The reason I was asking about the head being machined or if you were running a base gasket was, I thought you might have been trying to get more HP out of the motor, First thing anyone does thats serious about it has the head machined to bump up the compression ratio, If you get aggressive and grind off 112 thousands or more, you get to a point where you dont drop the cams in per what the book says,So I installed a new head gasket because I measured my compression back before I took the engine apart, and I was getting significantly lower compression on cylinders 2 & 3 than the other two (AKA two adjacent cylinders). After the head gasket change, one of two of the cylinders jumped to the 90psi range with the others. Yes, I do have a cylinder base gasket. No, I did not get anything machined during my rebuild. I asked a question on this forum about whether or not I would need to get the head machined, and I was told that I did not need to do it because the engine doesn't warp enough for that.
As for the valve lash, I had never heard of this term until now (unless it's just a fancier word for valve clearance). I've seen the manual I'm working with talk about setting valve clearances, but I didn't think is was possible to adjust the clearance (or lash) without individual rocker arms for each valve (or each pair of valves). When you say "wiggle the rockers," are you talking about wiggling the cams, wiggling the cam lobes, or wiggling the camshaft cap? Wiggling the cap for specifically intake or exhaust valves doesn't sound possible because it's one big piece of metal. Oh and when you say "bucket" you're talking about the cam lobes right?
I would hope carbon build up isn't the issue because I lapped my valves before reinstalling them, so they were squeaky clean. There wasn't too much to begin with since the bike only has 14k miles on it. Your explanation makes sense though, so thank you for the detailed response.
I'll take a picture of my timing at the #4 TDC mark, and you guys can tell me if it's off or not. Please let me know if I should take any other pictures.
I did that on a 85 zx 900. We did a lot of work on that motor, Falicon lightened the crank, shot peened the rods, web cams, ported the head, 1990 zx 11 valves, shimmed up the valve springs for more open seat pressure, We machiened the cam gears so we could degree the cams, No base gasket, punched / bored the cylinder and went as big as we could with some wiseco pistons as well ran a billet clutch basket etc etc etc,
I know I know, Wiseco doent know what round means but I had a shitload of money into it and $1000 set of pistons was out of the question so I went with Weiscos. The piston kit came with a cylinder head gasket. That dam gasket must have been 3/16". Leave it to Weisco to avoid any issues with piston to valve clearances with their big bore Hi Comp pistons by supplying a ridiculously thick head gasket so the pistons and valves could not possibly touch.
Any of the machining we did would be for nothing if we used that head gasket. I bought an OEM head gasket and had to remove a small amount of material in the cylinder holes because the OEM head gasket cylinder holes aren't as big as the amount we punched out the cylinders for the weisco pistons. We got it running good but my compression numbers were like 160 psi, I remember we were having trouble degreeing the cams and couldn't get it to where we wanted it. I cant remember why but we had to get back into the top end and after carefully inspecting everything just off of a visual we dropped the cams in wrong, the factory marks were redundant because we took so much material off the head + no base gasket the factory marks dropped below where you could see them, What I saw that caught my eye was the cam lobes for the intake and exhaust were not 180 degrees opposing one in other, But the factory index marks were correct. We dropped the cams in 1 tooth difference and the lobes looked like they were supposed to be, But the cam gear index marks looked wrong. We re degree the cams it and got it locked in at ??????? I can't remember but it was where it needed to be,
My compression numbers were now at 205 psi in every hole. That bike now ran like a raped ape. Dyno pulls were in the 140 HP range, Stock was 85 HP.
Thats why I asked you about machining the head + no base gasket, Your compression number are low and was trying to establish where your cams were installed,
LOL reg Lash / Clearance, I think Valve clearance sounds way more scientific and correct, Lash is the term my car gearhead guy friends and my dad use. But yes were talking about the same thing. And yes, the buckets are the pocket at the top of the valve stems where the shim or tappet goes to obtain the correct valve clearance.
I was asking if at top dead center you could wiggle or move the rockers up and down at all was to determine if there was in fact some clearance and an incorrect adjustment had the valve hanging open and causing to low compression numbers because what you got going on is not right.
Also to just make it easier I suggested you remove the cams to remove that from the mix as a clearance problem and do the leakdown test again, also it with the cams removed it would make it a lot easier to tap the shim or tappet in the bucket to see if that helps the amount of leakdown. If you did all that and had dam near zero leakdown We could assume you need to lash the valves correctly with proper shims and your problems would be solved.