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Nitro RC car question

iamwiz82

iamwiz82

Lifer
This is my second nitro car and it is an HPI MT2 18SS. It's all built and such, and I started break in yesterday. It took awhile to get her started since the manual had reversed the routing of the fuel lines :roll:. Anyways, after the two static runs, I get ready for the first powered movement. Started it up andgave it alittle throttle and it goes nowhere. I give it more and it barely moves, up to half throttle and the poor thing cannot even go up a 1-2% grade.

So now I'm remembering when I broke in my old HPI SNR and I don't remember it being so sluggish at breakin. The clutch is engaging properly, and I think that the slipper clutch is dialed in correctly, and I know for sure that the brake is not dragging. So is this a factor of the HPI factory setting being so super rich? The head also doesn't feel like it's getting up to temperature.
 
Probably running too rich. Low engine temps, sluggish performance generally = running rich. At least that's how my T-Maxx was.
 
Originally posted by: thirdeye
Probably running too rich. Low engine temps, sluggish performance generally = running rich. At least that's how my T-Maxx was.
Click to expand...

Should i keep it rich for the entire breakin and then tone it down, or tune the carb slightly more lean for breakin?
 
Originally posted by: iamwiz82
Originally posted by: thirdeye
Probably running too rich. Low engine temps, sluggish performance generally = running rich. At least that's how my T-Maxx was.
Click to expand...

Should i keep it rich for the entire breakin and then tone it down, or tune the carb slightly more lean for breakin?
Click to expand...

Well I recall when I broke my T-Maxx in I wasn't supposed to touch the a/f ratio. I was able to run perfectly without touching, but once I started tuning it, what you're describing was a tell-tale sign that it was way too rich.

You could also be flooded, since you said your fuel lines were reversed. Do you know the de-flood procedure for the engine?
 
Originally posted by: thirdeye
Originally posted by: iamwiz82
Originally posted by: thirdeye
Probably running too rich. Low engine temps, sluggish performance generally = running rich. At least that's how my T-Maxx was.
Click to expand...

Should i keep it rich for the entire breakin and then tone it down, or tune the carb slightly more lean for breakin?
Click to expand...

Well I recall when I broke my T-Maxx in I wasn't supposed to touch the a/f ratio. I was able to run perfectly without touching, but once I started tuning it, what you're describing was a tell-tale sign that it was way too rich.

You could also be flooded, since you said your fuel lines were reversed. Do you know the de-flood procedure for the engine?
Click to expand...

It's not flooded, the fuel line was actually pumping fuel into the muffler, but I cleaned that out. I know it's running ultra rich, because if I blip the throttle, the engine shuts right down.
 
Then you may want to back the fuel off a bit. Just mark where you started so you can easily reset it if something happens.

Man I'm really tempted to fire my T-Maxx up again, that is, if it didn't have a destroyed bulk head and shock tower 🙁
 
definately too rich.

lean it in 1/3 - 1/2 turn on the hi speed needle. Or if you want look up the factory defaults for that motor and set the needles to that.

If you want to learn more about break in search for "heat cycle" nitro motor.

 
that pretty much describes it.

It's all I will do for new motors now. It works very well.

Keep the piston at bottom dead center when it is resting to allow the cylinder to cool without the piston in it.
 
you'll be fine.

Just run it like described, get it up to temp for a few minutes and then shut down.

heh, whenever I blow a motor it's just an opportunity to get a bigger one.

 
break in? what is this break in you speak of. open that sucker up, widen those ports, fluke that crackshaft, turn that conrod into a toothpick, put it back together and make it scream.
 
Originally posted by: iamwiz82
This is my second nitro car and it is an HPI MT2 18SS. It's all built and such, and I started break in yesterday. It took awhile to get her started since the manual had reversed the routing of the fuel lines :roll:. Anyways, after the two static runs, I get ready for the first powered movement. Started it up andgave it alittle throttle and it goes nowhere. I give it more and it barely moves, up to half throttle and the poor thing cannot even go up a 1-2% grade.

So now I'm remembering when I broke in my old HPI SNR and I don't remember it being so sluggish at breakin. The clutch is engaging properly, and I think that the slipper clutch is dialed in correctly, and I know for sure that the brake is not dragging. So is this a factor of the HPI factory setting being so super rich? The head also doesn't feel like it's getting up to temperature.
Click to expand...


Man I'd love to get a nitro car again, but I don't think my girlfriend would look at me the same again...
My brother had a sweet t-maxx truck way back when, that thing would jump over anything.
 
Originally posted by: iamwiz82
This is my second nitro car and it is an HPI MT2 18SS. It's all built and such, and I started break in yesterday. It took awhile to get her started since the manual had reversed the routing of the fuel lines :roll:. Anyways, after the two static runs, I get ready for the first powered movement. Started it up andgave it alittle throttle and it goes nowhere. I give it more and it barely moves, up to half throttle and the poor thing cannot even go up a 1-2% grade.

So now I'm remembering when I broke in my old HPI SNR and I don't remember it being so sluggish at breakin. The clutch is engaging properly, and I think that the slipper clutch is dialed in correctly, and I know for sure that the brake is not dragging. So is this a factor of the HPI factory setting being so super rich? The head also doesn't feel like it's getting up to temperature.
Click to expand...

You found the right guy to ask. I'm deep into RC. 🙂´
Sounds like you got some previous experience but here we go anyway.

I understand your engine is new and need a break in. Leave the needles at factory settings to start with. They are always set very rich.
Preheat the engine with a heatgun so the head is around 200F or so. An ABC engine should not be run too cool, you need to get it up to at least 200F otherwise it will wear out faster. (I can tell you why later on)
So... preheat to 200F
Start it. It will be rich so you will probably need to lean the high speed needle to get it to run OK (possibly the low speed too). Also make sure the idle screw is set so you got 0.5 - 1 mm opening on hte throttle.
If you can't get the temps up wrap the head in Alu foil to decrease cooling.
Run it around for a few minutes (~3mins) on the ground. Keep an eye on the temps.
Stop it and let it cool. Make sure the piston is at BDC.
Restart and lean it until it runs with a clean 2 stroke cycle. run for another 3 mins and let it cool.
Repeat this until you got around 30 mins of run time. Keep the temps up (200-220F or so). In the latter stage do a few half to 3/4 throttle runs and make sure you have it running clean.

After this you are ready to tune for performance. Start on the rich side and lean out until you get max performance. Lean the low speed until you get a snappy response with out a lean bog and without any rich stutter.

I run 1/8 buggies and can't answer any questions about slipper clutches or 2 speeds. Good luck. PM me with more Qs if you got them.
 
Originally posted by: iamwiz82
Originally posted by: thirdeye
Probably running too rich. Low engine temps, sluggish performance generally = running rich. At least that's how my T-Maxx was.
Click to expand...

Should i keep it rich for the entire breakin and then tone it down, or tune the carb slightly more lean for breakin?
Click to expand...

Read my earlier post. Do not tun rich and NEVER let it idle a full tank at low temps. This will severely cut back engine life.
 
Originally posted by: FrustratedUser
Originally posted by: iamwiz82
Originally posted by: thirdeye
Probably running too rich. Low engine temps, sluggish performance generally = running rich. At least that's how my T-Maxx was.
Click to expand...

Should i keep it rich for the entire breakin and then tone it down, or tune the carb slightly more lean for breakin?
Click to expand...

Read my earlier post. Do not tun rich and NEVER let it idle a full tank at low temps. This will severely cut back engine life.
Click to expand...

Too late 🙁

I followed HPI break in procedure for the idle, without touching the carb.
 
OK guys, I used a heat gun to check the temps and it's a whooping 130F after a fuel tank of puttering around. I'm going to wrap it with some aluminum foil and see what happens.
 
definately too rich. Needs to get up to temp to really break-in. 200+

There's nothing wrong with giving it some good throttle or even full throttle for short bursts to get it up to temp. Don't just putter around. Run that sucker.

FrustratedUser has heat cycle well described.
 
Originally posted by: spidey07
definately too rich. Needs to get up to temp to really break-in. 200+

There's nothing wrong with giving it some good throttle or even full throttle for short bursts to get it up to temp. Don't just putter around. Run that sucker.

FrustratedUser has heat cycle well described.
Click to expand...

I shouldn't say putter, I was giving it 50-75% throttle, but it didn't seem to really move it. How much should I lean it out. I already turned it 1/2 leaner, that was before the 130F.

How long to cool between runs?
 
let it cool to 100 degrees between runs. That's the whole heat cycle thing - get it warm enough for the piston/sleeve to mate well and then let it cool.

I wouldn't really lean it out any more right now, make sure you have good blue smoke. Wrapping the head should most definately get the temp up. Or you can check your needles and make sure they are at the factory settings (should be able to find this from motor manufacturer)

As you get more experience you will learn just by listening to the sound and how it performs.

I've got about 4 gallons through my picco right now and it is STILL nice and tight at the top with good compression. Still screamin'

what nitro percentage are you running? Higher nitro (30%) runs cooler.

Weird that the temp is so low. Newer motors are generally really tight and heat up quickly. make sure you're getting accurate readings, measured AT the glowplug.
 
20% fuel and I get lots of smoke after it runs for a minute enough to heat up.

Well, I ran it again with aluminum and it got up to 140-150ish, too hot for me to touch the head, but I'm a sissy when it comes to heat. And at 1/2 turn leaner than stock the engine still bogs heavily when blipping the throttle.
 
Interesting, next run started with the head at 82F. After wrapping it and not playing with the carb at all the engine ran at a nice 205F with a nice amount of smoke.
 
You might want to make sure the high speed needle is in the default position. Something could have happened from when it was made to knock it all out of whack. I've broken in several motors, and some will not come at the default setting, and it causes all sorts of oddities like you describe.
 
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