: Well, that's sort of the question... whether or not to follow the instructions explicitly or just point the cams away from the valves. I've done both, and there is a slight difference, but usually not enough to make a huge difference as long as you are not trying to hit the very top limit of the clearance range (which is a bad idea anyway). The base circle is pretty big, but depending on position, other valves are compressed or not, and that will affect how much the camshaft is deflected, which will affect the measurement.

Following the manual means being at TDC , at least in the 550 manual. If we assume there is no camshaft deflection (either by bending or moving within the bearing), and we assume the base circle is perfectly round (measuring it shows slight imperfections) then the Clymer's instruction will be the same as the FSM. In practice, the results are not exactly the same. The cmashaft does deflect a tiny bit, and the base circles are not perfectly round.

In my experience the camshaft DOES deflect in the journal clearance when the adjacent valve is not on the base circle. I always make sure both side by side valves are on the base circle so the cam lobes are not pushing up on the cam. My only comment relates to not having to follow a strict TDC approach.

Exhaust valves:
Aim #1 exhaust lobe forward at the gasket surface and then adjust both #1 & #2 exhaust valves. Then repeat with #4 facing forward.

Intake valves:
Aim #1 intake lobe straight up, Doing this will put both #1 & #2 on the base circle so you can check them. Then repeat with #4 facing straight up.

very simple

I am thinking about the dynamics of the running engine and how things like cam journal clearances, cam deflection, imperfections in cam grinding, and adjacent valves can affect valve clearances and timing and such. In that respect, if you are tuning an engine to exact "blueprint" specification, then you would want to use a degree wheel, dial indicator, and piston stop and set the valve lash so the individual cam lobes are centered on the base circle exactly as the valve stem sees it in the running engine, with the cams in their journals and loaded form adjacent valves exactly as the....

Never mind...I'll just point the lobes directly away from the followers and it should work just fine, every time.

Good Fortune!

Patton wrote:

Good Fortune!

Patton - that photo says exactly why you don't want to set valves to tight! Hot combustion gasses squeezing through a small gap (aka an exhaust valve that isn't closed all the way) can remove metal as well as an oxy-acetylene cutting torch!

We had a big block 427 tri-power chevy burn a 1/16" deep , 1/8" wide channel in the block between two cylinders when the head gasket failed. Did a leak down test and air was blowing out the ports of the neighboring cylinder!