Trail Tech Cylinder Head Temp gauge

[DimitriT]

I just installed one of these and wanted to share my experience.

For a while I wanted some gauge to show me the temp of either the engine or oil. The 550 doesn't have any place to install an oil temp sender (without tapping a hole) and it occurred to me that on an air cooled bike cylinder head temperature is probably more interesting.

After some research I found this little device:

http://amzn.com/B0031BIWX2

The sender is a loop of copper alloy which slides over the spark plug. The install instructions say to remove the crush waster and replace it with the temp sensor. The original washer is just a hair thicker than the sensor. But replacing it seems to cause no adverse effect. I installed it on #3 cylinder:



The cable was just long enough to route up through the frame and the triple-tee and to allow full range of motion. I have an L model so most bikes may require less cable length. I mounted the display on the bars using some double sides stick mounting pad. I'll probably figure out a better way to mount it later:



The unit is battery operated and I don't know how long the battery lasts. There is a small blue button on the back which you can use to reset it. The display indicates two temps: the current temp and the max temp since the last rest. It usually displays the current, but every 15 seconds it will briefly switch to the max temp.

The unit is not backlit.

On the road it worked perfectly. The temp rose up to about 280 F for most of my short ride and then rose or dropped from that by about 10 degrees depending on what the bike was doing. There appears to be about a 10 second lag from when the motor does something and the sender feels the heat. Probably due to the time heat takes to travel through the head to the sender.

It will be interesting to see what happens when I sit in traffic on a hot day. I've always wondered what the head temp gets to in this situation.

[Steve]

Nice info, thanks.

While it's nice to know the temperature, it's more important to know the limits to add some relevance to the numbers.

Anybody know what temperatures are safe and what temperatures indicate a problem?

.

[John Park]

Nice info, thanks.

While it's nice to know the temperature, it's more important to know the limits to add some relevance to the numbers.

Anybody know what temperatures are safe and what temperatures indicate a problem?

.

One of the reviews said it reads all the way to 472 degrees. I'm assuming that it was installed on the bike and the bike made it home on its own power.

Air cooled four stroke dirt bikes are perhaps the hottest running motors around. The finning is typically marginal and the oil capacity is small unless it has oil in frame, the single cams sit over the combustion chamber, one side is covered with a cam drive, and the airflow is mostly low speed. They'd be better off for cooling with pushrod tubes and rocker boxes. Apart from melting cam bearings due to heat coming from below and the oil being preheated by the cylinder passageways, the characteristic overheat symptom is ring failure, or more precisely ring lubrication failure.

Ring lubrication is marginal and once the cylinder wall temperature rises above the smoke point of the oil the replacement rate for the oil needs to be pretty high. Compounding this is the heating effect of blowby which not only heats the sealing surface of the ring but heats the replacement oil coming up from below. A smoky, high leak down motor will not show much if any difference in head temperature other than from the extra fuel burned to get the same power, but the cylinder will run hotter. Ring life on air cooled four stroke dirt bike motors is commonly pretty short [10K?] unless it's commuter use. Once the rings start to leak they go away pretty fast.

I think I'd rather have an oil temperature gauge. The temperature of the base of the spark plug is interesting but not so indicative of the proximity to doom of the whirry bits.

[tkent02]

What you want to see is a change in temps, not an actual number. These gauges are not very accurate, there are too many variables in installation and whatever else for an actual number to mean much. If your well tuned bike always cruises at 280 degrees, and one day it's at 350 or so, you want to find out why. Air leak?

I'd like to know if the temperature goes up or down while stopped in traffic. Let us know?

[DimitriT]

Yea I figured there's error in the sensor plus the position of the sensor will have some effect on the reading. Oil temp might be better to know if you want to compare numbers. I notice there's a round spot on the oil filter cover. That's probably a good spot for a temp sender.

I'll be watching the reading now to get some idea of what the motor is doing. One of the issues I run into is overheating and problems idling when it overheats. I'd like to find out when that's happening so I can replicate the situation and try to find a carb setting to fix the problem. The goal for me is to get the bike to operate as best it can over a wide range of conditions.

[JTGS850GL]

Attaching the sensor to the oil filter cover will not give you oil temperature and will likely be much lower then expected because of the direct air turbulence and engine mass in that area. I'd stick with cylinder head temp and place the sensor in an area that's not in direct air flow. As Tkent02 indicated... You need a baseline but the actual number may vary quite a bit from location to location. You're really looking for changes unless you can get accurate readings from the start.

[posplayr]

If you mount the ring lug somewhere like at the top of the transmission you will be surprised at how well it will, if not indicate, it will track oil temperature.

Mounting it on the spark plug it is going to be much closer to a EGT measurements and will fluctuate much more.

It really will matter little if you mount it in a direct air flow as the conduction of heat into the ring lug from the engine block will be far greater than any heat loss the ring lug might exhibit from airflow over it. If you read the literature, it says it is for engine, water or air temperature. If you had an oil hose like for a cooler, you could mount the ring lug under one of the banjo bolts.

[Katarat]

Ive ridden my 80 GS1100 @ 75 mph across the Mojave desert @ 116 degrees and thought that it wouldn't surprise me if the bike slid to a halt and melted down into a pile of aluminum but it doesn't even phase them. Maybe if you got caught in beach traffic during Daytona Bike Week it might but even the Harleys survive that