Weird noise
- Thread starter TapioK
- Start date
pauldeepsea
Guru
Just taking a stab, the hose behind the breather look loose, could be a vacuum leak. I would try putting a hose clamp around it to see if it seals it.
pauldeepsea
Guru
Also check your compression release to make sure the are not backed out mine made a similar noise and I found the rear compression release was stripped and backed out. Do you have any air escaping from them?
TapioK
Well-Known Member
Those were my first suspects, but I installed new ones like a thousand miles ago. Didn't notice them leaking, and they seem to move normally. My old rear compression valve practically exploded, replaced both. Sound is kind of similar though. Hmmmm.
pauldeepsea
Guru
I would check the hose that mounts to the backing plate. It may not be getting a good seal on the breather plate.
pauldeepsea
Guru
Only other thing I can think of is after you check the hose take a look at your carb and mounting bracket to make sure nothing is loose or backed out inside. Probably not the issue.
TapioK
Well-Known Member
Pulsating, there was no real pressure.Is there air pulsating there, or suction?
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SMCT
Active Member
Those are crankcase pulses. That is a vent that is in the rocker box area. You did a compression test, but if you do a leak down, you will probably see that it might have ring seal issues, getting blow by in the crankcase which breathes out that tube in the head.
Ya see, if the scavenge stage in the oil pump was properly engineered, it would absorb those pulses, but it's not because it's a shit design.
The ring package, even when new, is too light and you will have more then what should be for blow by. A blow by meter would show this up immediately, as it's a true way to test an engine dynamically.
I smoked some dope back in the day, but nothing like the dope that the engineers at S&S smoke.
Just think about this Tapio. Take one of your lit cigarettes and stuff it in that hole so the filter is facing you, then put your lips on it. Don't say I never helped you with a better cigarette design.
P.S. The actual noise is the flutter of that one way valve.
P.S.S. why would anyone want to put dirty contaminants back into their carb/engine? That shit is silly.
Ya see, if the scavenge stage in the oil pump was properly engineered, it would absorb those pulses, but it's not because it's a shit design.
The ring package, even when new, is too light and you will have more then what should be for blow by. A blow by meter would show this up immediately, as it's a true way to test an engine dynamically.
I smoked some dope back in the day, but nothing like the dope that the engineers at S&S smoke.
Just think about this Tapio. Take one of your lit cigarettes and stuff it in that hole so the filter is facing you, then put your lips on it. Don't say I never helped you with a better cigarette design.
P.S. The actual noise is the flutter of that one way valve.
P.S.S. why would anyone want to put dirty contaminants back into their carb/engine? That shit is silly.
Last edited:
Spikes05
Member
I was going to say check out the one way check valve that that hose connects to. The hose connects to the top of the rear cylinder head and then there's a one way check valve and then connects to the air cleaner backing plate. It is the crankcase breather.
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TapioK
Well-Known Member
So you figure if the valve is stuck open, it might cause the noise? That would be nice few dollar fix.
That doesn't answer the question: do I -and if, then why- too much pressure in crank case... looking at Andy's answer I'm a bit nervous...
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TapioK
Well-Known Member
Right, I understood what you say
what I will do about it is more of a question
I'll go and see the local guy today and ask if he can do the leak test, also will check the breather valve (S&S Part #50-8122)....
I have 3 weeks before I go to Europe and I should come back like a week before Wichita meeting....
So if the cylinders leak to the case, I'm looking at least honing and new rings, then hope for the best? Depending how the cylinders and pistons look?
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Last edited:
SMCT
Active Member
My suggestion is to get a new valve and re-route that line up under the tank, towards the neck and down one of the front frame tubes, and under the bike. I used a clear line from home depot and happen to have a nice sleeve that ascetically looks great when the line is covered with it.
That line is routed to the air cleaner for one purpose, and that it is illegal to dump crankcase fumes into the open. It's an emission thing that Big Dog had to adhere to, no different than any auto manufacture. With poor engineering, all these crankcase fumes, blowby go right back into the intake change. This causes detonation and contamination of that air/fuel charge.
That line is routed to the air cleaner for one purpose, and that it is illegal to dump crankcase fumes into the open. It's an emission thing that Big Dog had to adhere to, no different than any auto manufacture. With poor engineering, all these crankcase fumes, blowby go right back into the intake change. This causes detonation and contamination of that air/fuel charge.
TapioK
Well-Known Member
Compression is pretty much 190/190.
Like everyone else said just pop at the check valve first. And see if it's broke, it's easy to figure out it should only allow you to blow out to the carb side.
Stick it to you mouth and blow each side and see if it allows air both ways. Again should only allow air blown one way.
After you replace that you can see if you have any more damage. Cheap and simple stuff first.
It's just a standard one way check valve used on vacuum lines on Cars. Take it NAPA they can probably swap it out for $2-$3
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Stick it to you mouth and blow each side and see if it allows air both ways. Again should only allow air blown one way.
After you replace that you can see if you have any more damage. Cheap and simple stuff first.
It's just a standard one way check valve used on vacuum lines on Cars. Take it NAPA they can probably swap it out for $2-$3
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TapioK
Well-Known Member
I don't do blowjobs
TapioK
Well-Known Member
Hard to say, I am in Naples waiting for rear wheel pulley, or sprocket or whatever you call it, bike is in other side of the Florida.... have a little work to do and hope to get bike together around weekend and have time to ride it back early next week... we will see...