Drain cock valve assembly

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Roger that! How simple it would have been to orient on/off to north/south, or even east/west....but noooo, it's gotta be at 1:30/7:30 or some ridiculous shit!! :bang head:

That's how they roll in Japan. :biglaugh:
 
I was told by someone far more experienced than me to run in the open position. This open/off valve actually bypasses the thermostat which allows the coolant to drain. My experience has been that in the cooler weather running in open makes getting up to normal operating temp. difficult but in warm to hot weather it does cool the engine better.
david
 
Open ball bearing in top hole .
Closed ball bearing in bottom hole .
From what I saw one off the bike.
 
Of course I fully restore these when restoring my bikes. I know overly anal !
But I can't tell you how many I find with the plastic hex head already destroyed/rounded by people using pliers or some other inappropriate tool to turn these or attempt to pull them out without pulling the "Set " screw first. I use a 1/4 inch socket drive screwdriver with the correct sized six point socket. Use a 12 point and you may round it off it is corroded in place.
I can almost always tell the ones that have never been touched, which is good for part restoring but a bad sign for bike maintenance history.
 
This is a pic of the drain cock valve assembly. There have been different posts on where the on/off positions are located.

When changing coolant this valve is turned to the "ON" position to properly drain all the coolant, and to the "OFF" position after coolant change is completed.

The service manual refers to a "match mark on the valve housing," this is nearly impossible to see when the assembly is on the bike, and so small that it wouldn't photograph with my camera. The "match mark" is located at the 2 o'clock position in the pic.

The valve pictured is in the "ON" position. Turning the valve 180 degrees will place it in the "OFF" position.

Another way to tell is, if the stainless detent ball can be seen in the top hole of the housing the valve is in the "ON" position.

The valve will turn either clockwise or counter clockwise...it doesn't matter. It will also rotate 360 degrees without harming the assembly.

The phillips screw at the 9 o'clock position is a set screw which fits in a groove in the valve body, holding it in place. Remove this set screw to pull the valve body out for inspection. (Be prepared to catch the spring loaded stainless ball.)

If you have coolant leaking from this valve it is most likely the o-ring. The OEM assembly is priced at about $45 on the micro-fiche. I don't believe the o-ring can purchased seperately from Yamaha but you could prolly find a suitable replacement at your local hardware store or plumbing shop.

What is microfiche?????
 
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Great post! The metal ball and spring are missing from my assembly. Thanks for sharing.
 
More on that,
Yes, it does not matter if its on or off, coolant will still flow regardless, I ran mine in both positions, cooling was not different. I did go thru the bike and chgd all the hoses. if your bike is 10 yrs old or more and you never chgd the hoses, and not experienced any leaks or rot etc. good on you, however, in the interest of preventive maintenance, I did mine, what an ass pain. I noticed that the drain pipe assembly is only held in by two bolts and the press of the hoses that route to it. The tiny pipe that goes into the thermostat housing? Just an O ring and one bolt. I also noticed that the 90 degree plastic pipe that goes into the waterpump housing is held in place by sheer luck, two O rings and design path of being held in place only b/c the thermostat housing holds it there. I guess by heat and coolant pressure swells up the O rings to keep coolant in. I put on all new components, hoses, O rings, new clamps, drain assembly, sensors, poured water in to test for leaks, MANG!! water gushing out at the thermostat housing! I thought for sure I sealed it up, it contains one big O ring, a thick rubber gasket on top of the stat, and two bolts. I had to take it apart and reseat it and the leak finally stopped. Not sure why it leaked at all. But the reseat seemed to solve the problem. Next test is to pour water in again, start it up to temp, and really see if its leaking. The only other major ass pain is hose replacement, the fat hoses that go into the heads, You are pretty much relegated in using the pinch clamps, the screw type clamps will not have any room to tighten up, and does not even begin to clear the plug cap, even with COPS, still will not clear. I got it to work. One more thing fellows, I replaced the starter as well, good thing, I pulled the starter cable, best check it one and all, mine was dry rotted, split along the axis of the wiring. Of course being very close to the motor and exhaust pipe.
 
I replaced the O-ring from Ace hardware and the leak from the drain cock has stopped. But the other tube goes in to thermostat still leaks. It seems there are space fro 2 O-tings, so I might try to put 2 in there. Any better fix on this?
 

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I've never tried two and should not be needed. May need to remove and clean again.
 
I replaced the o-ring in the drain cock assembly, stripped the 6mm bolt hole in the thermostat housing. Any suggestions; tap deeper and use a longer bolt or go to a bigger bolt?
 
The 6mm thread is in the crankcase, not the thermostat housing so best tap out to 7mm and drill the plastic thermostat housing to take the 7mm bolt.
 
The 6mm thread is in the crankcase, not the thermostat housing so best tap out to 7mm and drill the plastic thermostat housing to take the 7mm bolt.
Atlest it's not a number 60 drill bit on the carb mixture screw eh Danny?
 

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