cat5-34cc race ported engine

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Running out of fuel should not kill the plug.
Nearly all engines tune a very slight bit different, and different carbs. also affect tuning a slight bit too, so starting at some safe settings, and only making VERY minor adjustments would be the best route to learning where this engine & carb. combo is happy.
 
looker2756 said:
Running out of fuel should not kill the plug.
Nearly all engines tune a very slight bit different, and different carbs. also affect tuning a slight bit too, so starting at some safe settings, and only making VERY minor adjustments would be the best route to learning where this engine & carb. combo is happy.
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Ran the OBR .34cc for 3 ours with the stops for cleaning the grass and cooling for 10 min. It runs exelent. I do not see much difference in power from leaning 1/16 or reaching it. it is powerfull ether way. And it sounds good.
 
Erutw5 said:
Ran the OBR .34cc for 3 ours with the stops for cleaning the grass and cooling for 10 min. It runs exelent. I do not see much difference in power from leaning 1/16 or reaching it. it is powerfull ether way. And it sounds good.
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1/16 turn to lean will only give you a pop noise at Wide open throttle Way up in the RPM.
If you don't know how to recognize the sounds of a lean engine, or the VERY small performance differences, you can easily lean seize engines.
I have watched it Many times.
Usually the only performance difference that can be noticed when the tune is too lean, is an extremely flat spot on the very top end of the rpm, or drop in performance at the very top rpm / speed, or the pop noise indicating to lean a fuel mixture.
Without knowing what this looks, feels, or sounds like.
It is a learning experience.
Always error on the rich side if you have good performance !
 
looker2756 said:
1/16 turn to lean will only give you a pop noise at Wide open throttle Way up in the RPM.
If you don't know how to recognize the sounds of a lean engine, or the VERY small performance differences, you can easily lean seize engines.
I have watched it Many times.
Usually the only performance difference that can be noticed when the tune is too lean, is an extremely flat spot on the very top end of the rpm, or drop in performance at the very top rpm / speed, or the pop noise indicating to lean a fuel mixture.
Without knowing what this looks, feels, or sounds like.
It is a learning experience.
Always error on the rich side if you have good performance !
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I have L 1/32 reacher then 1 1/8. if I reach more, then the idle starts to go down. The H is 1 3/4. I whish I had some one who understands the sound with me, but I do not. I probably could lean the H if I did not accumulate the grass . I always check the temp in different spots, even though nobody does it. If I go over 380 I stop and clean.
 
Erutw5 said:
I have L 1/32 reacher then 1 1/8. if I reach more, then the idle starts to go down. The H is 1 3/4. I whish I had some one who understands the sound with me, but I do not. I probably could lean the H if I did not accumulate the grass . I always check the temp in different spots, even though nobody does it. If I go over 380 I stop and clean.
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I hope you mean 280, cause at just over 320deg., engine damage usually starts to occur.
Even 280 is on the Hot side really, as I like to keep mine around the 250 mark.
Measuring the temp. on these engines is kinda' different.
Need to check directly at the base of the spark plug for a correct reading.
If you move to the exhaust side it will be much hotter, and on the intake side cooler.

If it runs good where it is set, I would leave it there.
Could probably go a slight bit leaner on the High needle, but remember " Safe " is ALWAYS best.
 
looker2756 said:
I hope you mean 280, cause at just over 320deg., engine damage usually starts to occur.
Even 280 is on the Hot side really, as I like to keep mine around the 250 mark.
Measuring the temp. on these engines is kinda' different.
Need to check directly at the base of the spark plug for a correct reading.
If you move to the exhaust side it will be much hotter, and on the intake side cooler.

If it runs good where it is set, I would leave it there.
Could probably go a slight bit leaner on the High needle, but remember " Safe " is ALWAYS best.
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Yes 380 is on the exhaust side. There is no other way to read by the plug. This is why I decided 380. that means less at the plug. I am so cautious and probably paranoied after I killed 2 engines. But the car runs great now. I use castor927 at 28:1 for obr. Very powerful. I noticed that in the beginning of the run it is more powerful, and later it is a little less. Hotter engine?
 
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Erutw5 said:
Yes 380 is on the exhaust side. There is no other way to read by the plug. This is why I decided 380. that means less at the plug. I am so cautious and probably paranoied after I killed 2 engines. But the car runs great now. I use castor927 at 28:1 for obr. Very powerful. I noticed that in the beginning of the run it is more powerful, and later it is a little less. Hotter engine?
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Engine temp. is probably the cause for the change.
Chances are that it is still a bit rich on the High needle, and onece the temp. comes up, it has a bit to much fuel.
I ALWAYS mix at 25:1 - Safe is ALWAYS best. ;)
 
looker2756 said:
Engine temp. is probably the cause for the change.
Chances are that it is still a bit rich on the High needle, and onece the temp. comes up, it has a bit to much fuel.
I ALWAYS mix at 25:1 - Safe is ALWAYS best. ;)
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what oil are you using at 25:1? Also the car is running great, extremely fast and powerful and sounds good to me, so I am not going to change the settings yet.
 
The Klotz Techniplate is a high load oil and it is concentrated so it will take half the amount of oil that it recommends
I used it by accident
I did not read instructions and boy does it gum up the ring
But it does protect the motor
It has to be run wide open in high load Applications to get to burn
Good oil just has a gumming problem if you don't read like I did [emoji24]
It would stick piston and ring together so no compression and motor would not start after it sat for a day or to
Unless you took head off motor and unstuck the ring [emoji90]
 
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I have used it for several years without ever sticking a ring once.
My cars have sat over the winter with no use at all, and still no problems with sticking a ring.
I know the guys at LargeScaleRC used it for years too without any of the ring sticking problems.
It does create deposits inside over time, but they are easily cleaned off.
I will run 5 gallons of fuel or more before tearing down to clean.

https://www.klotzlube.com/Ecommerce/site/content/PDFs/TECH/KL-100-Tech-Sheet.pdf
 
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I like Amsoil, it is a Very good guality product.
HPI and other mfgs. recommend 25:1 ratio on oil to gas.

I do mix my fuel that way,
But ... Once ...
I got to our 1/4 scale track & had forgot to bring my gas can.
I borrowed fuel from a fellow racer & it was Amsoil Sabre, I believe, Mixxed at 100:1.
I was VERY sceptical on that, but we do run a restrictor plate under our carbs. in that class, and I ran it with Zero issues at all.
 
looker2756 said:
I like Amsoil, it is a Very good guality product.
HPI and other mfgs. recommend 25:1 ratio on oil to gas.

I do mix my fuel that way,
But ... Once ...
I got to our 1/4 scale track & had forgot to bring my gas can.
I borrowed fuel from a fellow racer & it was Amsoil Sabre, I believe, Mixxed at 100:1.
I was VERY sceptical on that, but we do run a restrictor plate under our carbs. in that class, and I ran it with Zero issues at all.
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HI. If you say that castor 927 is good why you are not using it, and using Klotz.?
 
LargeScaleRC is like less than 10 minutes form my house, and they carry the Klotz brand, and I have been using it in " Most " of my large scale cars for nearly 10 years now.
If I were going to look to change brands I would probably look to Blue Marble? High Performance 2-Cycle Oil.
http://www.davesmotors.com/tt119.html

If you read about this stuff, it seems to be the way I would go if I decided to change, which I don't think will happen.

We now have a store in town, about 15 minutes away from me that carries the Amsoil line of products too, which would be another option if I were to chose to change, because it is Very good stuff.

I am not changing because I know I have had Zero engine failures in the Many years I have been running them.
I know how they run on it, and it works out good for me personally.

Several companies make good quality 2 cycle oil, and it is all in what you have available & have learned to trust, and work with.
 
I run castor 927, carried over from years and years of running in my motocross bikes. Make sure you are running high octane ethanol free gas too. Ethanol affects these smaller engines negatively. I ran 110 Sunoco for two gallons in my 30.5 with no issues. I broke the engine in with it. I'm running 50/50 with premium ethanol free pump gas and I will be switching back. The race gas is awesome because it burns better and there is no pre detonation that you get with pump gas. Some people say you need higher compression to run or you with lose performance and damage the engine. False. The general Sunoco 110 is just a high quality fuel. Your engine should run slightly cooler too. I have 9.5 hours on my engine now and it's still running like a champ.
 
I know in places the ethanol content can be more of a problem, but here in Indiana, I have never had any issues with the standaed mid grade 89 pump fuel.
I have ran 108 Klotz fuel also, and noticed no difference at all in performance, other that some Very small tuning adjustments.
Ethanol free fuel is definitely a help to the engines, but I don't believe that the higher octane is actually needed, or any kind of advantage, unless you are running a higher compression " Ported and Polished " type engine.
By all means if you chose to run ethanol free high octane fuel, you may see some benefits that I have not seen.
I am sure that altitude and other weather type conditions could be factors or reasons for doing so as well.
 
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