engine making a popping sound

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sharkattack99

sharkattack99

Well-Known Member
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926
Location
Moses Lake Wa
theres a popping sound from the engine is this normal. my needles are very rich and i had it about 240 to 250 I'm still breaking in my picco just wanted to know if the popping sound is normal or if that indicates if there is something wrong. also i don't think that its in the vid but sometime after i throttle it the idle will hang even as rich as i have them still hangs but not alway iv ran about 4 tanks through so far.

http://www.youtube.com/watch?v=rH3NFO3NDcE
 
well maybe I'm just hearing things then, but i did notice it wasn't closeing i fixed but sometime with i closed it will idle really high its strange in that vid my throttle linkage got messed up and was doing it by hand, at the end when it was reving high the throttle was all the way closed.
 
How much fuel is through the engine? Those temps are a little high for just sitting there but that also depends on how tight the engine is and how much "friction heat" accounts for it. To me, it looked like the engine was lean especially on the LSN, when you close the carb the idle should drop right away. This issue can be either too big of an idle gap (should be .5mm-1mm maximum) or a very lean LSN, I'm guessing it's a combination of both. As for the noise, that's a normal sound but not something you want to do for any length of time. This is a perfect example of why I say not to idle for more then a few minutes, then throw the truck on the ground and drive it fluctuating the RPM's while keeping them low for the first 1/2 gallon. What you are hearing is an imbalance in the engine at that particular RPM, as you raised the RPM the engine became much more smooth in it's operation. You DO NOT want the engine to idle even one tank in that state as it is extremely hard on all the internal parts. It's the same for basically any engine, you don't want to drive for any real length of time at a consistent RPM, your supposed to run at different RPM's for the first while. By no means is this reply directed at you, your video is great for explaining "my" theory on break-in procedures which I think will benefit many because there always seems to be a lot of confusion on how to properly break-in an engine. You can still "heat cycle" the engine with this method, 3-4 rounds is more then enough to achieve the results.
 
ya I'm by no means a engine expert like purenitro but i have never liked the break in method were u idle it for a few tanks or whatever,i think of it this way its not good to idle your real car for long periods so I'm sure its not great for your nitro either,i honestly just plop it on the ground and start driving it right away but slowly increase how much throttle i use over a few tanks and i vary the throttle during this as robin suggested,actually its pretty close to how traxxas suggests you do it!! i know, i know i said the "T" word,MY BAD!!!!!
 
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i wasn't letting it idle i was just verying the RPM's I'm a saw horse (thats why i was getting the 240 250 temps) or is that the same as still idling?

i have about 5 tanks all over 200F, i will have to get a picture of my idle gap to see if i have it right i know it will be hard to see but I'm sure you can tell a little.
 
no i know was just saying i have never liked that way of break in thats all lol
 
I agree with Robin, i remember Robin telling when you do the idle break in the fuel is just accumulating in the in the mill and bunging it up. My pinch wasn't that tight so i just plopped it on the ground and varied the RPMs.
 
ok hope you can see this ok but this is were my idle gap is set is this still to big of a gap?

idlegap.jpg
 
No, that would be on the small side of .5mm you could even open it up just a hair. For ease of starting, use the throttle trim on the radio to slightly open the carb, once it's started and warmed up a little you can close that gap back up.
 
i was just kind of guessing its pretty hard to measure, hopefully i will get to drive it some more tomorrow, so that sound is a normal sounding engine? and richen up the LSN a little more what about the HSN or just leave that at factory?
 
well from what i read your still breaking it in. If you are, leave everything at factory settings, after your done breaking it in completely, then play with the LSN HSN. Its the procedure i followed and my motor runs perfect and its completely good. But i need a temp gun
 
My simple to the point answer. That engine is lean popping.

I highly suggest to richen the needles some and i would start with the LSN. The engine should never do that with a proper needle setting whether its new and idling or 2 gallons in on the truck running on the ground.
 
How far out does it stick? you can't see it in the picture. They do tend to stick out a bit.
 
Yes it is sticking out a bit, but that doesn't matter, you need to adjust the needle for what the engine wants (which is more fuel), disregard any flush settings which the rtr engines use for factory settings.
 
IDN, but it seems as if the engine is about to die but it has just enough to compress the fuel and ignite, but not enough richness (fuel loading) to bog the engine. :dunno:
 
you can tell your engine is near dead when you can freely move the flywheel a whole rotation without feeling any compression. If you still feel compression then it's fine.
 
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