XT stalling out occasionally

[Neff]

I'm over the break in period and we're on about the 3rd tank of fuel now. After running it pretty hard up and down a grass covered field then slowing down to a complete stop. Then engine died on us. This happened 3-4 times overall in about a 30 min time period. Note that within a pull or two it started right back up and ran fine for a bit. Then it'd do the same thing again. But started up again fairly easily.


1... we were running the tank pretty low. Maybe a 1/4 inch of fuel at the time. Started thinking the bumps and fuel sloshing around might be the cause? Maybe it's not getting any fuel for a second and stall? Keeping in mind we broke it in the other day finally for prob and hr straight and no issues at all in a parking lot...opinions?


2... Seems it should have better acceleration and more power. Factory carb settings is where it's at now. Fuel I used is 89 octane and Yamalube oil. Mixture is 32/1. Any input on this setup? Seems a little boggy and when I pull the body off, behind the exhaust is small deposits of oil/fuel. I'm thinking it's running a little rich? Just a guess as I'm still learning this vehicle.


Any opinions are welcome. So please chime in


change the mixture 25/1?


Go to 91 octane?


Change the carb settings?...


Let me know guys. Thanks as always. Chris

 

[Deluge]

Sounds like you need to vent your fuel tank. The vent hole in the gas cap tends to get clogged fairly easily and once it's clogged it'll cause running issues. Take the cap off, take it apart and clean it up, that should help. You can run the gas cap a little loose so it won't build up pressure, or you can vent the cap even more.

Like this:

Just drill out the original vent hole, thread in a fitting and hook up some fuel line.

Factory settings are on the rich side. You can lean it out a bit to get better performance out of it. There are tons of tuning guides out there, here's just one example:

[ame]

[/ame]Your fuel mixture is fine, not quite as rich as 25:1 but still within the safe range. Octane doesn't really matter unless you're running a high compression engine. 89 or 91, both will run just as well.

 

[andyken]

Does it die when braking?

Does the idle change when brake is applied?

Could be the idle screw/linkage...gas cap vent, or low speed needle.

 

[Neff]

Tank is vented like above through the cap. I do still have the diaphragm in the cap though. Does that need to be removed when the cap is vented?

Seems like when it did die those few times at least one time was while braking I know of. I do not believe the idle changed when braking but it was 40 ft away so I couldn't really tell...

I'll check the linkage and low speed needle hopefully tonight. Other than this, it seems to be a fun RC for the kid and I.

 

[Deluge]

Remove the valve in the cap. There's a bulb portion that doubles as a cap seal, you can keep that in.

 

[Neff]

Remove the valve in the cap. There's a bulb portion that doubles as a cap seal, you can keep that in.

Noted. I'll remove that also...

and I was thinking maybe I've had it wrong all along. Maybe I ran 25/1 during the break in. For some reason I was thinking 32/1 was a richer mixture. I was thinking 32 is greater than 25 so 32 is more oil than 25. Sounds like I've been thinking it wrong.

So a 32/1 mixture is going to run a little leaner than a 25/1 mixture. Is this correct?

I'm gonna try my next gallon of gas at 32/1 to lean it out just a hair. I do have a Ratio Rite so would anyone advise a compromise and say do a 30/1 ratio? Just curious. I want the engine to last ( well lubricated) but want a little more performance as well. My opinion is a 30/1 mixture would be a little over mid point to do this. Thoughts?

 

[Deluge]

Right. The closer the mix gets to 1:1, the richer it is. That's how I look at it. So 32:1 would be leaner than 25:1. 30:1 would be fine. Just remember that when you're tuning with a leaner mix, it's going to be less forgiving than a rich mix.

 

[Neff]

Right. The closer the mix gets to 1:1, the richer it is. That's how I look at it. So 32:1 would be leaner than 25:1. 30:1 would be fine. Just remember that when you're tuning with a leaner mix, it's going to be less forgiving than a rich mix.

Got it. Thank you...