Rich, lean or ???

[snmhanson]

I've posted a few other times about my engine issues so I'm sorry if some of this is redundant. I have an RC10GT with an OS .18 cvrx engine in it. Although I can generally keep my car running through a tank of gas it can sometimes be problematic. First off it runs a little warm, usually around 280 and I usually don't keep the throttle pegged when it's running. I don't really worry about that in itself too much. What is making me think something is worng though is if it dies after I've been running it and the engine is warm I can not get it re-started until it cools down. I make sure the engine is primed, starter is charged, everything else seems ok but the engine just won't start. Any ideas of what this would indicate?

As far as tuning goes, if I richen it up it makes it difficult to start, if I lean it out it makes it run too hot. I just want to get it so the engine will run reliably even if it is not running at 100% of it's capability. If it dies I want to be able to get it started again and I don't want to have to worry about it giving me problems like overheating or stalling when it is running. Any ideas here?

Matt

 

[CorradoPsi]

what glow plug is in it, what fuel are you using. whats the weather like where you are (temp, and humidity) how much runtime is on the engine?

its overheating and thats why its shutting off, it wont restart because the carb is so hot, its vaporizing the fuel before it can get into the engine.

 

[sad_rocc]

I have the same problem and posted in the Power Plants section, but will switch it over here. Here's my previous post.

I have a .21 SH pull-start on 20% nitro fuel. No matter if the motor is hot or cold, I always have to put my finger over the exhaust while I pull it to get it started. Often I have to leave my finger half over the exhaust until it gets going. Once running it doesn't seem to have any problems. So, I'm guessing my idle needle is just a little too rich or lean, but adjustments either way don't seem to solve the problem. Any advice?

Weather is very dry and around 80. I forget the brand of the glow plug but it's rated medium (10-40% nitro or something like that). When the motor is hot, often it just won't start no matter what until it cools. When it's cold, it will usually start after a lot of tries with the above method. It sounds and feels rich, almost flooding when I pull it and leave my finger off of the exhaust, but sounds normal with my finger on it and will at least almost start when I pull it.

 

[4u2nv]

Sounds like both of you are running wayy to lean. Richen it up a bit, and see what happens. Plus when your engine quits from being to hot MAKE SURE you guys spin the flywheel so the pistons in the BDC.

 

[smokin al]

I had a very similar problem. Please see my post a few threads down HARD RESTARTS. I had tons of great tips from everyone that got me going so read all the responses. I ended up changing fuel brands from Trinity Platinum to Byrons and richened it up some. My XXXNT runs awesome now and re-starts very easy if it stalls or runs out of fuel. What was happening was the fuel would boil in the carb as it entered causing vapor lock(air trapped in the line). Let us know how you do!

 

[sad_rocc]

Here's the thread for others: https://www.rcnitrotalk.com/forum/showthread.php?t=33844&page=1

So I haven't heard or seen fuel boiling at all, but it's a definitely possibility. I am on the throttle a lot and I know it does get pretty hot. The general consensus from that thread seemed to be to richen slightly and just let it cool a bit. I think I'll try leaning the idle and richening the hi-speed a little. Also planning on switching fuels because I currently have some no-name brand stuff. And I'm bringing the car from 10,000ft to sea level when I go to NY this week, I'm hoping that'll make things a little easier but I'm afraid it will throw my current mixture way out of whack.

 

[snmhanson]

Thanks for all of the replies. Sorry I haven't gotten back earlier but we have a ten day old baby that is taking alot of my time lately. Anyway, I will try everything that was mentioned here and see what happens. Also, FYI I am running Blue Thunder Sport fuel, a #8 glow plug and the temp is 85-95 with little humidity (although I have run it when it has been cooler also with similar results). The engine is relatively new with probably about ten to fifteen tanks through it. When I get time (sometime before winter) I will run it again and see if any of the changes help. One question though, what is everyone's opinion about Blue Thunder? I don't need the best fuel, just something that will run well and be reliable. Thanks again.

Matt

 

[snmhanson]

Alright, I richened it up a little and ran it yesterday. Ran a little more reliably but after a while it still stalled. I checked the temp after it stalled and it read around 230 and I was running it moderately hard. One other thing I noticed is that it always stalled when I let up on the throttle or hit the brakes to turn or stop. I may have been a little lean before but it seems that there are other forces at work here. I didn't mention previously that I run in very dusty environment. As a matter of fact I can't imagine dirt being any dustier than it is at my house. Could a clogged air filter be the culprit here? I cleaned and treated my filter just before running it this last time but it was pretty dusty after a few minutes of running.

Matt

 

[4u2nv]

How much fuel has been threw your mill? Os .18 atre usually pretty easy to keep a tune, and to tune itself, so I'm wondering if its getting a little wore out. You want to keep it as rich as possible, but yet have the performance there.

 

[vbgagnon]

To the dude with the sh .21 they tend to run well at higher temps. Just from what I've read.

 

[Pinblaster]

Your temps sound like they are getting in the right range now but if you are still having stalling problems you may want to tweak the LSN a little. You can get the LSN close by doing the pinch test on the fuel line about an inch before the carb. It should run for 3-5 seconds before it dies. I usually set mine at around 4 second and do a few test runs letting it idle for about 10 seconds then gas it, if it launches clean w/o much of a bogg, its good. If it boggs a few seconds before it clears out, lean it a tad. Just remember LSN only needs 1/16 turns at a time and usually not more than a 1/4 total.

PS: if all else fails, Return everything to factory/break-in settings and start over with the tuning process.