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Just picked up a 2002 evo sporty chopper. The price was low and it's a cool little chop for my wife. The p/o said it was blowing oil out the carb and he didnt have time to look into it. He said a new custom oil tank was installed recently. I'm thinking improper venting...I started it up and it literally blew oil cap off and sent it flying at least 10 feet. I haven't had anything but flatheads since the mid 90s so I'm a little leery of this bike....man it sounds so strong tho! Any input on where to start and what to look for?
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Yer in luck. Oil tank is plumbed the same as on your flatties. The motor vents through the heads into the air cleaner box. You can plumb around that and vent toward the ground if you wish. There are kits of breather parts for that. Really easy.
JimComment
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May have wet sumped which can cause the oil cap to go flying ...
The rubber flapper breather valves in the rocker covers can become hard as a three day old biscuit and allow oil to pass by em ...
Easy to replace .. If you do, there is a small weep hole where the rubber valves are at, they need to be drilled out to .125" ...Take my 45 and outrun em all ..Comment
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Check the oil filter: It should be one made for your make/model. Many others will fit, and some will work, but many have anti drain valves (or whatever its called) that takes more PSI to open than a stocker oil pump can open
Ask me how I know
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Should I Run A 10 Micron Or A 30 Micron Oil Filter? By S&S Cycle.Check the oil filter: It should be one made for your make/model.
"...If you run the 10 micron filter with an evolution style engine it will not be able to return oil through the filter fast enough causing the oil to back up into the lower end robbing power and/or causing oil to puke out of the lower end. The 30 micron filter is designed to work best for your Evolution style engine, the filtration is still excellent and it will not cause oiling issues..."
If buildin' old school choppers was easy, anyone could do it... ain't nobody said it's gonna be easy...Comment
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I missed the Sporty part...
Crankcase Ventilation
1991-2003 Sportster Breather Valve
An important note:
Factory engine breather valves on all Evo Sportsters are inside the engine.
The lines / hoses that leave the engine and any apparatus to route the air to different places are part of the venting system. ..
The new breather system uses (2) one-way umbrella valves (26856-89) placed in the rocker boxes (1 each placed on the intake side).
The part number was later updated to (26856-89A).
These expel crankcase vapors through vents in the top of the cylinder head and into the carb to be burnt. 9)
On each piston downstroke, crankcase pressure (air and oil mist) is routed up the pushrod tubes into the rocker box (bypassing the falling oil from the rocker boxes).
Collected air pressure and oil mist in each rocker box is routed up into a sealed cavity in the lower portion of the box.
This mixture passes up from underneath a rubber one-way valve (umbrella valve) sitting over the cavity inlet.
The oil is designed to separate from the air by hitting the underside of the umbrella valve and dropping back down into a recessed area behind the umbrella valve in the cavity.
From there it should drain back into the main rocker box through a tiny hole behind the umbrella valve and then back to the lower end.
The separated oil flows into drain holes in the rocker boxes and back into the gearcase.
Air pressure is designed to continue up past the umbrella valve and exit a hole in each head on the intake valve side.
Air pressure escapes the head through the hollow bolts (one in each head) that hold the air cleaner mount..."
see more here:
If buildin' old school choppers was easy, anyone could do it... ain't nobody said it's gonna be easy...Comment
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Grab a factory service manual and parts book off the net. The factory books have great illustrations of oil and vent flow.
https://www.facebook.com/groups/1465028990466294/ has most of them. Ask if you don't see what ya need. Any five speed solidmount Sporty book will be close enough to get started. I always perform a cold compression test on new-to-me bikes.
Last edited by farmall; 01-10-2023, 11:15 AM.Comment
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Thanks for the info guys. Much appreciated. Farmall , great links that will get alot of use!Comment
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So I removed the oil tank today. The vent line fitting and hose were plumbed into the feed hole. (Lowest point) The feed line fitting and hose were plumbed into the return hole and the return into the vent.
It's a custom oil oil tank and has one fitting in the middle which is on the bottom of the tank(feed). One fitting with a pipe attached to the hole (also at bottom of tank) that extends up to the bottom of the opening for the oil tank cap. (Vent?) And one more fitting (at bottom of tank as well) that also has a pipe that extends about 3.5 inches or halfway up to the full level of the tank(return?)
I guess my question is does the return hole need to be able to breath or can it be submerged under 3 inches of oil? I've always had a traditional horse shoe with return and vent at the top.
Just looking for input before I start making changes.Comment
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MOVING OILI guess my question is does the return hole need to be able to breath or can it be submerged under 3 inches of oil?
"Routing the oil lines from the oil tank to the engine is simple task. There are only three oil lines needed to make your bike run: the feed from the oil tank to the oil pump which is located on the engine, the return line from the engine to the oil tank, and the breather line from the engine to the oil tank...
...When an oil tank, such as this horseshoe style tank, has the oil lines exiting the bottom of the tank there will be tubes (arrow) inside the oil tank for the oil return and the breather line.
The feed fitting will be flush with the bottom of the tank because you want “all” the oil to feed the engine.
The oil return and the breather lines should be above the oil level inside the tank. The oil returning from the engine is hot, and there’s less resistance if the oil returns to the tank freely, without having to push past the oil already in the tank.
The breather should exit above the oil level also for the same reasons. Because if it was below the oil level, the oil in the tank would run down into the engine and cause it to sump..."
If buildin' old school choppers was easy, anyone could do it... ain't nobody said it's gonna be easy...Comment
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Looks like I'll be increasing the length of the vent tube. Danka!Last edited by montuckymatt; 02-20-2023, 7:38 AM.Comment
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And?..............Comment
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