2.5R Overheating

[RC_KAOS]

Went to start my 2.5R today (running 20% nitro 14% oil) and it seemed to be hard to start and just wouldn't go well. So i resetted the needles back to the manual says (high 4 turn out - low flush) and started it again. It started but the temp starting going up real quick, before i knew it, the temp was up to 340F and it stalled. I now have the high speed needle up to 5 1/2 turns and it still does it but not as quick. Should i keep riching the high speed????????

Could it be a air leak maybe?

What is the usually needle settings does everyone use (HSN & LSN)?

The fuel tank seal was split but got a new thicker one in and it is still overheating

Cheers

 

[vbgagnon]

Either the lsn is lean oryou have an air leak. Take off your carb and backplate and seal with high temp rtv sealant.

 

[jon2]

Check your tank and lines. Those are the easiest to check.

The way I do it is with an fish tank air pump.
Empty out the tank completely.

First is to remove the tank and lines.

Then from the air pump, attach a fuel line to the outlet nipple that normally pushes the fuel to the carb.

On the Pressure line nipple pinch the line so the air would be compressed in the tank once the air pump is on.

Fill the tank with water and a DROP of dish soap. I mean a drop only.

Then turn the pump on.

What you want to look for are bubbles that may escape anywhere on the tank or lines. If you se any on the lines junk that fuel lline. If the tank starts to seep out bubbles on the side, then you know the tank is cracked. Now the cap may open up if there is no crack but that is normal since the pressure has to escape.

When done, Rinse thoroughly and dry completely. and re attach the tank if the tank checks out.

Mine may be long wonded but it works for me...

 

[REVOTMAXX.18TM]

Went to start my 2.5R today (running 20% nitro 14% oil) and it seemed to be hard to start and just wouldn't go well. So i resetted the needles back to the manual says (high 4 turn out - low flush) and started it again. It started but the temp starting going up real quick, before i knew it, the temp was up to 340F and it stalled. I now have the high speed needle up to 5 1/2 turns and it still does it but not as quick. Should i keep riching the high speed????????

Could it be a air leak maybe?

What is the usually needle settings does everyone use (HSN & LSN)?

The fuel tank seal was split but got a new thicker one in and it is still overheating

Cheers

2.5R will run hot about 270 give or take 10 degrees, they do not have a big enough head for one, but right now I think you have an air leak. My needle settings on my 2.5 are about 2 turns out on LS and 3.5 on HS. A good way
to test for air leak. Get about 1 foot of fuel line, car off of course, some soapy water and small brush. Hold carb wot hold thumb over carb intake and blow in fuel line (conect to carb) while adding soapy water to various spots back plate, carb base, carb pinch bolt, etc..also check glow plug while its running see if it is bubbling, that will make it hot (lean) also check exhaust flange @ head for air leak and low and high needle they will leak air also, should be no air bubbles in fuel line to carb when running, good luck.

 

[REVOTMAXX.18TM]

Are you measuring your temps w/body on? You must still have an air leak, try high temp RTV and reseal the backplate and carb base and make sure exhaust header is sealed? I have a 2.5 on my T Maxx and its doing the same as yours?

 

[MEGA MAXX]

2.5R will run hot about 270 give or take 10 degrees, they do not have a big enough head for one.

how does the 2.5 have a 'small cooling head'? because it is .15, look at other .15's, the heads on them are small.

my trx2.5 runs at 240 255 all day, i have sealed up the backplate and carb for the sake of it and it did reduce my temps quite a bit. i have found how ever, the 2.5 is quite picky on fuel brand (personal experience), too much oil and it overheats.

i run byrons 11%oil in mine and its great, i have run a very oily fuel in my old trx in my maxx and it was a pain in the ass, fluctuating temps, tuning lasted all of 5 mins before it needed changing, was a pain and what made me sell it, but i was a mere noob ( not sure if i am still one now:depress: ) back then, and realised it was the fuel causeing all my problems.

ran tornado and byrons in my latest 2.5 and its great.

i would seal up the back plate and carb for the sake of it even if it isnt them leaking.

sorry for the long post but, one other thing with my 2.5 is that, the tuning is quite a bit over factory settings, yet its at about optimum (slightly richer) tuning. are you loosing performance at all when richening the hsn? or try richening the lsn and see if it makes a diffrence?

 

[REVOTMAXX.18TM]

I have installed my extra 2.5R head, on my 2.5 about 1/2 inch taller and bigger diameter, have not pulled backplate and carb yet to seal them, will see maybe this weekend if time alows??? Thanks. Also running trinity monster 20/12 percent syn. oil.