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How is the crankcase vented on an Evo?

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Old Oct 20, 2015 | 03:17 PM
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Default How is the crankcase vented on an Evo?
I dont see any crankcase ventilation on my Evo motor. How are these engines ventilated? Ive seen reference to breather bolts and such but there is nothing like that on my bike.
 
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Old Oct 20, 2015 | 03:28 PM
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The 2 bolts on the heads with the cross pipe and hose behind the carb. the hose goes into the rear of the air cleaner.
 
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Old Oct 20, 2015 | 03:30 PM
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Mine doesnt have anything like that.
 
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Old Oct 20, 2015 | 03:39 PM
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Originally Posted by 89FLHTC
I dont see any crankcase ventilation on my Evo motor. How are these engines ventilated? Ive seen reference to breather bolts and such but there is nothing like that on my bike.
Look just inboard of your oil pump on the lower part of your motor.
It's kinda hidden but it's there.

Breather bolts are in the heads.
 
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Old Oct 20, 2015 | 03:45 PM
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Are the bolts used to mount the air cleaner bracket? I have an aftermarket air cleaner and regular bolts holding the bracket on the heads. Is that a bad thing?
 
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Old Oct 20, 2015 | 03:46 PM
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Originally Posted by texashillcountry
Look just inboard of your oil pump on the lower part of your motor.
It's kinda hidden but it's there.

Breather bolts are in the heads.
Yep yours is a bottom breather, the hose is either running up to back of breather or is running down to open air. Where the breather bolts are on 93+bikes is just a carb mount for yours.
 
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Old Oct 20, 2015 | 03:56 PM
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Your '89 is a bottom breather and doesn't have the hollow bolts in the heads. There is a breather line coming off the rear of the crank case, near the bottom, behind the oil pump that may or not travel to the back of the air cleaner housing. Stock will have the line going to the air cleaner but there a lot of folks who just take the line to atmosphere.
 
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Old Oct 20, 2015 | 04:15 PM
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I think if you look at your picture in your oil line thread the third line to the rear is your vent line...see where it goes. There will be two vent lines one to the oil tank and one mounted lower on engine either going to breather or open air.
 
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Old Oct 20, 2015 | 04:26 PM
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Found it! Thanks!
 
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Old May 2, 2024 | 12:41 AM
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Originally Posted by RANGER73
The 2 bolts on the heads with the cross pipe and hose behind the carb. the hose goes into the rear of the air cleaner.
do you know the orientation of those bolts? Do they both point into the cross pipe? or only one and the other into rear of air cleaner?
 
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