Author Topic: Valve Tap (Read 6763 times)

rmtcook · « **on:** March 04, 2007, 10:56:59 PM »

I hope this isn't a dumb question, but with a little more than 100 Miles on the bike I'm hearing a fairly obvious tapping when at idle. I assume it's valve tap, but should I get it checked out or is it normal on the Bandit or is it just cause it's still so damn cold here?

CWO4GUNNER · « **Reply #1 on:** March 04, 2007, 11:54:29 PM »

Its when the tappets are not prancing that you should worry. (Correction to my last) The valve will slowly wear its way into the engine, taking up clearance until the valve is held open and burns. This is almost always the case and the primary concern, hence no sound and the valves start to burn unable to close and you start back firing, then its too late. Being a little loose is not going to hurt but remind you that there is clearance. If you happen to install a jet kit early, that would be a good opportunity to pull the valve cover and check/adjust the tappets to the proper clearance cold and check them 3 times before buttoning up the job. Otherwise just wait for the scheduled maintenance period but don't expect the dealer to do a real check. 99% only make money when they let your bike sit for a day and call you thats its ready, so do it your self and learn something new.

ZenMan · « **Reply #2 on:** March 05, 2007, 01:32:19 AM »

Quote from: "CWO4GUNNER"

As cam wear occurs the valve clearance gets tighter and tighter until there is no more tolerance or clearance

Huh?

Uhh... cam wear would create looser tolerances, not tighter. And wear usually occurs on the followers, tappets, or valve stem caps much sooner than it would on the cam lobes.

The only things that would cause valve tolerances to get tighter would be the valves seating during initial break-in, or the valve seat surfaces eroding or "cupping" from prolonged heat.

Quote from: "rmtcook"

I hope this isn't a dumb question, but with a little more than 100 Miles on the bike I'm hearing a fairly obvious tapping when at idle. I assume it's valve tap, but should I get it checked out or is it normal on the Bandit or is it just cause it's still so damn cold here?

Make sure your oil level is good. Sometimes a fresh engine will use up a bit during the first few miles.

A little tapping is normal as the valve train "settles in" during initial break-in. It may get a bit quieter as the valves seat. The older Bandits have adjustable rockers, so they tend to be a bit noisier than the newer "shim-and-bucket" design.

They will be a little louder at colder temperatures. It should get quieter as the engine operating temperature rises. I'd just keep an "ear" on it for the next few hundred miles. If it's still getting louder by the time your first oil change is due, I'd suggest having an expert listen to it. (Not necessarily the dealership mechanic...

)

Red01 · « **Reply #3 on:** March 05, 2007, 10:42:21 AM »

It is completely normal on the air/oil cooled Bandits for them to have valve noise, even when warmed up. If they're quiet, you need to adjust them!

Bob Holland · « **Reply #4 on:** March 05, 2007, 11:09:02 AM »

In all my years of motorcycles, I have never seen a valve get lose from wear. I have seen the lock nut on the adjuster screws come lose and back off the adjustment.
Valves get tight because of valve cuping. The thin outer edge will cup, causing the valve to set deeper in the head, causing the valve to have no gap on the adjustment.
If a cam wears enough to let the valve get lose, you have a bigger problem.

Red01 · « **Reply #5 on:** March 05, 2007, 11:16:52 AM »

I haven't seen it on bikes either... but I have seen them get looser on car engines with mechanical adjustment.

Bob Holland · « **Reply #6 on:** March 05, 2007, 11:31:10 AM »

On small block chevys, I have seem them pull the stud out of the head. Back in the 60's and 70's, I built some wicked small blocks, and I always ran solid lifters. I liked the Z28's 30/30 cam, because you could really hear the lifters.

ZenMan · « **Reply #7 on:** March 05, 2007, 11:46:07 AM »

I've seen valve tolerances get looser from wear on cars and bikes both. Usually it's either the follower surface (where the rocker rides on the cam lobe) due to insufficient lubrication, or the valve stem cap can flatten slightly due to loose tolerances.

The adjusters can develop some flattening also, where they meet the valve stem cap. The threads can get loose. The rocker can develop looseness at the pivot shaft. And of course, cam lobe wear.

Most of these problems are caused from insufficient lubrication, or improper adjustment. As BHolland said, it would mean you have bigger problems, most likely lack of proper oil delivery.

The initial statement that cam lobe wear causes tighter tolerances is false, and I noticed has now been corrected. (you're welcome, BTW) I pointed it out as to avoid Rmtcook getting false information.

Also the cupping wear described is a result of heat and erosion over time, as I stated. It does cause tighter tolerances, as I stated. I never disputed that tight tolerances cause burnt valves, that's common knowledge. When a valve doesn't close, combusted gas escapes under compression and burns the valve, usually the exhaust valves go first.

Here's a good place to learn the basics: http://www.bandit-heaven.co.uk/public_html/valve_adjustment.htm

Valve train wear is not as common a problem these days, but I've seen my share of Nortons, Triumphs, and other older twins with adjustable rockers having such afflictions as described. Modern metallurgic developments have reduced these problems to a minimum, but the nature of the design is prone to wear.

All moving parts will wear eventually.

DaveG · « **Reply #8 on:** March 06, 2007, 04:00:47 PM »

I've had this discussion before and it has been my experience that valves get looser as they wear.

But agree that a little loose is better than a little tight.

Actually I have never found a tight valve on the many thousands that i have checked and adjusted.

mine were loose at 1,000km. and were adjusted. checked again at 13,000km. and they haven't changed a bit.

the most wear does happen in the first few kilometers. once the parts wear down any high spots adjustments are needed infrequently.

Bob Holland · « **Reply #9 on:** March 06, 2007, 05:25:27 PM »

The cams turn at 1/2 the speed of the engine, where does all the wear come from.
I have been building, and racing motorcycles for fourty years, I will be 60 in July, and my experience is that valves loose the gap, but it doesn't make any difference when you adjust them, as long as they are right when you get though.

ZenMan · « **Reply #10 on:** March 06, 2007, 06:18:15 PM »

Quote from: "BHolland"

The cams turn at 1/2 the speed of the engine, where does all the wear come from.

Half of 10,000 rpm is still 5,000 rpm.

Quote from: "BHolland"

I have been building, and racing motorcycles for fourty years, I will be 60 in July, and my experience is that valves loose the gap

Forty years and you've never seen a worn valve train component?

Maybe that's because race builders, especially drag racers such as yourself tear down and rebuild their engines so much more frequently, before they have a chance to wear. I'd say you'd see a lot more catastrophic failures on the racetrack than you would loose tolerances. (Unless you're a poor old roadracer like me who just ran 'em till they wore out.

)

I'm not trying to be a smartass, BH, I'm just trying to point out how our experiences could differ... I have 5-gallon buckets full of worn cams, rockers, adjusters, and other worn parts from over a few decades of wrenching. If you walk into my shop I can pull them out and show them to you.

28 years, ASE certified (9 certs) professional auto repair, and owner, builder, rider and racer of dozens of motorcycles during my lifetime (in my 50's) including many, many friends bikes.

Quote from: "BHolland"

but it doesn't make any difference when you adjust them, as long as they are right when you get though.

Agreed.

If they're quiet, they're probably too tight, and you need to adjust them before they burn. If they're noisy, they're loose. Not as urgent, but you still need to adjust them eventually.

The point is you gotta adjust the valves regularly, otherwise why did they put adjusters on them?

As far as cam lobe wear, whether it's common or not, it would cause looser tolerances, not tighter. And friction causes wear, period. (Unless maybe it's two diamonds rubbing together... in which case, you could afford to hire your own live-in master mechanic...

)

pmackie · « **Reply #11 on:** March 06, 2007, 07:07:38 PM »

Quote

I'm hearing a fairly obvious tapping when at idle

Some good info here. But a couple of things about your basic question.
1. If you have a loud "TACK", sounding like a single tappet, then you should get it checked. You may have an adjuster that came loose. Unlikely, but not impossible.
2. If you are hearing a VERY mild "ticking" or "clatter" sounding like a number of tappets, that is louder when it is cold, and gets quieter (but does not disappear) when warm, then yes, that is normal.

You should get all the valves checked at the first major service, 1000 km (600 miles).

I have checked mine a few times now. Never much of a change, but this last time (35,000 kms) I had 2 tight and 2 loose out of the 16. All still within spec, (+/- 0.001") just at opposite ends. I normally set them right in the middle. The 2 tight ones were on the exhaust side, the 2 loose ones on the intake.

CWO4GUNNER · « **Reply #12 on:** March 06, 2007, 07:35:47 PM »

That's always been my experience....

Quote from: "BHolland"

In all my years of motorcycles, I have never seen a valve get lose from wear. I have seen the lock nut on the adjuster screws come lose and back off the adjustment.
Valves get tight because of valve cuping. The thin outer edge will cup, causing the valve to set deeper in the head, causing the valve to have no gap on the adjustment.
If a cam wears enough to let the valve get lose, you have a bigger problem.

DaveG · « **Reply #13 on:** March 07, 2007, 10:37:42 AM »

not saying you're wrong just stating my experience, I'm only 57

i do however agrree that no ticking on a B12 is a bad thing.

rmtcook · « **Reply #14 on:** March 07, 2007, 10:56:52 AM »

The wealth of information on this board never ceases to amaze me! Thanks one and all for your feedback. As a non-mechanic, what I'm taking from this is that a fair amount of clacking is normal, what I'm hearing on my bike doesn't rise to the level that would warrant concern, so I'll at least ask that the shop check the valves at my first service. Thanks for the help!!