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Old 04-14-2003, 06:35 AM   #1
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Default what is too lean??

i just got my new hyper 7 pbs up and running.. started breaking it in on saturday (such a beautiful day in maryland), and got through my first 2 tanks, running it super rich.. cut out on me a few times but it never got above 230 degrees F

sunday i mess around with it a bit more and get up to about the 4th tank and the temp got up to about 260, and i cut it off.. i was just putting it around and my LHS said that i should be driving it around a bit to keep the air flow going through the heat sink.. (my first r/c so it's all pretty new to me)

the engine would cut out on me with a cloud of blue smoke from the exhaust, if i gave it more than 1/4 throttle.. on the 5th tank i began to lean out the top end and the low end needles some, and it actually ran much better.. i could take it up to 1/2 throttle and it would fly.. anymore throttle, it would cut out.. so i gradually leaned it out a bit more, and by the time i got to my 6th tank it was just about dialed in..

i ran my 7th tank last night at a baseball field, and i couldn't get it dialed in perfectly.. the top end was either too rich and i couldn't really get on the throttle, or it would overheat and get up to about 280, when i would cover the carb with my thumb to cut it off.. dont want it to over heat..

so my question is: why is it running so hot? is it overheating? which adjustments should i make to my carb to get it running perfectly?

i'm afraid to put the shell on it as i can't see the onboard temp to see how hot it is.. as far as running it on saturday and sunday, i ran it without the shell on, as i wanted the engine to get max airflow to keep it cooler, but apparently that's not enough.. any help would be mucho appreciated! thanks

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Old 04-14-2003, 07:55 AM   #2
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I always tried to keep my 1/8 engines running at about 220-230 at the hottest, you are able to run them as hot as you want, but the piston/sleeve life is killed by doing so. The on board temp guages pretty much suck, they dont give an accurate reading, but are somewhere in the range of 30-40 degrees of what the actual reading is (they usually give a lower temp than you actually have) It's always hard tuning your first nitro engine, so I would suggest you go to the LHS and see if one of their expert nitro guys could lend you a helping hand, once you get the car in tune, you will have to mess with it very little, and you will get a feel for what the needles do when you are at that point. I could tell you things to try, but without bieng there, and holding the radio in my hand, it is useless, as I dont know how the car is reacting to the changes.
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Old 04-14-2003, 06:17 PM   #3
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i believe i found my problem.. i richened up the top end about a 1/4 turn (in increments) and it seems to be running much cooler now, even with the shell on.. doesn't even get above 240 F.. so i have that worked out nicely.. =)

i have another question though: now that i've run about 11 tanks through the engine, i can use my fingers to work the flywheel around and move the piston up and down the cylinder..

have i worn my engine out too soon, or should the compression eventually become a bit loose to where i can move the piston up and down the cylinder with my fingers? should the compression still be super tight to where i can't do that?

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Old 04-16-2003, 10:29 AM   #4
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bumping the post in hope for a reply..
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Old 04-16-2003, 02:32 PM   #5
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Yes the engine will lose a bit of compression after break-in. You should be able to feel the piston when it gets close to top dead center. As for temp gauges, they do not suck, I use the on board type and have had no problems (run my engines around 260). The problem comes in when it is not installed right. I have the loop between the last two fins on the heat sink(per the MIP instuctions). I have found that by putting the loop around the bottom of the heat sink at the top of the block it will give you false readings
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Old 04-16-2003, 03:39 PM   #6
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There is a great article on tuning in the latest Nitro magazine. You can pick one up at your LHS.

Sean Sanchez

A.K.A. the real Orange that got banned from Trinity site.

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Old 04-17-2003, 11:32 AM   #7
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what if you are running lean(running higher than 270 degrees) and you put on a really good cooling head on, which drops it to normal running temperatures. I know this doesnt correct the problem. How do you check if its running too lean?
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Old 04-18-2003, 08:57 AM   #8
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When you lose compression in one run.
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