TRM VX-231 Help

[chopperhopper]

Hello there,

I have a few questions about my new motor; first a little background. I have been flying helis for about 10 years on and off but have only had one other gasser, a Predator with the Hanson 260 back in 2004. I have had a few HPI baja gassers as well, so I consider myself somewhat familiar with these engines.

The setup in question is a Radikal G30SE with the TRM VX231. Pitch curve in normal (which is what I am using of course) is -5, 0, +10. Throttle curve is 0, 19, 21, 27, 43, 65, 100. I am on my first tank of fuel in it and I am having problems starting it and keeping it running. I am using Coleman Fuel with Ace Hardware brand 2-Cycle Ashless Engine oil mixed at 4.5 ounces per gallon (the only ashless I could find around here). I am using the pull start. I started with both needles at 1.5 turned from closed and it fired right up, that was the only time it has started easily. To get it started every other time the choke has to be closed to get it to to fire off for a second, and then pull again with the choke off, this is especially true after it has been warmed up. This gets it going.

With both needles @ 1.5 turns it will not idle and, it requires a "feathering" of the throttle to get the headspeed up without killing the motor, the transition into a hover usually ends with the motor dying, and the transition back onto the ground always ends with the motor dying immediately.

With the LS needle @ 1 3/8 turn from closed it starts easier but surges very badly, to the point that I cannot get near a transition into hover without the heli violently yawing.

With the LS needle @ 1 5/8 turns from closed is is very hard to start, usually end up being about 15 pulls to get it going. The throttle has to be pretty far open to start and idle also. I can get it into a very low hover like this after I let the head speed come up very slowly, but as soon as I let off the throttle even a little, the engine dies. It feels like I am right on the edge of going onto the HS needle.

I have only run about 1/2 tank through it so far. Am I being too cautious? I feel like either I am doing something wrong, or something is out of whack. I have never really had any trouble with a gasser motor before. I am absolutely NOT complaining at all, just looking for some advise before I do any damage . Thanks!

Here are a couple pics of my setup just for you to look over:

[Peter]

Is the tank vent on the other side ??

Try to get the carb butterfly approx 1/3 open at your hover stick position , a throttle " curve" of 5, 10, 15 , 20, 25, 35 , 100 is common !

[cbergen]

I would suggest talking with Al on this and following his recommendations, but it sounds to me like you are VERY rich on the needles.

Consider the fact that you are having to open the throttle quite a lot to get it to idle and hover. For the engine to run, there has to be a proper fuel/air ratio. With the needles (fuel) this rich, you are having to add a lot more butterfly opening (air) to match it to get the right fuel/air ratio.

[baseclass]

I'll second Peter's question.... I wondered about a vent as well.

And I love your choke handle ;-). I ended up doing the very same thing because the stock lever was just too big. I'd love to hear how others may have changed this up as well.

[Mega325]

I say your rich and I always tune HS needle first then low. If you have to adjust your throttle stop. may be closing to much.

[chopperhopper]

Thanks for the replies. So the popular opinion right now is too rich, got it, I will lean it slightly and so what that does. The tank vent it an excellent question; does the primer bulb return line not work as a vent? I will add third line to the tank as a vent if not. I imagine that would probably be my hard to start problem and poor running performance if my tank is completely sealed! I am glad you guys are here to make me think. I also PMed Toxic Al the same original info.

[baseclass]

The lack of a vent is almost certainly the problem. I started my TRM at 1 1/2 open on both needles to start with and that was very close. It seems a tad rich when it approaches hover but until I have the first gallon through it, I'm keeping it rich.

I"m curious, is your setup how Century has it in their instructions? I don't see how that can possibly work.

k

[chopperhopper]

Ok, I feel like a fool. Vented tank, problem solved. Running great now!

[baseclass]

Good to hear Chopper... and don't feel bad. Even seasoned pros of 20 years overlook something now and then. That's why forums like this are so nice. You get an extra 100 pair of eyes to look over your issue. So nice compared to 20 years ago when all we had was a buddy or two at some dirt road in the middle of nowhere to look at our stuff!

k

[cbergen]

Great catch guys!! Do the instructions tell you to install a vent line?

[Toxic Al]

I want to thank you guys for helping out, this is what I like about this site. I am sorry Chopper for not getting back to you. I did not get pm notification and I have been away from the sites lately. You guys can always call me anytime you need for help. Peace, Al 407-461-9225

[chopperhopper]

No problem at all Al, got it figured out and I am good to go now!

[carey shurley]

Great catch guys!! Do the instructions tell you to install a vent line?

these do:

Gas Helicopter Tank Fuel Plumbing - My Way