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CVO Technical => Twin Cam => Topic started by: busarealfast on December 31, 2020, 06:53:31 PM
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I ordered a vented oil filler cap from A1 cycles and was thinking about blocking off the air filter housing to throttle plate vent to keep oil from entering. Should I still externally vent the air filter housing? Is the oil filler cap vent enough?
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Just change the head breathers to external. There are several instructions online to do that. No filter is needed. If the oil coming out is excessive there is either breather umbrella valve issue and/or excessive blowby.
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My understanding is that the head venting is a separate issue from the oil and crankcase venting that comes from the oil cap. I think it would be harmful to block off the head vent bolts. Externally vent them.
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I ordered a vented oil filler cap from A1 cycles and was thinking about blocking off the air filter housing to throttle plate vent to keep oil from entering. Should I still externally vent the air filter housing? Is the oil filler cap vent enough?
Yes you should keep the heads vented a ccv cap may not be sufficient venting. When CCP is building up from your crank case to the top of the motor and if you block off the means to relieve that pressure it will build in the rocker covers and will try to escape at the weakest point, pushing past v/v stem seals (oil burning and blue smoke on start ups are a sign of v/v stem seal leakage) as the CCP forces oil past the v/v stem seals into the cylinders, popping rocker box gaskets, are possible issues that may occur.
It's simple to do there's lots of ways shown on YouTube
The CCV cap wouldn't hurt to have but not as the only way of venting .
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I ordered a vented oil filler cap from A1 cycles and was thinking about blocking off the air filter housing to throttle plate vent to keep oil from entering. Should I still externally vent the air filter housing? Is the oil filler cap vent enough?
First I've seen a company that also has a vented cap for the old style push in dip sticks. May give this a go to see if I can keep my stick from becoming airborne.
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First I've seen a company that also has a vented cap for the old style push in dip sticks. May give this a go to see if I can keep my stick from becoming airborne.
If you're puking old dipsticks out have you done the suck and blow test at the vents on the heads? Maybe some old cylinder head breathers not up to par anymore?
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If you're puking old dipsticks out have you done the suck and blow test at the vents on the heads? Maybe some old cylinder head breathers not up to par anymore?
It's pretty much been an issue since I had the dealer repair bent valves under warranty (guide drop).
I never beat on the bike much so it did not immediately become a problem. I thought I found the cause when I removed the cylinders several years ago and found the winning lottery ticket of all 5 ring gaps lined up (you probably remember that).
Since then the cams were changed, new cylinders and heads of which John S worked over before I put them on. Breathers were new at that time and sometime later they were removed and replaced a second time. Very rare this bike sees above 5K or has WOT pulls.
There are other things I've tried along the way that I have forgotten as well.
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It's pretty much been an issue since I had the dealer repair bent valves under warranty (guide drop).
I never beat on the bike much so it did not immediately become a problem. I thought I found the cause when I removed the cylinders several years ago and found the winning lottery ticket of all 5 ring gaps lined up (you probably remember that).
Since then the cams were changed, new cylinders and heads of which John S worked over before I put them on. Breathers were new at that time and sometime later they were removed and replaced a second time. Very rare this bike sees above 5K or has WOT pulls.
There are other things I've tried along the way that I have forgotten as well.
If Sachs was the last one in there I'd bet dollars to donuts the breathers are in just fine. The newer/better/current style are easy to assemble wrong though. The suck and blow test will tell you if they're wrong (or just screwed up due to failure, age, etc). And when they're messed up they will cause a dipstick to go flying.
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Please explain this "suck and blow" test you are refering to.
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Please explain this "suck and blow" test you are refering to.
Hook a tube onto the breather fasteners on the heads if you can suck on the tube 👍 if you can blow on the tube👎
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Please explain this "suck and blow" test you are refering to.
I use old breather bolts with their heads cut off. But just anything that would allow you to suck on and blow in to a breather hole in the head. If you can suck on it and it's open you should not be able to blow. If you can blow in and its open it should not be open when you suck. One works and the other does not if the breathers are working right.
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I ordered a vented oil filler cap from A1 cycles and was thinking about blocking off the air filter housing to throttle plate vent to keep oil from entering. Should I still externally vent the air filter housing? Is the oil filler cap vent enough?
When I work on Twin Cam heads, I give the customer the option of installing external breather fittings. This system lets you use regular solid bolts, washers, and lock washers to hold the air cleaner. Also eliminates the oil snivels, and oil weeping in the bolt area. Just connect hoses, and route where you want. ;)
John
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Nice and clean John.
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When I work on Twin Cam heads, I give the customer the option of installing external breather fittings. This system lets you use regular solid bolts, washers, and lock washers to hold the air cleaner. Also eliminates the oil snivels, and oil weeping in the bolt area. Just connect hoses, and route where you want. ;)
John
Do you do that to the 103 SE heads as well?
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Do you do that to the 103 SE heads as well?
I can.
John