Engine bogging - Oily Plug

[Guantanamo Joe]

Ok guys:


The last few times I have run my XT, it runs great for about 10 minutes, then the engine starts to bogg... When I pull the spark plug out, it has lots of oil on it. After cleaning all that off- another great 10 minutes. Any help? (The engine is barely broke in, I have not even run a whole gallon through yet).


Thanks

 

[cordy]

Are you using 25:1 mixture ?How is your head gasket?The gap on your plug-.020-.025.Are you running rich?

 

[Guantanamo Joe]

My mixture is 25 to 1best I can tell. I don't have a fancy mixing cup. Lsn and hsn are still at factory settings. Plug is gapped well. Just put a new one in this morning.

 

[Guest]

You are rich if your plug is wet.

 

[Guantanamo Joe]

So... which needle do I need to turn clockwise? What should I look and listen for?

 

[Guest]

You start with the low. You can lean it a bit and use the idle screw to keep the idle down. As you lean the L needle the rpms increase. Once you get your idle set you can then start with the H needle. Lean in small amounts 1/16 to 1/8 turns at a time. Wright down your adjustments incase you have to go back. Do some high speed runs, shut it down immediatly after. Don't let it idle. Pull the plug and check the color. Your shooting for a brown paper bag color.

 

[MyNewXT]

Just ran my new xt today,with hop-ups installed,I just love this truck,It is awesome,running it at close to half throttle,Duh,forgot the video camera.Will post vids soon.

 

[Guantanamo Joe]

So... I cleaned up the plug, replaced it... watched the tuning video by Squirrel on youtube... and after playing with the needles- same thing. The engine just seems to bog down at high throttle... WTF?

 

[Guantanamo Joe]

I think I will dump out the rest of my gas and re-mix.

 

[MyNewXT]

I had that problem with the engine bogging for the first 10 min.,It cleared up after that,no bogging for the rest of the tank.

 

[Deluge]

Try these carb settings...

HSN - 1 1/2 turns out

LSN - 1 1/4 turns out

Have you vented your fuel tank?

 

[Guantanamo Joe]

No... I haven't vented the tank. Seeing as we have limited resources here, what can I invent to do that with? Also, with the needle suggestions do I run them all the way in then go back those turns?

 

[Deluge]

Yep. Turn them in until they stop (Don't force them!) and back them out to spec. To make a basic vent, just drill out the tiny vent hole in the gas cap, get a 10" long piece of fuel line and push it into the hole about a 1/2". You can either use some sealer to seal up around the fuel line, or just drill the hole so it's a little smaller than the fuel line, for a snug fit.

 

[Guantanamo Joe]

Ok... so I have a theory as to why my gas might be bad. Bear with me and don't laugh if I am just speaking out of my ass here.

Pretty much all week (every week) my Rampage is in the trunk of my car. Reason for this is because I never know when I might want to go play during my lunch break. It is hot as hell down here in GTMO, and if I don't crack the windows then the fumes are unbearable in the car after being shut in all day. Could this be evaporating the gas and leaving a rich oil mixture in the tank? Thoughts?

 

[Deluge]

Yeah, you don't want to do that. It'll evaporate, especially in hot weather.

 

[Guest]

If you are leaving truck in the heat and your tank is not vented, the expanded fuel gets pushed into the carb and engine flooding it out.

 

[RAMJET]

yep my guess would be the tank vent ,both of my machines would bog down after 5-10 min before the tank vent was installed.Roger

 

[Guantanamo Joe]

Ok folks- here is the latest:

I drained the tank and adjusted the needles some. Ran them all the way in and back out to the specs that Deluge suggested. After some minor tweaking beyond that- I found this:

It is quick off the line- however, if you pull the trigger all the way back, it just boggs down again. It will easily get to top speed, but it wont race there.

I went to the local auto parts store (never has anything you need in it). They have no kind of fuel line to make a tank vent. I did leave the cap half twisted to see if that would help to figure out the problem- no affect.

So- what do you guys think now?

 

[Deluge]

Sounds like it's just a tuning issue. Start leaning out the HSN about 1/16 of a turn at a time and keep an eye on your plug color. Do some high speed passes and kill the engine before it idles. You're shooting for a brown paper bag color.

 

[RAMJET]

is it possible the air cleaner is choking the engine , if the foam is over oiled or the oil you are using in the filter is to heavy it may be choking the engine at the higher RPM.take the foam and squeeze it in a piece of clean paper towel to remove the excess oil .the carb on my first truck had some dirt in the needle valve when it was new causing the motor to flood ,funny thing was it would start and run ok for a while then it would just start flooding and die down and quit, I took the carb apart flushed it out and it was fine after that .