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HelicopterHIROBOOther › about ready to toss my evo 90!!(vibration is back)
07-10-2008 01:29 AM  9 years agoPost 1
RICH.L

rrKey Veteran

east springfield p.a.

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Let's just say I will NEVER EVER buy a used heli again,I have been fighting this evo 90 for almost two years now!!

What I thought was going to be a used evo 90 turned out to be an evo 90 with an x-spec head on it.(my fault as the guy told me it had a full metal x-spec head,but being new to hirobo I didn't know the difference)!!

The only way to keep my blades from going into a thunderous flutter was to do the blade grip flip,If I try it the right way it sounds like coal being dumped into a hopper!(and even now on certain hard manuevers it still sounds like once In a while it flutters,but could also be the v-blades)

I just replaced the tail hub,tailblades,tailblade grips and installed the new 91 tooth main gear and the 11 tooth clutch bell,dial indicated the fan hub and start shaft to under .003" and took out the extra shims in the head,back to the original .008" shim.

I went to try it out today and it still shakes the whole damn heli all over the place,I can see the header tank moving,the canopy,the tail,and the tailboom,it acts like the main shaft or the center hub is severely bent!!

today I dial indicated the mainshaft,less than .001" runout as well as the tailshaft .001" runout,and the center hub had less than .001" runout.

The only conclusion I can come by is there must be something wrong with the metal head,either the yoke or grips?

With every part costing a ton of money on the metal x-spec head I really can't afford to keep tossing money at it,If it wasn't for the 12 gallons of 30% magnum fuel that I just bought I would just part it out and buy another electric heli to go along with my mini titan.

I tried to save a few bucks two years ago and it bit me in the a$$!!
I barely get to fly that much anyway but summer is half over and I have one tank run through this thing this summer and still am no closer to flying it.

I know that it's hard to help without actaully seeing what it's doing,I am just venting as I spent all afternoon on my day off trying to figure out what the heck could be wrong.
rich

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07-10-2008 02:38 AM  9 years agoPost 2
nighttrain

rrApprentice

Louisville KY

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Rich,
Hang in there. EVO / X Specs are wonderful helicopters. Theres probably something wrong in your head. Look there first. Try to find a local to help you, sometimes a second set of eyes really helps.

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07-10-2008 04:04 AM  9 years agoPost 3
Skidsup

rrNovice

PA

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Evo 90

Rich,

Just sent you a PM

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07-10-2008 04:30 AM  9 years agoPost 4
TMoore

rrMaster

Cookeville, TN

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You want me to fix it for you?

Delayed Response Operator Not Engaged

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07-10-2008 04:53 AM  9 years agoPost 5
Ivan

rrVeteran

Hutchinson Kansas

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The center hub bends fairly easily. I fought a vibration problem until I found this out.

FWIW, the Xspec and/or pre evo head is still a pretty good head. I enjoy mine immensely.

I would guess with the flutter and wobble you should check the center hub. Just replace it. Many times when the center hub on any heli gets bent and moves around in flight, it will cause tracking and flutter problems. On the Raptor V1s they called it Woof and Poof. It boiled down to being a loose head block. Mine never had the problem, but I had to use a hammer to get it on the main shaft.

Something to think about.

I came, I saw, I hovered

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07-10-2008 12:14 PM  9 years agoPost 6
RICH.L

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east springfield p.a.

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I am not giving up,I just have to see what this thing flies like with the new 8.27 gear ratio!!

Last year I gave up on my evo 50 and after I sold it found out that some dumb person/builder forgot to tighten up the servo tray screws!!

I put a new center hub on last fall and have not had any crashes since then,and even that was just a hard landing auto when the engine flamed out on me back in september.

What I can't understand is why did I have to do the blade grip flip to get the severe blade flutter to go away?

It's like the head geometry is off but I can't figure out where or why.

rich

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07-10-2008 12:39 PM  9 years agoPost 7
Jayray123

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Erie, Pa

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Hey Rich,

You have me intrigued on this, maybe we can meet up this weekend and compare notes at the field. We could swap out the X-Spec head on yours with the evo head on mine right there and try it to see if anything changes. Also try your head on my shaft. I'll be available anytime starting friday morning if you want to give it a try.

Jay

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07-11-2008 04:39 AM  9 years agoPost 8
tadawson

rrElite Veteran

Lewisville, TX

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What I thought was going to be a used evo 90 turned out to be an evo 90 with an x-spec head on it.(my fault as the guy told me it had a full metal x-spec head,but being new to hirobo I didn't know the difference)!!

The only way to keep my blades from going into a thunderous flutter was to do the blade grip flip,If I try it the right way it sounds like coal being dumped into a hopper!(and even now on certain hard manuevers it still sounds like once In a while it flutters,but could also be the v-blades)
I have both a stock Freya and and X-Spec, and have not had to do anything unnatural to either head to get it stable - they perform fine, with no flutter straight box stock. The biggest issue for flutter is slop in the linkages to the head. Tighten that up, and no problems (same with the Sceadu, btw . . . been flying a non-Evo Sceadu for 5 years or so, and same story . . . ). What Jeff Green at MRC told me, which helped immensely, is to check the mixer and washout arms for slop in the bearings (can you rock them back and forth?) If so, take them off, and take a fine file, and shorten the part that looks like a top hat that the arm rides on until they are slop free. Reassemble, and you should be good as gold.

Oh, and the center hub is the same on the X-Spec and stock Freya, so if that *is* a problem, being an X-Spec won't cost you any more than any other Freya or Evo to replace . . .

You might also try different blades, since these seem to be a common factor in your problem as well . . .

- Tim

Friends don't let friends become electrotarded . . . .

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07-11-2008 04:53 PM  9 years agoPost 9
spy29

rrApprentice

USA

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check the clutch... when my limer was going bad..it had vibrations i could not detect.. until it slipped big time.. after i replaced..no vibrations!...also a our engine and muffler..are they tuned well.. i remember..a while back i had a bad motor mufffler combo... NOTHING BUT VIBRATIONS....

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07-11-2008 10:01 PM  9 years agoPost 10
RICH.L

rrKey Veteran

east springfield p.a.

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well I found the vibration problem.

The yoke was wobbling when you spun the head assembly with the main blades off,you could see it plain as day!!

I pulled the head stopper off the top of the head and I could see where the feather shaft goes through the center hub on one side it was just about touching the center hub and on the other side the distance was equal.

I checked the screws that hold the yoke to the center hub and one of the upper ones was about 1 and 1/2 to 2 turns out,tightened it up and spun the head and guess what(yes the wobble is gone)!!

I will pull those screws back out add more loctite!!

And as for the blade flutter I think that tadawson hit it right on,I do have some slop in the washout arms and mixer arms.
gotta see if I can get the slop out and hopefully I will have a new machine!

I have been a mechanic for over 25 years and I like to diagnose a car not just slap parts on it,and the same goes for my heli's!!
Sure if I put a whole new head on it everything would be great but I would never learn anything that way!!
rich

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07-11-2008 10:32 PM  9 years agoPost 11
helicopterMark

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Rumson, NJ

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Glad to hear you were able to figure it out Rich. vibrations can be one of the most annoying things to track down sometimes. let us know how she flies when you take her out!

M3

Mark Schneider
Team Heli Wholesaler; Rotor Rage; YS; Perfect Regulators
www.helimark.com

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07-12-2008 12:08 AM  9 years agoPost 12
tadawson

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Lewisville, TX

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Glad to be of help!

- Tim

Friends don't let friends become electrotarded . . . .

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07-14-2008 02:13 AM  9 years agoPost 13
RICH.L

rrKey Veteran

east springfield p.a.

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I found 2 bad ball link ends off the main blade grips,they both had a lot of slop and I thought it was in the arms.(amazing what reading glasses will do!!)

The vibration is gone,had to adjust the tracking just a turn on one blade grip and after that it was smooth.

Now for the bad news,ran just like crap again,even after the gearing change,new glow plug,new fuel.

My mini titan has more pull than this evo 90 right now!!

I don't get it,I tried every possible tuning possibilty and still no luck.

On the 4th tank the muffler came loose probably from being too lean and I was forced to do a tail in auto.
1)maybe I took too many shims out of the head?(I was running .020" now down to .008"
2)rear bearing in engine going bad?(it does have 10 gallons on it and you know how OS engines love rear bearings)

This thing should be a freaking rocket,os91 szh non-pumped,curtis mp5,30% magnum fuel,v-blades,v-paddles,running 11 degrees pitch and 6 degrees cyclic.

I guess the bright side is I will not have to worry about fuel for next year!!
rich

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07-14-2008 03:27 AM  9 years agoPost 14
hornet dave

rrKey Veteran

Cedar Rapids, IA USA

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I run all three head shims in my 91 sz on magnum 30, I found it went from rich to hot with .016 of shims. Switching to a uniflow setup in the main tank keeps the motor from running lean during the last 1/3 of the tank. The 'sweet spot' on the main needle is only about 3-4 clicks, so don't overadjust. But really, I don't think you will have any chance of getting it to run well on magnum 30% with only .008 of head shims. The new magnum value blend pseudo 30 will probably run great on .008, but 30% of real nitro fuel needs more head shim.

I got a fever! The only prescription is MORE 6HV

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07-14-2008 12:08 PM  9 years agoPost 15
RICH.L

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east springfield p.a.

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Thank's hornetdave,
I will toss the shims back in it again and try readjusting the carb,at this point it's free and I have nothing to lose!!

I did look at the rear bearing when I had the engine out and it looked a little tarnished but felt smooth and I didn't have any noises coming from the engine!!

rich

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07-15-2008 01:44 AM  9 years agoPost 16
RICH.L

rrKey Veteran

east springfield p.a.

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I put the shims back in tonight and reinstalled the muffler,hopefully I can get it out on wednesday and try it out again.

I am keeping my fingers crossed that it's going to run great!!

rich

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07-15-2008 09:08 AM  9 years agoPost 17
Brendan78

rrVeteran

NSW Australia

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Good luck Rich, hope it goes well for you, was just out flying mine, love the Freya Evo. I'm actually looking forward to trying a set of Vblade TST extremes on mine when they are available

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07-17-2008 01:54 AM  9 years agoPost 18
RICH.L

rrKey Veteran

east springfield p.a.

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Two more flights today and still runs bad,except this time I do have a new twist.

On the second tank I noticed I had air bubbles in the header tank and the fuel in the header tank was also about 1/4 inch low!(normally it stays right at the top and no air bubbles)

I just replaced the fuel line in the tank maybe a month ago after it fell off due to the major vibration,it was in need of replacement anyway.

Looks like I will have to pull the tank back out and check all my lines again.

After that I have no clue,might be time to take it up to the flying field and get a second and third opinion from some of the other guys.

rich

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07-17-2008 09:23 AM  9 years agoPost 19
Brendan78

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NSW Australia

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that's no good Rich. None of the fuel lines are kinked are they? it always helps have another set of eyes on it

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07-18-2008 01:47 AM  9 years agoPost 20
RICH.L

rrKey Veteran

east springfield p.a.

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Tonight I pulled out the tank again and used my hand held vacuum pump and tested all the hoses and the tank and the header tank,absolutely no leaks anywhere.(everything held 20" of vacuum the 2 minutes I tested them for)

here are my carb settings
(Idle mixture screw)just off center to the right to lean it out to idle

(Mid needle valve) about 3/4 turn out

(High speed needle)about 1 and 3/4 out

tonight I decided to replace every fuel line on the heli again and I also did the uniflow setup to see if that works at all.(I already had all the stuff to set it up laying around)

Just a thought and maybe get some input on this but on my mini titan e325 just by changing to lighter paddles my headspeed increased and the heli has a ton of guts now and flips and rolls like you would not believe.

Is there any chance that between the 690 v-blades and the 95 mm v-paddles that I could be losing power?(these are the only two original items that have been on it since I got it)And no I really don't have the cash to go and buy another $120.00 set of blades!!

I watched a buddy of mine named Brian Reed fly the crap out of his freya x-spec 90 for years on and old beat up ys motor and the thing had tons of guts and that is one of the reasons I bought the evo 90

rich

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HelicopterHIROBOOther › about ready to toss my evo 90!!(vibration is back)
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