07 yz450 O-ring question

Last night I took off the left side crankcase cover to re-seal the stator grommet, and while putting back together I cannot figure out how this o-ring fits. The owners manual shows the o-ring as fitting on the case side while the drawing in the thumpertalk store shows it on the other side of the gasket case cover side. Can anyone help me out here.

First Picture is out of my manual, showing the O-ring on the case side. This is how I think it came apart, since this side has a recess for an o-ring...


This picture is from the TT store, showing the O-ring on the cover side of the gasket. I can't imagine this is how it fits? Part # 11 on this sketch


I just noticed that the breather hose holders are pictured different in each picture. The second picture displays this correctly. Is the second picture better than the OEM manual?

Edited by motorcross242

You could try going onto bike bandit and go to the oem part where theres a diagram and see what that says. Then try which side fits. Does the o-ring not fit on one side? I would go with the manual.

Bike Bandit shows the same drawing as the TT store - O-ring on the cover side of the gasket. If i recall correctly, this side does not have a recess, it would just smash the o-ring on this side?

Edited by motorcross242

There are several of these sealed dowel sleeves in the engine assembly. In ALL cases, the O-ring goes in the recess cut for it, regardless of which side of any gasket that places it on, or how the exploded view shows it.

So in theory - only one side will have this recessed channel for an o-ring?

Also, in your experience, how do you go about mitigating these inconsistencies in the manual? This is the first time inside the case and it makes me nervous about doing anything else. If you look at the case bolts, the manual is way off. The case has different size bolts, and the manual does not help. In the first picture it shows the rubber hose hanger at the top of the case, the exploded view on the TT/bike bandit store have it correctly?

If two diamgrams show the same i would go with that. you might want to go talk with someone at your local dealer.

That's what I was thinking, but as grayracer513 said it is on the side with the recessed edge which goes along with what the manual shows, but then the TT store and bike bandit are wrong.

One is a parts catalog, and should not be used as an assembly guide. And absolutely every service manual I've ever spent a great deal of time with contains errors. (Don't ever lap your valves on that bike, for instance). Then too, people fail to read the entire book, for obvious reasons, I suppose, and mistakes are made a s a result.

In any case, the fact is that regardless of any illustration or other information to the contrary, the O-ring goes IN the counterbored recess. This prevents it from being crushed or split by being compressed between the two cases, keeps it from slipping out of position or expanding, and prevents it from holding the two cases apart, all of which would create a leak.

With regard to bolt length, that's not too hard to sort out on your own. There will always be some uniformity to the amount of thread contact they all have, for one thing, but here's a tip:

Looking at the Yamaha parts fiche, the bolt part numbers will tell you how long each bolt is and how many are needed. For example, that cover calls for 1 PN 95022-06040-00 and 7 95022-06030-00. The bold section of the number tells you that the 95022-06040-00 is an 6 mm bolt (M6x1.0) that is 40mm long. The others are M6x1.0x30mm.

you should ask the dealer. Just call them up.

Just curious about two things:

Who do you think you'll get on the phone at a dealership that will even know there's an O-ring there in the first place, let alone where it goes, and why is it that you don't think I don't know what I'm talking about?

I do not even need to question what grayracer says. I took the cover off to double check everything. This o-ring sits nicely only on one side, the recessed side. He's right. /thread

Just one thing to add - I would take grayracer's recommendation over an "expert" mechanic any day! (and I have - Maxima FFT, Regina Chain, Lube, Oil, Sprockets). I would pay the man to teach me.

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