Close Valve Shim Clearances

Howdy everyone. In the middle of doing the valves on my XJ550 (first time I've done it, and probably first time in a while this bike has had them done), and my intake on number 3 is measuring at .006, which is just barely in spec. would y'all swap this one out, or leave it?

 

I’m assuming .006 inches. If so, spec is up to .0059. I would say .0059 is .006. So it’s in spec as far as I’m concerned. The gap will tighten as the valve wears, so I wouldn’t want to tighten it up by .05 mm.

that’s my $.02

 

In spec is in spec. Close up and ride.

 

Will do, jayrodoh. Just as soon as I get the 4 other valves that are definitely out of spec back into spec (assuming that solves my low compression issue, which I'm not sure it will)

 

mm = 0.006 × 25.4 = 0.1524 mm
spec .11 to .15 mm

.05 is shim increments going 1 size thicker would put you at .10 that would be to tight.

you could find BMW shims they come in .025 increments which would put you in the middle of the spec range .1274 mm
in the end .0024 mm is not fixable with yamaha shims so close enough for the tool your using
i would advise you to get metric feelers just because your working on a metric bike

 

Get a set of metric feeler gauges and measure it more accurately. It is easier to do the math and eliminate errors.

 

if you look at the inch spec in a 550 manual you will see that the .006 is considered .15 mm (max intake spec) and .16mm Minimum exhaust spec.
so you could infer that your intake shim is .15 or .16

 

Keep in mind that over time the valve clearance will always move towards a smaller gap so if the spec is .11-.16 MM and you are at .16 then you are fine with .o5 mm to move into. If you are at .12 with the spec being .11 -.16 mm then you are in danger of not having enough clearance. If you end up with no clearance you stand the chance of the valve not closing and getting a good seal which can lead to a burned out valve. If you err on the side of too much space your valve may not open soon enough and close too quickly to get either all the exhaust gasses out of all the fuel air mixture into the cylinder at higher RPM, sacrificing performance but no danger to the engine. So err on the side of too much gap is better than to err on the side of too little gap. Also use metric feeler gauges, anytime you can take a conversion out it is much simpler to keep it straight. I would also suggest getting a dial caliper that does metric as well, I have seen plenty of shims that you cannot read the size on.

 

spec is .11 to .15 so he is in the gray area using .006 inch feeler and battling a low compresion issue if he knows the size of the shim he may be able to pick up a BMW shim and put his clearance in the middle of the range.