I HAVE A FUJI50 GAS GNG. IT RUNS AROUND 300F TO 350F IS THAT GOOD RO BAB???? ENG RUNS GREAT

You can handle up to 380F, ideal is the temperature that you handle now 300F- 350F.

thanks osilfa, for the quick reply.

300 F?????
You guys are joking......right?

Here is the bottom line -
forget the measuring stuff - -run it and listen to it - if you can't make it "four stroke" -it is to fu----in hot!
Measuring tells you nothing except on twins as a balance comparison -
the engine should never slow on uplines -never - never .
Tryinf to determine setups on a single using a pyrometer is -in my book a complete waste of time -- fun maybe - but a waste of time .

300?!?!? 350?!?!? No Way!!! I have a DA 100 that doesn't run that hot. My engine is running around 170-180 right now and last time it was checked it was 91 degrees out. I saw Dick's post and agree with him on most things, but on this one I have to disagree. I have found measuring temps very useful. It's helped me identify engines that were having problems, and by moving the laser around I have found hot spots where we found problems with cowl ducting before saving the guy an expensive rebuild. You can only set one so rich before it fouls the motor up. I also diagnosed engines that had a cylinder cutting in and out even though you couldn't quite tell exactly what (or which one) it was it was so intermittent. I did this by measuring (very carefully around that PROP!) the header temps...we found one that was drastically cold. It was obvious that the cylinder wasn't firing right then, but barely noticeable when the engine was running. I also use them to check and make sure the engine is running in the range it should be (the range it 'normally' checks at) if it doesn't then I know there is a problem developing, and I start looking. In the case of this post, it's obvious that using one caught another overheating problem, so I wouldn't say they were useless. It's only a temp tool though, and that's all it can be used for...it's not gonna tell you what's wrong...only the 'ole brain will help there.

The only to measure engine temp is when its at full throttle. Landing and usingan IR gun is a reference but no way accuret.
You need a data logger to get true inflight temps.
On a test stand with the IR temp reader only 1/2" from the spark plug boss, 320-360 is normal after 2 min WOT.
Our engines run a lot hotter than we think, BUT this is where they are designed to run.

I am not trying to kill the temp gun craze - but on singles - I can't find any need - as noted tho -- a cold side on a twin can be easily detected.
Frankly the so called ducting -or lets say the positioning of the twin cylinders in many cowls - is horrible - from an air flow standpoint
Typically the rear cyl is very close to a bulkhead.
I pylon mount my twins - so that there is a big distance from cylinders to bulkheads .
Where required - I redo the front of the model .
I know that the point and measure devices are handy - but for our uses - I sure wouldn't spend any money on one -

I think the temp gun is controversy tool. Some can use it for good reason others will upset their self. As for temperatures on engines it is very common for them to be 300 degrees plus. Most go kart racers tune their air-cooled engines by head temperature. They adjust the high speed needle as they go around the track and try to maintain 300 degrees. Engines will build less carbon and will perform admirably at 300 degrees. Tune it to pull the hardest on the up-line and quit paying so much attention to the actual temperature. If the engine will richen up and burble its not to hot.


Keith
BME

Here is something for you guys to scoff at. We used to run our 100cc Yamaha cart engines in the 350-400 range. There were times in tight races that I would lean out enough to hit 425, although not recommended. The temp units were placed under the spark plug, like a washer, so you can not get a hotter reading.

Cart racing is wild - wish I could still do it - sometimes -- 40 years ago -
I had a Moss cart with dual Mac 10's which are old hat now - the temp gauge is understandably necessary on them - However on our models - just another gadget .

There's some truth and some misconceptions here.
Temperature measurement is useful if done correctly.
You always need to measure the same location on the engine in order to know if the engine is running hotter or colder than a previous run. There is a wide range of temperature distribution on any engine. You can't easily compare engine temperatures to some standard "good reading" without knowing that both were measured in the exact same location and under the same conditions (wide open throttle or was it idling, how much time after how much throttle etc.). I don't try to set needles by engine temperature, although I understand that is the procedure on full scale planes with exhaust temperature measurements. EGT changes rapidly with carb changes. Engine temps change more slowly because of the thermal mass. This lag in temp response would make it difficult to set needles based on temps measured at the cooling fins.

read that --impossible --

TwoStroker

You are correct!!
When i race Kart a few years ago i set up for 320F- 340F+o- but and the end of race the engine are near to 400F and many times we have to pop puf the carburetor into the turn for down the temperature

For the engine in RC are the same.Engine below 300F don't work good, is too cold.
About the infrared temp is very precise, but you have to take the temperature at the moment.
In 10 second of difference you can have a variation of until 40F

If you take a engine in the test stand and and run for five minutes for and put full throttle a make the measurement you can see easy 300F.

Dick about the Mac 10'S is McCullough and you running it with alcohol?

way back then -- Steen C oil and alky
Now I run in my ZDZengines - 35% Redline Racing Oil -and gasoline
The business of trying to measure after the fact -to me , is ludicrous.
I run em and listen to em - if you have trained your ear - you can tell when the engine peaks and when it is too warm
also you can tell rpm - as rpm is a frequency thing .
you can't hit exact rpm -but close .
When I played music - ( I was trained on clarinet fom age 7) I learned to hear very, very small changes in pitch .
Ask any classically trained musican -

Dick:
Yes !! I know that it easy that we can note when the engine is hot and peak but not everybody can do this

The Red line that you are actually use is that use in racing car?.
I like more that you give more information about it that is very interesting.
Take care

The oil is made by same people - but is different blend.
Red Line synthetic oil Two Stroke Racing Oil
That is exact name -they have other two stroke oils
look at www.redlineoil.com

When I worked for a chain saw Mfg we never measured engine temps to adjust the saws. I suppose we could but after adjusting so many one learns whats the "best sound". Since I work in engineering if I wanted engine temps I would use a therma couple and a data logger to see what the temp was in flight. But I doubt thats necessary .. especially for Singles. A better tool would a Vibra tac. It operates much like a tuning fork except its a single wire. You lay it on your cowl and run your engine. When the wire vibrates at its widest point.. you take your reading and that's your RPM. You can tweak your plane using that.
Two cycle engines need the oil in the fuel to scavenge off the heat. If your too lean..ya loose power because of increased friction. If your really too lean you can toast your engine. If your too rich you loose some power but not the engine. Better to err on the side of a lil rich. Just my 2 cents.. BobH.

Awe shucks Bob - that's just too easy
I just looked in my ancient parts box and there it was !
a genuine Fowler Vibra Tak
reads from 2000 to 15000 rpm.
I now use a 'lectric thingy " which I don't accidently stick in the prop --
also I am still hung up on 35% oil - but the only adverse effect is that my engines read rpms too high --
somthin wrong here --

well there ya go dick.. some things never go out of date! lol BobH.

I spit on the engine and it sizzles and boils. So I know my engine is above 212 degrees F.

when i checked mine it had been off about 2 min. 340 F. maybe i should check it while eng is runing? thanks for all the help ..

eng still runing around 330F no problems yet.

I just wanted everyone to see this thread again. Too many people have no conception of what our engines really run at. Let alone how to test it, or even why to test it. I still feel that a good ear can not be beat.

I was told at a club by many that anything over 250 was trouble. After discussing this at length no one would believe me either.

Gotta love that search engine!

We run onboard data loggers in our race planes...We measure the exhaust temp with the thermocouple right in the exhaust pipe flange at the cylinder..We try to maintain about 850F in the straightaways, and it will jump to 900 in the turns, then right back down to 850 in the straight..The engine manufacturer has run 1000 degrees exhaust temp on the engine dyno, with controlled air flow...He says the engines run best at about 350 head temp, measured under the spark plug...They fly 6 hour missions at 7000 rpm....350 is no problem, but like Dick says, you can't point a laser heat gun at the engine when it's on the ground and expect to get meaningful results, a well tuned ear works just fine...
Hey dick...35% oil ? 44.8 oz in a gallon ? I though my 20% was high