Danyboy
10-01-2007, 06:01 AM
Hello fellow Helifreaks!
I am expiriencing a strange problem...
I do have a Venture30 with a Webra 36 GTH in it.
Everything runs fine and smooth until I'm trying to get anywhere near a proper mixture. As soon as I start to lean it out, I'll start to have bad high-frequency-vibration in the tank. The leaner, the more vibrations. It'll get so bad, that I can observe a white worm of foamed fuel reaching from the fuel-clunk to the tank's wall and thus, the engine sometimes sucks foam, sometimes proper fuel, changing from a too lean-mixture to a over-rich and back and forth. As soon as I get down to a rich mixture, it'll stop foaming, but I'll get 4-stroking and a lot of spitting out of the exhaust.
On the first tank, I had that much vibrations that *all* the fuel turned into foam, making me think of an empty tank - which refilled itself when engine being slowed down to idle... :) That's gotten much better withing the first two tanks.
I did have the needles set as per instructions, though in the beginning I had to open the low/medium needle one additional turn to 4,5 turns to get the engine running, high needle is as per instructions on 2,5 turns open. I am now just a tad over the recommended 3,5 turns and still have fourstroking.
I also noticed that the engine has some aggressive sound to it, like a high-speed-saw or something. Sounds like a way too loose gear mesh on a high-speed gear...
I changed almost everything on the heli (especially the tail, was my first guess, all new there now...), also checked the runout on the fan (before 0,016mm, now 0,004mm, though hard to measure on that rough and uneven surface...), all is fine and its flying *smooth*, perfect for precision-hovering... :)
But with the current rate of fuel-consumption, I'd rather pour the fuel directly out on the lawn instead of running it through such a noisy machine... ;)
I did check the piston is installed in the correct orientation, the engine is featuring an ABN-garniture. Total fuel through the engine is now at around six litres, fuel used being 11% Nitro 13% oil. Since Webra is known for using low/non-nitro fuel, I also checked two tanks with 0%-fuel and readjusted mixture, no help... Temperature was always betweeen 90 and 100°C or lower in the beginning.
From the looks of the internal, the piston and cylinder almost look like new, only on the upper part, the cylinder's colouring changed from its original goldish colour to a somewhat more silverish, though nothing spectacular. No scraping, no chafing, no nothing...
Could it be, that after all that runtime, the engine is still not being broken in - maybe due to too well lubrication?
Or is it simply a manufacturing fault, like a non-balanced assembly or similar?
Any other guesses?
I'm all ears to your suggestions and comments!
Cheers,
Daniel
I am expiriencing a strange problem...
I do have a Venture30 with a Webra 36 GTH in it.
Everything runs fine and smooth until I'm trying to get anywhere near a proper mixture. As soon as I start to lean it out, I'll start to have bad high-frequency-vibration in the tank. The leaner, the more vibrations. It'll get so bad, that I can observe a white worm of foamed fuel reaching from the fuel-clunk to the tank's wall and thus, the engine sometimes sucks foam, sometimes proper fuel, changing from a too lean-mixture to a over-rich and back and forth. As soon as I get down to a rich mixture, it'll stop foaming, but I'll get 4-stroking and a lot of spitting out of the exhaust.
On the first tank, I had that much vibrations that *all* the fuel turned into foam, making me think of an empty tank - which refilled itself when engine being slowed down to idle... :) That's gotten much better withing the first two tanks.
I did have the needles set as per instructions, though in the beginning I had to open the low/medium needle one additional turn to 4,5 turns to get the engine running, high needle is as per instructions on 2,5 turns open. I am now just a tad over the recommended 3,5 turns and still have fourstroking.
I also noticed that the engine has some aggressive sound to it, like a high-speed-saw or something. Sounds like a way too loose gear mesh on a high-speed gear...
I changed almost everything on the heli (especially the tail, was my first guess, all new there now...), also checked the runout on the fan (before 0,016mm, now 0,004mm, though hard to measure on that rough and uneven surface...), all is fine and its flying *smooth*, perfect for precision-hovering... :)
But with the current rate of fuel-consumption, I'd rather pour the fuel directly out on the lawn instead of running it through such a noisy machine... ;)
I did check the piston is installed in the correct orientation, the engine is featuring an ABN-garniture. Total fuel through the engine is now at around six litres, fuel used being 11% Nitro 13% oil. Since Webra is known for using low/non-nitro fuel, I also checked two tanks with 0%-fuel and readjusted mixture, no help... Temperature was always betweeen 90 and 100°C or lower in the beginning.
From the looks of the internal, the piston and cylinder almost look like new, only on the upper part, the cylinder's colouring changed from its original goldish colour to a somewhat more silverish, though nothing spectacular. No scraping, no chafing, no nothing...
Could it be, that after all that runtime, the engine is still not being broken in - maybe due to too well lubrication?
Or is it simply a manufacturing fault, like a non-balanced assembly or similar?
Any other guesses?
I'm all ears to your suggestions and comments!
Cheers,
Daniel