Valve lash set at .004 and .006, still pretty loud.. normal?

[Jaymichael]

My bike engine experience is pretty limited. I've worked on solid lifter BMW engines a million times and have a good sense for what valve train noise sounds like loose and tight. I'm in my final tuning phase on my XS and I've got my valve lash set at .004" on the intakes and .006" on the exhaust. I can still hear the distinctive valve clack cold and warm, its not totally annoying but its definitely there. Do these engines just sound that way? I know on car engines if the lash is set carefully on the low side the noise is very limited or nearly gone all together. I fully understand it probably better to hear the valves then to risk them not seating fully reducing cooling and sealing ability. Thoughts?

 

[5twins]

They will clatter quite a bit if you use .004" on the intakes. Try .003", usually quiets right down.

 

[fredintoon]

hi Jay,
0.004" is a bit much for the inlets but it won't harm nothin'.
I've posted this before but it is appropriate.
Letter from disappointed customer:-
"My engine sounds like a bucketful of ball bearings being poured onto an iron plate."
Reply from Ettoire Bugatti:-
"From the description, your engine is running perfectly."
BTW, you sure it's the lifters? They ain't the only thing that rattles.

 

[Jaymichael]

Thanks for the reply, the ball bearing on an iron plate quote is well done
I'm pretty confident its the lash causing the noise, the frequency is valve speed and the chain tension is dialed in properly. I would say the noise is stronger towards the exhaust valve side, and its very equal left and right.
As far as intake lash goes, how low have you gone?

 

[fredintoon]

Hi Jay,
I chickened out at 0.003" and what with a life time of industrially induced hearing loss my ol' bag of nails purrs like a sewing machine.

 

[5twins]

.003" is about as low as we go. Yamaha did spec .002" for a couple years in the mid '70's but the general consensus around here is that's a bit tight for proper oiling. Yamaha changed valve clearance specs several times during the production run but there doesn't seem to be any clear cut reason for it. The motors didn't really change much as far as the valve train is concerned. Most of us use .003" on the intakes and .006" on the exhausts. Yamaha's specs varied from .002" to .004" on the intakes and .004" to .006" on the exhausts over the years.

 

[Jaymichael]

Thanks, Ill try dropping the intakes to .003" see what they sound like.

 

[mrtwowheel]

Keep in mind that the clearance changes between a cold engine and a hot engine. Noisy valves are better than burnt valves and holey pistons.

Scott

 

[EvenmoreXS]

I've always been told its better to hear the valves then smell them.

.003 wont be too tight. But no tighter. These engines make a bit of noise. It will never be... " Quiet ".... but it will sound "right". You'll know it when you hear it.

 

[5twins]

Yes, this is an old motor design and not quiet like a newer one. Get it right and you'll have a "tisk, tisk, tisk ...." instead of a "tick, tick, tick .....". Just part of it's charm, I guess.

 

[rebel542]

Check this out on youtube. Yamaha XS650 valve adjustment made easy

 

[Jaymichael]

Thanks for this video, this has actually resolved something for me. I played around with my valves tonight at discovered my lash gets a bit larger off of tdc where I was originally adjusting it from, what I though was .006" on my exhaust valves actually was as high as .008" in a different part of the cam rotation, totally explains why I was getting more noise then I was expecting, thanks a ton.... This forum rocks!

 

[franklin270h]

Personally I would still stick to setting them at TDC. That's not saying the other method doesn't work, but you're setting at TDC on the compression stroke because that is where it is most critical that you afford enough clearance for the valves to fully seat in all potential conditions. Rotating to find where the largest gap is you're basically just digging for where the cam lobe is at its smallest point, and the machining on these older engines wasn't so precise that there weren't variations there and machining errors. You're ideally setting so that the valve is seated through the duration of cam travel that it is designed to be seated, not just at the point where the cam is furthest from the rocker (where if you were running really tight, there's a chance as the engine heats up that the valve spends more time off the seat than it needs to)

If you set it solely at the point where the contact is as at the absolute farthest from the valve stem, you're actually running the valve lash even tighter than what are already some pretty tight settings on these engines to start with. These older engines have really slow ramps on the camshaft, especially compared to newer OHC designs or even newer car pushrod designs (think Comp Cams Xtreme Energy or similar). Running a very tight lash to a small extent makes the camshaft perform effectively as if it is "bigger"- more time off the seat, longer duration, less dynamic compression. And if you're too tight the side effects might not show up for you in casual use like short rides or decent weather but you get a really hot day or ride for a while and the engine heats up further you'll know it.

The general consensus of .003 intake, .006 exhaust at TDC is a good one to default to. Mine tends to do best at a snug .004 intake and .006 on exhaust

 

[Jaymichael]

Franklin, thanks for the reply, I agree with your thoughts to a point. Really what needs to be done is a close inspection of each lobe finding the highest point of clearance and compare that to the clearance at or near tdc. With ALL the information one can then decide how loose or tight to set the valves, it will be a trade off between how much noise you can tolerate and how risky you want to be about possibly holding the valves off the seat.

 

[franklin270h]

That would definitely be the ideal way to go.

I'd actually think with that methodology that the "ideal" solution if one wanted to run as tight/quiet a lash as they can get away with and still have as much longevity as possible would be to find at what point of the base circle of the camshaft gives your *smallest* gap between the adjuster and valve stem, and make that be the point that you set a tight lash. Then even if the stock cam had any runout along the base circle you'd still be good to go because that would be the point where you're adjusting it and you would ensure that the valve remains seated throughout. Obviously that's something that would be hard to do with the motor in the motorcycle and not being as able to visually see the camshaft or use a degree wheel/dial indicator-you'd have to know the exact point that you were on the base circle of the cam.

The other is that the largest/smallest gaps at the adjuster when the cam is rotating along the base circle might not necessarily hit at the same point for each cylinder, whereas when setting at TDC you're adjusting at the same point of the compression stroke. Likely not a huge difference between the two with most engines, but it is a factor to consider.

 

[rebel542]

I think we're working way to hard here. The procedure you saw in the video was given to me at a Yamaha Service Seminar between 1978 and 80. The procedure covered a valve noise in the shim over bucket 1977 XS750D due to loose manufacturing tolerances in the cam grind. The loosest point in valve clearance was rarely at TDC but rather just before the valve opened or just after it closed, intake was one and exhaust the other but I can't remember which. Of course I tried this on lots of different engines including our best seller, the XS650SE [the only year, 1978, that Yamaha beat Honda in sales] and found that hardly any engine had the loosest clearance at TDC. You can use this procedure on any engine built by anyone, except hydraulic lifters and get excellent results. It's just so simple......

Like the video say's,
"Use it if you like it, or do it the hard way."

 

[franklin270h]

Oh I have no doubt that the loosest is rarely at TDC, it isn't the case on many of the engines I've seen either from cars or motorcycles (outside of really well machined aftermarket cams).

And I definitely don't question the methodology either, I've used the advice in that video myself. I think it's a good thing to consider both. Ideally you're setting as tight a lash as you can get away with while having just enough room for heat expansion of the valvetrain components while the camshaft is running through the whole base circle. If you're getting a lot of noise and clatter, determining and tightening up at the loosest point gives a great indicator. If you're worried that you might be on the tight side of things, you'd want to know if there's a lot of runoff on the base circle and know that you have enough clearance at the tightest points. Unfortunately one of those things where the advice of "every engine is different" rings very true because as far as machining what you have can very well be a crapshoot

 

[Jaymichael]

After a careful measurement and adjustment of my valves tonight I found about .001" difference in lash size between tdc and either just off closing or just before opening of each of my cam lobes. It was a good exercise to get a better understanding of what I am dealing with on these camshafts. I cleaned up the settings taking this info into account and now my valve noise while still clearly audible sounds much more tidy and clockwork like, definitely within the tolerable range. Thanks everyone for chiming in on this thread, it made me dig into some research and get to know my valve train much better!

 

[TwoManyXS1Bs]

There was a service bulletin on the early XS1Bs covering faulty camshafts.
I've wondered if this may have been the genesis for Rebel542's procedure.

 

[TwoManyXS1Bs]

*A lil' update*

Another thought to add to all this.

Imagine that you're setting valve lash on the left cylinder, engine at TDC. The left rockers will be loose, the right rockers will be holding their valves a tad open, at that cylinder's overlap stage. There'll be some downward force on the camshaft from those rightside rockers, and will hold the camshaft down for reasonably reliable measurements.

Now, rotate the engine +/- 100°, and repeat the left cylinder lash measurements.

At those +/- 100° positions, the left rockers will still show clearance, and will be near the entry and exit ramps of their respective cam lobes.

However, one of the the right rockers will be setting atop one of its cam lobes, fully opening a valve, pressing on its valvespring, adding in excess of 100lbs downward force on the camshaft. That extra downforce will:

Flex the camshaft downward a bit.
Seat the camshaft end bearings a little deeper into their grooves.
And, likely increase the lash measurements of the left rockers.
Which may feed the presumption that cams are ground with extra clearance near the ramps.

For reliable repeatability, setting valve lash at TDC sounds prudent...