Overheating on 2.5

[unccpathfinder]

Alright guys I'm still chasing the 2.5...I get it to what I think is tuned then i'll body it up and run it for 5 mins or so and the temp will go from being pretty consistent when not bodied at about 250-260F to jumping over the 300F mark

It is not running lean and I have both HSN and LSN set to the rich side (is still putting fuel out of the exhaust) and it idles pretty good sometimes it will speed up but usually stays pretty constant...

how do you check your fuel tank to see if it has a leak...I believe its loosing pressure and not feeding enough fuel to the carb after it warms up so its starting off rich and nice and jolly then goes lean

Thanks

 

[Timmahh]

is the body cut out allowing some airflow? what fuel you useing? this is a 2.5 TRX motor? if yes i say drop an os 11mm carb in it and start over. i hate traxxas carbs, pisspoor design and useability imho.

a lil more info. when temping with no body, i take it your running it around lik eyou would with body on, not idleing around slowly by you and not really Running it?

 

[chuck3]

sounds like its not getting enough airflow to cool it off, especially if its running just fine with the body off and then heats up when you put it on.

 

[unccpathfinder]

is the body cut out allowing some airflow?

I believe it is...the entire front windshield area is gone...I was actually thinking about creating a diffuser or something to create a ram air to make sure all the air went there...

i take it your running it around lik eyou would with body on, not idleing around slowly by you and not really Running it?

yep even had a couple of nasty roll overs the only difference is I tune it on the street instead of the dirt b/c its a lil less prone to having a roll over I run a good couple (5 or 6)of wide open passes

I noticed the previous owner cut away some of the fins on the cooling head so the fuel line would tuck in nicely...I believe that is hurting me a good bit too...

Is there a rule of thumb on the amount of frontal area required to cool these things off i'd say i have about 8 sq in right now without measuring maybe a lil bigger maybe a lil smaller?

 

[Timmahh]

ok things to keep in the rear of your head when tuning. if you tune on the street and all is great, then go to the grass/dirt and it gets hotter, the most likely reason is Drag. the dirt/grass will cause More Drag on the care, thus make the motor work harder, thus more heat. the road offers much less resistance over grass/dirt. so when you tune on road is all good, but once you take the fresh tune in the grass/dirt, its now going to be a bit lean, cuz the road has less resistance. see what i mean?

if your running on the dirt that race/bash/day, then you need to tune your motor while running on the dirt. if your race/bash/day is on the road, then you need to tune on the road for that race/day ect...
keep in mind these motor, though powerfull are small, so any differance in surface condition will undoubtedly have an effect on the tune you have.

the longer the grass/ deeper/softer the dirt, the more drag you ll have, so the more heat the motor will make, so the more rich your tune needs to be.

hope you understand what I'm getting at here.

you have to tune for the conditions your running in. richen it up a bit when your moving to higher drag surfaces.

 

[unccpathfinder]

I'll try that out and see what happens...just didnt really think the contact patch got that much greater in grass/dirt and put that much more resistance into it...

 

[Timmahh]

it dont take much. is like the differance between sliding across ice ( street ) a nicely polished wooden floor (groomed track) or concrete (grassy) with just a good clean pair of sox on.