spura1

Sorry, sorry,

I got a question I am running MCD RR with .26 zenoah, what should be a correct temp for that engine???
one thing is a plug colour but what about temp. level?

Thanks for a help

P.S. I was a measuring targeting into side motour ribs...

Earth Surfer

If your running lean, it will seize at high RPM before you get the car back to you for a temp reading. Nitro's have to use a temp reading because they do not have a spark plug to read. It really is not applicable for the gas engines, and probably will not give you useable information (head temps and exhaust temps are kept track of in some racing applications for gas engines though--those are usually the hard core guys). If your plug is carmal color or darker at full throttle readings--you will be safe from a lean mixture failure. A plug could be black at half throttle settings, then run to lean at top RPM and seize, so that could fool you. It is best to creep up to top rpm while checking the plug color (trying to not let the engine run at any RPM than the one your testing so you don't get a false plug reading from ideling or something before you shut the engine down to pull the plug). Then if you get to full throttle, and still have a dark plug, you can lean the h jet 1/16 or 1/8th turn at a time for full throttle runs to set your high speed jet. It is dangerous to set the high speed at lower RPM, as the low speed jet is still flowing fuel over 1/3rd throttle, and the high still may not be fat enough for full throttle runs---so creep up the RPM while checking the plug. Even if you have a clogged fuel system, you can prevent a lean seizure if you creep up the RPM. If the plug is light in color while your gaining RPM, and if the H screw is over 2 turns out, you better get a new carb and or clean every part of the fuel system. If you did not creep up on it--you would most likely seize.

The engine size is measured differently also. It is not .26(what ever the unit is), it is a Zen 26cc "G260" engine. It is a good engine.

spura1

Thanks Earth Surfer,

It is always pleasure read your posts.

It helps me a really lot[8D]

P.S. Anyway, what could be a good running temp??

kennyrccars

MCD's work the engine really hard & the engine does tend to run hotter than in a 2 wheel drive car.This is due to a combination of things such as the 4 wheel drive system, the amount of time you are on mid throttle runnung under high loadfs & the way they are driven (HARD). Like Earth Surfer said tune the carb for good plug colour to prevent a lean seize. One way to keep the temp down is to use a castor based 2 stroke oil, a synthetic oil although giving good lubrication can lead to higher engine temps.

Zenoah engine temps vary quite a lot depending on where you measure the temp. The third fin down the head on the fan side should be around 80 celcius, but I have seen as high as 110 celcius third fin down above the exhaust port. Remember if the head gets too hot you just loose compression, if the piston gets hot due to lean running you will get a sieze....

Earth Surfer

Good write. For my information though---why do you think syn oils run hotter than castor/syn blends? I have never heard that before.

kennyrccars

To be honset Earth Surfer I'am not 100% sure, is it due to the synthetic lube being burned off during combustion leaving less lubrication on decleration??

Wolf[NL]

You can tell a lot of the temp by looking at the primer bulp.
Is the bulp less then 1/2 the engine is a little bit to hot, just adjust the carb setting a bit richer. When the bulp is empty the engine is to hot ((vaper lock). De fuel evaporate in the carb.
When the bulp is 3/4 full or more the engine isnt to hot.

kennyrccars

I had this exact problem when with my MCD when I switched to Castrol A747, although the same fuel /oil was ok in my 2WD cars. Changed back to castor based oil problem solved.

Wolf[NL]

You could adjust the carb. settings to correct the problem instead of changing the oil... (Castrol A747 is really good oil.)

kennyrccars

Carb settings where really good, and you are right Castrol A747 is really good oil if not regarded as the best but in this instance it was not a good option.