Summer Too Hot For Running?

[hamster huey]

What is the hottest temperature I should drive my Ramp in? The temps in KS are getting to 90 and I notice my Ramp running differently lately(sputtering/idle/dies) . Under body temps are hot enough to melt a corner of the body, melt the one tank old yellow fuel line, and change my x-can from blue to brown. I do not like the yellow fuel line I like black rubber but hobbytown did not carry. I don't know if the yellow line cant take the temps? I know the air filter needs to be cleaned but not badly. My needle is at 1.5h and 1.25l. Supply and return fuel lines both have air bubbles. Im thinking the culprit is the gas tank because the carb is sucking air bubble from it which could cause a lean condition and explain the rest......My MT body is slammed so I am also thinking about scoops or hole put in it for cooling air. Will I be able to run when the air temp is over 100? On a sunny 100+ degree day objects can have a surface temperature of over 130 very easily when at rest let alone with a running motor.

 

[kryptonite]

the outside temps mean very little. the sputtering at high rpms is a lean condition, wich will melt things. the tiny bubles in the fuel line are normal and wont effect anything. i agree with the yellow fuel line. it melts. i use the black fuel line myself and its resting on the case and pipe. we run our on-roads with sealed bodies in 120 degree weather. and snad queens run in the dessert all day long. no issues. i would not vent the body like a nitro. i would work on the tune. if you run in a short space one day and then run it wide open space the next day it will need to be richened a tad. pull the plug and let us know what color it is. with a proper tune you should be able to redline that mill with little air flow and it not over heat. also check the under case to make sure its not clogged with grass. the needle settings seem rich, but you can have 2 of the same motors with the same pipe and 2 diffrent needle setting. also, did you change the exhoust?

 

[DemonRC]

Did you fuel line melt on the XCan? It looks like it. That would explain why you sputtered out. You'd be sucking air with your fuel which would cause an extremely lean condition.

 

[kryptonite]

its odd how it melted right there. i am sure you have a hole cut out on the top for the exhoust, but do you think the heat wrpped around and melted the corner or something?. what gets hot all the way down there? the clutch

 

[hamster huey]

The rough running is not constant. It has been going on over the last 3 tanks. The problems are all intermittent. When Im coasting and floor it their is a dead spot on the low end. When I stop the idles goes low then dies. Holding it floored after high speed is reached it wil hiccup for a second but keep going. All problems are intermittent. The exhaust was not recently installed. I put the yellow fuel line on one tank ago just to see if my old fuel/return lines were bad or sucking air because I noticed the carb to and from lines had bubbles. Is the black fuel line tank plug supposed to leak or be sealed? I would assume its that way because if the tank was air tight it could crack under pressure but a little presure is needed to feed fuel to the carb so the black plug is not completely sealed so it can vent a little? Fuel filter is not plugged. BTW what is the fuel tank vent mod? After I put a clean filter on it, check head gasket/bolts, and new lines again I will see if it works. Thanks for letting me know hot weather is not the culprit so I can check something else. Where can I get the black fuel line?

 

[kryptonite]

all those symptoms are tuning issue. sounds like your rich on the low side and lean on the high side. pull the plug and see what color it is. the only way to properlky tune the motor is by the plug. correct. the tank is not sealed. but if it was, it wouldnt crack. it would simply build pressure and stall the motor. the bubbles are ok. even if they are on the return line or in the primer bulb. if there is a pressure issue, it will be with the cap. the rubber gromet were the fuel lines go to should be sealed. if you replace the black lines you need to use the upgraded tank gromet. now, if you pull the plug out and its chocalate brown, then look into the tank venting. if you poull the gas cap and its presurized, then its not venting. ifr its a lean condition, then your plug might be a little grey. i suspect its lean just becouse of the way you decribe the how it runs and the excess heat under the shell. as for the gas tank vent, just put a small barbed end fitting thru the gas cap with some extra fuel tubing. make sure you pull the guts out of the cap.

 

[kryptonite]

When Im coasting and floor it their is a dead spot on the low end.
that means the low needle is too rich


When I stop the idles goes low then dies.


this is also means the low speed needle is too rich. when you lean out the low speed, your idle will be fixed


Holding it floored after high speed is reached it wil hiccup for a second but keep going.


this happens when the motor is heat soaked. thats too lean on the high side.


Is the black fuel line tank plug supposed to leak or be sealed?


yes, but mine will leak very slightly if turned upside down. the vent that you are thinking of is ontop of the gas cap.. tiny pin hole

if the tank is not vented, witch that could very well be the problem(on my rig) it stumbles right in the middle and pops ot the top. idles just fine and takes off ok till mid throttle. never stalled out, but i would assum it could

 

[Piranha2]

Yeah, the yellow fuel line sucks too. I have some clear and have always used the original exhaust coupler to protect the fuel line since putting my 77DOM on.



/monthly_2009_03/583c6058c80af_Ramppipe007.jpg.2e9faa4cc7bfdf566823c659fbb48613.jpg

 

[hamster huey]

I checked it out. Put on a clean filter, cleaned spark plug, changed all fuel lines, checked for leaks, put on MT tires w/stock MT gearing. Ran great. Started with stock H/L settings of 1.5/1.25. It was pretty hot out and had to add 2 hours on H so I could run full throttle accross a fottball field without hiccupping. It choked out while holding full throttle if I went any leaner than 1.5 on the H. Im thinking about doing a carb cleaning/dissasembly maybe rebuild just to make sure carb is in good shape. I am approaching 20 tanks.

 

[hamster huey]

I just got back from running 2 more tanks. The erratic idle came back very slightly but I figured it out this time. When I hit the brakes the idle changed so that kind of tippped me off. My throttle shaft where it goes through the carb has slop and a little tiny air leak with small bit of wetness coming out around the shaft on the carb body. Plus the throttle shaft was not tight at idle so I adjusted the throttle shaft with my trim to make it tight at idle. I think its time for the carb teardown. Maybe I should buy a new one and rebuild the old one for a spare when this happens again? Im now at 20 tanks. Now it runs great at H1.5 and L1.25 but not any leaner. Outdoor air temps are in the 90s today.

 

[Piranha2]

Wow, I was thinking this same thing with my truck and well, here is a solution. Thanks

 

[kryptonite]

your really putting some good time on that machine. i think its time for an 813 pumper carb. you'll love it. helps alot on the low end. i never really rebuild carbs, but its worth it for a case like this.

 

[hamster huey]

Im over 30 tanks now. As I mentioned earlier my throttle shaft has slop in it. I found this is common on the baja forum and the throttle shafts are made of soft brass so you replace them when they get slop. The temporary fix was to put some tension on my throttle shaft w/ the trim on the radio so the shaft was not a bit loose. I thought I would replace the carb "block" that the shaft goes through but now I think Ill replace the shaft and get a rebuild kit. I will also order a spare carb for a backup. Maybe the one Kryto rec'd.

 

[buz]

I know this is an old thread but i may have an idea on the body melt. The fan on the back of the recoil coming off the crank shaft pushes air across the engine and out exactly where the body melted. I noticed it on mine right away thinking that there was a major exhaust leak. I can't even imagine getting the engine that hot but i guess it could happen. Just have one tank on mine so far can't wait to see how the DOM ex wakes it up. Coming from 1/8th buggies this thing runs forever.