Odd to Me 2-Stroke Running Characteristics

[allonsye 85]

I wasn't sure which forum thread to put this in but since it all seems engine related here it is.

So, what IS and what ISN'T normal vibration for a 582?

I'm getting vibs between 3200  -- 5200 rpm. 

At t/o power all is well and smooth -- engine runs right up to 6400 -- throttle her back to 5800 or 6 and climb out.  Rolling downwind pull her back to 5200 a disconcerting feel in my seat and sound "bump", nother second or 2 *bump*;  that I can feel and hear how I best can describe it.   Mixture? --  Lean or rich (because of improper fuel/oil ratio)?  I'm running the injector and Rotax Rick wants me to add an extra 3.2 ounces per 5 gals to ensure adequate main bearing lube as he puts it.

Pull back to around 4k and let the nose down to base leg; now I'm getting a tingling in the foot pedals.   Rolling on to base, 3500 rpm and my feet are tingling and the plane is vibrating.

Is this normal?

The other factor is the IVO prop.  I hear they can be rough.  I'm thinking I've got 2 distinct problems going on. One ea with the prop and the engine.

Today at warmup. I did take notice on the ground the vibration is definitely beginning at 3500.

All you folks running IVO IFA please chime in.

Thanks.

Edited 4 Nov 2015 by allonsye
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[Av8r3400 1179]

IVO props are normally very, very smooth because they are light and the pitch design is equalized between the blades.

How many hours on the gearbox?

[allonsye 85]

GB has 325TT

[Av8r3400 1179]

It may be in need of servicing.  The belview washers relax after a while and no longer hold the lash tight.  This will definitely cause vibration. 

Edited 4 Nov 2015 by Av8r3400

[Av8r_Sed 82]

Could be belleville washers on a B gearbox.  A C gearbox doesn't use them.

If you have any friction in the carb slides, it could do this if they don't drop smoothly together.  I had to replace my original throttle cables because I was unable to get smooth action even after lubing them generously.

[tx_swordguy 20]

is this a new engine to the plane/you? or is this a new occurance to an old engine combination? It sounds more GB related to me, but I have no experience with the c box.  If it was a b I would say first thing check the  gear lube level and add some lucas oil stabilizer. It seemed to really tame noise in the gb on my gyro . Unless the bump you feel in the seat is from an rpm change in the engine, I don't think you would feel or hear the carb slide hitting the stops. If it was a warp drive prop I would say check the prop balance but again I have no experience on your prop

[C5Engineer 1170]

My Ivo runs 10x smoother than my Warp ever did. I would rule that out of the equation unless you are missing a chunk of blade or something. Has it been retorqued ever? Very easy to change the Gearbox oil and check the magnetic drain plug for anything that would lead you to believe there is an internal issue. Please post what gearbox you have and what ratio.

The other thing that caught my eye was your mention of adding oil to your gas on top of the injector. I'm not sure why Rick has such a deal with running such a rich mixture. I did the math and if you are adding that amount of oil you are running close to a 32:1 mixture. Coming from a guy who ran 100:1 for 352 hrs and 5 years before an uneventful rebuild that makes me cringe. I don't think an overly rich engine would really describe what you are feeling though. I think it would manifest itself more as a miss. I've only ever heard of two gearbox issues before and both of them caused mysterious symptoms that drove their owners nuts before they figured it out.

Please keep this thread updated. This is one of those type of issues that we need to see some closure to. Good luck finding a fix!

[allonsye 85]

Hey Guys - all very good feedback, much obliged.

This is a fresh RR rebuild.  It's a '92 gray head w/"small" crank.  C-box 3 to 1 (I think - books are at the hanger to verify).   About 325 TT, 5 since the RR rebuild

Joey -  I hear 'ya about adding oil.  Seems crazy to me.  It's got to be getting tons of oil becuz I'm watching the reservoir deplete itself at a good rate -- doesn't take long for a mess on the belly and r/h gear leg either.  Actually, more oil will lean the fuel/air mixture; yes?  I need to do a plug read ASAP.  The thing to do is a measured qty of oil and fuel levels -- do some equations and figure out my actual ratio.  I'm inclined to stop adding oil to the gas, I think the injector is doing it's job famously.

One of the IVO blades has some minor tip damage that does concern me a bit.  Yes, I've verified the torques.  

Another thing Rick did having added a balancer to the end of the crank - it's documented in the Eng log.  Something about the old cranks needing it.  Again, got to look at the engine logbook to verify but I wonder if this is a suspect.

I'm left at a total loss but everytime I pull the throttle back I wonder if there's an imminent failure.

So, the read I'm getting from the 2-stroke collective is there shouldn't be any vibration at all felt.

[allonsye 85]

Ruling out carb slides.  Both work and sync smoothly.

[tx_swordguy 20]

"the read I'm getting from the 2-stroke collective is there shouldn't be any vibration at all felt." Not quite. At idle a two stroke (at least 503,582) will rattle and shake like a pissed off snake! my experience above about 3K it should smooth out and you should not really notice vibration (from the engine) between 3-6.5K rpm . When you cut the throttle back to 5200 does it drop from cruise all the way down to 5200 and then you feel the bumps? or is there a gradual decline in rpm and as you are trying to reach 5200 you feel a bump? I am thinking if you drop your rpms all the way down to 5200 and then you feel a bump it would be more gb (poss the unloading of the prop allowing some slack in the gb), if you are gradually dropping it to 5200 and you feel a bump on the way down to 5200 it would be more engine (poss carb) related. As for the added oil Rick is against the injection-period. My Rick 582 has about 30 hrs and is premix (he wanted me to run 40-1) I did that for the first 10+ and slowly started backing it off to 50-1. He is just overly concerned with getting lube throughout the engine. I have about 15 hrs now running 50-1 and have no issues (this is on a gyro). My suggestion would be to get some time on it and go back to injection only- as long as you feel it is oiling like it should.

 

Edited 4 Nov 2015 by tx_swordguy

[C5Engineer 1170]

Rick is only against injection because it can't do 40:1 like he wants. There are thousands of Rotaxs out there running 50:1 and thousands upon thousands more non flying machines running it. You are correct saying that there is a point where there is so much oil going thru the jets of the carb the mixture effectively becomes leaner. I am not familiar with the crank balancer. Rick is pretty receptive if you come at him with the right angle. Have you tried talking to him?

[tcj 150]

Here's the Mike Stratman article on aligning the marks on the oil pump arm and pump housing for proper oil injection ratio. http://www.cps-parts.com/cps/pdf/Part45.pdf 

A bump felt in the pedals every couple seconds sounds like the mid range is too rich.  To lean it raise the clips on the needles one notch.

It is recommended to run premix in the first tank of gas after an overhaul.  That gives any air in the injection time to work out and you also can check the oil ratio the injection pump is using.

For what its worth.  I pull the power all the way back to idle when abeam the numbers on down wind and leave it there for the rest of the landing approach.  Usually have to use a lot of forward slip on final if I want to touch down on the numbers.

[Dusty 126]

What are your egt's doing when you get the bump ,they are slow to react so you may have to loiter in the rough area .

does it feel like it is trying to 4 stroke?it would have to be way rich and show low egt

check that the screens are on the float chamber,bings don't like to run smooth without them.

as a sideline ,oil injection 

we set for an average of 70:1 I had a fiddle with he adjustment to be sure my 670 project would get enough oil,the standard setup will deliver up to40:1 average which I would estimate is around 30:1 at full throttle.

i don't think any more oil would be an advantage!

be wary of adding excess oil to premix,the fuel air ratio will change,also excess oil increases he risk of detonation by affectivly lowering the fuel octane

[allonsye 85]

Yes, have been in communication w/Rick. He's saying the prop.  I'm not so quick to think at all.  I think you guys are more on the mark.

Yes TC, I did verify the injector aligning marks.  I think the injector is working as it's supposed to. I'm w/you Joey on this one.  Think the 50:1 via the injector is the way to go and more than adequate. In Ricks quest for better oiling I think there's a sacrifice at the expense of the fuel air mixture.

I've not done any cruise yet.  So far, I've been staying in the pattern close to the mother-ship aerodrome until I'm confident flying this thing.  I should take it up more though to test more fully I agree.  That said, the "bump" is felt rolling off of a 500' climb at 6k rpm to 5200 -- right at 5200 I feel it.  I'd say the prop is still loaded at this point as I pull back gradually to 5200 .......*bump*.

I think first thing to do in the equation is rule out an excessive oil ratio -- get it closer to 50:1 as I dilute the remaining fuel with fresh unmixed 93 octane no lead and look for any changes. 

 

 

[allonsye 85]

What are your egt's doing when you get the bump ,they are slow to react so you may have to loiter in the rough area .

does it feel like it is trying to 4 stroke?it would have to be way rich and show low egt

check that the screens are on the float chamber,bings don't like to run smooth without them.

as a sideline ,oil injection 

we set for an average of 70:1 I had a fiddle with he adjustment to be sure my 670 project would get enough oil,the standard setup will deliver up to40:1 average which I would estimate is around 30:1 at full throttle.

i don't think any more oil would be an advantage!

be wary of adding excess oil to premix,the fuel air ratio will change,also excess oil increases he risk of detonation by affectivly lowering the fuel octane

Exactly what I'm thinking.  That bump could be detonation.  Octane lowering as well as lean fuel mixture.

I'm going to replace the fuel w/fresh unmixed and observe if I get some time late this afternoon.

Bing screens are installed.

Can't recall any 4stroking but I'll try to loiter within the problem rpm ranges and observe egts

 

[TJay 1041]

I would do a static run up with the cowl off and make sure your engine/ exhaust isn't laying up against a frame rail or firewall at certain rpms also check to make sure your starter isn't hitting the box that comes through the firewall.

[Bandit 286]

If my 503 is running rich it will make the rudder pedals thump when you pull the throttle back. I just lean the carbs out one turn.

[thebriman 69]

I see this too when im too rich

[allonsye 85]

I see this too when im too rich

Right you are Brian! I found the smoking gun today.  Rotax Rick called me yesterday to check on things and said DO dbl check that I had the slide needles in correctly he said it's sound too rich.  Sure enough, I had the clip on the outside (on the top of it) of the plastic what cha ma call it instead of seated down in it's little nest within the inside of the slide -- between that and the plastic wha cha ma call it,  *d'oh* .  The plugs were as black as coal. It's a wonder the needles didn't get hung up as high as they were riding.  I've not been able to take her out for a run yet to verify but think this was likely the problem and the "4-strok'in" it was doing.  "ya think?"

Stay tuned.

[Bandit 286]

Been there done that. My Artic Sparrow mixture control ended that problem.

Edited 8 Nov 2015 by Bandit

[allonsye 85]

Been there done that. My Artic Sparrow mixture control ended that problem.

I've been thinking about adding a mixture control.  I've only one worry, forgetting to enrichen after lean when going rich again is necessary could toast a 2-stroke in quick order I surmise.

[allonsye 85]

http://ultralightnews.com/enginetroublshooting/arcticsparrow.htm

This mod might actually be worthwhile as I give it some thought.  The ability to lean and improve fuel economy on xcntry trips is beckoning me, not to mention the infrequent high altitude flying.

Perhaps I should approach Artic Sparrow about a group buy.

Anyone else interested in the mod?

[Bandit 286]

I have been running my mixture control for years and have not had any problems with it. Mike Jacober from Alaska did the conversion for me. Unfortunatly Mike was killed in a trike.  Leni would know more about it than me, he is also using the mixture control  I think.

[allonsye 85]

Yeah.  I think since Mike died, it's no longer being marketed.  Looks like Greenskyadventures has one that's referred to as the HACman.  Don't know if it's the same design.  I'm going to look into it.  When you think about it, as you vary in altitude, it really is essential to have the ability to adjust mixture.

Edited 9 Nov 2015 by allonsye

[thebriman 69]

I just installed the Hacman last week.  I havent used it yet as its been raining for three weeks.  Joey installed it on his avid a few years back.  He would be the one to ask.