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Discussion Starter #1
Alright before I begin YES I've used the search function and NO I didn't find my answer. Ok so now that's out of the way here we go!

My 70 T120 is SPEWING oil out of the tank vent (aftermarket tank) and primary breather. The entire back half of the bike is covered in oil including the rear wheel. It only seems to do this at higher speeds 50mph+. Now whoever built the engine before it fell into my hands ran the rocker feed from the oil pressure switch. (yes I know that's wrong and parts are on order to fix it, changing the tank out as well) My question is could this be putting too much pressure to the tank/crankcase causing this oil slick spraying out of my bike? The primary breather is an off/on problem with this and doesn't spray as much as the tank vent.
 

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This is all just my opinion.....But that happens a lot on those horizontal round chopper tanks on the market, not enough vertical room for the oil/foam to seperate and it ends up belching oil/foam out the undersized vent hole when riding at sustained freeway speeds.
No aftermarket tank works as well as the stock Triumph tanks do with the froth tube and the vertical size necessary to let the oil foam condense back into a liguid again.
 

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Discussion Starter #3
Tony do you mean there is not enough room from the top of the return pipe to the top of the tank? I'm more concerned about the rocker feed line causing too much pressure, am I right that this can happen when it feeds off the oil pressure switch?
 

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Too much oil? Last time this happened to me, I wasn't able to run the bike before I changed the oil. I over filled it and it puked all over the back end.
 

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Tony do you mean there is not enough room from the top of the return pipe to the top of the tank? I'm more concerned about the rocker feed line causing too much pressure, am I right that this can happen when it feeds off the oil pressure switch?
oh ya, that rocker feed off of the pressure switch fitting never worked, it ends up putting a constant flow of 60+ PSI oil up there and that leads to the push rod tubes filling up with oil, I'm surprised the rocker shaft seals and the copper washers on the feed lines didn't burst, as well as it robbing some of the volume of oil that should go to the crankshaft.

I was going off on those little round oil tanks that can't hold more than 1 quart of oil at a time without puking all over everything.
 

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Discussion Starter #6
I usually keep the tank level fairly low as it seems to either piss it out or burn it off. The rocker shaft seals are leaking slightly not to mention the rocker gaskets are completely shot and the pushrod tubes usually leak a bit too. Sounds horrible I know but the motor is getting rebuilt soon. But I take it you mean that some of the oil/foam from the return line is going straight out the tank vent?
 

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On a stock Triumph the oil tank holds 2+ quarts of oil, that allows the return oil and foam mixture to go into the oil tank and sit there and cool down a while the air separates out of the oil and the engine still has plenty of pure liquid oil to get pumped back into the engine. a good custom oil tank also has enough vertical room to allow all this to happen. you can run a whiskey flask as an oil tank if you want, but it will effect how long it runs at freeway speeds.
In my opinion, it is the amount of oil and vertical height of the oil tank that allows the oil to cool down and do the air separation thing .

As for that vent tube puking, on a stock Triumph that vent tube is supposed to be run up to the oil tank and the oil is put back into the oil tank and the air is allowed to go out of the oil tank air vent tube.
Many bikes just have the breather tube point to the ground and don't have much of a problem, some bikes have an issue when they first fire up. Your bike likely has a lot of issues with oil because of all that pressured oil going up to the top end, all the oil comes down the pushrod tubes and lands on the cam, that is right where the breather vent hole is.

The problem really is, almost every "garage chopper engineer" just figures the last 70 years of Triumph factory trial and error results were a giant waist of time, and a little "Budweiser brainstorming" can come up with a much better idea for everything.
I imagine they say... " Why didn't those stupid Triumph engineers just do it that way?"

just about every weird thing you can do to a Triumph has been tried in the last 70 years, (backwards heads is a good one). all the things that work well you will see on bikes being regularly ridden.

bottom line.... get rid of that rocker feed and see what happens.
 

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I usually run the case breather back into the oil tank ..and drill another hole and tap the tank again. then run a hose down to vent the tank..works for me..I agree on the other post too..too much oil will cause alot of probs and u need space in the tank for the oil to settle and help it cool somewhat..
 

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Discussion Starter #12
yeah my tank has about 1/2-3/4" of an inch between the top of the return tube and the roof of the tank. Gonna slip a bit of hose over the top of the tube and point it away from the vent for now. As soon as those parts come in that tank is getting swapped out!
 

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Discussion Starter #13
ok so i've fixed the rocker feed oil line to run the proper way and changed the oil tank. Still aftermarket but better than the old tank. However it still pisses oil out the tank vent when it gets above 70mph. Cant figure it out and it's driving me crazy! Tony? Anyone?
 

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Is the oil pressure release valve ok...I was just thinking it might be dumping more oil into the bottom of the crankcases and being scavenged back to the tank all the time...just a thought.
 

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As far as oil spewing out of the breather...does your engine sit horizontal in the frame or is it laid back like some of the older choppers did? This can cause oil to accumulate in the breather baffles and blow out the vent. My old T100 chopper did this, kept OPEC very happy for the summer of 1980. Where it only seems to happen at higher speeds, it could be a blow-by issue too. You might want to consider some of the crankcase breather mods some people on this board have done. I hope you get it sorted out.
 

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mine did the same thing when i first put it together i swore it was wet sumping but drained the sump and only had roughly 90cc's in it my problem was i had the tank over full so on return with air in the oil to the tank it was coming out the tank breather all over everything. seems my bike likes the tank a little over half full.
 

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I usually run the case breather back into the oil tank ..and drill another hole and tap the tank again. then run a hose down to vent the tank..works for me..I agree on the other post too..too much oil will cause alot of probs and u need space in the tank for the oil to settle and help it cool somewhat..
Drumrooster and Torch,

Looks like you both have the same configuration. I get a little oil out of my breather hose at highway speeds also and what you both posted makes sense.

I only have three ports on my horseshoe oil tank. Feed, Return, and Vent which has a T that connects to the crank breather and vents towards the back of the bike.

I'm curious about the following:
- Any concerns with adding a fitting similar to what's in the picture to the oil tank, which will be directly connected to the crank case breather tank? This will eliminate the T that connects the oil tank and the breather.

- If so, I assume it can be placed anywhere on the oil tank, even the top since it is essentially another return. Just as long as it's above the oil level.

- Would there be any concerns with oil tank pressure loss or anything?

Thanks in advance!
Ken

 
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