I'm stumped(overheating)

[darnoced]

I've sealed the engine(carb,backplate,even the ezstart)
put in a new glow plug(mcCoy MC-59)
rebuilt the carb
pressure tested the lines and tank
taken out the piston and sleve and checked for pinch

It is a 2.5 with the stock clutch flywheel and exhaust pipe and for the life of me I can't get the thing to run.
I've reset it to factory(HS and LS) so many times now and started over.
At present I'm at about 2 turns LS and about 4 1/4 HS and it is still running over 280. If I go any richer on the HS then it won't give me any rpm.
Any richer on the LS and raw fuel is coming out the exhaust and it dies when you try to accelerate.
The outside temp is around 50F and the humidity is "normal" for here.
Anyway the outside condidtions shouldn't play into anything because my sons 3.3 is running fine.
It seems that the only thing this engine is good for is burning fuel while idling and driving me nuts.
Please tell me that I am missing something

Signed..slowly going hairless

 

[martrix]

what fuel are you using?

 

[aligc]

have you thought about getting a new carb?? the carb might be faulty.

 

[65535]

Drop it down to 3.5 on the HS and 1.5 on the LS. Lean out the main mix a little. Once you get it idling slowly add throttle. Lean it out until it stops bogging down.

 

[darnoced]

I have replaced the carb body as the inlet threads were stripped.
I'm running sidewinder 20%.
I will try out those settings. It can't hurt seeing as I've messed with it so much that I can set it to stock blindfolded.

 

[Rolex]

Have you done the pinch test? Too lean of a LSN will overheat the engine very quickly, and nothing you do the the HSN will solve the problem.
Pinch the fuel line close to the carb when the engine temp is up. It will increase the RPMs and then stop. You want between 3 & 4 seconds. Less than that and you're too lean. As you richen it, you'll also need to adjust your idle setting to compensate. The LSN controls the idle and punch off the line till about half throttle. Then the HSN determines how it runs at WOT.

 

[darnoced]

I've got it to run around 263F. I guess that is all the performance I can get out of it.
I'm thinking that it is just too much truck for the engine with all the metal parts that are on it now and the new tires were just the straw that broke the camels back so to speak(about 14-15lbs).
I won't shift into second unless there is a tailwind with a downhill slope..lol and the acceration is a little on the slow side.
Just for my reference, when you check the engine for "pinch" how close to the top of the sleve should the piston go whenyou try to slide it through? mine is about 1/8" down from the top of the sleve on one set and the piston pokes up about 1/16" on the other set.

 

[martrix]

I've got it to run around 263F. I guess that is all the performance I can get out of it.
I'm thinking that it is just too much truck for the engine with all the metal parts that are on it now and the new tires were just the straw that broke the camels back so to speak.
Just for my reference, when you check the engine for "pinch" how close to the top of the sleve should the piston go whenyou try to slide it through? mine is about 1/8" down from the top of the sleve on one set and the piston pokes up about 1/16" on the other set.

260 up to 300 is fine inmy opinion. Its when your up at 300 for long periods of time is when you start doing damage.

1/8" from the top is what you want. If the other pushes through 1/16" then its definitely cactus.

 

[darnoced]

I tried to get more out of it, but the temp just takes off and it flames out. Settings right now are just a hair shy of 4 turns HS and just under 1 3/4 LS. It is a pig on fuel compared to the sons 3.3. Going through about 2 tanks to 3/4 of his. At least it is running the best it has since I got it in Sept. A definite learning experience.
Thanks everyone for the help. I still have "some" hair left(if only the grey ones had of fallen out).

 

[darnoced]

Well...I did the pich test on the fuel line and even though it was under 4 secs I tried richening it up some and the temps started to come down. This is one fussy engine, but it is a great "learner" I"ve managed to get the temp down to about 255F and am getting better punch off the line and nice shifts into 2nd. It still doesn't like to do more than 2 long passes with WOT(temp takes off) with out cooling it down, but I can live with that cause I just want to have fun with the kid. Thanks everyone for your input!

 

[nightwolf67]

I had the same problems with mine they just like to run hot 250 to 275 all the time!!!! Run it till it dies trade it for a 3.3 and then do it again!!!!

 

[Suicide]

yeah the 2.5 is a piece of crap. i had all kinda issues with mine until i used the erp and got a 3.3