Idle is low I hope?

[Buckaroo]

I took the wife up today and had a perfect flight except upon landing and exiting the runway the engine stopped. I immediately restarted it and taxied in. I notice my alternator will glow on idle and I always have to add a few rpm's to get into the bottom of the green. 

Many good news appreciated!

[Anticept]

Don't rest your hand on the throttle.

It's a design flaw in flight design airplanes, they are supposed to have an adjustable stop in the cockpit per rotax's recommendations, due to the fact the carbs don't have very sturdy (read: pitiful) stops. Resting your hand on it can stretch the stops and cause the idle to drop too low.

I see it happen a lot.

I try to sync the carbs so that the throttle stops right near the edge of the of the recess that it sits in, but it can be a pain to do.

[Tom Baker]

I like to see an idle speed of 1750-1800. you can set it lower if you want, but that has always worked well for me. 

Corey,  I was taught to use the slot as the stop instead of the idle stops on the carbs either during my initial Rotax training or my Flight Design factory training. After you get the balance and idle set that way then run the idle screw in until you can't slide a business card between  the idle screw and stop. That will leave a very small gap between the screw and stop, and it serves as a secondary stop at a slightly lower RPM if something changes.

[Buckaroo]

I normally land and on the landing roll I up the rpm to the bottom of the green. This time I landed long and immediately exited the runway not having time to adjust the throttle up to green. I think I was at pure idle and it quit. 

So resting the hand or pulling throttle back harder can actually reduce the rpm more because of the added rearward pressure correct??

 Thanks 

Dave

 

[Buckaroo]

34 minutes ago, Tom Baker said:

I like to see an idle speed of 1750-1800. you can set it lower if you want, but that has always worked well for me. 

Corey,  I was taught to use the slot as the stop instead of the idle stops on the carbs either during my initial Rotax training or my Flight Design factory training. After you get the balance and idle set that way then run the idle screw in until you can't slide a business card between  the idle screw and stop. That will leave a very small gap between the screw and stop, and it serves as a secondary stop at a slightly lower RPM if something changes.

Tom is adjusting idle and simple process without un-syncing the carbs?

[Tom Baker]

I always put the gauges on when I am adjusting idle to keep them balanced.

[Buckaroo]

Gotcha! My friend who was a OV-10 pilot in Nam who lives in a hanger home at the airport will be back next week for the summer. He ran a Rans sales and build operation for years and always used Rotax in his builds. Hopefully he can help me with my annual and 5 year rubber job. 

Id really like my CTSW experience with Rotax if I had local support but we'll get through this!

[Roger Lee]

Hi Buckaroo,

 

With all the things going on with you and your new plane and trying to learn it you absolutely need to align yourself with a TRAINED CT CFI and a TRAINED CT / Rotax mechanic. Too many things have happened. 

First the  proper way to balance a carb is that it should hit its stop at the same time the throttle in the CT hits its back stop. If there is extra space for the throttle to go back then the carbs are not properly set up. Leaving it this way will only end up bending the idle stop plate on the carb.

You should not have the idle on the ULS set below 1650 because you may do this very thing and lose the engine.  Idle should never be set so low as to lose an engine. That said if you do set it down that low for SHUT DOWN purposes that's okay just don't idle that low. Keep it above 1800 and 2000 would be better while sitting and taxi. The reason for this is the compression is 10.8:1 and it will hammer on the gearbox letting it idle at low rpms and especially when cold at warm up.

If the throttle in the cockpit doesn't hit the stop at the same time the carb does then adjust the cable length and do a mechanical sync before the pneumatic sync. If anyone is having problems with this you should call me.

Anytime carbs are adjusted they need to be on gauges. Not even the idle can be set without them.

 

 

I don't set idle rpm's artificially low because it can get people in a bind and there's no real good reason to do so.

[Buckaroo]

I'm glad someone removed the smart ass reply to my post from assctls! Good job!!?

[Buckaroo]

7 hours ago, Roger Lee said:

Hi Buckaroo,

 

With all the things going on with you and your new plane and trying to learn it you absolutely need to align yourself with a TRAINED CT CFI and a TRAINED CT / Rotax mechanic. Too many things have happened. 

First the  proper way to balance a carb is that it should hit its stop at the same time the throttle in the CT hits its back stop. If there is extra space for the throttle to go back then the carbs are not properly set up. Leaving it this way will only end up bending the idle stop plate on the carb.

You should not have the idle on the ULS set below 1650 because you may do this very thing and lose the engine.  Idle should never be set so low as to lose an engine. That said if you do set it down that low for SHUT DOWN purposes that's okay just don't idle that low. Keep it above 1800 and 2000 would be better while sitting and taxi. The reason for this is the compression is 10.8:1 and it will hammer on the gearbox letting it idle at low rpms and especially when cold at warm up.

If the throttle in the cockpit doesn't hit the stop at the same time the carb does then adjust the cable length and do a mechanical sync before the pneumatic sync. If anyone is having problems with this you should call me.

Anytime carbs are adjusted they need to be on gauges. Not even the idle can be set without them.

 

 

I don't set idle rpm's artificially low because it can get people in a bind and there's no real good reason to do so.

I agree 100% with you but ain't gonna happen! No one within 800 miles of here. 

Roger fly up here and do my rubber service and I'll top the bill with $1000 tip!?

[Buckaroo]

I understand about the idle situation with the Rotax. The low idle shut down caught me off guard as I was busy exiting the runway and didn't have time to set it to low green. The wife gave me a ? look! 

My experience with this plane would be really nice with a Rotax expert down the road!

[Roger Lee]

Hi David,

 

Look here for maint.:

http://www.rainbowaviation.com/repairman.htm

and here under "find a technician":

http://www.rainbowaviation.com/repairman.htm

 

95% of my clients don't come from Tucson and come from all over.Look for another CT pilot in a neighboring state and see if you guys can link up for a weekend. It would be time well spent.

 

[Buckaroo]

9 minutes ago, Roger Lee said:

Hi David,

 

Look here for maint.:

http://www.rainbowaviation.com/repairman.htm

and here under "find a technician":

http://www.rainbowaviation.com/repairman.htm

 

95% of my clients don't come from Tucson and come from all over.Look for another CT pilot in a neighboring state and see if you guys can link up for a weekend. It would be time well spent.

 

Yes I've called many of the local folks listed and get an impression after testing them with questions about certain service issues wonder if I really need a qualified service center. 

If anyone can recommend a great Rotax repairman in the Montana please advise!

[FlyingMonkey]

If you carefully adjust the idle screws the same amount on both sides, you should not affect the sync.  I have done this a few times.  It takes *very* little to change the idle, I usually start with 1/8 turn per screw and see how that affects things.  It has been a while, but I think 1/8 turn gives about 50rpm.  

But if the engine seems at all rough afterwards, you'd need to do a sync, and if you don't have experience doing that you are back into needing a mechanic anyway.  I'm not suggesting you make your own idle adjustments, I'm just telling you it can be done.  It comes down to how serious a problem it is.  Did you say what your idle RPM is when warmed up?  If so I didn't see it.

[Tom Baker]

6 minutes ago, FlyingMonkey said:

If you carefully adjust the idle screws the same amount on both sides, you should not affect the sync.  I have done this a few times.  It takes *very* little to change the idle, I usually start with 1/8 turn per screw and see how that affects things.  It has been a while, but I think 1/8 turn gives about 50rpm.  

But if the engine seems at all rough afterwards, you'd need to do a sync, and if you don't have experience doing that you are back into needing a mechanic anyway.  I'm not suggesting you make your own idle adjustments, I'm just telling you it can be done.  It comes down to how serious a problem it is.  Did you say what your idle RPM is when warmed up?  If so I didn't see it.

One good tug on the throttle lever and you are right back where you started, with bent idle stops to boot.

[Roger Lee]

"If you carefully adjust the idle screws the same amount on both sides, you should not affect the sync."

 

Sorry Andy this is wrong thinking. One carb will ALWAYS be more in control than the other depending on which way you want the rpm to go. You MUST put a set of gauges on them to keep them equal.

Put a set of gauges on and watch if you you try to do both equal turns. The human ear can not pick up the difference.

[FlyingMonkey]

Sorry if I gave wrong information, I read that info on this forum, but I dont recall who said it.

[Buckaroo]

21 minutes ago, FlyingMonkey said:

Sorry if I gave wrong information, I read that info on this forum, but I dont recall who said it.

Hey Andy your cool and very helpful all the time for me! This forum is very helpful and I love it but I'm trying not to feel like a stupid chump! 

I say what's on my mind and what my limited experience is telling me to ask for help or advise. I'm not trying to be the big brain here or a fool I'm just trying to understand my new airplane mostly for safety and treating her properly! 

Everyone has been the best to me and I greatly appreciate all your help! 

I have learned so much through this forum it's amazing!??

[FlyingMonkey]

Okay, this bothered me.  I was SURE that I had heard to use the idle screws for idle adjustments from Roger.  I went back and found the following posts:

http://ctflier.com/index.php?/topic/784-carb-sync-tool-on-steroids/&do=findComment&comment=13213

http://ctflier.com/index.php?/topic/62-carb-balance/

In these two posts, it seems clear to me that Roger is suggesting using the idle stop screws to adjust idle speed.  The point here is not to "call out" Roger, but just to find out how I'm misreading the posts, or if Roger has changed his guidance, or what else is going on.

I don't like doing things wrong, and HATE giving incorrect advice.  I need to know how I got the impression doing it the way I have mentioned is okay if it's not.

[Roger Lee]

Nobodies a chump, ever. It is just tossing info and ideas back and forth and there is never a dump question. There should never ever be any malice involved.

So back to the problem.

You do use the idle screws for idle adjustments, but not without a sync tool on them. You can't just turn both idle stop screws equally and have the idle vacuum stay equal. If that were the case once you set a mechanical sync then you wouldn't need the gauges to set the idle sync. One carb will always affect the system more or less than the other even when the screws are turned equally.

 

Andy,

 I looked at those two post. Where did you see to turn the idle stop screws equally and it won't change the idle sync?

 

I think we a crossing two different ideas.

[FlyingMonkey]

Roger, I suspect there is just a misunderstanding.  I thought you were saying you don't use the idle screws at all to adjust idle, instead only using the cable.  Those posts would contradict that.  But it seems you are just saying you use the idle screws, but only with a sync tool.  That makes sense.

I have not adjusted my idle in quite some time, and my carbs stay pretty close to synced.  I just re-synced them after doing my annual and hose change, and it took very little to bring them back into a very good sync and smooth idle at 1800rpm.

[Buckaroo]

Well it looks like I'll need to learn a carb balance quick. I have a twin max and a TV set. Watch out YouTube!???

My idle is 1450.?

[Roger Lee]

1450 idle is absolutely too low and it could mean a loss of engine at the wrong time and a beat up gearbox. So long as you keep that idle with the throttle up then no problem.

 

Bowden cable adjusters for the higher rpm sync and idle stop screws for idle. Do not do a sync like Lockwood and back out the idle stop screws all together and then try only setting the carb sync at 2500 rpm with just the cables. It's wrong and not written or taught any any appropriate Rotax class.

There are correct videos on the Rotax forum, Youtube and written in the manual. It's just too easy to do things the right way vs the wrong way.

[FlyingMonkey]

Buckaroo, if you are not a member, joining rotax-owner.com is worth it.  It costs $35 a year, but you get access to some full length, very detailed videos on subjects such as carb syncing that you can't get elsewhere.  Plus the forums there have a lot of great information.  I just used one of their videos to do the oil system purge after finishing my hose change, and it was step-by-step and went wonderfully.

 

And like Roger said, a 1450rpm idle is very low.  Shoot for 1700-1800, that seems to work for most members here.  You should not taxi at idle at 1450, give it a little juice and get it up over 1600rpm.  Does your Dynon have the low rpm yellow arc programmed in?  That is there because of the gearbox chatter issue Roger mentioned, and it's good to have a visual reminder to stay above that on the ground.

[Buckaroo]

2 hours ago, Roger Lee said:

1450 idle is absolutely too low and it could mean a loss of engine at the wrong time and a beat up gearbox. So long as you keep that idle with the throttle up then no problem.

 

Bowden cable adjusters for the higher rpm sync and idle stop screws for idle. Do not do a sync like Lockwood and back out the idle stop screws all together and then try only setting the carb sync at 2500 rpm with just the cables. It's wrong and not written or taught any any appropriate Rotax class.

There are correct videos on the Rotax forum, Youtube and written in the manual. It's just too easy to do things the right way vs the wrong way.

The prior owner made it pretty clear to always keep the rpm in the Rotax friendly 2200 range. We never tested low idle it was always shoot for 2200. 

Today when I flew her I added idle RPM management to my flight duties. It seems the flying wind forces keep her spinning well in flight but I can picture a Antelope runway go around just getting a cough and stopped prop!  I think their mechanic was slack in proper maintenance now that I'm learning what to look for. The engine has no fuel pump bottom overflow tube on the bottom, several of the carb cables were not shrink wrapped, the muffler was misaligned pressing against the oil filter, he used the Tempest oil filter, the 2015 and 2016 annual entries are carbon copies of each other indicating the exact compression readings, the annual 50 hours before I received the plane the RPM's are dangerously low, the heat wrap has shredded off where applied, the fuel tubes are dark etc. I'd really love a Roger or Tom full service as honestly I'm getting hesitant to fly her with my wife! By myself who cares!?

No names just hopefully constructive observations for safety!