Small port on right side of head


Anybody know what the 2-3mm diameter hole/port on the side of the head is on the 2002 426? I browsed through the manual and couldn't find anything on it. When sitting on the bike, it is on the right side of the head, about an inch or so above the cylinder to head interface. I've noticed a small amount of oily residue coming out of it. Looks like some kind of bleed or indexing port. What's it do?



its a drain hole from the spark plug area

anyone else have a rusty spark plug?

So, that residue is the result of washing down the bike and water collecting in the spark plug area, then draining out of this hole?

Hmm, the plug boot design must not be too goo.

or maybe the water is getting into the Hole "YA THINK"

Before washing your bike... plug the hole with a golf tee... and when you are finished, remove the golf tee... simple two step procedure...

if you have rust in there, then clean it up... and a spray of WD40 occasionally won't hurt to keep it cleaner and less prone to rust...



What about that ball bearing in front of the oil gallery tube on the head? I wonder what its funtion in life is?

To plug the galley. Its a bitch when they leak.

Some good comments. Hmm. Maybe some oil is seeping past that check valve. Hope not. I'll keep an eye on it. If the oil gallery ball bearing is really a check valve, that's gotta be a poor Yamaha design or machining process. I guess they figured they needed to drill all the way across to the oil gallery to machine the drain valve, then plug the gallery with a ball bearing. Not good...backyard mechanic style.

EgoHole: Seen your type before. I really don't need any of your "grand" wisdom. Really, I don't have time to d*ck with your type. Seen enough smart a** posts from you to know all there is to know about you. I'm sure there are many on this site that have more to offer than you could imagine...on or off the track. If you want a spam session, go to a HD site where the crotch rocketeers/power rangers like to spam out RUBs 'cuz they're jealous, or whatever else.



Checked out your website. Lame, but funny, bail. I thought it was gonna be a real wreck. Not to worry though, we've all low sided before. No spamming intended.


Well, that is a tough post to follow. Ego... I love you man! You sometimes have something good to say too. Oh, now for the topic. Capping the hole with a golf tee is a good ideer. I leave it open and shoot a bit of wd-40 in after a wash. Seems to keep everything from rusting.

That hole is so "if" water gets in the sparkplug area while engine is cold, later while bike is running, the steam generated doesn't blow off your sparkplug cap! I also blow air thru it before removing sparkplug, so that way no foreign material will find its way into my top-end! Maniac

i thought that hole was to remove spark wonder i could never find a wrench that would fit in hole.

yo jack, we dont need anyone like you going around hatin' other people who obviously know alot more about bikes than you do! So if your gonna act all gay, then take your little prick and shove it cuz we dont want any of your **** !

vanilla gorilla[jsthejack],i think you are in wrong need to find a forum where idiots are appreciated.we dont need anyone like you going around hatin' other people who obviously know alot more about bikes than you do! So if your gonna act all gay, then take your little prick and shove it cuz we dont want any of your **** ! how old are you?11 maybe?we dont want any of your ****WHEN YOU SAY "WE" WHO ARE YOU REFERING?i doubt all the members of TT have given you right to speak and make decisions for them.especially since you have only been member for a the way why do you keep changing name?are you just here to cause trouble and spam forum?

[ June 11, 2002: Message edited by: freestyle111 ]


There's a topic here. There are lots of places to bicker, try one of them.

I still don't understand what the ball bearing looking thing on top of the head if for. Is it a block, a check valve, a bleed point?

Good luck,


A buddy of mine has an 01 250f and it leaked COOLANT from the spark plug drain hole after each ride. It wasn't much, but enough to know there was a problem. The bike was only weeks old. Yamaha replaced the head. No problems since. If that is coolant and your bike is new, I'd show it to the dealer.

I'm surprised to hear that coolant seeped out of this mysterious drain hole if it's an oil gallery check valve/ball. Is there a reference to it in the manual? If it really is a an oil gallery check valve (band aid) and coolant leaks out of it, sounds like the spark plug area of the head cracked and allowed coolant to escape. Not for sure. Haven't looked at it close. But, new engine designs are incorporating cooled spark plug interfaces and exhaust valve seats.

Vanilla Gorilla....there's one on every website, and apparently you're it. BTW, I'm a mechanical engineer and do engine research every day; so, I probably know more about engines than you could imagine. Just because I don't know everything like you, it doesn't mean I can't ask the question. The one who doesn't ask is the ain't just turnin' wrenches buckwheat.

To everybody else, I like the input this website has to offer and don't plan on offending anyone. Thanks for all of your helpful replies.


[ June 12, 2002: Message edited by: skthom2320 ]

That weep hole is a goldmine. First of all, you can just shoot a little compressed air and it will pop the spark plug cap right off and you won't have to try and get a grip on that thing. Secondly, after removing the cap, shoot plenty of air through the hole to clean the area around the spark plug before changing. This prevents debris from falling into the engine once the plug is removed. Personally, after I loosen the spark plug a little, I shoot some more air through the hole to blow out the trash from doing the intitial plug lossening. I deplore the idea of junk falling into my combustion chamber!

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