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250 RR cylinder base gasket

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Hi, I just did a top end rebuild and after putting it all back together I realised that I fitted the base gasket the wrong way - upside down. The gasket is symmetrical except for a bit of extra material near the power valve linkage and there is a raised silicone bead on one side.

I think it will be ok without the extra material near the power valve linkage as that could be solved with a bit of extra silicone, but I’m not so sure about the silicone bead. Can that go either way?

Thanks!

B981344C-5C29-46FD-A6B9-5C67AB250F9A.jpeg

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Did you re-use the old gasket? Best not to. 

If it was me, I would set aside 2 hours, unzip the top end & put a new gasket on, right way round. 

It may not leak, but if it does you’ll probs get over it & do it again anyway. 

Edited by KatoKonvert
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I'd imagine the silicone is supposed to be on the bottom side to help prevent leaks where the crankcase halves come together.

 

But even if it doesn't leak, you'll now have an open gap on the PV linkage side where that square is supposed to be. So it'll hold water, dirt, grease, etc. So it just depends if that part bothers you or not.

 

If you do leave it, make sure you cut that square off that you have sticking out the left side of your engine though. It announces to everyone that you put your base gasket on upside down. Lol

 

 

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True, I hadn’t considered about the cases coming together. It’s a new gasket but I’ll replace it now before I get the bike dirty. The advantage of doing it now is that it’s all super clean which should make it faster and easier.  

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Wonder when they started adding the silicone?

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3 hours ago, BassMan said:

Wonder when they started adding the silicone?

End of 2014

Edited by dirtbird

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Ok, I have done 3 top ends since then and never noticed.

Perhaps I was still using old stock. I don't even remember it last year. Lol

 

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7 hours ago, BassMan said:

Ok, I have done 3 top ends since then and never noticed.

Perhaps I was still using old stock. I don't even remember it last year. Lol

or maybe you were putting them in upside down too! lol

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7 minutes ago, randysoo said:

or maybe you were putting them in upside down too! lol

You'd have a big square sticking out of the left side of the engine. 

 

Don't ask me how I know...

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16 hours ago, Goatse said:

You'd have a big square sticking out of the left side of the engine. 

 

Don't ask me how I know...

You saw my bike? 😂 

 

Also, Beta Australia said it would be fine up side down and that the small bead of silicone would stop dirt being left in the tiny gap. 

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10 hours ago, danieltsuji said:

 the small bead of silicone would stop dirt being left in the tiny gap. 

What small bead though? With your gasket flipped there is no gasket or anything in that area. It's a gap with metal over metal that is as wide as whatever thickness of base gasket you used. 

 

Maybe they're saying for you to put a small bead of silicone on that part yourself. Not take the cylinder off or anything, but just apply it at the joint from the outside. It would at least keep stuff out of there. 

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1 hour ago, Goatse said:

Maybe they're saying for you to put a small bead of silicone on that part yourself. Not take the cylinder off or anything, but just apply it at the joint from the outside. It would at least keep stuff out of there. 

Maybe...I wouldn't risk it

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Maybe...I wouldn't risk it
I don't think it's actually risking anything really. Maybe the surface finish in that area, but even then, it's not a sealing surface out that far. So even if the surface was less than perfect, I doubt it would even affect his next base gasket/top end at all.

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Yeah, I'm sure you're correct. That's just me, when I'm not really sure of what I'm doing, I follow the manual explicitly. If it said to hold my breath and rub the top of my head while installing the gasket, I probably would.

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