too hot

[ksrichard]

while fine tuning my new 2.5. noticed i was running hot so i kept
richining the mix with the hsn. actually melted the rpm head guard
a little. found out i used to much filter oil. motor couldnt breath.
what do i look for internally to see what needs replaced? and is a
rebuild something i could do or should i just exchange the motor
for a new one?. will a 3.3 fit on a tmaxx 2.5 frame.

 

[Phins Fan]

Piston/sleeve looking for obvious wear and melting and possibly your crank bearings need an eval. What makes you think it needs to be rebuilt? No compression? How hot did it actually get?

 

[ksrichard]

not sure. it melted nylon head protector a little. shop estimated
approx. 300+. dont know that it does need rebuilt. does need looked
at. power loss. no spunk. cuts out at high rpm. shop said problem
definatly in motor. is it easy to take apart.

 

[joshman1204]

No power and cutting out could simply be a bad tune and there is no way to know for sure until you get a good tune on it.

How long did it run once you got it hot? If it just hit 300+ for a few seconds than it is more than likely fine. I would set the carb back to factory settings which should be pig rich and see how it runs from there. If it runs decent then read the guide on the ERCM site for tuning and try to dial it in. If it wont tune or still runs bad on factory settings then I would open it up and inspect everything.

 

[ksrichard]

did retune. same same. ill open it up then and go from there.
probably need help from all of u. will keep u up to date

 

[joshman1204]

Set the HSN to 4 turns out from closed and set the LSN to flush with the collar. This should be a very rich and safe tune. Depending on your glow plug and weather conditions you may have to lean both needles some to get it to run decent without bogging down and dieing.

 

[ksrichard]

i swaped motors for now. i have all parts to rebuild front end of
my other maxx. just need time. ill put motor on and try to tune
once more. couple days. THANKS!!!!

 

[Rolex]

If it gets that hot and the HSN changes nothing, then probably your LSN is too lean. That's a problem that's often overlooked.

 

[Zdragon71]

+1 on what Rolex stated^^^^.

 

[2revo1maxx]

So you over-oiled the filter which kept it from getting enough air.
You kept leaning the needle until it seemed like it wanted to run, but over-heated it in the process because it couldn't breathe and you leaned it out to compensate.

Set the lsn to flush and the hsn to 4 turns out, making sure the idle gap is at 1mm or less....a small paper clip works well for that. Take the filter apart and roll it around in some paper towels and re-install it. You may also want to use a new glow plug.

 

[ksrichard]

i switched motors. cutting out at high speed. going to tune from the begining.
lsn, when u say flush u mean at the bevel on the inside not the throttle arm itself.
right?. as for idle 1mm or 1 1/2 turns out approx.. i hope. let me kno.. very new
i appreciate all of your help.

 

[Zdragon71]

Hsn is the main screw sticking up off carb and needs to be 4 turns out from closed. Lsn is the screw in the middle of the slide where the linkage connects and needs to be flush with the barrel not the linkage arm. The idle screw is on the side of the carb body and while looking down into carb the gap needs to be 1mm or the thickness of a paper clip. Once the gap is set you do not need to adjust it anymore. Once all of these settings are done then follow this link for tuning.
http://www.extremercmods.com/content/tuning-popup.html

 

[ksrichard]

thanks alot. very helpful. i need to let settings alone. keep adjusting to see if i can
get better performance and end up messing up the whole thing.

 

[Phins Fan]

It can be a PITA if your not used to tuning nitro rigs. I will typically find the "sweetspot" and richen it about a 1/3-1/2 turn from there. I prefer to sacrifice a little power for a longer engine life by running rich. If youve got the $ available than screw what I just said and run it as lean as possible for top power output. It wont last long at all but will perform like no other rig typically does.

 

[joshman1204]

It can be a PITA if your not used to tuning nitro rigs. I will typically find the "sweetspot" and richen it about a 1/3-1/2 turn from there. I prefer to sacrifice a little power for a longer engine life by running rich. If youve got the $ available than screw what I just said and run it as lean as possible for top power output. It wont last long at all but will perform like no other rig typically does.

I am the exact opposite

I tune to the bleeding edge of performance and just keep a spare piston/sleeve on hand when it does go bad. I have upgraded the con rod so I think that helps keep me from having catastrophic failures on my 3.3.

With that said both of my 3.3's and my 5.9 are still running strong on the original piston/sleeve with almost 3 gallons through each of the 3.3's and a little over 4 on the 5.9.

 

[2revo1maxx]

Juat because an engine is making it's maximum power doesn't mean it can't last over 5 gallons. You can have the best of both worlds with proper tuning.

 

[ksrichard]

I used your guide for tuning. GREAT HELP!!. But when i shut motor off it
Just dies. Thought it is suppose to idle up then die. Hsn or Lsn. Runs ok
But off a little. Wish you could here it to help. What is a good running temp?

 

[2revo1maxx]

If it dies instantly when you pinch the line then it means a lean LSN. An ideal temp range is 200-260 degrees, but you can't tune by temps. 200-260° just means the engine is warm enough to expand and not too hot either.

 

[ksrichard]

Thanks to all.. Running great for now. Time to finish other maxx. Titled "first front end rebuild". Hope
To have your help there as well.

 

[Zdragon71]

Woohoo! Front end rebuilds are therapy. A few cold brewskis and your fav tunes blasting in the background and a few hours to spare in the day. Almost as fun as breaking it!!