New to RC World - Used DuraTrax Warhead refuses to start

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MotoGod

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OK so let me first say hi to everyone out there ;-) I'm a new guy trying to get into the RC Truck hobby so my son and I can have some fun as he gets older. He's 3 at the moment and loves his little electric RC Car.

I bought a used DuraTrax Warhead that was upgraded to the EVO model and has a few other upgrades on it as well, but this thing just flat out refuses to start.

Here is what I have done thus far:

-Fully Charge my Glow Plug Ignitor and tested it on a plug screwed into my plug wrench. Glows up nicely.
-Put brand new Batteries in both the radio and the truck receiver (Energizer rechargeable made for digi cams)
-Emptied the old fuel and filled the tank with fresh O'Donnell 20% Nitro
-Reset the High Speed Screw to 4 turns out from fully seated (recommended by an RC Buddy)
-Reset the Low Speed Idle to 1.5 turns out from fully seated, and also tried flush with the ball knob (RC Buddy recommended)
-Adjusted the Idle Screw out in 1/8th increments to see if it would fire
-Removed the motor and disassembled it to see if it was gunked up. Looked clean to me, but seems like an ounce or so of Nitro came out of the bottom end and/or Exhaust Port, but the piston crown seemed to be dry.
-Replaced all the fuel lines

I'm out of ideas except to bring it to a Hobby Shop and have them get it running. The motor seems to have good compression, but I have not tested for leaks as of yet. It appears as though no fuel is making it to the glow plug (assumption here). I used to race motocross so I know a fair share about 2-stroke motors since I used to rebuild them all the time. RC Motors are a tad different, but same concept.

Any help anyone can offer would be GREATLY appreciated. I can snap pics of anything as needed as well ;-)

Thanks!

Scott
 

MotoGod

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I have tried 2 methods.

1. Hold my finger over the exhaust pipe, with the throttle wide open (also tried with no throttle), and crank the Kwit Pit for @ 3-4 seconds.

2. Remove the line from the pipe to the tank and blow in it.

Sounds like a lack of fuel to me as well....just not sure why ;-)
 

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You have opaque lines? If so blow into the pressure line and watch the fuel work up to the carb. When it gets there blow another second. Replace the pressure line then spin the motor. If it won't catch put your finger over the stinger tightly for a couple seconds. It SHOULD fire if it isn't sucking in air everywhere. Good luck!
 

MotoGod

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I assume a safe test for air leaks would be the good old soapy water trick? Motor seems to be in a safe place to lightly spray it. Let me go give priming another shot with both methods. I just replaced the lines with slightly less opaque ones, but before I replaced them fuel was getting to the carb just fine I could see it clear as day in the tube. Now a bit harder to see, but hey.

So as far as the low speed idle goes....how much of the carb body should I see open in the carb before I start tuning? I see a good portion of it open at the moment. Maybe a tad less than 1/4" with the low speed needle @ 2 turns out from fully seated.

Off to try better priming....be back in a few ;-)
 

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No more than 2mm and 1mm is better on the carb. 1/4" is WAY too big! With an opening like that you should have raw fuel getting into the exhaust.

Think the thickness of a creditcard...

As for air leaks the soapy water test is the way to go. Remove the fuel and brush some soap solution around everything. Blow into the pressure line again and look for the tell-tell bubbles.
 
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MotoGod

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OK so primed it again....still get nothing. I have the low speed needle set nearly flush with the body now. Let me try to test for air leaks. It's the only thing that makes sense to me right now. The exhaust gasket is a bit torn on the outside and seems to be fairly loose on the cylinder which may or may not mean anything, but it's worth a mention. The spring is fairly mangle that's holding it in place and I plan to order a replacement soon as well as a new gasket. I'll snap a few pics while I'm out there this time as well.
 

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The LSN should be completely flush with the housing. Pull the air filter and verify 1-2mm on the carb opening. The torn gasket won't effect starting but could effect the running pressure to the tank and can mess up things if left unfixed. Good luck!
 

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OK well.....I did manage to hear it pop almost like it had life left in it after I blew my brains out in the vent tube and filled the carb with fuel...effectively flooding the crap out of it.

Here is the million dollar question. How much compression should these little motors have? It doesn't seem any harder to turn over with the glow plug in it than it does with the plug out of it. Almost making me think this motor is just a bum motor. I'm literally getting no thumping, no pops....pretty much nothing until I flooded the carb with fuel.
 

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Well with the exhaust gasket in the shape it is in I am not surprised if it has zero compression--it's all blowing out the port. Take the exhaust off and plug the port. Spin the engine by hand with the plug in. It should resist turning at Top Dead Center.
 

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Well the gasket is only ripped where it flares at the base of where the pipe hooks to the cylinder. It's NOT ripped around the surface where the pipe and the cylinder meet up. That seems to be OK. If anything the pipe has been bent and it's causing a bad seal or something. I don't want to blindly start ordering parts for it without knowing anything though....so maybe my best route is to bring it to an expert here in the Raleigh area.
 

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If your carb inlet checks out at 1-2mm and all the other "did you check this" things are ok (glow plug, igniter, etc) then the only other thing I can suggest is the air leak test.

Anyone else have some thoughts for this gentleman???
 

MotoGod

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I did a quick air leak test, without too much soap mixed in, and didn't see any bubbles forming....but I didn't want to really hose it down so close to Servos and such.

One thing that I did notice was that when the carbed filled with fuel, and the motor finally "popped" the Kwik Pit definitely was harder to spin. That's the ONLY time it has had any kind of resistence at the Kwik Pit though.
 

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A flooded engine will do that. Try spinning the flywheel by hand with the glow plug in. You will feel resistance at TDC if the piston isn't toast.
 

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There is resistence when I spin it with my hand, but not a whole lot. You can certainly tell when it hits TDC though then a tiny thump as it goes back down the stroke. When I had the motor apart last night everything looked OK to the naked eye.....but I never removed the piston. I just peeked inside.

Uploading a few pics now from earlier and from last night's tear down.

http://picasaweb.google.com/spouliot/DuraTraxWarhead/
 

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Looks like a nice rig. Piston has a little rust on it but that is nitro for you. The carb opening in the pictures looks a little too small but other than that I really can't see much.

Someone with more brains than I PLEASE chime in and help this fellow!!!
 

Racer 1966

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Almost making me think this motor is just a bum motor. I'm literally getting no thumping, no pops....pretty much nothing until I flooded the carb with fuel.

This was going to be my first qusetion. Starting to sound like it's worn out.

Is the plug still dry when you remove it after trying to start it? If so try putting a few drops of fuel in the plug hole, put the plug inand try it.

I just bought a Warhead myself(see my thread Another Cheap Project - Warhead). Let me go check the manual for the factory carb settings and get back in couple of minutes.
 

MotoGod

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The plug has been pretty much bone dry except for the one time I over-primed it and got a pop out of it.

As far as I know factory settings were:

HSN: 4 - 4 1/4 Out
LSN: 12 1/2 turns out
Idle Screw: 1mm

I tried a ton of combos without any luck thus far....and of course I don't have a compression tester that will fit this darn small plug hole ;-)

Oh and it sure LOOKS like a nice rig....but I didn;t buy it to stare at it. hehe So right now....all I'm doing is swearing at it for the most part. haha Not a bad setup for $150....but if I have to buy a new motor the deal just went south in a hurry and the previous owner will be getting a nasty phoen call from me since he swore up and down it ran perfect but had been sitting since before X-Mas. Of course he didn't say which year....
 
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Racer 1966

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You're close enough on the settings,book says 4 1/2 on HSN.

What temp is it where you are trying to run it? If it's cold have you tried heating the head with a blow dryer first?
 

MotoGod

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It's been anywhere from 40 to probably 70 the first day I tried to fire it up. Right now it's cold out....but a few hours ago it was probably @ 50-55ish. So pretty mild.
 
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