MR.Maxx

My Feedback: (7)

I have been trying for some time to tune my 2.5 engine. It starts and runs, but it cuts out, it doesn’t stall just chokes. I have returned the carb to the factory settings and it still cuts out. It leaves the line fine, but it starts cutting out like it is to lean. If I lean it out is sounds funny when it idles, if I richen the carb it stalls. I have checked the fuel lines and the glow plug and I just finished pulling the engine of the truck. I have cleaned it thoroughly and checked everything I could think of. Nothing looks wrong. I pulled the car off to make sure the o- ring wasn’t cut etc. This motor will not tune anywhere close enough to play with let alone race. It has great compression and only has about 3 quarts of fuel through it and it starts instantly. I have several other nitro trucks and have never had any problems like this! Any ideas. I am at my whits end.........

MR.Maxx

My Feedback: (7)

I forgot to mention that I checked the drivetrain to make sure nothing was binding.

ZondaC12

my sportmaxx had a 2.5 engine that was a year old until about 2 weeks ago. it now has an o.s. .18 cv-rx(s). i had similar problems to yours. not the same but pretty close, its just a pretty powerful engine that unless youre lucky is damn near impossible to tune. i am anti-traxxas since my 2.5. i had a nitro sport with a pro .15 and that was crap, always overheating, im sick of traxxas and their stupid .15 engines, they all suck, they are now on their FOURTH one trying to squeeze every last bit out it, BS! ive heard complaints about the 2.5R and saw a video and it looked weak. i wish they would smarten up and be like others. every other friggin company is using an .18 or bigger in their next-gen monster truck. wow traxxas is so friggin stupid.

steve77423

My Feedback: (14)

i had problems close to this i took the engine apart cleaned it put it back together and the same thing happed nothing changed so i did lots of reading and found cv sealant found at automotive store its red something like that and put it carefully around where the carb go's into the crank case and on the back plate do not put it on the head also check the head gasket to see if there is any damage to it look for very very very fine line even that can be an air leak this is a very sensitive engine to that stuff i have a very good running 2.5 i broke it in right and drove it pretty rich for about a gallon maybe more and im starting to lean it out it has tons of power and i never get above 240 i run it cool its super fast and its still rich but thats what i do you should give it a try

stephen

MR.Maxx

My Feedback: (7)

I took it to hobby town and they told me it is an air leak and to use the red rv sealent around the carb. I will give it a try.

Thanks you for the advice.


Don

steve77423

My Feedback: (14)

it should work perfect it did for me the engine will run after that if it was an air leak.
if it dont you have a problem that beyond me.

redheat8

The weak link on the 2.5 in my opinion is the carb. itself, the gasket or rubber seal thats between the carb. and manifold tear and the H/S needle wears , rebuild seems to do the trick on 2 of the 3 -2.5 engines that I run, RED