Shim problem

[Miles]

Hello folks, this is holding up the rebuild some what.

Found that my shims are out and was told by two very well respected engine tuners that I dont have to put the cam chain on to measure shim clearance. Just the bottom of the lobe to rocker as usual.

So I measured all my clearances by putting the camshats and cam caps in and torquing them to the correct setting.

I picked up my regroud shims, after being ripped off big time, from the machine shop and eagerly got to rebuilding the engine. But guess what, none of the shims are right. All are still way to tight. (I measured the shims and they have been ground to my spec)

Would measuring the clearance at the bottom of the lobe as opposted to what kawasaki say make a difference? I would be inclined to trust the two engine builders that I saw as they have a long history of building car and motorcycle engines but have I just wasted my money and time on the regrind

any thoughts would be welcome.

[zimm]

what shim sizes did you need ? I've always just bought new from kawasaki if I've not had some in the right size in my collection.. on occasion i've reground a couple if i've really needed to because of time restraints/laziness/impatience

what clearances are you aiming at and how tight are the clearances with your new shims ?

*edit, if you measured the clearances and calculated the required shim sizes before it was stripped and the valves lapped and those seats cut, they will all be tight now.

[Miles]

Needed
11 @ 2.95
4 @ 2.90
1@ 3.00

Was aiming for 0.15 inlet, 0.18 Ex

No took the measurements after the head work had been done. They all are too tight when I measure them as per the Kawasaki manual.

If I measure them by what the engine builders told me ie: just the cams and cam caps then measure between the bottom of the lobe and rocker arm, then 99% fit.

But I don't know if I should be going off Kwak or the engine builders.

[zimm]

Can you clarify the detail of and difference between the 2 methods of measuring the clearances that you are comparing >?

I measure the clearance from the base circle, between the rocker and the shim as per the kit manual, but with tighter clearances

0.20 ex
0.15 in

ish

clearance.png

[Miles]

Engine builder way- Put the camshafts in and screw down the cam caps. Don't put the cam chain on. Turn the cams by hand until the lobe is pointing up/ inline with the valve. measure the gap between the bottom of each lobe and the top of the rocker arm.

Kwak- As per service manual. Rebuild timing circuit, piston 1 to TDC, measure various valves etc.

[banner001]

those shim sizes are pretty big, i was expecting them to be more around the 2.75 size, have you had the base circle on the cams ground down? is that why they are so off.

how tight is tight? you wanted 0.15/0.18, what have you been left with? are you out by a set amount all around (i.e. they are all 0.05 too tight) or does it vary?

the manual states to do clearance between cam and rocker arm, thats how ive always done mine, ive never done it rocker over shim before - thats only in the kit manual that way.

[Miles]

No, no work has been done to the camshafts as far as im aware. I get the exact same measurements with the stock cams as I do with my SP set.

Just not happy that when I follow kwak instructions my shims are still way too tight but following the engine builders most, but not all, fit.

So I dont know who to trust on the matter. Im inclined to go for kwak which means I need to reshim again.

[JamieNeve]

I have around 10 shims spare, will measure them tonight/ tomorrow and let you know. Free of charge if they're your needed size!

[Miles]

That would be fantastic as I get the feeling my reground shims are still wrong.

Thanks

[Miles]

I've rebuilt the engine and timed it per manual. My question though is when you turn the engine to piston 1 at TDC ie the T mark to the crankcase join and the cams at 9 & 3 o'clock, should the lobes of piston 1 not be pointing away from each other? Ie the cylinder is about to fire

On my engine their pointing at each other

[zimm]

sprockets on 180' out ?
or counting cyl #4 as #1 ?

logic says lobes should be pointing away from each other at tdc on compression stroke

[Miles]

Possibly. Cylinder 1 is left hand side as you sit in the bike?

[zimm]

Possibly. Cylinder 1 is left hand side as you sit in the bike?

yep

probably/possibly the sprockets on the SP cams

a lot of engines have the cam timing marks facing each other when aligned rather than away from each other like the zxr, so quite possible they were assembled that way .. my zx6r kent cams are like this .. dont know what the OE ones are like though