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‘00 Valkyrie Interstate, ‘01 Spirit 1100, 99 VLX
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Discussion Starter #1
As some of you have heard my clip of my pipes, I have my idle set pretty slow. I don't have a portable tach (and Honda didn't include one on the bike :( ), so I don't know where it is set.

You can lug them down (ie: Cleobens video clip) but you're just hurting your engine by letting it idle that slow.
Am I damaging my engine with a slow idle?

CB
 

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Yes it is a little hard on them..Part of the problem is due to the iregular firring pulses that make it sound so cool are putting the main bearings under alot of stress, and you may not get much oil to the top end due to low presure at low rpm's. I cannot give you a percise answer on how much more wear but it does happen. But I have been known to turn mine down every now and then just beccouse it sounds so cool.
 

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Tom,

No real cut and dry answer for you...Because the oil pump is driven by the motor, the slower the idle, less oil is being pumped through the motor. Are you getting enough oil...I don't know. My engineering background tells me that if Honda says the idle needs to be at 900 rpms...then that is where it gets enough oil flow to properly lube the motor.

I checked the Service Manual to see what they said...and the only thing they indicate is the oil pressure at 5000 rpms (64 PSI). I also checked the information on the oil pressure switch but it doesn't offer a setting for the switch.

But, as long as we are talking about the oil pressure switch...it is set to come on when the oil pressure is too low to properly lubricate the motor...right?...not just when the motor is shut off.

So, I would think that as long as you have sufficient pressure to maintain the oil pressure switch...then you will be fine at a lower idle.

I would like to hear other's opinion on the matter though.

Joe
 

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Because it is a positive displacement gear pump I imagine it will pump enough oil even at low rpms. You don't need as much oil flowing through the galleries to lubricate everything at slower rotations anyway. I would have to believe that as long as the low pressure light does not come on you have enough flow to create needed pressure.
I would be more concerned with a lower voltage supplied by the stator windings at idle.
 

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ribman442 said:
Yes it is a little hard on them..Part of the problem is due to the iregular firring pulses that make it sound so cool are putting the main bearings under alot of stress, and you may not get much oil to the top end due to low presure at low rpm's. I cannot give you a percise answer on how much more wear but it does happen. But I have been known to turn mine down every now and then just beccouse it sounds so cool.
ribman442,

Keeping the motor turning over fast enough to have oil at all the right places is important for sure, but I'm not sure that lowering the idle down will put anymore stress on the motor than a recommended idle. It might very well affect carburetor efficiency and it's ability to get a correct mixture to the cylinder because it isn't developing enough power to continue to run fast enough when a load is applied to it. That's kinda what happens when you let the clutch out to fast when trying to take off. Too high an idle and you'll always be slipping the clucth for longer than necessary to get smooth take off.

The problem might arise if you try too much throttle at too low of an RPM, with too heavy a load. Those conditions are just about perfect for ruining an engine. Heat and pressure are the major factors that wear out motors that are properly designed and maintained, I think.

That's the reason I start to cringe when I hear about people wanting to lower their RPMs at cruising speed. There is a fairly narrow band where Manifold pressure and RPM are at their optimum. Outside that and premature wear takes place. I don't know the exact points where that starts, but I've got to believe that the Honda Engineers know. If they say 1000-1100 RPM idle, that suits me just fine.

John
 

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Olivereaman said:
ribman442,

Keeping the motor turning over fast enough to have oil at all the right places is important for sure, but I'm not sure that lowering the idle down will put anymore stress on the motor than a recommended idle. It might very well affect carburetor efficiency and it's ability to get a correct mixture to the cylinder because it isn't developing enough power to continue to run fast enough when a load is applied to it. That's kinda what happens when you let the clutch out to fast when trying to take off. Too high an idle and you'll always be slipping the clucth for longer than necessary to get smooth take off.

The problem might arise if you try too much throttle at too low of an RPM, with too heavy a load. Those conditions are just about perfect for ruining an engine. Heat and pressure are the major factors that wear out motors that are properly designed and maintained, I think.

That's the reason I start to cringe when I hear about people wanting to lower their RPMs at cruising speed. There is a fairly narrow band where Manifold pressure and RPM are at their optimum. Outside that and premature wear takes place. I don't know the exact points where that starts, but I've got to believe that the Honda Engineers know. If they say 1000-1100 RPM idle, that suits me just fine.

John

Olivereaman,

ribman442 is right.
Irregular firing pulses hurt the engine more than anything.
Engines are designed to idle and RPM through a specific range.
Firing pulses are harmonics that travel throughout the engine as it's running.
Some engines have 'harmonic balancers' that have no purpose but to
absorb those firing imbalances.
Some people think that these 'balancers' keep the rotating assembly
in balance, but it not the case. It's to absorb the firing imbalances.
These imbalances can and will harm an engine.
It does indeed cause stress on parts. The oil pressure being high
enough isn't about lubricating parts at low RPM.
items like the cam shaft, crank in the mains, etc actually run on a film of
oil... they do not run on the bearings. The oil pressure keeps these
parts suspended in the film of oil. Low pressure can cause the parts to
contact the bearings.

If the RPM is off 50-100rpm, it's not going to hurt anything.
If you start dropping it down to 500-600, it may very well cause some
problems down the road.
 

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Now you wanta change your idle????? After all this time!!!! :roll: And I was JUST getting used to that "plat......... platie plat" of your Shadow...CleoBen!!!!! :p :p :lol: :lol:

Your idle "sounded" like it was about 500-600 RPM the last I heard it coming home from the KY Rally. Mmm, maybe turn that idle screw just about a "half-turn-3/4 turn" to increase the idle RPM (speed). That should get you in the ballpark. But you'll be thinking (and listening to this increase) that your "motor" is really racin' now!! :shock: :shock: :lol: :lol:

Not sure if I can give a good explaination as to your "concerns" about this issue. But I'd worry about low oil pressure at idle and possible carbon build-up as the engine is getting "hotter" at a lower RPM condition. This shows up as you try to take-off quickly and the bike "stumbles" (carbs not getting enough air/fuel mixture). But there's others that know a whole lot more than me. :roll:

Bullzeyet
 

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litnin said:
Olivereaman said:
ribman442,

Keeping the motor turning over fast enough to have oil at all the right places is important for sure, but I'm not sure that lowering the idle down will put anymore stress on the motor than a recommended idle. It might very well affect carburetor efficiency and it's ability to get a correct mixture to the cylinder because it isn't developing enough power to continue to run fast enough when a load is applied to it. That's kinda what happens when you let the clutch out to fast when trying to take off. Too high an idle and you'll always be slipping the clucth for longer than necessary to get smooth take off.

The problem might arise if you try too much throttle at too low of an RPM, with too heavy a load. Those conditions are just about perfect for ruining an engine. Heat and pressure are the major factors that wear out motors that are properly designed and maintained, I think.

That's the reason I start to cringe when I hear about people wanting to lower their RPMs at cruising speed. There is a fairly narrow band where Manifold pressure and RPM are at their optimum. Outside that and premature wear takes place. I don't know the exact points where that starts, but I've got to believe that the Honda Engineers know. If they say 1000-1100 RPM idle, that suits me just fine.

John

Olivereaman,

ribman442 is right.
Irregular firing pulses hurt the engine more than anything.
Engines are designed to idle and RPM through a specific range.
Firing pulses are harmonics that travel throughout the engine as it's running.
Some engines have 'harmonic balancers' that have no purpose but to
absorb those firing imbalances.
Some people think that these 'balancers' keep the rotating assembly
in balance, but it not the case. It's to absorb the firing imbalances.
These imbalances can and will harm an engine.
It does indeed cause stress on parts. The oil pressure being high
enough isn't about lubricating parts at low RPM.
items like the cam shaft, crank in the mains, etc actually run on a film of
oil... they do not run on the bearings. The oil pressure keeps these
parts suspended in the film of oil. Low pressure can cause the parts to
contact the bearings.

If the RPM is off 50-100rpm, it's not going to hurt anything.
If you start dropping it down to 500-600, it may very well cause some
problems down the road.
litnin,

Thanks for lining me up in the right direction on that point. I had some idea about harmonics, but actually don't know a lot about it. Most of my education, and a lot of it is self learned, comes from destroying engines by some type of mis-use. And believe me when I tell ya, I know many ways to do it! :D Most of the damage that we've encountered was the result of improper loading. It also seemed like most of the rods came apart when the engine was suddenly throttled back or unloaded quickly. I also know that a lot of problems with the earlier in line 6 engines were caused by some irregularities due to the lengrh of the crankshaft and not enough main bearings. Was this the effects of irregular firing also?

THese are serious questions asked for a better understanding of it by me.


A question on firing pulse irregularities....is this condition amplified as the rpms go lower or does it just come about at a certain point and remain steady? I guess what I'm trying to ask... is the destructive effects greatest at the point where the engine is just above the point of not being able to sustain a running condition? If so, it would seem that the most stress on the engine would be at start-up with very little or no oil pressure. Am I on the right track here, or just getting crazy?


Also, what are the effects of bouncing of the rev limiter, as to the irregular firing? Are there flywheel forces that tend to smooth them out at these great speeds? Does a misfiring cylinder increase it's effects at low speeds? What about high speeds?

I know I'm probably driving YOU crazy, but this subject has my mind spinning faster than a Honda engine. I appreciate any info on the subject or any book or website you can point me to.

I've edited this post down to about 1/3 of what was, that's how interesting this particular subject is to me.

Thanks,

John
 

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Olivereaman

I have the same question regarding the rev limiter....And if I had to guess I would say its not a great thing to create these imbalances at red line but it beats the alternative of spining the parts faster than they can handle.

As far as the firing iregularities being worse at Idle. I would assume it is because they are spaced farther apart that what creates the cool sound, but this cadince also can create harm.

I know you did not ask for my reply but I wanted to give it a shot.
 

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ribman442 said:
Olivereaman

I have the same question regarding the rev limiter....And if I had to guess I would say its not a great thing to create these imbalances at red line but it beats the alternative of spining the parts faster than they can handle.

As far as the firing iregularities being worse at Idle. I would assume it is because they are spaced farther apart that what creates the cool sound, but this cadince also can create harm.

I know you did not ask for my reply but I wanted to give it a shot.
ribman442,

I am absolutely delighted you replied! I value an experienced persons advice and instruction highly.

I had a small understanding of harmonics, very small. This discussion has raised my interest in it greatly.

I've got one great website I've found on it, but unfortunately my grandaughter is demanding my attention right now before she goes to bed. If I get a chance tomorrow I'll come back and try to create a hyperlink to it for anyone else that may be interested. It basicly deals with aircraft engines but the theory and science are still valid.

Again, thanks for jumping right in. I love it when I get a chance to increase my knowledge about something, and especially if it's a subject I enjoy.

John
 

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Olivereaman said:
A question on firing pulse irregularities....is this condition amplified as the rpms go lower or does it just come about at a certain point and remain steady? I guess what I'm trying to ask... is the destructive effects greatest at the point where the engine is just above the point of not being able to sustain a running condition?
Actually, a lot of it depends simply on engine design.
The biggest problem at low RPM isn't the firing pulse itself, but the firing
pulse in conjunction with low oil pressure.
Oil pressure in and around the crank/cam areas is a cushion.
The crank and cam actually ride in an oil cushion, not on the bearings.
At low RPMs, the firing pulses are erratic and can cause the crank/cam
to bounce. Not good. I've never seen a crank break from this, but
I have seen cams break from it.

Olivereaman said:
If so, it would seem that the most stress on the engine would be at start-up with very little or no oil pressure. Am I on the right track here, or just getting crazy?
The worst time in the world for an engine is the startup time.
The engine is spinning with no oil pressure for a split second and firing
pulses just beat the hell out of the cam and crank.
This is where a good quality oil comes in to play.
You need something that's going to hang around and provide
"start up" protection for those first few spins until oil pressure gets
built up.

Olivereaman said:
Also, what are the effects of bouncing of the rev limiter, as to the irregular firing?
Bouncing off the rev limiter is absolute HELL on a rotating assembly.
It throws the complete rotating assembly out of balance.
I'm sure you can see where that is bad..
Out of balance... then out of balance at extremely high RPM.
What happens to the "heavy" part that is out of balance as the RPM's climb?
Centrifugal force takes over and starts trying to pull the engine apart.

Just bumping the rev limiter by accident and coming back off won't hurt.
That's what it's designed for... But hitting the limiter and holding it
will definitely cause havoc.
I can tell you personally what a 526 inch motor does when it taps the
rev limiter at 9800 RPM. :shock: :shock:
And I have pictures of a nice EXPENSIVE engine with a nice BIG hole
in the side of the block because of it.

Olivereaman said:
Are there flywheel forces that tend to smooth them out at these great speeds? Does a misfiring cylinder increase it's effects at low speeds? What about high speeds?
Not really. The flywheel really doesn't absorb harmonics.
However, depending on the style of clutch, it "can" absorb some of it.
Mostly, it's either done with a harmonic balancer or high oil pressure (the cushion).
 

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Just something else that came to mind, since Tom's bike has hydraulic lifters, could it be "assumed" that if the lifters have enough oil pressure not to "tick", it has enough oil pressure to be safe at a lower idle speed?
 

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Jim in NW OH said:
Just something else that came to mind, since Tom's bike has hydraulic lifters, could it be "assumed" that if the lifters have enough oil pressure not to "tick", it has enough oil pressure to be safe at a lower idle speed?
You have to go back and read the entire thread. There will be a test on Friday. :lol:
 

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Just to be on the safe side, I would turn up the idle a bit (my opinion) I've heard alot of Harley owners complain about having to rebuild the top end of their bikes at certain intervals. I notice the guys that make the daily run to the bar (right across the highway from me) come out, start their bikes up to warm them up. You can literally count the engine revolutions they have the idle set so slow. That may sound cool to them, but they will pay in the long run!!
Our Shadows are not made to idle quite that slow. >PD<
 

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Link to great site about engine vibration

Because I was interested in this thread and its discussion on vibrations, I did a little searching and even though I haven't read through the entire site I thought there might be some interesting reading for anyone interested in the subject.

http://epi-eng.com/BAS_TOC.htm...A great link to engine vibration


Edit: Finally figured out to post an hyperlink.....YIPPEEEEE!
John
 

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Re: Link to great site about engine vibration

Olivereaman said:
Because I was interested in this tread and its discussion on virations, I did a little searching and even though I haven't read through the entire site I thought there might be some interesting reading for anyone interested in the subject.

[a href="http://epi-eng.com/BAS_TOC.htm"[A great link to engine vibration[/a]

John
PSSSTT!!!! Hey John...not [a href]... :D This software uses its own little convention for posting links. [url=http://epi-eng.com/BAS_TOC.htm]A great link to engine vibration
 

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Re: Link to great site about engine vibration

Spirit_1100 said:
Olivereaman said:
Because I was interested in this tread and its discussion on virations, I did a little searching and even though I haven't read through the entire site I thought there might be some interesting reading for anyone interested in the subject.

[a href="http://epi-eng.com/BAS_TOC.htm"[A great link to engine vibration[/a]

John
PSSSTT!!!! Hey John...not [a href]... :D This software uses its own little convention for posting links. [url=http://epi-eng.com/BAS_TOC.htm]A great link to engine vibration
Spirit_1100,

I've been trying to figure out to get a hyperlink. I was reading the FAQ's and thought maybe I needed BBCode and was trying to figure it out.

Can you help a not so computer savvy guy out and tell me how you did it?

Thanks,


John

PS Did you check out the site, and if so do you think it's appropriate?
 

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Re: Link to great site about engine vibration

Olivereaman said:
Because I was interested in this tread and its discussion on vibrations, I did a little searching and even though I haven't read through the entire site I thought there might be some interesting reading for anyone interested in the subject.

A great link to engine vibration

John
If you don't know the code, there are code bottoms at the top of the
text field that you enter your posts in. You'll see the Bold, italics,
underline, quote, etc etc etc...


On the website, I'm wondering how old this site is...
I didn't read over the site real close (not enough time right now),
but just looking at the definition of dampening where it talks about shocks:
The term damping is frequently misunderstood. The property of damping enables an object to DISSIPATE energy, usually by conversion of kinetic (motion) energy into heat energy. The misnamed automotive device known as a "shock absorber" is a common example of a damper. If you push on the ends of a fully extended "shock absorber" (so as to collapse it) the rod moves into the body at a velocity related to how hard you are pushing. Double the force and the velocity doubles. When the "shock" is fully collapsed, and you release your hand pressure, nothing happens (except maybe you drop it). The rod does not spring back out. The energy (defined as a force applied over a distance) which you expended to collapse the damper has been converted into heat which is dissipated through the walls of the shock absorber.
Guess they never heard of gas shocks?

Oil filled shocks do not spring back out... but gas shocks do.
Most vehicles these days come with gas charged shocks.
There are still some that use oil, but not many.
 
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