(Proposed) Central Florida "Shim-Dig" Event

[Steve_in_Florida]

My tip for this is to measure the shims, just because it is marked 275 doesn't mean it is. I use a micrometer to do this, but a caliper will work also. When I did my last adjustment, a 275 was only 271. Sucks when you change a shim to find out no change in valve lash.

That's the beauty of having the use of a kit with 95 assorted shims in it. There are several of each of the various sizes, so if one is out-of-spec, another can take its place.

Besides, it really doesn't matter what's printed on the shim, as long as the measured valve lash is within the recommended range, then all is well.

I'm rechecking the valve lash after making any changes, just to be certain.

Having access to this kit has been good practice. I'm glad Randy put it together. Thanks Randy!   

I also found both my metric feeler gauge set (and a second, lesser one that I might donate to the kit) and the compression gauge set that I'd misplaced in the garage.

Steve

[racerrad8]

Also, remember after the valve shim has been removed the first time, you can not measure and get a true reading on the replacement shim.

The reason for this is the cold oil runs onto the bucket/shim surface when the shim is removed. The oil will not compress fully out of the surface until the engine is run up top operating temperature.

I have race car guys calling all the time trying to figure out why the change from a 265 to a 260 does not change on the feeler gauge. Once they run is and cool it down they can now see the change.

Randy - RPM

[Steve_in_Florida]

Also, remember after the valve shim has been removed the first time, you can not measure and get a true reading on the replacement shim.

The reason for this is the cold oil runs onto the bucket/shim surface when the shim is removed. The oil will not compress fully out of the surface until the engine is run up top operating temperature.

I have race car guys calling all the time trying to figure out why the change from a 265 to a 260 does not change on the feeler gauge. Once they run it and cool it down they can now see the change.

Randy - RPM

Thanks for this info, Randy. This whole process is quite the learning experience!

Steve

[Steve_in_Florida]

Update:

This past Sunday, I was preparing to finalize my use of the FJ club shim kit and send it back to Randy.

Most of the valves on my `92 FJ were on the loose side, just outside of the tolerance range. I decided to make one final adjustment to bring them right within tolerance; neither too tight nor too loose.

Swapped out the last shim, and buttoned everything up. Rolled the bike outside, and cranked her up. On the first engine rotation, I heard the distinct "ping" sound of a shim being seated (I'd heard them do this before when turning the crank over by hand after a shim swap), followed by the tapping of an extremely LOOSE valve.

Not good.

Shut her down, rolled her inside, and opened her back up.

Sure enough, the VERY LAST shim I had swapped, had not fully seated, and proceeded to SHATTER into four large pieces when I cranked the engine over. Additionally, the edges of that camshaft lobe had evidence of having contacted the shim bucket.

I called Randy (RPM) as soon as he opened Monday morning. I feared the worst!

Randy reassured me that this was not the catastrophe I imagined it was, and said he had dealt with that at the racetrack on several occasions.

I retrieved all four shim pieces, and ran a magnet through the oil pool around that shim bucket, attracting the minuscule amount of shim dust that remained. Replaced the broken shim with a fresh one, and put everything back together.

Took her for a ride, and things seem back to normal.

One final check of the clearances and I'm boxing the kit up to send back to Randy.

It's always SOMETHING! I'm just relieved that it wasn't much worse.

Steve

[The General]

Wow! Thanks for posting the lesson Steve.  (I`m surprised to learn of it`s common occurrence at the track.) How many times do you reckon I should manually crank her over (as a check) for normal precautionary practice? Then maybe starter motor without spark plug leads?

[Steve_in_Florida]

Wow! Thanks for posting the lesson Steve.  (I`m surprised to learn of it`s common occurrence at the track.) How many times do you reckon I should manually crank her over (as a check) for normal precautionary practice? Then maybe starter motor without spark plug leads?

Well.....

I don't know if it's actually considered "common", but Randy stated that he had seen it before (just not in the bikes), out on the racetrack with the Legend cars.

Honestly, I don't recall if I actually *DID* turn the engine over manually before I buttoned her up. Last valve in a long line of swaps. Complacency? Maybe.

On previous shim swaps, the new shim would (sometimes) "snap" into place in the shim bucket within the first couple of rotations of the cam, often accompanied by a slight spray of oil droplets. I DO recall that on the last shim, a bit of a stream of oil sprayed out for a second from the notch in the side of the bucket (no more than 1/8") when I installed it. None of the others had done this, that I had witnessed.

I'm guessing that the shim was somehow resting on the lip of the shim bucket, and couldn't drop into place when the cam lobe came around like the others had done, and instead, gave way with a BANG!

Randy suggested that next time, CAREFULLY rotate the crank by hand FIRST, then crank the engine a couple of times before putting the valve cover back on. If something is amiss, you've saved the step of having to remove and replace everything AGAIN.

All seems well, now. I have the bike back at the maintenance facility, cooling down for the final check.

Steve

[yamaha fj rider]

Steve glad that everything turned out ok. As they say "all's well that ends well". Thanks for the posting.

Kurt