[Nestercruise]

He says he lapped the valves already. Then the zero lash issue? I'm lost now. Unless lapping closed up the clearances and didn't recheck.

You're correct that I already lapped them. This is my first time checking the clearances. When I took the head off, I lapped all the valves, put the head back together, reinstalled the head and engine, and now I'm troubleshooting the loss of compression. I'm gonna keep going with putting in the new shims and getting the clearances all set. It might be a week before I have another update on the status of this repair because my shims are set to arrive on Friday.

Maybe if I checked the valve clearances before I took the head off the first time, then I would have another piece to the puzzle.

You do all that and your leakdown test will be at 0 % loss.

I heard that you can't actually have 0% loss of air because of the small openings around the valves that allow for the valves to expand when they're hot, right?

And to answer your question of how much I paid for the bike, I got it for $1,400. Probably should've asked for less, but I learned from my mistake. The guy sold it as "not starting" even though it started when I bought it from him. He also said he was afraid that he messed something up with it when he ran it with no exhaust for some time. That's the main reason why I've been so focused on the valves during this entire repair.

 

[Chevy Fan Attic]

Yes, you will never get 0% on a leakdown test.
Ran it with no exhaust,? Like took it for rides with no header???
So did it have the exhaust system on it when you picked it up?

I read the last post yesterday and typed all of my last post out and hit post reply. In that time you posted that you lapped the valves prior. I was thinking well that was a waste of time.
Yes, you will never get 0% on a leakdown test

 

[Nestercruise]

Yes, you will never get 0% on a leakdown test.
Ran it with no exhaust,? Like took it for rides with no header???
So did it have the exhaust system on it when you picked it up?

I read the last post yesterday and typed all of my last post out and hit post reply. In that time you posted that you lapped the valves prior. I was thinking well that was a waste of time.
Yes, you will never get 0% on a leakdown test

Haha I'm sure it'll help someone else out who reads through this post if they have a similar issue. I commend you for going into so much detail though.

And no, the bike had an exhaust and a muffler. I guess I meant to say he ran it without the muffler for a bit. But I've read that that can mess up your exhaust valves because of something to do with change in back pressure.

 

[CrashTheSuzi]

W 7% leakdown u dont need to lap the valves unless there is an actual problem. Put it together, set ur clearances and run it. Check em again in 20k miles.

W using a feeler gauge its go or no-go. Ur not gonna compress a valve spring w.o folding a feeler gauge. Theyre minimum 40 lbs installed pressure. Usually more.

 

[Nestercruise]

Alright my shim kit came early, so I put in the new shims and rechecked the clearances. In order to get to a good clearance, I had to downsize some shims by as much as 0.40mm 😮 With the new shims in and the engine properly timed, I did another compression test. Oddly I'm still reading 95psi across all cylinders (more than I started with, but I guess that's still on the low end). Even if my clearances for each valve aren't exactly in spec, as long as they aren't zero then that shouldn't effect leak down tests or compression tests right? It would only be an issue if the clearances were zero because the valve would be slightly open at TDC.

I'm ruling out piston rings as a cause because I get no difference in compression on a wet vs dry test. I'm also ruling out valve seats having carbon buildup because I lapped all of the valves when I had the cylinder head off.

So my original question of air leaking past the valves has been solved, so huge thank you for the help. I guess my new question, which may be related still, is why is my compression low? The only thing I could think of is a valve issue, but I checked valve wobble and they were all within spec. Maybe I'll go out and pick up a new compression gauge? The one I'm rocking is a $20 one from Amazon, cheap as they get lol.

 

[Chevy Fan Attic]

That $20 comp tester might be the issue. If its not then, Early on I was asking about the cam timing, When you drop the cams in on the # 1 cylinder are the lobes on the intake and exhaust cams facing 180 degrees opposite direction?

 

[Nestercruise]

No, the lobes on cylinder 4 were in opposite directions. The lobes on cylinder 1 were facing inwards towards each other if I remember right. That's how I had it with the timing mark on #4 TDC, the EX mark on the EX cam parallel to the cylinder head cover mating surface facing the exhaust, the IN mark on the IN cam parallel as well facing the intakes, and 30 chain links between the two.

 

[Nestercruise]

Well guys, I'm back with some great news. I went out to Advance Auto and picked up a new compression gauge for a little more $$. Turns out my cheapo one from Amazon crapped out on me because I was cranking 170-180psi in every cylinder on the new gauge. I retested my Amazon one, and it only read 90psi. The gauge would jump up to 90psi in 2 cranks, and then just stop. Kind of annoying because I don't know how long the old gauge was broken, but at least I'm confident I don't have to take the bike apart again. It's still not starting, but that's something I can tinker with to figure out

Really really big thank you to all you guys who helped me out, especially Chevy Fan and Old-n-fast.

For those wondering, the compression gauge I had from Amazon was the one by 8MILELAKE. The new one was by INNOVA. $20 for the Amazon one, $30 for the INNOVA one, but I used the 10mm end from my Amazon kit because the new gauge didn't come with one.

 

[Old-n-fast]

I should have thought about a faulty compression gauge, been down that road too.

 

[Chevy Fan Attic]

Im glad to know that was it because other then the cams being 1 or more teeth off I was out of ideas.
There were a couple of things i needed not so long ago, I went into Autozone and rented it and never returned it, Got a nice torque wrench fort $50.
Kudos to you,
That was very cool for you to drop a message with the outcome, most strangers after we help them out we never hear from them again.

 

[Chevy Fan Attic]

I should have thought about a faulty compression gauge, been down that road too.

Ohh ya Sure,,,, Now you add that,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, : )