Will it hurt?

[Honzilla]

Hi everyone,

I was just wondering, I've got a 91 CB750 Nighthawk.

Sometimes in the morning I am pressed for time and the bike may not be warmed up to its proper running temp.  
Will it hurt the bike if I were to ride off with the choke on?

Will it hurt the bike to keep the engine running with the throttle until it reaches a temp that it will run on its own?

Thanks...

[Honzilla]

sorry everybody i have no idea why this posted twice...

[TOOLS1]

 I know they had problems with oiling in the early years especially on the 450s. It might not be a problem on the newer bikes, but I have always been led to believe that Honda,s should be warmed up before riding, or giving a lot of throttle.
TOOLS

[LukeM]

I took care of the duplicate posting.
Luke M

[Honzilla]

What is "oiling?"

[TOOLS1]

The circulation of lubricating fluid through the engine.
TOOLS

[Honzilla]

DUH!

I thought "oiling" was a specific term for a phenomenon that occurs with our older bikes.

I am understand the idea of running the motor for a minute or two in order for the oil to penetrate the places it needs to for proper lubrication.

My question is not so much about the engines distribution of oil but once the bike has been running for a couple minutes it may still be below the optimum running temp.
I have come to the conclusion about the running temps, because my bike never idles correctly until it is at correct operating temps.  Generally it will idle low and occasionally die.

I NEVER have the choke open all the way, if I do that the engine will race up to nearly 4000 rpm.  I am just assuming, but that doesn't seem good for the motor.  Generally I will adjust the choke lever so the bike will idle about 1500 rpm, as the idle increases under choke I back it down until the bike idles at 1000 with no choke.

Since I don't always have the time for the fore-mentioned routine, is it bad to ride off with the choke still on?
Is it better to just turn off the choke all together and ride off, using MILD throttle to keep the engine idling properly??

[sgtslag]

What I was always told by my father (former auto mechanic), was that running with the choke on, will make the fuel-air mixture very rich -- much more gas, than air.  This will increase the unburned gasoline that blows out of your exhaust (not a big deal as it is only one bike, for a short time, with regards to pollution...), however, this tends to wash the oil off the cylinder walls -- now that is something to be concerned about.

Your best option is to get up earlier, let the bike idle to operating temperature, or at least close to it, before you leave -- you want it to run without any choke applied, to avoid running too rich.  There is another concern you should be aware of:  until your oil reaches 212 F, it will not boil off the water formed during combustion, which will accumulate in your oil.  Short trips are hard on every internal combustion engine.  Short trips, where the engine never gets up to full temperature, will cause issues in the long run.  Warm it up, then take it out...  Your engine will thank you with more care-free miles.

To get rid of water already in the oil, just take it out for a long highway run.  With the engine running at 212 F, or above, the water will boil off soon enough, leaving nothing but oil.  The 180 F temperatures you may have read of, refer to the boiling point of the acid produced in combustion.  The acid boils off at 180 F, and that is far more dangerous to your engine.  Motor oils contain base chemicals to neutralize the acids.  For those who run extended oil changes, it is important to have a Total Base Number (TBN) analysis done as well as the usual oil analysis.  There are oil additives you could use to disburse the water, but some folks believe they can cause harm to your wet clutch (I have never had an issue with SeaFoam...  read/follow directions carefully, if you use it!), so I won't recommend them here.  Cheers!

[Honzilla]

WOW!!!

Thanks sarg, that is the kind of answer I was looking for.  However, now I am a bit concerned.  
I only work about 15 - 20 kilometers from home, and only about 5 kilometers of that is what you can call a freeway (80 kph).
We are so busy, my wife and I, I'm lucky if I can get out on the bike for pleasure for two or three hours every 2 weeks!

Now, about being "near" running temps, would it be better to run her at a higher RPM, for the first couple kilometers?
The bike appears to red-line at 8,000 but I've never had it above 6,500.  It seems to like it around 4,000.  Does that sound right to you?

Will running it at a "low" temp cause it to run rich, or is that only a choke phenomenon?
Will running it at a "low" temp cause the bike to burn oil?

[sgtslag]

The rich mixture comes from the choke being turned on.  The ideal air-fuel mixture rate is 14.7:1.  With fuel injection, this is handled by the computer; in carbureted engines, it is accomplished by the various jets, and the choke...  The choke just blocks off air entering the carburetors, making the mixture richer.  The only good way to run your engine, is to let it warm up to 212 F, or higher.

The water, and the acid, that accumulate within your oil will lead to problems long term, not much short term damage will occur.  The water is non-compressible, which means that if it should enter the combustion chamber, it won't shrink -- at all -- when the piston rises, and should there be enough liquid water in the cylinder, it would break something, but that would take more water than we are discussing here.    Realistically, the water will settle into the bottom of the oil pan (oil floats on the surface of water, which is far denser).  This can lead to rust particles forming, and that can be bad.  The acid, on the other hand, will circulate, and dissolve metal particles from whatever it contacts.  Getting your oil to 180 F, or above, is far more critical (the acid boils off at 180 F).

I would recommend you get an oil temperature gauge (needs to go to 280 F, at least!), and connect it off of a T-adapter, to the Oil Pressure Sensor.  Monitor your oil temp's, and try to get it above 180 F every time you ride...

Running the engine at red-line will shake it apart over time...  Just because you can, does not mean you should.  Occasional high rev's are tolerable, but consistent high rev'ing will lead to premature failures, particularly of the timing chain.  Running it at higher RPM's will generate more heat, but it stresses the engine, which has cold oil in it.  The best thing is to let it warm up before riding, so that it reaches 180 F, and 212 F, for several KM's -- to let the liquids boil off, which takes a bit of time.  Your oil will not go above 212 F until the water has boiled off, so temp's above that, are a good thing, until you reach 250 F, where your oil breaks down into carbon, and varnish...  But that is another thread.  Cheers!

[Honzilla]

THANK YOU!!!   


You definitely seem like one of the knowledgeable ones here, thanks a ton for letting me pick your brains.

The information was more than helpful.  I was thinking about upgrading the oil cooler, but now I am beginning to think that is not the best idea.  Although the oil cooler looks ridiculously inadequate I'm sure the engineers at Honda made it that small for a reason.  Especially now that I realize how important it is to maintain the correct temps.  Perhaps I may just replace the oil lines with nice ones just to ensure optimum flow.

I've had a problem with the bike "marking it's territory" like crazy.  So I went ahead and replaced about a thousand gaskets.  So no leaking...  Now I am closely monitoring the oil level because I have a suspicion that the oil is going somewhere...

I wish I lived in your neck of the woods, or at least somewhere with better riding!  Then I would certainly invite you for a ride.  Thanks again sgtslag.

[sgtslag]

Whoa, Partner!  What is this about an oil cooler?  That changes everything...

Factory oil coolers from Honda typically do NOT have an oil thermostat installed.  Honda engineers like to push the engine's oil through the cooler, regardless of its temperature!  What this means is that your engine is bleeding off heat through the radiator, making it take even longer for the engine, and its oil, to reach optimum temperature!

I am not familiar with your bike, sorry.  I installed an oil cooler from a CB900C on my CB750K, and I discovered it prevents my engine from reaching 180 F, at 30 MPH, in air temperatures of less than 55 F.  At highway speeds, it will make it to around 180 F, and I DO have a Thermostat which pushes only 10% of the oil up to the radiator when the oil is below 180 F.  Below 55 F, I will need to cover my radiator if I ever want my oil to reach even 180 F!

My oil cooler is seven rows; it is bypassed (90% goes straight back to the engine, 10% goes up to the radiator) by a thermostat, until the oil reaches 180 F (at which point 95% goes to the radiator, 5% shunts back to the engine).  Without the Oil Cooling System installed, my engine ran at 250 F, riding highway speeds, two up, full saddlebags, trunk, and fairing, with an air temperature of 80 F.  The day prior, same load, but an air temperature of 90 F, and the Oil Cooling System operating, my oil temperature was a steady 210 F!  Your factory Oil Cooling System is bleeding off a LOT of heat...

Since you have an oil cooler, and no thermostat, you REALLY need to invest in an oil temperature gauge.  After that is installed, you should try covering your radiator with cardboard, or windproof fabric that can withstand temperatures of 250 F, minimum.  You are bleeding off a tremendous amount of heat through the radiator, which is preventing your engine from reaching proper temperatures.  You need to closely monitor the oil temperature, though, to avoid going above 250 F!  Either an electric, or a mechanical gauge will work.  The mechanical gauge has a "Bourdain Tube" which must be handled carefully (no bends, or kinks; cut it, and you will need a new gauge...), but they can be more accurate than an electric meter:  mechanical gauges sometimes have a 270-degree needle deflection, where electric gauges nearly always have a 90-degree deflection -- the wider the deflection, the more granular the reading, hence the more accurate (Bourdain Tube gauges are an average of 2%-3% off, which at this scale of up to 280 F means they can be 1-2 F off...).

An oil temperature gauge can be had off of e-Bay for around $20 + S/H, if you are patient.  With that, and some cardboard, you should be able to warm that engine up m-u-c-h sooner.  An Oil Thermostat could help, but you would need to cut the Cooler lines to insert it, and it would not help much at, or below, 55 F air temperatures.  Cheers!

PS:

I am NOT an expert motorcycle technician -- I am just beginning to learn the art, and science.  I know more than most about oil coolers since I have researched the topic, and installed one on a bike which was never designed for it.  I used off the shelf parts, and it was actually not terribly difficult -- just scary as heck because oil leaks fell right in the path of the rear tire...

[Honzilla]

ok...

BIG question, what is the difference between an oil temperature gauge, and an oil thermostat?

The oil temp gauge, would i be correct if I'm guessing this is like the harley style that screw in where the dip stick is, and the top is the reading?

[sgtslag]

Here is an example of a mechanical oil pressure gauge:

http://cgi.ebay.com/ebaymotors/Summit-mechanical-oil-temp-gauge-_W0QQcmdZViewItemQQhashZitem4aa817305aQQitemZ320647671898QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories#ht_500wt_1182



<http://cgi.ebay.com/ebaymotors/Summit-mechanical-oil-temp-gauge-_W0QQcmdZViewItemQQhashZitem4aa817305aQQitemZ320647671898QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories#ht_500wt_1182>And
here is the Perma-Cool Oil Thermostat I used:

http://www.perma-cool.com/Catalog/Cat_page14.html


<http://www.perma-cool.com/Catalog/Cat_page14.html>The Thermostat can use
(4) hose barbs to connect to the oil cooler lines, or you can use AN
connectors.  I used hose barbs (available in the plumbing section of any
hardware store), with T-bolt clamps (high pressure, had to mail-order these
off of Amazon.com due to their large size:  1"/25mm-27mm).  Check the
Factory Service Manual (FSM) for your bike to see if the oil radiator has a
separate pump, which draws oil from the pan, pumps it through the radiator,
and back into the pan.  This is how they did it on the CB900C -- there is no
pressure regulator, so it flows quite fast, but at a low pressure as there
are no restrictions in its path.  The engine oil, however, has restrictions,
and a pressure regulator:  the 750's average 71 PSI @ 5,000 RPM, while the
larger bikes run at 78 PSI @ 5,000 RPM, roughly.  At these pressures, a
worm-drive hose clamp will not hold.  On my bike, the entire oil supply,
under pressure, flows through the cooling system, so the T-bolt clamps
prevent the 71 PSI oil from escaping the hoses.

With regards to the location of the oil temperature sensor/transducer, no,
not the dipstick, but this is a possible way to do it.  The best placement
would be off of the oil pressure sensor which triggers the idiot light when
your oil pressure drops too low -- check the FSM for its location.  The best
option is to use a T-adapter, which will allow you to connect the OEM
pressure switch on one end, and the gauge's transducer on the other end of
the T.  The T-adapter is something like this:

http://cgi.ebay.com/ebaymotors/VDO-240855-male-T-adapter-JEGS-/200567429703?pt=Other_Vehicle_Parts&hash=item2eb2c01a47#ht_2091wt_939


They are, again, available from your local plumbing supply stores.  To seal
the threads against oil leaks, I recommend using Permatex High Temperature
Thread Sealant:

http://www.amazon.com/Permatex-59214-Temperature-Thread-Sealant/dp/B0002UEOP0/ref=sr_1_1?ie=UTF8&qid=1296281112&sr=8-1


This is available at your local automotive supply shops -- no shipping
charges.  Read and follow directions:  apply to upper 3/4 circumference of threads only,
leaving the first threads clear, screw into place at proper torque, let set
for 72 hours before running the engine.

Spend some time reading through the FSM, or Clymer, or Haynes...  These are
really quite good at showing you the parts and systems of your bike.  It may
take some time to make sense of what they say, but it will come.  Start with
the simple procedures, and work from there.  Study the diagrams that show
oil flow, and other things like air flow.  They will help you understand how
the systems work.  Spend some time with Google, or other search engines, to
locate additional forums.  Learn to use the individual forums' search
functions, and experiment with key words.  Some of the folks on some of
these forums can get testy if you ask a question that has been discussed, ad
nauseum, too many times already.  That will help you to ask more
specific questions as well, which they won't mind.

Here is a link to photo's of my cooling system.  Please excuse my unwashed
bike -- I took these photo's for myself, not for pubilcation...  The
password is "plastic":

http://photobucket.com/guestlogin?albumUrl=http://s1136.photobucket.com/albums/n489/SgtSlag/


In the photo's, you can see the Thermostat, the T-bolt clamps, and the
spin-on filter adapter with the ports for the cooler hoses, and the
transducer port occupied by the Oil Temperature Gauge's gizmo (white wire on
the bottom of the aluminum spin-on adapter).  Let me know if you have any
further questions.  Cheers!

[Re-run]

That would be correct. A thermostat would be if you had an oil cooler.
As for running with choke, I guess I never worried about it. I suppose a lot depends on the state of engine tune and wear. If you are worried about it, certainly warm the bike up. Be warned it will take a while though to warm up while just idling so if you are running late, you would be taking the car as you would need 10 minutes to warm up approximately.
I start and warm for a minute or 2 and then go. usually on a decent morning(60F or higher) within a minute or 2 I have no more choke. I have never noticed fuel in my oil or anything like that. I also use synthetic oil in my bike and that protects much better than regular oil. I suppose in years past, oil was not as good and rings were not as good(leaded fuel days) and so it was probably more of an issue. Starting in the 70s on the cb750s, the valve seats were hardened for use with non0lead fuels and tolerances for rings were much closer.

If you still have reservations, when you change your oil next, you can find companies that will analyze your oil and that will give you the best info possible on your engine state.
Certainly not arguing with anyone, only putting in my 2 cents.