shim vs screw and locknut adjusters

[Guest]

I have read on here that shim adjusters tend to lose clearance over time and that (I think) screw and locknut rocker type tend to loosen over time. Is this a good rule of thumb?
Reason is I was going to work on my bike tomorrow and debating whether to do valve lash as well. Its only been about 3k kms since the last time IIRC and the manual says 6k kms between adjustments. I seem to have noticed more valve train noise lately.

[hillsy]

Screw and locknut need to be adjusted more frequently than shims. Both will reduce in clearance over time as the valves eventually bash their way into the valve seats.

If you notice more noise than yes it's a good idea to check them. Could be a loose tappet which can damage itself if left unchecked.

[gsrick]

When valve clearance gets tighter it gets quieter, does it not? I'm guessing if it's getting noisier it's cam chain noise, unless it screw and locknut system that has loosened and clearance has increased.

[Steve]

What bike is this for? The '89 Katana in your signature?

Either way, you will not lose much, except for a bit of time and possibly the cost of a new gasket to put your mind at ease by checking the clearances.

Yes, both systems seem to tighten up with wear, and the rate of wear slows down as more miles (kilometers) are piled on, but the screw adjusters have the unique ability to loosen up and change clearance whichever way they want, so do yourself and your bike a favor, check your clearances.

.

[gearhead13]

Ya, ok I will check it, might as well if I am pulling it down as far as I am already going to.
Compression test, valve lash, oil change, re torque head.

[Steve]

Personally, I woule re-arrange the order:
1. re-torque head
2. valve lash
3. warm up engine
4. compression test
5 oil and filter change

.

[gearhead13]

Yes, I would normally warm up the engine, but I have a bitchy, loud mouth neighbor that hates bikes and my bikes exhaust smells gassy for some reason I havent figured out yet. It even runs at 14-1 AF ratio at idle.

[hillsy]

Yes, I would normally warm up the engine, but I have a bitchy, loud mouth neighbor that hates bikes and my bikes exhaust smells gassy for some reason I havent figured out yet. It even runs at 14-1 AF ratio at idle.

Blocked air filter perhaps? I'm assuming it still has the airbox?

[mrbill5491]

My locknut adjusters have never loosened, one thing I did observe though, after a few years running, they tend to get seasoned and don't require the adjustments all that much. Out of 16 adjusters, seems like I only need to adjust 3-4 at any one time.

[hannibal]

Why are you re-torquing the head?

[wymple]

On many engines, re-torquing the head is a good idea. I adjusted the valves several times on a V65 Guzzi, for example, and ended up pushing the side out of a head gasket as that spec got lost with age. Heads should be re-torqued before a valve adjustment to re-establish baseline settings. You would be surprised at how pressure on the head bolts changes with age on an XS650 Yamaha.

[gearhead13]

Yes, it has the airbox still and an oem type filter, it has an O2 sensor and it reads 14-1 AF ratio at idle. Guess it wouldnèt hurt to take a look at the filter though. I am re torquing the head because the head was off a few thousand ago and I usually recheck it just to make sure. You never know.