The valves are not opening then, correct.

So the camshaft is not spinning under a load? maybe?

Like under low pressure of a compression test they seem to roll over fine, but higher pressure are holding the valves closed and what, allowing the timing chain to skip?

 

Okay, I pulled up these pictures, Looks like the camshaft drive gear on the crankshaft is most likely uses a keyway? Could that key be sheared? that would allow it to kind of grab sometimes and explain a lot.

Number 11 in the top picture.

 

OK, I made an idiot mistake doing the leak down test with my comp tester. I forgot to take out the shrader valve so NO air was going into the spark plug whole. Sorry for the stupidity!!
So I go that squared away and notice a ton of air coming out the intake. Noticed intake valve was open so I unscrewed it practically all the way out until it stopped leaking air. It bottomed out actually, and I can hardly even get clearance under there. But no air leaking, so has to be much improved. Hook up compression tester for test and I get 0psi. WTF... I check my intake valve and there is about a 1/4 inch gap clearance. So when there is air pressure coming in, there is little clearance and when there is no air pressure there is massive clearance.
Sorry for my misinformation.
I dont see a key within the camshaft, only on the crankshaft, unless I am missing something. attached is a pic from the service manual that may or may not be helpful.

I don't know if a push rod got pushed out of the rocker arm or what, but need to be done with this for now as there is other stuff I am behind on.
Thank a lot for the help.

 

Not sure if I was reading your posts right but you need to have the engine on TDC on the compression stroke when you set valve clearances, any other part of the four stroke cycle and you get a wrong reading, The cam won't have any pressure on it from the valves when it is set at TDC on the compression stroke so shouldn't need holding while you get the cover on if you leave it in that position. There should be timing marks on both cam and engine gear to tell you when they are correctly timed. There has got to be something in the manual about this. If the bush, item 3 on the parts drawing, is worn, you may get problems with the camshaft slopping about.

 

Yes, I adjusted on TDC. I used a big green perm marker to make it obvious.
Its not valves tension. It is, what I assume, coming from the springs in the camshaft assembly. There is two seperate camshaft wheels and they resist slightly from alignment. I have circled in red a blown up pic of what I am talking about from the service manual. you can see the teeth from each seperate camshaft "disc" aren't perfectly aligned. When I install the camshaft, those springs shoot the assembly up out of the gear teeth. I will look into it when I get time to work on the atv again. Good call on the bushing.

 

Merryman
thank you for putting that in bold. It took me a while. I now realize there is a TDC compression and exhaust stroke. Ughhhhh. I thought as long as marks where aligned all was good. However that's not the case.
I still need to tear I to the camshaft. Please see my previous comments regarding the spring and tension

 

Right so the cam gear is split into two with the springs there to cause misalignment. I assume this is to take all backlash out of the assembly, and will tend to make the cam gear try to move away from the crankshaft gear. Seems a bit over the top for a 50cc engine. Have a feeling the 700 King Quad has similar split cam gears. Did you check that top ring gap? Not sure what it should be but the manual should show it. A worn bore is never going to give good compression, though it would be hissing away on the leak down test. In fact, if there are no valve leaks at TDC on compression stroke, head gasket leaks, or leaks past the piston, with a leak down test, that is as good as you are going to get regarding compression. It is just possible it is a very low compression engine. I know I found a new one we sold, to be disappointingly gutless, compared to the two stroke LT50s I normally maintain.

 

I took the cam gear out and discovered that the bushing was not even installed into the upper crankcase/cylinder and luckily I found it on the shop floor haha. Cleaned it up and installed it, camshaft sat much snugger, and I could use two hands to install the generator case cover while eyeballing the camshaft to ensure it stayed in place.
I put the engine back together and did another leakdown test after adjusting the valve clearance. At TDC of compression stroke, there is a very small amount of air coming out the intake(not enough to move a paper towel hovering above it), maybe air coming out exhaust, and small amount of air coming out the generator breather orifice.

I did notice there is some scoring in the cylinder that is noticeable but being nika cylinder, not much I can do.
I did not get a feeler gauge in the Piston ring end gap as I was hoping the missing bushing is the culprit and dreading installing the piston and rings back in the cylinder. Below are my specs. I am going to throw this all back together and see if it will run.
Service Limit (1st): 0.50 mm (0.020 in)
(2nd): 0.50 mm (0.020 in)

 

Wow, 5th pull, much to my surprise it fired up and sounded pretty good. Drove it around a bit still can't get my big butt up a hill but it sounds great, no smoke. Put everything back on, double checked oil, is ready to go for my son right in time getting home from school. A huge thank you to this forum but special call out to Merryman, tiha, and djshad1469. You guys were all spot on with advice, regardless of the bad info/results I was providing you. I can't thank you enough. Feels good to get these parts of my bench!!!! lol
Hopefully it continues to run well and this is the last of the hand-holding in this thread.
Thanks again.

 

Glad it worked out. That missing bush would certainly mess valve lift and timing up.