Author Topic: Tackling the valve clearances  (Read 107 times)

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Offline Joffa1

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Tackling the valve clearances
« on: February 04, 2020, 09:21:10 PM »
So the next thing I want to do on my XS500C is adjust my valve clearances.

Iím learning as I go here but I believe it will be possible to do this with the engine still in the frame and just removing the tank, plugs and whatever else might me in the way before removing the valve cover?

I believe our valves are screw type adjustment too? And that apart from the usual tools all Iíll need are some feeler gauges?

I have a print out of the Yamaha workshop manual and that will be helpful no doubt but Iím wondering if someone would be kind enough to either put up the relevant pages from a clymer/Hanes manual and or give me a little beginner friendly step by step on how to do it?

Just want to arm myself with as much knowledge as possible before giving it a go and appreciate any help and tips.

Thanks so much

Offline guylr

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Re: Tackling the valve clearances
« Reply #1 on: February 04, 2020, 11:25:37 PM »
I wish it were possible to accurately describe the right feel of a feeler gauge as you pull it through the valve stem and the tapped but it's a hands on thing that really can only be demonstrsted in person. Without that the only advice is the ever true RTFM  ;)

Guy
Now Retired Yamaha guy. Cut me and I bleed "Cinquasia Red"

Offline Joffa1

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Re: Tackling the valve clearances
« Reply #2 on: February 05, 2020, 09:05:41 PM »
Yes fair enough on the feel thing I get that... Iím tipping if anything itís better to be slightly on the loose side rather than tight -but ideally spot on.

Like I said Iíve got the workshop manual and have read the relevant section but I donít have the more diy friendly Clymer/Hanes manuals.

So I take it there is no write up on this site on how to do it? Anyone willing to post up the appropriate pages?

Offline berniebee

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Re: Tackling the valve clearances
« Reply #3 on: February 06, 2020, 12:39:42 PM »
Yes, you can adjust valves with engine in place. As you said, remove fuel tank and plugs, air scoop and valve cover.
The engine should be cold to adjust valve clearances.
You'll need a 10mm wrench (Box wrench is best) and 3mm Allen key to adjust the valve clearances, and a 10mm Allen key to rotate the engine. You may need a valve cover gasket as well. (Mine tore apart when I first removed my valve cover.)
Remove the points cover. Just to the left of the points is a 10mm Allen key bolt. Remove this. Insert the same Allen key into the hole and turn in order to rotate the engine. The engine should always be turned in it's normal direction -clockwise. (Most bike engines are clockwise.)

The engine needs to be at the right point in it's rotation in order to adjust the valves. Basically you want the camshaft lobe to point upwards  (Away from the rocker arm.) for the valve that you are adjusting. You can do this visually at the cam shaft, it's not a super precise location. But if you aren't sure, look at the marks down by the points. Rotate the engine (always clockwise) so the "T" mark lines up with the index line. If you've adjusted the points/timing, you know which marks I'm talking about. Now the exhaust and intake rocker arms for one cylinder will have play. (Ie: either the left cylinder or right cylinder.)  That "looseness" is the play you are adjusting. Check and if necessary, adjust those valves clearances.Then rotate the engine one complete turn to get the "T" mark to align again, and check/adjust the other cylinder's valves. 

To adjust a valve, loosen the 10mm lock nut, and rotate the the adjusting screw to get the proper clearance.Then with the allen key still holding the adjusting screw in place, tighten the locknut. Always check the clearance again after tightening the locknut! You'll find that sometimes (often) the clearance has changed, so you'll have to start again. On some bikes, tightening the locknut will always change the clearance. You'll have to compensate by adjusting the clearance "wrong" so that when tightening the locknut, the clearance becomes correct.

As Guylr says it's hard to explain how the feeler gauges should feel. What you're looking (feeling actually) for is a light drag on the feeler gauge as you pull it out. (But what is a light drag? LOL) The feeler gauge should not bend when you push it into place. And the gauge next size up should definitely not fit.
Generally speaking, if you have to err, err a little on the side of too much clearance. Too much clearance will result in a little more engine noise but unless you are WAY off, nothing else will happen. Too little clearance results in the valve being open too long. Valves get very hot, especially the exhaust valve. They cool off when they contact the the relatively cooler cylinder head , that is, when the the valve is closed. Too little clearance results in less time closed, and can lead to valve overheating and damage. And the  XS500 engine runs very hot even under normal conditions. I always adjust my exhaust valves at the looser end of the range.

BTW, I have both the Clymer and Haynes manuals. They are both lacking when it comes to the valve clearance adjustment section. If I was less experienced, I think I would be confused by either manual!

Hope this helps!

« Last Edit: February 06, 2020, 12:47:41 PM by berniebee »

Offline guylr

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Re: Tackling the valve clearances
« Reply #4 on: February 06, 2020, 01:58:06 PM »
Very good explanation. I would only add that at Yamaha we always taught to rotate the cam a couple of degrees in either direction from what appears to be where the lobe tip is opposite the rocker pad to make sure you are actually at the loosest point of clearance. That is due to the way cams are ground with quieting ramps. The object is to get the adjustment done at the point of widest clearance.

The other thing to warn new 500 owners is to never try to rotate the engine with the point shaft nut. You will break it off the shaft and curse loudly. Always remove the blind plug and use the 10mm allen.

Guy
Now Retired Yamaha guy. Cut me and I bleed "Cinquasia Red"

Offline Joffa1

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Re: Tackling the valve clearances
« Reply #5 on: February 07, 2020, 07:13:58 AM »
That is exactly the type of write up I needed! Thanks so much Berniebee and Guy. Well versed in the Timing marks and rotating the motor now after installing my electronic ignition so I think I will give this a go.

While Iím in that area and have clearer access are there any other maintenance items or parts I should be replacing?

Thanks again.