Temperature

[Darkbluestar]

I tried searching for this but couldn't find an answer.

Does anyone know what temperature range the engine operates in? Also, what temperature would be considered bad?

-Blue

[mister]

I tried searching for this but couldn't find an answer.

Does anyone know what temperature range the engine operates in? Also, what temperature would be considered bad?

-Blue

Are you talking ambient air temp?

If so, I don't think there is a range of air temp that would hurt the bike.

Michael

[LimaXray]

Yeah, in terms of ambient air temperature, I'd say the bike has a wider operating temperature range than the rider.

In cold weather you may have trouble starting.  A hot summer day stuck in traffic can cause overheating - I'll usually kill the engine when stopped for an extend period (ie at a traffic light) if it is safe to do so.

[lucifer_mr2]

Do you mean oil temp?

[Tombstones81]

Do you mean oil temp?

most likely.
like the temp gauge on a car
but isnt one on say, a GS500.

[Darkbluestar]

Some background might be useful. I installed a Vapor on my GS and it comes with a temp sensor. The vapor has a feature that warns you when your bike is getting too hot. I'm trying to find out what a good temperature range for the GS motor to set this setting.

BTW, here is a video of the vapor in idle.
http://youtu.be/_qDigOIsemI

-Blue

[noiseguy]

Where do you want to measure it? Head temp at head bolt/spark plug, exhaust temp instream, exhaust temp header...?

Most air cooled bikes I'm familiar with (2-stoke, forced air) run ~350F at the spark plug, with >400F indicating overheat issues. Assume these bikes are in the same range.

[Darkbluestar]

I am taking the reading from the spark plug.

This worries me, my bike was reaching 428 F going uphill yesterday.

[ben2go]

I am taking the reading from the spark plug.

This worries me, my bike was reaching 428 F going uphill yesterday.

Has your bike been rejetted and does it have an aftermarket air filter and/or exhaust?Lean condition,low oil,old oil,or internal damage is about the only thing that causes these bike to overheat.Oh plugged cooling fins do to but that's rare.

[Darkbluestar]

I have the stock exhaust with a K&N lunchbox.

Jetting is 40 Pilot, 140 Main and 2 washers, which are half the thickness of a #4, under the needle. 2.75 turns.

Oil level is good and was changed a few hundred miles ago. probably < 600

Could it possibly be a carb sync problem?

[LimaXray]

Check your plugs and see if you're lean.  Otherwise, there's no way to really tell if there is anything wrong with the readings you're getting - without some real idea of what it's supposed to be, the temperature is totally meaningless.  If you have oil, and you're not running lean or detonating, then you're fine and should try not to be a hypochondriac with your motorcycle.

And I doubt carb sync has anything to do with it.  Carb sync is mostly just an idle issue.  The error between the carbs becomes increasingly insignificant as you open the throttle.

[noiseguy]

How are you measuring your temps? Ring washer on spark plug? Have you calibrated the thermocouple in boiling water?

I quickly google'd CHT's for bikes. Reports are reading anywhere from 250F to 350F in normal operation. Lower were things like Harleys, which I'm betting run cooler in general, being lower performance for the displacement, and less fuel efficient. Higher were little twins e.g. Rebel.

There is a physical basis for this. At some point the piston gets soft and seizes. So there is an upper limit for temps that's not completely arbitrary. It's knowable.

This is of interest to me; I've a theory that my bike is getting too hot when run at 70-80 MPH on the interstate, and actually likes lower speeds around town with less stress. I've been considering installing a CHT to check this, as well as temp on each side (I've noticed plugs from Cyl 1 look different than Cyl 2; perhaps they run at different temps)

My guess is that the GS500 engine runs fairly hot, b/c it's fuel efficient for it's size.

[Darkbluestar]

I'm using a Trail Tech vapor to get my temp readings. It came with this sensor. http://www.trailtech.net/7500-3012.html Don't think there is a calibration procedure for it.

[ben2go]

How are you measuring your temps? Ring washer on spark plug? Have you calibrated the thermocouple in boiling water?

I quickly google'd CHT's for bikes. Reports are reading anywhere from 250F to 350F in normal operation. Lower were things like Harleys, which I'm betting run cooler in general, being lower performance for the displacement, and less fuel efficient. Higher were little twins e.g. Rebel.

There is a physical basis for this. At some point the piston gets soft and seizes. So there is an upper limit for temps that's not completely arbitrary. It's knowable.

This is of interest to me; I've a theory that my bike is getting too hot when run at 70-80 MPH on the interstate, and actually likes lower speeds around town with less stress. I've been considering installing a CHT to check this, as well as temp on each side (I've noticed plugs from Cyl 1 look different than Cyl 2; perhaps they run at different temps)

My guess is that the GS500 engine runs fairly hot, b/c it's fuel efficient for it's size.

If one spark plug looks different than the other,then one of your cabs is off or one side of the ignition system isn't functioning correctly.

[Darkbluestar]

So I got home and I checked my oil and my plugs. The oil was a tad bit high so I took some out. I hardly took any out so I doubt that was the problem.
Here are pictures of my plugs. They both look about the same except one has a little bit of brown around the white part.

Right:

Left:

[LimaXray]

The brown ring, or lack there of, on the porcelain means something but I'm not sure what.  There is a whole art to plug reading, but from my limited understanding is it looks like your mixture is OK - at least at idle which I'm guessing is the last state these plugs saw before the engine was cut.  The other thing I'd check is make sure the heat range is correct since the threads are all shiny and clean.  Don't know how many threads are supposed to be have carbon deposits on the GS, but those plugs may be sitting too far back into the head meaning they're pulling too much heat out of the engine (aka they may be too cold).  This would put more heat on the sensor.  Anyway, just check they're correct.

I still think the measurement is meaningless without something to relevant to compare it to.  Saying one bike sees a given temperature at a given location using a given sensor has little bearing on what another bike, at another location, using another sensor should be - especially when we're talking about a relatively small difference between what you 'want' and what you 'have'.   I agree what you are seeing does sound high, but unless you're experiencing other issues, it's hard to draw conclusions from it.  Of course this is just the engineer it me talking - you're not actually measuring CHT, you're measuring the voltage across a junction of dissimilar metals strapped to your spark plug and are using it as a proxy for CHT.  There's bound to be some error in there.

If you're concerned, I would install an oil temperature gauge.  This will give you a better average reading over time and over the mass of the engine.  Plus there is a solid reference of other users to compare it to.

[gsJack]

I agree, the oil temperature would be a more significant indication of engine temperature on an air cooled bike but I'd never be concerned about measuring it on a GS500.  Of the bikes I've had (all air cooled) the GS500s are the coolest running and the CB750K was the hottest running.  A bike can run too cold also, the oil temp should be around the boiling point of water or a bit higher to boil out the accumulated water in the oil.  Water is a natural byproduct of internal combustion.  On the other hand if it runs close to 250F or higher it's going to be destructive to the oil. 

[Darkbluestar]

I'm using NGK DPR8EA-9 plugs and they are only a few days old so that is probably why they still have shiny threads. (Only take her out once since I put those in.) I am putting them how the clymer manual tells me. Screw in by hand until it seats then tighten another 1/4 to 1/2 a turn using a wrench.

I know that the temp reading is probably not dead on but I would think that a product sold by a company advertised to get cylinder head temperature would be at least somewhat close.

I have a 92 GS(no oil cooler) and I don't think there would be anywhere to install an oil temp gauge.

[ojstinson]

You could always carrie one of those inexpensive non-contact digital temp gauges, you could carry it in your jacket pocket and even sitting at a light read the aprox. oil temp by aiming it at the engine block, or whatever area you want to read. These things are very accurate and simple to use and give instant readings.

[ben2go]

If your oil level was higher than the last time you checked it,then you may have a carb float sticking and flooding the engine with fuel.Check the oil for a fuel smell.If it smells like gas,change it,and fix the sticking carb float.