Valve Clearances Question

I checked my valve clearances today. Here's what I got (in mm):

0.152 E (4) I 0.127
0.203 E (3) I 0.102
0.203 E (2) I 0.102
0.152 E (1) I 0.102

According to my shop manual, all are within spec.

The reason I checked the valves is because the bike has developed a rather noisy ping-ping-ping noise after it warms up. I though it might be a valve rattling. Now I'm not sure what to check next.

Anyone have any recommendations on where to look next?

 

My gut feeling is that it's due to "Summer Gas"

Last Summer I was running Regular and the pike started "Pinging" on the Regular Gas we get served-up in New England.

I put a tank of Sunoco High-test in it and the Pinging stopped.

Now, I "Blend" the gas. 50% Middle -- 50% Premium.

No pinging.

 

Don,

3 of your intake and 2 exhaust valves are just a bit tight. Intake spec is 0.11-0.15mm, exhaust 0.16-0.20mm.

 

Rick, thanks for the suggestion. I drain almost all the gas from the tank and refilled it with premium (92 oct). It seemed to help a bit, but I think I may have another problem coming into play here. I forgot that the exhaust on this bike is in need of repair. The mufflers have several holes in them. I wonder if they're sucking air which is causing some of the pinging I'm hearing. Also, while riding, I noticed an incredible vibration coming from the exhaust around 4700 Rpms. If I lay my heel on the muffler it quiets down.

In light of the new information, what are your thoughts now?

(Oh, and thanks Carl. I checked the valves a bit after parking it. It was still hot, but not as hot as it should have been. Due to this cooling off, I called them close enough. At least not so bad as to cause the rattle I'm hearing.)

 

might be a baffle come loose, if the mufflers are rusty.

 

If anything ... tight valves are quiet.
It's when you can't hear them that you need to start worrying.

Your exhaust system might be rotting-out from the inside-out.
You might have parts that, like Wizard says, are broken loose from the rivets or spot welds.

Take the vibrating Silencer off and shake it or tap the end that bolts to the collector on a 2X4 and see if you hear loose parts or the guts pour-out in a pile of rust.

 

^^^That's on my to-do list for tomorrow.

 

Check your down pipes for looseness and exhaust leaks at the head flange gaskets.

 

I thought we are checking our valve clearance when "dead cold" or room temp?? And I thought we are running 87 Octane with no problems??

 

Valve clearnaces ARE supposed to be checked "cold", which probably means "room temperature" (whatever that is) and Yamaha never specified what "cold" nor "room temperature" meant.

CHecking them when the valvetrain is at all warm to the touch will give you false readings...........gosh I hate that when it happens!

 

"Dead Cold" means ...

The same temperature as that of a dead corpse, if one was laying on the garage floor, right there, next to the bike.

 

Cold? Holy Crap!!! 8O I thought it said hot!?!

<<<Grabs book and violently flips to page 11 in the Yamaha Service Manual.>>>

Yep, there it is: Cold. Well... don't I feel like an idiot! And to think I burned myself for nothing. Whatsit they say? Always time to do it twice? :roll:

 

For valve clearances, I believe the proper tired cliche is:

"Measure twice, don't ever re-use old shims, and replace those valvecover bolt Sealing Washers with new ones to prevent oil leaks after you're all done with things, HCP1621SET4 and HCP1622SET8 for most applications......."

It's a tongue-twister, sure; but saves you lots of grief further down the road less travelled.........

 

Actually, you know, "room temperature" is a saying from the wine-drinking world, and refers to the temperature that some wines should be served at..........however, that saying came into use way back when, before central heating or air conditioning was common, and "room temperature" referred to about 45-55 degrees F during wine-drinking months (autumn and winter, after the grape harvest came in), which is basically what a modern refrigerator is set at........

So all those people who drink their fine red and white wines at modern-day "room temperature" of about 70-F are really drinking their cheap or fine wines "warm" or "hot", which may be why it tastes so bad.........

 

As Johnny Carson used to say...

 

See, this IS an educational forum.

 

We are running 87 octane. You don't want to run high octane in a low compression engine. You won't get the proper detonation. Summer Gas in New England on the otherhand is something I have never heard about. Perhaps the refiners cheap out a bit and sell low grade gas in the summer.

 

My service manual is at the shop, but I believe it said room temperature (68 deg F).

Oh, by the way. I doubt any of us has the equipment to measure any change in clearance within 30 degrees F of that number. Just make sure it's cooled to ambient (whatever it is in your garage, driveway etc.) before checking them.

 

1982 yamaha maxim xs400j service manual LIT 11616-02-91 says


NOTE:Valve Clearance must be measured when the engine is cool to the touch.

btw where can I get some of these adjusting pads?

 

a change of 50 deg F changes the length of a three inch bar of regular old steel just under .001 inch (.00096somthin)