30% of the way there...

It's not the carburetors, valves or timing.

 

The obvious issue is you have your engine protectors upside down and left to right....

But seriously, is the head gasket twice the thickness? Even if it was it would drop the cr by one point or two (I can't be bothered to work it out), and millions of bikes have run over time on 8 to 1 cr...
Rings? squirt some oil down each bore then do a comp test, if the rings have miracurously worn out between you fitting them and starting the engine it will prove you're right..
So that leaves you still with carbs issues, assuming you have checked your cam timing correctly - easy visual check is the inlet valve starts opening just before tdc, as the exh valve closes - in days of pushrod engines this used to be called "on the rock", it's actually the overlap period. It takes minutes to do, using one of the outer cylinders.
Done all this? all correct? Then I suggest you either send your carbs to one of the gurus on here (i'm not going to name them) or ask to buy a good working set.

 

I assure you, it absolutely is not the carbs.

I know this because even with the carbs off the bike, the cylinders are still only reaching 80psi, which has nothing to do with the carbs. This is a compression issue. And compression issues only come from valves/timing, rings, gaskets, a hole in the piston, or a cracked head.

I just lapped the valves, and checked their clearance, and it is spot on. The timing has been checked and re-checked and is perfect. The head has no cracks, the pistons have no holes. That leaves the shitty internet Chinese head gasket and rings.

 

I can’t imagine how frustrated you must be. You’ve put a ton of time into this bike.

As Minimutly said, you can prove if your rings are the issue fairly easily, and even without tearing into the engine.

As far as the head gasket being the issue - I think the bike would run even if the head gasket wasn’t perfect. I don’t think it would run well.. But I think it would still run / idle.


I think everyone that has owned one of these bikes has gone through their own trials & tribulations dealing with the carburetors. I certainly have. I probably worked on the carburetors by themselves for 50+ hours (over four carb racks), before I got my bike to run properly - and it’s still far from perfect.


I would try to prove the issue before anything drastic.

 

I don't see anywhere in the thread where you mention honing/deglazing the cylinder walls. That might cause a compression issue with new rings.

 

Have you tried another compression gauge?

 

Yes, I did that a few months ago when I had the engine completely torn apart.

 

Does my finger count?

The braille method.

 

The charity run is tomorrow.

I'm attempting a zero hour Hail Mary play.

 

After a VERY long day, I have a dumb question.

Will just changing out the shims correct this, or do I have to do some more grinding?

 

Yes, thinner shims will give you more lash. More grinding would reduce it further.

 

In the skip then?

 

Update:

Got some shit parts from fleabay, the seller refuses to issue a refund, eBay says they don't have the ability to issue a refund from a seller on their own site. So my bank is just going to reverse the charge and get my money back. And I'll never buy anything from eBay ever again.

I ordered parts from MikesXS, thus far I'm not overly impressed with their operation.

...so I'm just waiting for some parts to come in, and I'm only ordering from Len from now on.

 

My experience as a part time seller is anything that is received by the buyer and doesn't work the buyer can return within 30 days, no questions asked. The seller doesn't have much of an option other than to dispute that you didn't return what was shipped. If they don't send you a shipping label to return the non working item eBay doesn't care, they will still pull the funds from the sellers account and the buyer will be told they can just keep the defective item along with the refund. Unfortunately, this policy that favors the buyer also causes sellers a lot of grief as unscrupulous buyers will pull good parts and install bad parts and then submit a does not work claim.

 

And that's is highly recommended by many here to get the known good parts, quick delivery, and a lot of shared knowledge from Len

 

Which parts then?

for carbs I would only use genuine, and if I was in the states I would only buy from Len @chacal , think I've said that more than once...

 

You just keep going on and on about the carbs. Those are like new.

I ordered new valve shims, a new clutch lever, and new starter solenoid. The latter of which, doesn't work (2nd one in a row from two different suppliers, most likely coming out of the same Chinese factory).

 

This is because you have never answered the question about the starter jets in the passage at the bottom of the bowl. Everything can look like new and still have those jets clogged. That will affect starting.
You never answered if you tried another compression gauge. I thought I had low compression using a Harbor Freight gauge but it was junk.

 

I have a nice Snap-On compression gage, but the hose developed a leak. Same thing...I thought I had a motor problem. It was a tool and user problem.

 

I did answer it, you may have missed it though. Yes ALL carb jets, passages and orifices are clear.

The gauge 'could' be an issue, but the valve lash measurements confirmed the issue is the valve clearance is wrong (the valves are being held open just enough to not build sufficient compression. Can't blow up a balloon with holes in it. lol