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05-30-2012 05:37 PM  6 years agoPost 1
Kos

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Athens, Greece

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I recently built a new Trex 700 Nitro Pro kit which was immediately converted to helibug gasser , using a TRM 270TT engine….everything went fine with the breaking-in of the engine, according to the manual…after the first gallon (breaking-in), I attempted to raise head speed above 1200-1300rpm, which I used during breakin-in….to my surprise, above 1350rpms, the heli develops extensive fuel foaming and kind-of rotary-like vibrations, the short of one gets when the clutch is misaligned, ie in the main body of the heli…i tried to raise the rpm more, hoping that I may overcome it, but its getting worse as the rpms are increasing, seems like the heli ll explode above 1500-1600….
It cant be:
- Main shaft (new)
- Blades (balanced)
- Grip tightening (ckecked)
- Paddles (checked)
- Trackibg (checked)
- Clutch and bell positions are fixed (not slotted, so I cant experiment on that)
Has anyone experienced something similar??? Any suggestions?? I am running out of ideas… Thanx in advance…

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05-30-2012 06:08 PM  6 years agoPost 2
Rototerrier

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Fayetteville, GA - USA

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The sloshing in the tank is, unfortunately, normal for this conversion.

It doesn't matter much what engine you use, the fuel in the tank is going to slosh around. What you will usually encounter is sloshing and foaming at only certain fuel levels. I actually find that my fuel usually levels out after I burn a half tank. Above a half tank and it's swirling and foaming pretty badly.

I have also discovered that as the performance/power of the engine increases...so do the vibrations.

I had a stock G270 that would be perfectly smooth throughout the entire tank.

Running the Toxic 270TT and even the Hanson 29 Max, both churn the fuel.

For me, the important indicator is the tail fin and skids. When my skids aren't shaking and my tail fin is stationary, I am happy.

Despite what anyone tries to say, there is no 100% vibration free gasser. This particular model gets a lot of attention in this area because of the position and visibility of the fuel tank. By moving the fuel tank up under the nose and far away from the engine, you eliminate the swirling and therefor models in those configurations are typically deemed to be "smoother" or "Vibration Free".

I have also found that these modified engines have a sweet spot. They must be tuned almost perfectly and run at whatever RPM makes them perfectly happy. Anything outside of that is going to be rougher.

I have spent a lot of time, money, and patience trying to get the smoothest heli possible and these are my findings.

In regards to the engine, what does your plug look like? From your description, I almost suspect you are still running rich. But, don't go leaning out the needles before reading the plug. Is it wet, brown gummy, milk chocolate looking? Or is it light gray and whitish? Light gray with very little brown color is going to indicate it's lean. If its totally gummed up and dark brown, then it's too rich.

Check out this link to a plug chart for a rough idea of what you are looking for. http://www.4secondsflat.com/plug_chart.html

A couple things you can try with the Kit:

1) Runout on the clutch hub. You are correct that it isn't "adjustable" but it can be slightly off from one fitting to another. You can dial indicate the hub and keep installing/uninstalling it until it fits perfectly.

2) Not all clutches are created equal...or balanced. You can try a different clutch. Give the lynx gasser clutch a shot if you haven't already. You can also go with a QuickUK.

3) You can try opening up the frames around the fuel tank. I found that the looser the tank fits into the frames, the less sloshing and foaming it will have. Just be extremely careful to not over do it or your tank won't fit tight enough and you will have to add wedges or shims...which isn't necessarily a bad thing. I wouldn't put this modification at the top of the list because of the danger of overdoing it. But..if you can loosen the tank up a bit in the frames you can almost completely eliminate the sloshing and foaming.

4) Make sure the blades are perfectly tracked.

5) Make sure the clutch stack bearings aren't worn or notchy.

The truth of the matter is that you will probably never get all that sloshing out. Because of the position of the tank right on top of the engine and how tight it is in the frame, its going to transfer vibrations into it. Sometimes they are at different frequencies and the sloshing will stop or be worse depending on fuel level.

Engines vibrate and the tank is in the pefect position to show it.

Gassers Rule, Nitros Drool, Electrics...uhhh...Joule?

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05-30-2012 06:34 PM  6 years agoPost 3
fastflyer20

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N. Tonawanda, NY

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Well written Rototerrier.

The Lynx clutch gasser version is the best clutch available. Runout of the clutch/pinion is an issue with both Helibugs I built. Loosen the bearing stack nut and try, try again, not the best fit of the pinion to the bearings. Reline your clutch down to .020-024" clearance or it will slip. Use paper behind the liner if necessary. This is just good building techniques I have found to get the clutch to hold up and minimize vibration. I tried a new stock Align clutch bell and it lasted exactly 8 flights before major slipping. Slight slipping is very hard to detect.

I am betting that you are too rich, can you take a picture of the plug? Gas tuning is much different than nitro, 1/8 of a turn is a lot, so adjustments are made in small increments.

The gas engines also do get smoother as they break in, the carbs need to be adjusted accordingly, richer when breaking in. From my experience, gallon one is the tough one, gallon 2 they settle down nice, and by the end of gallon 2, you can ring it out as hard as you like.

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05-30-2012 06:44 PM  6 years agoPost 4
Kos

rrApprentice

Athens, Greece

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Rototerrier and Fastflyer20

Your input is...invaluable at least, and thank you for that again...concerning the points you raised:

1) clutch is LYNX, Gas, heavy duty
2) plug is BLACK, piston too, engine must be too rich (but according to TRM manual) and must have more oil than it needs...oil bottle said 1:50, i used 1:40, out of anxiety mainly...

I ll definitely implement all your advices, thanx again...

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05-30-2012 06:53 PM  6 years agoPost 5
Rototerrier

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Fayetteville, GA - USA

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I assume you are also running the 990 carb? What are your current needle settings?

Gassers Rule, Nitros Drool, Electrics...uhhh...Joule?

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05-30-2012 07:00 PM  6 years agoPost 6
Kos

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Athens, Greece

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yes, on the carb it says "WT 126 990", and the needles are 1 1/2 high and 1 3/8 low, the recommended for breaking-in by the manual, and by the way, i am in my 2nd gallon

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05-30-2012 07:04 PM  6 years agoPost 7
fastflyer20

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N. Tonawanda, NY

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What is the temperature?

40:1 is not too much oil, I run mine at 32:1

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05-30-2012 07:10 PM  6 years agoPost 8
Kos

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Athens, Greece

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Ve never read more than 75-80C, it is quite low, isnt it??

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05-30-2012 07:12 PM  6 years agoPost 9
Kos

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Athens, Greece

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Ve also used 32:1 on the very first tank, the plug was destroyed after ten minutes!!! i had to change it in order to manage to run the engine again!!!

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05-30-2012 07:18 PM  6 years agoPost 10
shawmcky

rrElite Veteran

Isle of Wight,United Kingdom

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I found getting the throttle and pitch curves just so helps a lot,my 700 was a vibrating mess until i got the headspeed sweetspot and throttle curves synchronised.I am running a 5.75.1 ratio with a tuned 270 motor,my 990 needles are at L/1 turn H/1 1/4 anything more and it does not like it at all.Plug is still dark at this and i am using 50-1 mix on mineral oil.

Team- unbiased opinion.K.I.S.S principle upheld here

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05-30-2012 07:21 PM  6 years agoPost 11
fastflyer20

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N. Tonawanda, NY

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What is the temperature outside?

75c engine temp is too cold, you are too rich, an G270RC depending on outdoor temp will run between 82-95 degrees c.
It should run all day at 32:1

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05-30-2012 07:33 PM  6 years agoPost 12
JKos

rrProfessor

Redondo Beach, CA

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> 40:1 is not too much oil, I run mine at 32:1

Depends on the oil...

- John

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05-30-2012 07:40 PM  6 years agoPost 13
Kos

rrApprentice

Athens, Greece

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air temp 21-25C...weather is one of the few good things we got left here, hehehe...

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05-30-2012 08:20 PM  6 years agoPost 14
fastflyer20

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N. Tonawanda, NY

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You can adjust your low speed screw (one closest to engine) to 1 1/8 turns, this should be close to your final setting +/- 1/16 of a turn. This has a major impact on the high speed setting, for now set it to 1 1/8 to get this thing sorted out, You can fine tune later.

High speed screws take a little more work. Everyone has a slightly different way of finding the sweet spot. Turn in 1/16 at a time, do not fly long at these settings, only for test in case it is too lean. Take off and do two extended climb outs then land. If you have a GV1, clear the memory each time and read the max rpms. If not, use a tach. You will be able the hear a major change in RPM, but slight changes of 20 rpms will only be able to be measured by some type of tachometer. Once you find the max rpm, I usually turn it 1/16 richer for best protection of the engine. Since you can, also measure engine temp immediately after landing and getting the blades stopped as quickly (and safely) as possible. If you are at 95c or under, it is not too hot.

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05-30-2012 08:24 PM  6 years agoPost 15
Rototerrier

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Fayetteville, GA - USA

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Agreed...that low needle is too rich. Lean it a bit. I am at 1 also on the low and 1 1/4 on the high.

Gassers Rule, Nitros Drool, Electrics...uhhh...Joule?

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05-30-2012 08:25 PM  6 years agoPost 16
DEDO

rrApprentice

FREDERICA, DE.

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Did you buy your Helibug conversion direct from Helibug are a seller in Europe?
On the Helibug web site there is a caution that some sellors in Europe are selling CHEAP knock off conversions as Helibug...

Peace Out BOBBY D.
"GOBLIN PRo GASSER"
ZeN G290,HC3SX,MKS,
Maidened 8/24/12 FL

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05-30-2012 08:33 PM  6 years agoPost 17
Kos

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Athens, Greece

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i bought it from Rick~K...he had gotten all the stuff, but never put it together...

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05-30-2012 09:38 PM  6 years agoPost 18
AtTheCross

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Southern CA

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ok 95c for indirect reading, i've been told that i could be 150c for direct reading can you confirm deny this? i have the spektrum telemetry temp wire wrapped around the forth cooling fin of the head

ASI Green Mongoose CY29RC - 67 flights

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05-30-2012 09:55 PM  6 years agoPost 19
fastflyer20

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N. Tonawanda, NY

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I only have experience with indirect temps and RC, I am told PUH will run a bit hotter. The climb out method and reading the plugs is all I use now.

Do you have access to a temp gun and gather your own data?

IMHO temp should only be used as a rough reference when you are learning how to adjust the needles and not get into hot water.

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05-30-2012 10:03 PM  6 years agoPost 20
AtTheCross

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Southern CA

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yeah, i read the plug. i'm breaking in a cy29rc and right now i'm on the lower good side #12 is closest to what i have but my plug looks better, i only have black on the arm no where else

i'm running about 107c direct temp in 29c-35c outside temp

ASI Green Mongoose CY29RC - 67 flights

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