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Case vent?

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03 Cr 250, behind the ignition cover and flywheel there is a factory made small hole that leads to I assume the crankcase. I noticed gear oil puddling near the hole and it caught my attention. I was thinking it may have run down from the clutch crank arm seal, and I ran the bike with the cover off to check if the clutch arm seal was leaking, the bike ran very very lean, due to the air that was being pulled in, after reinstalling the ignition cover the bike ran fine. Im pretty sure Ill need a right side crank seal, but Im still wondering why that vent is there, since there is already a vent tube on top.?

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Correct me if I'm wrong but that hole does not vent anywhere, check it with a flash light.

Agreed on needing a crank seal.

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Correct me if I'm wrong but that hole does not vent anywhere, check it with a flash light.

Agreed on needing a crank seal.

Its hard to see even with a small led light near the hole. If it doesnt go to the case, then I have a left side seal thats bad too due to the instant lean condition when the ign cover is removed.. I think im going to do the bottom end pretty soon anyway.

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I had the same problem with my 125 no one knew what it was i got around to splitting my cases and determined its a weeping hole for the gasket, when the gasket is bad oil drips past the gasket and out that hole there is a pocket that the oil collects and drips out the hole i swapped the gasket but the bike hasn't ran so i cant tell you if it fixed it but the crank seal was in good shape and no oil was coming out of it. btw you wont be able to see anything its a pocket pretty much and leads no were

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thanks for the reply !

I'm asking this because I have some dirt who go inside that case side...

I had to clean by spraying somes water with spraying can into this hole and somes dirt came back

boyosen cover don't fit well with the gasket... I don't understand why

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yeah i had a bunch of grease in that hole also i sprayed some wd40 in there to try and get most of the junk out when i split the cases i just took a turkey baster and sucked all the junk out then cleaned it out with some break parts cleaner and looked good as new. when i get it running again i'll let you know if it was because of the gasket for the case.

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if you splitted the case, should I care if I had dirt in that space ????

I still don't understand the purpose of this room

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no dont worry about it its sealed off from the engine the only reason i split my cases was because my left side case was cracked and replaced it and while i was in there i just sucked the stuff out of the thing

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what can I do to prevent dirt to come into behind the boyosen cover ?

what people do to seal the wire that goes into the pickup coil ?

thanks

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maybe you could try some silicone im not sure do you still have the stock cover?

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the stock cover uses a oring and the boyosen cover

I have it but it looks like ***

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