Valves | GTAMotorcycle.com

Valves

M

Merkid

Well-known member
What are the symptoms of an engine that requires a valve adjustment ?

My understanding is that they don't emit any rattling sounds as the valves tend to get tighter and provide less opening.

Would there be any starting and/or operating issues?
 
You *may* notice slightly worse performance or rough running. The primary symptom is your motor running very poorly due to a burnt valve. Check valves according to maintenance interval - if you don't know how long it's been, then now is a good time and you can start tracking mileage from there. Valve clearance checks are very easy to skip so when I get a used bike I generally assume that it's due.
 
^These guys have it.

You won't hear anything mechanical unless it has gone horribly wrong (eg. adjuster came loose and now gap is way too big).
 
A single cylinder engine will get hard to start. My experience has been that the engine goes inoperative before it gets to the point where damage can be done.

A multi might do that ... but if it has one weak cylinder due to a tight valve, it's quite possible that the other cylinders will drag it along once started, and there is a bigger risk of having a burnt valve.

There is no substitute for going in there, taking the valve cover off, and taking a look around.
 
I guess the cleanliness of the valve cover itself is a sign as to whether anyone had gotten in to adjust the valves?

I was looking at a bike this week that allegedly had a valve adjustment a couple of years ago but the engine, including the underside of the tank , was greasy and dirty, due to a seeping valve cover gasket.

It was carburated and did have a decent cold start.
 
Valve cover gaskets leak ; some models are prone to leak quicker than others. What is the make/model of the bike you are looking at?

I have done valve adjustments on a multitude of bikes that had leaking covers. Owner choose to replace the gasket when the work was being done. The 'problem areas' & around the cam get a extra amount of carefully applied silicon. The valve cover bolt gasket's also leak over time, so I always ensure those are clean and get a thin layer of gasket maker.

Out of adjustment valves are hard to tell . even between generations of motors they are impossible to tell. For example....ZX6R '98-'04 will run quiter than '05/06. There is the issue of cam chain and tensioners and the noise they emit.

If you are hearing rattling, it might be more from the chain/guides.
If you want to isolate the sound to - valves - out of adjustment will be louder at very specific rpms.

As the motor ages or abuse it takes, they will get tighter.
It will get harder to start when hot.

Depending on the bike, valves are not hard to adjust.
Put a set of plugs in and check TB sync after they are adjusted.
A MCCT will also be a update if they have auto-CCT issues.
 
Well I finally did the valve adjustment on the Bandit. This was the bike that had half a dozen previous owners and while I managed to contact half of them, they all thought the valves were checked when a Hamilton dealer took it in on trade at the 25K point. This didn't give me any confidence so I took it on.

At 54K, all indications did not indicate that the valve cover was ever removed. As it turned out all but one exhaust valve was tight and needed resetting. Interesting, the intake vales were all within spec with only one needing an adjustment. Thankfully, the cams showed little wear.

Rebuilt the carbs and synced them too along with installing new sprockets and chain.

Starts easier and sounds better at idle and while underway. ... (y)

Hoping to get some marathon trips on it this summer.
 
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