EMERGENCY..... GURUs Needed

[xschop]

About a quarter mile from my morning commute exit, I hear a very distinct sound like someone popped a champaign bottle, then hot oil on my right leg (I was in shorts too) Parked the bike at the first establishment (Mickey D's) and front Cam rubber plug is gone.... ....My question is, can the bike be driven 7 or so miles back to my home if I baby it? or do I have to go get the plug from Yamaha, and most importantly, can it be installed without removing the Cam Cover? I need to take care of this, as I won't be leaving the bike there in that Hood...Thanks Chop

[XSPastor]

Bummer!

I had that happen to me. I used an old t-shirt and just wrapped it around the hole. It still leaked all over and down my right pant leg but the oil level only dropped a little in 7 miles. I probably lost less than a cup. Messy but doable. Don't put the plug back in in with Yamabond. They squirt right out in my experience. Seal the top edge where it hits the cover gasket with yamabond or your favorite sealant but leave the rest of the plug dry. Make sure the plug and the groove that receives it is clean and free of oil. I squirted out two of these before I learned this.

[XSPastor]

As far as why it popped out, maybe the gurus can weigh in. Could a leaky valve or piston blow-by send the pressures up so high under the vave cover that it would pop a camshaft plug? Could his crankcase vent be clogged? Maybe the plug just got tired? Hey Chop, have you had the plug out or the valve cover off recently?

[xschop]

Strange

When Trbig came over, he commented on my PCV valve at the rear off the engine, when I get home I will take it off and see if it is clogged. Isn't this breather the purpose of letting out internal engine pressure buildup?

[xschop]

cover

I haven't had the cam cover off since 2 years ago when I replaced the cam chain. It's very ironic that this happened as I was about to be posting a question to the GURUs about the plausibility of copying the cam plug rubbers from alloy and permanently welding them in, But if this is what they are designed to do, then fugettabboutit. I always figured the cam plugs were there because the factory line bored the head for the cam journals only on the right side....makes sense.

[XSPastor]

Yes, the breather vents blow-by gasses so that pressure doesn't build up in the crankcase. These engines did not come with PCV valves so if you're using one, you might want to consider replacing it with just a filter so as not to impede the venting function. That's not neccessarily why you jetisoned the cam plug though... I think you're right on why the plugs are there though; just a product of the cam journal boring process. I don't think their fuction is to blow out if the internal engine pressure rises, although I can imagine that they would if the vent was blocked. I've wondered why they don't have lip on the inside edge too so that they wouldn't be able to slip out. You can't install the plug properly without removing the cam cover. If you want to do it right, get a new cam cover gasket and both plugs (they're like 4 bucks each) and git 'r done!

[prometheus578]

Why they blow out... ' cause Yamaha didn't expect these things to last 30 years!
Rubber plug, or the goop they used when installing, it has shrivelled or decayed or whatever.
Either way... it no longer sticks in it's hole and the blow-by pressure in the engine pushes it out.
Clean the area well with Brakleen or solvent and goop up a new plug. (some people just fill the hole with goop)
I always lay a piece of wire over the plug and hold it in place with a small automotive hose clamp around the tensioner body.
"Ain't gonna pop out no more."

[XSPastor]

Hey Prom, any chance that we could see a photo of your anti-cam plug spitter contraption? Does the wire go all the way around the cylinders?

[xschop]

I've wondered why they don't have lip on the inside edge too so that they wouldn't be able to slip out.

I was thinking about machining the alloy half moons with an inner lip like you say and then Yamabond or epoxy the halves and the cam cover does the rest.....But wasn't sure about pressure inside cam cover/head.....I will drive it home slowly.....and work out the details this weekend for the plugs....any more info/suggestions appreciated

[XSPastor]

I don't see a problem with alloy cam seals but they would have to be just right to seal on all sides. Of course, the "goop" as (Prom puts it) would make up for any small differences. The cam cover pressure can't be any higher than the crankcase pressure due to the fact that they share the same space because of the cam chain tunnel and all the oil return holes.

[xschop]

A-Ha!

Thanks fellas, the thought hasn't crossed my mind about the cam chain galley. I will work on some alloy plugs with the inner lip .... Mouse at Yamaha in Okc is getting a new plug so I will mic it out and make a couple for a test run since this situation reared its ugly head...20w50 Castrol is not my favorite cologne at work today

[xschop]

temp. fix

Got back to work after lunch and found a rubber bottle stopper the right diameter and cut it longitudinally in half....voila'.... It works like a charm....I also pulled of the PCV from the crankcase breather and sure-enough, it only let air in and not out, so I'm sure this was the culprit .....I will check Pep Boys for a small air filter to put back on at the breather....live and learn

[XSPastor]

Got back to work after lunch and found a rubber bottle stopper the right diameter and cut it longitudinally in half....voila'.... It works like a charm....

Very resourceful!

[skids]

Prom, he was referring to the half-moon seal, I think...

Originally posted by prometheus578
(snip)
Clean the area well with Brakleen or solvent and goop up a new plug. (some people just fill the hole with goop)
I always lay a piece of wire over the plug and hold it in place with a small automotive hose clamp around the tensioner body.
"Ain't gonna pop out no more."

[prometheus578]

"Pay no attention to the man behind the curtain..."

Thanks Skids...
After carefully re-reading the post, I see my error.
Most times, when someone writes about a plug popping out, they're referring to the cam chain tensioner plug.
I just figger'd that since it was XSChop's post...
someone didn't know what he was talking about.
Turns out it was me!
Apologies to all.

But for what it's worth... this is a quick road trip repair.