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Baffle change bike running rough

Started by genzer, May 23, 2021, 08:05:41 AM

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genzer

I'm running a 2 into 1 pro pipe with standard baffle, bike ran flawless then changed to the competition baffle and it shakes and idles low . When riding it feels like its not smooth and some oil leak from the a.c. even though I have the catch can bypass. Bike is a 16 103 RG

kd

May 23, 2021, 08:40:39 AM #1 Last Edit: May 23, 2021, 08:45:47 AM by kd
How many miles, what cams, compression etc.?

It sounds like 2 problem that have coincidently appeared at the same time.  The idle could be as a result of a rich condition that can occur when reducing exhaust flow (like a smaller or different baffle).  The slower idle condition may have allowed the other condition to become more obvious but IMO I expect it was already there in some form.  If you have vented externally I suspect you have one or both cylinders pulling oil past the rings, a valve seal / guide or head gasket. With the lower idle speed, cam overlap and timing can push the oil vapor back into the manifold.  If it is substantial enough it will pool in the runner and flow into the breather.  Becoming an oil burner can further effect the idle speed and likewise oil vapor standoff.

If you pull the breather off you may be able to tell which runner it is coming from.  If it passes a leak down and compression test it could be one or both intake valve seals.  Remember that if one cylinder is wet (check the plugs too) it could read higher on both tests because the oil tends to seal the cylinder walls better unless it's a really bad ring issue.  In that case it may not or even could be lower.  For example, I had the oil feedback thing happen when the rings lined in the rear cylinder.  In that case it passed the leak down and compression test with flying colors.  Because I could see which runner was the wettest I was able to zero in on it after confirming the valve seals were OK.  (Using a Nub Tools Harley valve spring compressor kit can save you big time and money if you track it down as a valve seal.) 
KD

genzer

Kd, hard to believe just changing a baffle could lead to all this also I might add I'm running  a t-max and a tech suggested run to see if it pulls in the tune ( which I doubt). I thinking maybe put the standard baffle in and see if it's any different, before the change never had an oil leak and plugs look perfect :nix:103 575 cams and stage 1+ by WFO Larry forgot to mention always can hear the throttle body cracking but now much more pronounced ? Almost 8000.mi.

kd

May 23, 2021, 09:56:42 AM #3 Last Edit: May 23, 2021, 10:02:53 AM by kd
I am not saying it lead to the problem.  In my opinion the different baffle changed the idle to a point that it started the oil feed back at idle to increase and be more distinguishable. The CR575 has a later intake closing, more duration and considerably more overlap. That's why you hear the throttle valve clucking at idle.  The compression signal is back feeding out of the cylinder into the intake manifold behind the butterfly because of the extended valve event timing. I expect if Larry knew you were using a CR575 he would have set the compression at about 10.5:1 with his head package.  The extra compression increases the strength of the back-feed signal in the manifold.  The extra flow because of that will carry any oil vapor in the combustion chamber with it and it will stick to the runner walls to eventually build up to an amount that will drain out into the breather.  You do not have a leak as you call it.  There is no other connection to engine oil once you remove the venting from the breather. If you blocked off the vent holes in the breather when you installed the catch can there is absolutely no other way for the oil to appear in the intake other than feeding back from the cylinders or leaking past an intake valve seal or guide.

Does this engine use any oil at all?  IMO If you reinstall the previous baffle and the idle returns to what it was along with stopping the oil from appearing in the throttle body / breather, you have not resolved the engine problem.  You have simply masked it again so it is not noticeable.

BTW, knowing it was Larry that did your heads, I expect you will have high quality viton seals attached properly to the guides, good clearances from the valve springs and excellent guide condition at the time of assembly.  That's how he is.
KD

rigidthumper

Ignorance is bliss, and accuracy expensive. How much of either can you afford?

kd

I think we are both singing out of the same hymn book.  I just didn't call it "reversion" and you're right in pointing out that some exhaust characteristics cause it too.  Drag pipes are a good example.  I feel (IMO) it is excessive oil content because it is being described as a "leak" and that has to be coming from an unusually high concentration in the combustion chamber.  That is being carried in the reversion flow and traveling further due to the lower and slower rpm pulse. I think it's not to the point of stand-off but headed in that direction.   :nix:
KD

genzer

Update: put the standard baffle back in last night bike returned to normal ,sounds like it was reversion. Is reversion something that can be corrected by tuning?

rigidthumper

Reversion can be dealt with in a couple of ways- steps in pipes/exhaust port, and baffle design have the most affect.
Ignorance is bliss, and accuracy expensive. How much of either can you afford?

kd

Rigid, where do you expect the excess oil came from?  That's the part that caught my attention.  My thought is if everything is sealed properly the reversion should have only contained fuel.

Genzer, You never said whether or not your engine used any oil between oil changes.
KD

genzer


rigidthumper

Fuel is refined oil
Reversion carries the sprayed fuel (from the injectors) to the AC filter element, where it combines with dust, coagulates, and drips (if enough is washed back and forth) out the element.
Ignorance is bliss, and accuracy expensive. How much of either can you afford?

kd

Quote from: rigidthumper on May 24, 2021, 07:28:12 PM
Fuel is refined oil
Reversion carries the sprayed fuel (from the injectors) to the AC filter element, where it combines with dust, coagulates, and drips (if enough is washed back and forth) out the element.

Rigid I know where fuel comes from and understand the refined oil column.  The OP described an "oil leak" in the first post.  I am 70 years old and spent my life with tools in my hands with several certifications.  Built lots of engines too.  In 50+ years of professional for pay background (and still at it) I have never seen gasoline turn into engine oil at idle speed or any other speed.  I am sorry but I will never be convinced that if there is oil dripping out of his breather that it was caused by gasoline stand-off. It may have been carried in it but it is still engine oil.  I do believe if his conversion to the catch can didn't include disconnection or plugging of the vent line into the breather that it could be that.  It could also be an over oiled breather getting a fuel wash but that would eventually end and smell like gasoline while active.  Otherwise, if there is oil in the manifold runner (he hasn't confirmed if he checked) and it is dripping out of the breather, then there is a problem other than the baffle.  The baffle obviously had an extreme effect on the running of the engine with the present tune.  I agree that the baffle could be an influence in creating or exaggerating reversion but will hold fast on the fact that if there is engine oil dripping out of his breather it did NOT come from the injectors. There is another problem causing the oil to appear in the breather.  In the opening post it clearly says an "oil" leak.  If it has gone away with the old baffle back in place I wouldn't be surprised if there was still an oily film in the manifold.  Just not as much because of the reduced reversion.

Quote from: genzer on May 23, 2021, 08:05:41 AM
I'm running a 2 into 1 pro pipe with standard baffle, bike ran flawless then changed to the competition baffle and it shakes and idles low . When riding it feels like its not smooth and some oil leak from the a.c. even though I have the catch can bypass. Bike is a 16 103 RG


KD