Checking valve clearences

Just came back to the bike after six long months away. A little tinkering, runs great.

About to check the valve clearences. I've never done this before. I'm scared. But the question I have is, since I'm about to take off the cylinder head cover, do I have to (or should I) order a new gasket ahead of time to replace the old one? That is to say, should you always replace the gaskets when you open the cylinder head covers?

Oh, and what sort of measuring device do you need to measure the clearences?

 

BY ALL MEANS. Get a new gasket, AND all the little rubber do-nuts for the screws. Those troublesome little rubber donuts are KEY to having the valve cover pull down aginst its gasket correctly. Chacal has 'em. Once done right, you should NOT have to replace the gasket for quite a few "removal cycles" afterward. I have a set of Craftsman feeler gauges that go down quite small (.0015") which, by combining blades, can get you real close. It's not a difficult process, there are a few IMPORTANT things to remember: Must be done bone stone cold as in hasn't run since yesterday. Be real careful about which way you turn the motor with the valve bucket hold-down tool in place, you can actually fracture the cylinder head. The cam lobe has to be PERFECTLY centered on the bucket for the tool to work correctly (learned this the hard way.) WRITE EVERYTHING DOWN. Makes it a lot easier to double-check yourself. DO NOT use a magnet to remove the shims; the valve buckets can easily become magnetized and will then attract miniscule shards of metal=bad. I use a tiny flat-bladed screwdriver and a pair of hemostats. Be sure to dip your new shims in clean oil prior to installation. And be prepared for how much stronger your bike will run afterwards. I accidentally pulled a wheelie (in my jammies) when I went to put my '81 away right after I did the valves.

 

A new gasket would be nice but not needed if yours doesn't break or crack in the removal process. I reuse mine a few times before a new one goes on. Black Permitex silicone works to re-seal the old gasket.

With the engine cold you remove your tank and gain access to the allen head screws that hold the cover down. Remove them and lift the cover off. You will also need to remove the left cover over the ignition pick up coils. There is a hex end on the crankshaft so you can turn your enigine over. I like to remove my spark plugs so it is easyer to turn the engine.

Pick up a long angled feeler gauge at the local auto parts store. Look up the specs and check your valve clearances write them down and compare. I keep a record of the measurements for future reference. If your shims are too tight you can order new ones from chacal

 

For the new gasket: Glue it to the cover using the gasket sealer of your choice (I use high-tack sprayed into a cup and applied with a paintbrush.) Then wipe down the other side of the gasket with MMO, silicone grease, gear oil, whatever. That way when you pull the cover the next time, the gasket will stay with it. If this is the first time you've done the procedure, you are most likely dealing with a 26 year old gasket that will crumble on you (mine was CRUNCHY.) The new one will be good for quite a while.

 

Some good tips so far. I'm also about to check mine for the first time as a new owner. One question I had after reading my Haynes manual is how often the valve clearances are checked afterwards? The manual suggests annually, but wonder how often the XJ Nation completes this procedure on their bikes?

Thanks!

 

Just done mine - very easy...... after I found out about using three large ties, taped together making one thick tie, which you can feed through the spark plug hole to jam between the value and the head, holding the value down as you rotate the engine, once the ties have held the valve, rotate the engine until the cam is 180 degrees away from the shim, so that you can measure, remove and replace.
A fairly quick job as long as you have the correct size shims to hand to adjust the clearances.


http://xjbikes.com/Forums/viewtopic/t=7 ... chool.html.

 

yeah, and you can use a hunk of #12 insulated wire too; I feel safer with "the tool." And unless you're clairvoyant or have a really BIG box of shims, it's a two-step process: break it down, measure, send Chacal an email, replace the shims when they arrive. Frequency? For the 550 the factory book says every 5000 miles. Dunno about 650s for sure.

 

Hopefully chacal will chime in on this thread about price and availability of "new gasket, AND all the little rubber do-nuts for the screws", to quote bigfitz52. I have the same bike as oak450. I recall seeing a post of shim sizes/prices but not the gaskets info from chacal.

 

Send Chacal a PM or email him (better yet) at info @ xj4ever.com (take out the spaces in the email) and he'll get right back to you.

 

Can you get gasket sealers (to glue the new gasket to the cover) from advance auto, etc.?

 

Yep. I personally prefer High-Tack Spray-A-Gasket, I believe it's a Permatex product. I spray some into a paper cup or other convenient small disposable container and apply it with a small paintbrush. You can also use RTV (high temp silicone seal,) or anything else you prefer. I like the spray stuff because I spray more gaskets than I have to "paint." In this case, spraying the sealer onto the gasket isn't an option because we only want it stuck on one side, and because of its size and shape.

 

This looks like a good place to ask my question since it's related...
(I didn't see a thread on it.)
Will I encounter any PITA in regards to unbolting the valve cover and removing it? I know for a fact it's never been removed. I will be replacing gasket and do-nuts with new, but hopefully no bolts.
Any tips, tricks, hints, etc...?

Thanks

 

PITA; not especially. Tips/hints sure: you might want to slide whatever relay might be hanging down off its mount up and out of the way (I have to do that on the 550s) and then pull all the plug wires and tie them up out of the way with a garbage bag tie or the like. Undo all the bolts, they may not want to come all the way out because of the donuts being mashed in place but that's ok. Just be sure they're 100% loose. Then use your handy-dandy wooden hammer handle (if you don't have one go buy one you'll need it for the carbs--thanks Rick) to gently pry on it here and there (there are tabs) and once it breaks loose lift it up about 3/4" and finagle it out. You may then have to give the bolts a quick smack from the backside with a non-marring hammer to pop them out of the cover.

 

On a 650 Maxim all you have to do is remove the fuel tank, tie up the plug wires and remove the horn. It's a tight fit but you can wiggle the cover over the camshaft sprockets.

 

bigfitz52 was right on about what to do, starting remember to rotate the timing chain gear around at least one time to make sure you have all slack out of it . Those shims are marked, usually with a Y and a number, the number was the original shim thickness, not what it is now. if there is no # on the shim, you will have to mic it for sure.

 

Good deal, thanks.