Umbrella valve upgrade - w/ so many options, how do you pick
In an effort to maximize the gains and results of my effort on this rebuild, I'm looking for the stuff that is easy to do, but a PITA to get to. - since I have it stripped down so far.
That included new cables, along with a final approach to the breather setup that I made last year.
I had never finished or painted the bracket, so it only makes sense to do it now.
That made me wonder why there was so much oil in the can and tubing.
Remember, it was lying on this side for a bit following the accident, so there's that .
As others already know, excessive blow by could be a sign of a gunked up or failed umbrella valve in the rockers.
No better time to address this upgrade than when the tank is already off.
With so many upgrade/replacement options out there, how do you know if any one version is really any better (or different) from any other brand?
Prices range from about $40 to $250, but I noticed the higher priced models also come with gaskets and new (shorter) bolts to make installation easier.
The inexpensive versions seem to only have the bare minimum in required parts.
With the engine still IN the frame, what features or specs in a kit should I be considering to make this upgrade easy?
I used the Harley kit. Inexpensive and all you need. Make sure to blow/clean the bolt holes out so any oil that may have snuck in there doesn't create a problem.
ETA: What does a $250 umbrella kit include? Having a hard time wrapping my head around that.
Now I can’t locate the kit that included rocker cover gaskets so from these options all i$250 gets you is a machined and anodized finish on a part that can’t even be seen. 🤷♂️
They're all mediocre at best for a stock engine and its just dumb you have to tear it down as far as you do just to replace them. For a built engine, especially one running higher rpms, they lack in my experience.
I eliminated them and use an external reed valve off each breather bolt. Reed valves open/close quicker eliminating any air being sucked back in and maintaining a slight vacuum. This makes for better ring seal, the cause of blowby in the first place.
I left the housing and drilled out the drain holes under them and I can run my oil on the full mark and not get a drop of oil ever out of the hose running under my bike.
These reed valves can be disassembled and cleaned if necessary and no need to pull the tank and rocker covers to do it or replace them.
One on each side going to a T fitting and out under the engine. Never leaves a drop.
They are street and track tested in BMW twins and made to mount directly in the case. There's a version to replace the sump plug. I just use a universal inline version but have toyed with doing a case mount.
Nothing wrong with the stamped ones.. I run them in mine without any issue at all.. Just make sure you do like Max said and drill out the plate to 0.125"
If you're truly concerned about blow by do a leak down test..
They're all mediocre at best for a stock engine and its just dumb you have to tear it down as far as you do just to replace them. For a built engine, especially one running higher rpms, they lack in my experience.
I eliminated them and use an external reed valve off each breather bolt. Reed valves open/close quicker eliminating any air being sucked back in and maintaining a slight vacuum. This makes for better ring seal, the cause of blowby in the first place.
I left the housing and drilled out the drain holes under them and I can run my oil on the full mark and not get a drop of oil ever out of the hose running under my bike.
These reed valves can be disassembled and cleaned if necessary and no need to pull the tank and rocker covers to do it or replace them.
One on each side going to a T fitting and out under the engine. Never leaves a drop.
They are street and track tested in BMW twins and made to mount directly in the case. There's a version to replace the sump plug. I just use a universal inline version but have toyed with doing a case mount.
I drilled the oil return holes to 1/8" and used Cyco umbrella seals and foam. I also added a couple of hoses and an external breather filter. Seems to work great even at higher rpms it doesn't really spit oil. The biggest thing that helped my problem was going back and aligning the oil pump because I forgot to align it when I put it back together last spring 😂 Breather is above the air filter.
The guy I know that tested didn't test for power/performance increase but crankcase pressure or lack of it. These particular reed valves maintained a constant crankcase vacuum. The stock umbrella valves were up and down pressure when new. Presumably because they allow air back in briefly before closing. What happens to them after being exposed to the high heat of one of the hottest places in the engine? Its a dumb design . There's a reason every other big twin with 2 cylinders going up and down at the same time or nearly the same time use reed valves. Feel free to use the stock umbrellas if you think they're all that. They are obviously considered a maintenance item. That's why replacements come in gasket kits.
Do you know how much crankcase pressure you have? Would you agree or disagree no positive pressure is best? There's a reason race engines run vacuum pumps and it's not cuz they look cool.
I don't have to run my oil a half quart low either. In fact ATM it's slightly over the full mark. Not a drop hits the pavement where I park.
Running low on oil isn't a fix for poor crankcase breathers or oil pump scavenging for that matter.
08-10-2023, 09:28 PM
Umbrella valve upgrade - w/ so many options, how do you pick
