Ken448

OK Im using Trinity Platinum 20%, and stock plug.. Engine is running either really rich, and blubbery (190 degrees) or a little less rich (like 1/4 turn!) and hot (270ish range) problem is: until I get it running in the hot range, it doesnt respond. No snappiness what so ever. When running hot, it still has plenty of smoke comming from exhaust HSN is 4.5 turns out from closed and the truck runs OK. If I lean it more, it gets real nice, responsive, quick (in the 40mph range, snaps into second, and pulls like mad. BUT when I check temps its up to 280-290 range and still a decent smoke trail out of the exhaust. I have taken apart the motor and sealed the back plate and carb. What gives?? This is about the most stubborn engine I have encountered, and it just makes me sick hearing about bash sessions and temps in the 210's!! Is that even possible?

It also runs VERY strong around 300, and leaves a smoke trail, starts right up when hot, etc.. Im tempted to live with it there, but I dont wanna have a junk motor soon. Ive got about 3/4 gallon of that Platinum through it so far..

This is checked with 2 temp guages too, one is a Raytec, the other is unknown brand, and there is not much variance.

What I dont understand is: It runs great real strong, doesnt sputter or want to stall on the top, Leaves plenty of smoke at the line, and following the truck. Idles great, and starts effortlessly if the motor does happen to stall. All signs lead to OK running conditions EXCEPT the temp. Could it be the plug?? Could it be the fuel?? There is no oil percentage on the bottle.. Does anyone else use this fuel?? Should I try Top Fuel? Maybe Ill pick up a Qt tomorrow and see what it does.

oatmealman

My Feedback: (1)

try riching your lsn it should increase you accelaration alot,i richened mine out and it goes probably 15 without touchin the throttle.as for the temps i'd say just leave it there

Dale Gribble

My Feedback: (4)

sounds like outmealman is right... Your LSN is probably lean. People forget the 2.5 has more then one needle. You can play with the HSN all you want, if the LSN is out of tune you will get bad performance. I also agree due to the high temps that your LSN is lean. All of my 'overheating' conditions with the 2.5 have been associated with the LSN, rarely the HSN.

BTW outmeal, that is a nice pic in your avatar!

redheat8

Dale, have you tried the OS 10D carb on your 2.5 yet, people say it's like day and night, Iput a 10e on the wasp .18 and it flys, RED

Ken448

lol... yes LSN has been adjusted as well... I do know there are 2 needles.. sheesh... I alleviated the problem today with a fuel change.. seems the platinum has just 10% oil.. I ran top fuel through it, and its acting fine now..

Dale Gribble

My Feedback: (4)

didn't mean to sound derogatory- sorry if it came across that way. It was nothing against you- just a lot of people have tuning issues because they forget about the LSN.

Good catch on the fuel!!! 10% oil is low for the 2.5. I didn't even think about that. I have run Trinity Monster HP with I believe 13%, but other then that it's Top Fuel.

psycooclimber

what is an avatar?

ThermalRD

I run Odonnell 30% in my 2.5R. Engine is tuned for performance, and i see a HIGH temp of around 233 after a hard run. I ran several tanks in a row at my local track last monday, never over heated.

tommythecat

My Feedback: (2)

Mine was the same all of the time. I played with it and played with it, it would run ok at ok temps if I ran it extremely rich, but I'd find it still overheating when I'd run it WOT for short periods. I tried resetting the needles to factory and retuning several times, with no luck. Then I saw a post in another thread on this forum where someone mentioned the HSN fixture. Then I remembered that one time when resetting it to factory settings I had the high speed needle fixture back out instead of the needle, so I tightened it back in. I didn't know that the Highspeed needle fixture is fed fuel through a hole that HAS to be lined up with the fuel hole on the fuel line nipple. So after taking off the HSN fixture all together and realigning the fitting over the housing with the fueal line, it fixed everything. For the past three days I have been running it out in hot weather in heavy grass at WOT for extended periods with rare temperature spikes in the 230-250 range, but pretty steady temps in the 215-220 range. I was really getting frustrated but fixing the alignment of that fixture fixed my problems. Now if I could just learn how to drive and quit hitting things at high speeds. I'm on my second steering servo, damn I need to learn to drive.

But my point was, have you checked the alignment of the HSN fixture? If not, you should.

psycooclimber

how did you fix the fitting? i have that prob. i took it out and now i think it is wrong.

tommythecat

My Feedback: (2)

you need to take the fitting out all of the way, and then mark it so when you screw it back in you know how to line it up.

OK

1 remove the high speed needle, unscrew it all the way until it stop coming out and just spins in the fitting, then pull it straight out

2 now remove the high speed needle fixture by unscrewing it, note the way it is set up, there is a tube with a hole going straight through it out both sides, then a plastic fitting over it that holds the fuel tube with small washers on either side of it

3 mark the HSN fitting with a marker a scratch or a small dab of silicone sealant or whatever, mark it on both sides where the hole is, mark it in a place that will be visible when it is screwed in

4 now thread the fitting in GENTLY until it is in tight and one of your marks is lined up with the hole in the fuel nipple that fits over the highspeed needle fitting

5 put your high speed needle back in and reset it to factory 4 out, and retune

It sounds confusing from my description, but it is really obvious what i mean once youve taken it out and see how simple the setup is.

I have to warn, be very gentle rethreading the HSN fixture back into the body of the carb. If you have it in tight but aren't ligned up with your marks, back it out to the mark, do not tighten it in to the next mark. The carb body strips out very easily, so you don't want to overtighten it. Trust me I already bought a new carb because I overtightened mine.

psycooclimber

ok thanks

mgth

I am new to the forum, however the thread title caught my eye as for I was having the same issues. I see temps with the revo in the 300-315 and have been at this thing for 3 weeks. I also have a T-maxx so I swapped carbs to see what happened. The temp problem went away! Just fixed tonight. Prior I had replaced the gaskets on the carb and the lower carb o-ring, as well as the crankcase o-ring. I think my carb has a bad casting seal just to the right and below of the HSN, at the aluminum cap. There is a casting mark where the haves are put together. I think my carb is sucking air there on high speed passes.

Anyway I called Traxxas and they said send it in and they will replaced it. Try swapping the carb with a know good one if you can. I should have done this 2 weeks ago and I would still have some hair left.
Hope this helps.

tommythecat

My Feedback: (2)

you can also just use a small beed of high temperature silicone sealant. Just loosen the carb a pull it out, then put a small beed of high temp silicone sealant around the top of the opening, then slide the carb back in. Even if you have a deformation in the carb or block the silicone should seal it up.

mgth

I havn't tried the silicone, however the crack is above the aluminum plug on the carb just below the HSN, not at the point where the carb slides in the block. It appears to follow the cast line in the carb; like a bad carb cast. I posted the info. because I had the same problem and isolated it to a bad carb. I had even rebuilt the carb and inspected it several times before trying the swap. It has an air leak on it somewhere during a high speed run. Not several high speed runs, just one, will take it from 220 at idle to 300 +. And I have adjusted both low and hight speed needles to extremes and back. It was a last ditch effort and it solved my temp problems. Just at factory setting the max temp on several high speed runs after the swap was 220. My post was to inform psycoclimber that he very well may have a carb with a hight speed air leak that can not be fixed with new o-rings and may need a new carb.

Thanks for the info. but since Traxxas is going to swap for free I am not going to take a chance and give them any reason to reject the one I send back.

tommythecat

My Feedback: (2)

I misunderstood you. Thank you for clearing that up. Very valuable info for anyone struggling with temp climbs at high speeds

BAP 62

Go with the OS 10-d carb they work great, keep tune a lot better. Try Blue Thunder Sport 20%. Before we switched to the OS carb we had high temps and had to retune all the time. Now no problems. We have had ours at 400 +,didn't seem to hurt anything, the engine has over 8 gal. in it and still runs great!

infernoMP

What oil content is the O'Donnell? I'm can run around 240-250 and run pretty good but I'd like to lean it just a bit more to make it fly....but I dont want to fry it. I'm running sidewinder 12% oil 20% nitro and I'm considering trying some of the top fuel to see if it changes the temps much.