Open Primary Seal Reversal?

[Harpo]

Hey all - heard a fella say that when you install an open primary belt drive that you should reverse the main seal.  Any truth to this?  Thanks.

[Ohio HD]

I reversed them for belt drive.

At one time James sold a double sided seal. I never used them, but remember they had them. You might check them.

[Deye76]

In the 70's & 80's I ran primary belts all the time open & closed, never did anything different with seals, as long as things were aligned correctly, never a issue. When I ran them closed, they weren't sealed, always ran without a outer cover gasket and other means of venting.

[Ohio HD]

The Seal will do it's job in in either direction. I flipped them to keep the spring around the seal in an oily environment. Other wise it's exposed to dust, humidity, possibly water spray. Just the same reasons most all seals like this are spring internal. In the OEM HD world, both sides are exposed to sealed oily cavities. 

[Deye76]

My experience with primary belt drives were on 4 spd, trannies. The seal didn't care if it was oil, dust or moisture, it's job was to seal, and I never experienced any problems.

[Ohio HD]

John, I guess JW describes it better than I did in his post here.


https://harleytechtalk.com/htt/index.php/topic,89932.msg1033762.html#msg1033762


I always placed the spring outward, unless an open primary, or a dry primary. Over time the spring can get gunked up, rust, etc. But when subjected to oil that doesn't happen.

[Deye76]

  Makes sense. I was thinking mainshaft seal on the trans. Although never did anything different with the engine sprocket seal either, when running a belt drive.

[JW113]

Just my opinion here. You point the seal (i.e. the side with the spring) in the direction you DON'T want oil to transfer from. A little anecdote... Every bike that I have has a crank-vent type device on it. This creates an average vacuum inside the crankcase. A vacuum in the crankcase tends to not push oil out, and draw outside air in. Ever since I added these, all of my bikes stopped leaking oil. All of them, esp the 1945, are very old. Amazing, yes? If you run an open primary, I would highly advise adding a crank-vent device to the breather tube, and install the left side seal with the spring pointing toward the right (toward the inside the crankcase). That should seal any oil trying to come out of the crankcase into the open primary.

Just my 2 cents....

-JW

[thumper 823]

OK, I am lost. Crank type vent?  Obviously, you are refering to something  then is already there.

Draw me a picture?
thanx

[76shuvlinoff]

Thumper, google up Hayden Crank Vent.  I have had one on my S&S "shovel" for 16 years. Some will insist it's snake oil but I am a believer and it sounds like JW is too.

[david lee]

Makes sense. I was thinking mainshaft seal on the trans. Although never did anything different with the engine sprocket seal either, when running a belt drive.

my hd mech said makes no difference. that said how would you tap it in spring side out

[thumper 823]

Thumper, google up Hayden Crank Vent.  I have had one on my S&S "shovel" for 16 years. Some will insist it's snake oil but I am a believer and it sounds like JW is too.

OK I did that and thanx.

It must be a one-way diaphragm like upper umbrella seals on latter Evos.
I have to wonder about the claimed HP gains claimes by their advertisement ...
My little Evo has not ever had anything but the S.S. timed breather in it ( I replaced the plastic crap years ago) and it is an open belt drive.
No problems.  ( and I run less than 11 lb ring drag)
I think if I was going to buy that i would just by a twelve dollar PCV valve ....It does the same thing for a hundred dollars less.
Thanx for the information.

[Hossamania]

I always loved the horsepower claims by using a company's product.
"Up to 30% horsepower gain!"
** When used with other engine improvements, including cams, carburetor, high compression pistons, etc.

[thumper 823]

Little things do add up...but it is the many many little things.
Running the crankcase air further prolly is not a good thing.
Next with a properly timed breather and running at even a
low 2ooo RPM how much air could actually be sucked back in the tiny breather tube??
Large stroke big bore engines may have more of a problem ...I know the timed breather hole gets enlarged.

But I sincerely doubt any little Evo will ever have a problem.
As I stated  I run really low ring pressures.
Neve a drip.

[Scotty]

Thumper, google up Hayden Crank Vent.  I have had one on my S&S "shovel" for 16 years. Some will insist it's snake oil but I am a believer and it sounds like JW is too.

Hayden Krank Vents have been tested on the Dyno and by multiple people and do not increase HP or torque in anyway.
Even Hayden Enterprises admitted it was only to stop blown rocker cover gaskets on Evo's 20 years ago.
Plenty of reading on the internet says they are a waste of money.

[JW113]

The only value they add in my experience is fewer, if any, oil pools under the bike after a ride.

-JW

[thumper 823]

Ok, Ok, then we have to allow the question -Why do some bike engines do this? And others do not?

If mine sits the 6 to 7  months through the Winter here (generally Oct to May ) It sometimes will dribble a couple of drops
@ Spring start-up .
Sometimes not always.
Other bikes will always be catching up sumping and dripping. Even outright puddles on the floor!
All the time.
The answer is of course sometimes.
Not consistent and obtuse,  not symbiotic.
Most likely-
Check valve
The Nasty plastic timing gear.
Breather Timed wrong.
Mixed up parts between head breathers and old school vented style .
These are thing s to stay up all night over and contemplate. LOL

[Burnout]

Some won't make it a month without a catch pan under them.
It's not a problem if you ride it, You could drain the tank when you park it to prevent it.