Open Header question

Hey guys, I gotta question for ya.

I heard the other day from a engine builder that when I go to fire my bike up for the first time (I rebuilt it completely), that I should leave the muffler OFF, meaning it is just the header. He mentioned that with the muffler off, there was some certain change in back pressure or something, and it helps seats the rings faster. He said don't ride it without the muffler, but when I got to fire it the first time and have it on the stand, to let it run for a bit with open header.

Now I have build a few motors in my life, and I have run them open headers before, but not because it 'seats the rings faster'. Any opinions on this?


FWIW: The bike is coming along nice. Almost ready to fire once I get that peice I ordered



Post edited by: cuddies, at: 2007/05/26 12:11

Post edited by: N0NB, at: 2007/05/26 22:52

Hm, never heard of that "trick" before. :huh:

But hey, it if works w/out causing any damage, why not!

I'd always heard that you should run it hard (not peg the redline of course) to help seat the rings = break the engine in like you intend to ride it.

cuddies wrote:

... I heard the other day from a engine builder that when I go to fire my bike up for the first time (I rebuilt it completely), that I should leave the muffler OFF, meaning it is just the header. He mentioned that with the muffler off, there was some certain change in back pressure or something, and it helps seats the rings faster. He said don't ride it without the muffler, but when I got to fire it the first time and have it on the stand, to let it run for a bit with open header....

Where was it you're taking that auto shop class?
Just rattling your cage :laugh: and still learning with each page turn.
Have heard of spinning the engine over without plugs
for an hour or so to better seat new rings,
but never tried it
and don't understand that theory either.

Post edited by: Patton, at: 2007/05/26 12:36

Post edited by: Patton, at: 2007/05/26 12:42

Patton wrote:

Where was it you're taking that auto shop course?
Just rattling your cage :laugh: and still learning with each page turn.
Have heard of spinning the engine over without plugs
for an hour or so to better seat new rings,
but never tried it
and don't understand that theory either. <br><br>Post edited by: Patton, at: 2007/05/26 12:36

I don't understand the spark plug theory either. You need to run the motor in order to break it in. Things need to be hot and at running temperature in order to do their expanding and be at the right tolerences, alone with the oil pressure being there. Without the motor on there is no oil pressure, and with no oil pressure the rings will unsmoothly. I don't understand that one either. And who would sit there for an hour? LOL :silly:


P.S. THe auto shop I am in is Auto ROP in high school; it's advanced automotive if you will.

Never heard of that one either; but a few years back Motorcyclist posted an article that said to assemble the motor 'dry' and just add oil normally into the cases. This assured metal to metal contact between rings and cylinder wall for a few brief strokes (easy there...) and also insured oil would be 'there' in a second. Their theory was that this allowed the rings to seat and that motor break in would be much shorter.

Just sayin' what they said...I don't know. You would probably have as much working theory on that as me, I just thought I'd throw that out to you and let you know "...that's what they say..." :whistle:

Does that sound like it makes sense to you???

Sounds odd. I think i would stick to the norms.just my opinion.

been building engines for a long time, never heard either of them.
to break in the motor, bike, fire it up keep the rpm at about 2000, check the timing, put a fan in front of it so it will stay cool and run it for about 30, you can bring the idle down some after the first run in, then ride it like you stole it.
it takes cyl pressure and heat to make the rings seat.
There are some places most being the big production rebuilders that will spin the motors on a machine for a some time, but they are looking for bearing faliures and cam break in

Oil pump should operate in usual manner without ignition and without plugs.
The "without plugs" was supposedly to permit
easily spinning engine over by using the 17mm crankcase "nut" with a socket fitted to
electric drill.

Myth? Old wives' tale? Stupid idea? Sick joke?

Anyhow, be sure oil cooler lines are firmly
attached before spinning "unplugged" engine
to check compression. Rest assured the oil
pump is indeed pumping. (Don't ask ...)

Post edited by: Patton, at: 2007/05/26 13:38

Post edited by: Patton, at: 2007/05/26 13:39

If your bike is jetted properly for
the baffle being inplace,that is the
way I would leave it.I still believe
in putting a light coat of oil on the
bores and giving a motor a slow break
in.I just ride it gently for at least
500 miles then gradualy increase my
speeds up to 1000 miles then ride it
like I normally would.I have had 25
bikes,tried a few quicker methods,but
if you want it to stay together for a
long time,I found this method the best.

Bad Kaw wrote:

Never heard of that one either; but a few years back Motorcyclist posted an article that said to assemble the motor 'dry' and just add oil normally into the cases. This assured metal to metal contact between rings and cylinder wall for a few brief strokes (easy there...) and also insured oil would be 'there' in a second. Their theory was that this allowed the rings to seat and that motor break in would be much shorter.

Just sayin' what they said...I don't know. You would probably have as much working theory on that as me, I just thought I'd throw that out to you and let you know "...that's what they say..." :whistle:

Does that sound like it makes sense to you???

ive done my motors with rings dry for years without problems .weve had some really colorfull discussions on this and everybody seems to think im nuts:whistle:

Nah, you're not nuts wireman, you just got your ways of doing things and I got mine, as long as they both work then who cares


But it's still fun to argue

steell,did kzcsi kiss you or something?you turned into a frog!:whistle: thats gonna cost me!:woohoo: