valve clearance needed

[Rik]

hey

im in the middle of doing my valve clearances on a j1 zx6-r, after checking each valve clearance i found the exhaust clearances to be between .02-.05mm too tight.

i took only the exhaust cam off as the intake clearances were ok, took each follower and shim out in turn, keeping them in order. i put each shim in its own bag with a number corrosponding to what valve it came from. the shims were measured by my local bike shop and replacement shims were put in each bag, the old shims were taken in px.

i've since put the shims, followers,cam and cam cover back on, on the correct order, however i checked the clearances again and there all way too tight, including the inlet clearances which werent touched

i have tourqued the cam cover down correctly and double checked it all, but im totaly stumped as to why there out now, any ideas?


cheers

rik
____________________
Homer Simpson wrote:
.....quick, Operator! Give me the number for 911.....

[instigator]

Possiblities:

-The shop measured them incorrectly.

-You done the valve clearances when the bike was still warm(ish)

-Sure the crank is in the correct position when you're taking the clearances? (on the correct cycle, exhaust or compression)

[finpos]

Whenever I measure gaps like that, I keep spinning the engine and re-lining the timing marks until I get consistent readings several times on the trot.

finpos.

[Rik]

[Rik]

[finpos]

Makes no difference whatsoever to the actual clearance - but it'll help eliminate, errr... "human error". Personally, I find getting the cams in just the right place tricky, so I do it a good few times so I can compare the readings and get some confidence I've done it right.

finpos.

[Rik]

im 99% sure i havent but once that doubts there its hard to get rid of.

theres a difference on the inlet side of around.06mm which is huge concidering i never touched it


rik
____________________
Homer Simpson wrote:
.....quick, Operator! Give me the number for 911.....

[finpos]

I suppose the other thing to check again is that you've not put either of the cams back on 1 tooth out. It's surprisingly easy to do. Again, I always paint marks on with tippex because I'm an idiot.

finpos.

[Walloper]

If in doubt, whip it out.
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W-ireless A-rtificial L-ifeform L-imited to O-bservation P-eacekeeping and E-fficient R-epair

[Pete.]

I always measure cam clearances near the end of the base circle just before it starts to lift the valve rather than with the lobe pointing directly away from the bucket. You cannot assume that the base circle is evenly ground. Some are perfect, some are less than. Measuring on two different points of the cam can conceivably give different readings.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[Rik]

i'll try measuring it from the end of the base cycle then, although i never took it from there originaly so the readings should be the same as before.

walloper, i've taken it off and re-fitted it 3 times and its still out.

and there is tipex on the pullies already and the timing is exactly as it was before i touched it.

if it was just the exhaust side that was out i'd be inclined to say that the shop has made a mistake with the shims but with the inlet side being out too now its got me totaly stumped.


rik
____________________
Homer Simpson wrote:
.....quick, Operator! Give me the number for 911.....

[Pete.]

Are they "shim under bucket" valves? If so another (extremely unlikely, but you never know) is that the valve stem top might have worn a dip in the old shims, causing the effective thickness to be less than the measured thickness of the shim.

[Pete.]

Have you checked that you have the cams the right-way-round? Thet you neither have the inlet and exhaust cam reversed or that you have actually got the cams in the right place but backwards.

It's a very easy mistake to make on some bikes.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[Rik]

im going to check the gaps tomorrow, turn the engine over a good few times on the starter, re-measure and if necessary re-fit the whole effin lot again including the shims and followers, if there still the same then i must assume the first time they were measured(not by me but a qualified mechanic) they were wrong for some reason, maybe valves not seating correctly, and adjust them again with new shims and put it back together and re-measure.

its a total pain in the arse but will be worth it come march

the cams are 100% in the correct place, and if i had fitted them 180 degrees out the i think the clearances would be the same? it just wouldn't start when put together.



cheers

rik
____________________
Homer Simpson wrote:
.....quick, Operator! Give me the number for 911.....

[Stalk]

Silly suggestion but have you put the shims in the same way up as when they came out? By that I mean that the shim face that was against the cam may have worn concave (?) and by turning the shim upside down it may give a different reading. This assumes that your bike is shim over bucket.

Hope that helps and sorry if its a crap idea.

Stalk

[Stalk]

Silly suggestion but have you put the shims in the same way up as when they came out? By that I mean that the shim face that was against the cam may have worn concave (?) and by turning the shim upside down it may give a different reading. This assumes that your bike is shim over bucket.

Hope that helps and sorry if its a crap idea.

Stalk

[edd]

OEM shims should be so flat that it shouldn't matter which way up they are. Though it might make a very small difference. This sounds unusual, the clearances cant just change themselves. The only situation I've had that is with bent valves, just a touch bent and they look ok, but put them in and the clearances change slightly evry time. Take them out and put them on stands with a dial guage and it shows up whats wrong

I dont think thats what has happened here though, sometimes if you dont get the feeler gauge at the right angle the clearances can feel tighter than they are. I usually give each bucket a squirt of oil so that the feeler gauge slides in with less effort. Its likely you have just made human error.

To prevent re installing the cams incorrectly, Tipp ex is good, but add to it by cabke tying whichever cam's sprocket you arent changing to the camchain.
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Bluespark Automotive - Diesel Tuning for Performance and Economy

[sanchezz_182]

did you torque the cam caps down before making the orginal measurements?

if not it can give funny readings when u put the caps back on. just a thought.
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no sig, thats gay!!

[Rik]

got it sorted, re-measures the gaps and changed the shims, all the gaps are within tolerances now.

i think it must have been human error, or sanchez's point about the cam cover not being torqued down's also a good one.

but cant wait for the test ride

thanks all


rik
____________________
Homer Simpson wrote:
.....quick, Operator! Give me the number for 911.....