TOPIC:

wrote:

wrote:

Your mark is not horizontal with the head, i can see that in the picture, set the ignition timing marks up at TDC,  then check camshaft marks, also adjust cam chain
tension. i assume the bike has been running well up until now, if it has the timing is not 180 degrees out.

 

The mark is horizontal with the head. Maybe the blue line I put in is misleading.
Already at TDC, exactly.
Camshaft marks: notch is as seen in the pic. It faces rearward (correct) and downward (not supposed to do that, as per the diagram in the manual).

The bike has been running. Not sure about running "well" LOL. Seems a bit agricultural but does run. It started getting rough and uneven at idle when I took it for the short ride yesterday. Then cloncked out once. Started again, seemed normal but then backfiring/afterfiring - I would guess only on one cylinder.

I've had time to whip the cover off one more time. Have a look at this picture and see what you think. What's been bothering me is the angle of the exhaust cam lobe (the one closest to the camera in this pic. According to the diagram, it should be more upward-facing, like the other one next to it (intake valve cam lobe).

I've looked at it really carefully and tbh I see nothing that could be changed to make it resemble the workshop manual diagram. I'm no longer sure that this valve timing has been causing me my issues. It amounts to being less than one tooth out. The cam chain is nice and taut. To me it looks like Kawasaki intended it to be like this.
It isn't 180 degrees out. There is only that one dash mark on the cam gear .There is no arrow, nor any other markings.

I now think my misfiring issue must come from elsewhere. Possibly a vacuum leak that only appears when the cylinder head gets hot.

I've got a few tricks up my sleeve, will try an experiment tomorrow and report back.

Lash is to tight. 
.004 to .007


.
 

Now that's really interesting about the cam lobes not being symmetrical despite the technical drawing in the workshop manual. Makes a lot of sense, thanks.

I've double checked my valve clearances. Adjusted them all - a couple were slightly tight. Will try again when it cools down.

I noticed there is a backfiring issue when the bike is revved up from "cold" (I say cold, but what I mean is after it's been idling for 30 seconds or so in this boiling temperature we have here). It only happens if I very quickly blip the throttle when cold. I suppose this can be expected, as the fuelling system is a Mikuni round slide and a 2-into-1 manifold. After a few minutes I can't recreate a back/afterfire by blipping the throttle.

Now all that's left is to take it for a ride, let it get hot, and see if it shuts itself down again.

I think valve clearance is supposed to be checked with a cold engine.  Your last post seems to suggest you did it warm.

wrote:

I think valve clearance is supposed to be checked with a cold engine.  Your last post seems to suggest you did it warm.

 

Valve clearance should always be checked when the engine is cold, as the point of having valve clearance is for that clearance to reduce as the engine gets hot and the valve stems expand. It was done cold.

Valve clearances were one of the first things I checked and adjusted, when I acquired the bike as a project a few months ago, but I'm not sure I did them correctly back then. The main issue with checking valve clearances on this bike is that the exhaust valves have to be accessed at an angle, going down and back into the valve cover. I have angled feeler gauges, but even then it's tricky, because the lip of the aperture which allows you access to check the exhaust valves gets in the way, making it difficult to check if you have a lot of drag or just a little. The inlet valves are easy to check.

Did not mean to offend.  What caught my eye was when you said "Will try again when it cools down."  I wasn't sure if you meant the engine or the outdoor temperature.

Carry on!

wrote:

Did not mean to offend.  What caught my eye was when you said "Will try again when it cools down."  I wasn't sure if you meant the engine or the outdoor temperature.

Carry on!
 

No worries mate.

It's the weather here. It's too hot to do anything at all.
When it cools down I'll try to ride the bike again. Hopefully there will be some discernable improvement when I do so.

I continue to suspect an elusive vacuum leak. It has one of those 11th Hour 2-into-1 manifolds, and a VM34. I've sprayed copious amounts of electrical contact cleaner around absolutely everything: the carb rubber joint and the manifold-to-head connection. No change at all. However, that doesn't mean there isn't some really tight vacuum leak that appears when it gets hot.

I say this because the cylinder head is damaged. A previous owner must have overtightened one of the inlet rubbers, and stripped out the hole to the cylinder head. Then, they tapped out a new, larger hole where the previous one was. As a result, the surface between the manifold and the cylinder is very thin in that one place. There is a possibility there's an elusive vacuum leak there. I have some carb cleaner on its way to me and will try to make any vacuum leak reveal itself.

PROBLEM IDENTIFIED!

It wasn't the valve timing after all.

There's a tiny vacuum leak in the cylinder head. No amount of tightening stuff up will make any different, as there isn't enough aluminium around the right-side intake. This is all because some previous owner had overtightened that bolt, and then drilled and tapped in, causing chunks of aluminium to fall out. When you look at it, it looks sufficient to hold on the manifold and create a good seal, but it isn't. Around the intake going into the cylinder, there is only a few mm of aluminium, normally. In my case, this has been reduced a lot on one side.

I wasn't able to identify this vacuum leak before, because my electrical contact cleaner wasn't flammable enough. With the help of some German "montage cleaner", I managed to find the leak.

I could get a local machine shop to fix the head by filling up with aluminium weld then drilling and tapping, but I've found a replacement head complete with valves, and it's on its way to me. I'm not going to bodge it with JB Weld or anything. I'm pretty happy with this situation because I'm completely confident now that everything on the bike is sorted, apart from this. This will also give me an excuse to do some mild porting.

Thanks to everyone who responded.

 fingers crossed it all works out well.