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Engine Temperature

B

beemer

Tuned and Synch'ed
Joined
Feb 15, 2009
Messages
63
G'day Everyone,

Out of curiosity today after returning from a ride I used a Lazer Thermometer to see what sort of temperature the engine and headr pipes get up to. Not very switched on when it comes to the mechanicals and thought I would ask the question. The temperatures at the headrs was about 20 deg difference between left and right pipes at the same location and the engine variance was around 10 to 15 degrees difference. Biek is running fine. Mre curious than anthing else. Oh and its the left cylinder that seems to be cooler.

Ride safe

Beemer:huh:

Melbourne Australia:
 
Interesting. What were the temps?
I've often wondered, and since you've done the hard work, I think I'll take advantage. Actually, I've used a product called Pot Belly Black to respray an old heater and since the finish is reasonable, I was thinking of using it on my headers to paint them black.

Robert
 
beemer wrote:
G'day Everyone,

Out of curiosity today after returning from a ride I used a Lazer Thermometer to see what sort of temperature the engine and headr pipes get up to. Not very switched on when it comes to the mechanicals and thought I would ask the question. The temperatures at the headrs was about 20 deg difference between left and right pipes at the same location and the engine variance was around 10 to 15 degrees difference. Biek is running fine. Mre curious than anthing else. Oh and its the left cylinder that seems to be cooler.

Ride safe

Beemer:huh:

Melbourne Australia:
Click to expand...

You are slightly out of syncronization or the left injector is delivering a little extra fuel. Also the question is, was the engine still running? and which side did you check first? At the temperature the headers are when running they will cool quickly once the engine is off, that is, the greater the difference in temperature between the air and header, the greater the rate of change.
 
Beemer: Is there a noticeable difference in discoloration between your header pipes? If so, that would be another indicator that the cylinders may be out of synch.

Also, I have noticed while balancing the throttle bodies on by B11, engine temperature briefly increases after shut down. I run an industrial fan on high directly blowing on the oil cooler and both heads during balancing and after shut down. I use the VDSTS engine temp reading to make sure I don't overheat the engine. The increase in temp after shut down is pretty rapid and the decrease in temp is slow. If you are taking the temp immediately after shut down, the difference in temperature may be a result of the initial rapid increase in temperature.

Although this is academic, the engine temp is taken from a sensor on the right side. It would be interesting to see a reading from the laser thermometer near the sensor and the read out on a VDSTS.
 
I will redo the temps and pass on the info next when next I can use the Lazer
 
The increase in temperature is properly due to heat inertia, heat built up in the cylinder walls and such that is no longer being evacuated by circulating oil and fuel.

I know someone here in France who installed cylinder temperature sensors on both heads with a read-out in the cockpit, on his Norge. I could ask if he has any observations to share, but they'd have to be taken in the light of a machine that can't seem to be cured from a bad case of pinging.
 
Well, I have a digital probe thermometer, and my Norge was within 2 degrees celsius on each side when I checked. It also tracked exactly the resistance of the sensor on the RH head.
 
I put a head temperature gauge kit on my 1200 Sport (see 1200sport.com forum for photos), head temperature whilst riding on a warm day is around 200- 300F, at idle it climbs to 350F plus. At 400F I either pull over and turn the motor off or take a different route. It doesn't like hot days in traffic, the high first gear and engine pinging when hot makes it not the ideal commuter.

At temps of 300F plus it tends to ping under load.

Jason
 
It's not a really good idea to measure motor temps on various external spots, IMHO. If you don't know what to compare to, what's the point?
Only useful measurement will be an average temp, as the oil measured in the sump. Most air-cooled motorcycles will reach 105-110*C, a few some or much more - and among them some Guzzis. Do not forget that the oil works as a coolant as well.

Maybe that's one of the good reasons to follow the recommendations on motor oil specs, issued by MG? Those oils will withstand high temperatures found occasionally in Guzzi-sumps. :dry:

Ooh, but who am I to blow against the wind.B)
 
I have the pickup mounted on the exhaust flange, and whilst it maybe cooled by the air flowing over the head whilst riding, at rest I would imagine it is reading one of the hottest parts of the head. Measuring oil temp is fine, but the bike already has an over heat oil temp sensor, so why measure it again? Also, the average temperature doesn't matter, the hottest point should be the reference. I believe there can be hot spots around the exhaust valve that will not be relected in the average oil temp (especially since it would have cooled significantly by the time it reaches the sump). Over temp here could ruin the exhaust valve seats, cause warping etc. I have seen it on VW air cooled motors.

I do have a reference point, the cylinder head should not run more than 500F. At this point the molecular structure of the metal changes, i.e. its stuffed. In traffic on a hot day (Australian hot day not european hot weather) I think it would be getting very close. My bike will ping like crazy after only a few minutes idling in traffic on a 40 degrees C + day.

I have an aircraft engine manual (3350 cubic inch aircraft radial engine) which states 260 degrees C (500F) as a maximum permitted head temperature reading, though this is with a probe buried in the hottest part of the cylinder head, the placement of my pickup will not be in as hot a spot (and will also suffer from some air cooling when the bike is moving). The specs for the Corvair (A 1960s rear engined Chevy with an aircooled flat six), list head temperatures: 200-300F at idle, 350-475F at 30-60MPH cruise and 460-575F from 3000-5000RPM at full throttle.

Since aircraft manufactured air cooled engines come standard with a head temperature sensor, I guess it is a useful measurement......

We could argue all day about this. Oil or head temperature are both okay, as long as you know what the normal operating temperature range is (from experience and reference to other models handbooks), if the temperature goes outside this range either due to a problem or idling too long, then you have the choice of turning it off, going another way or ignoring it and hope there is not a problem. I just prefer the head temperature as I believe it will give a faster reading and at a point of the highest temperature. I would prefer to err on the side of caution.
 
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