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wadeg
08-02-2008, 05:50 PM
Back to the throttle tugging question.
Been taxiing the fox. If I let go of the throttle, it lurches to about 3000 rpm. What are you all doing to fix it? What springs are ideal for a replacement? To avoid it from happening, I have to really tighten down my throttle lock. Seems hazardous to me.
Thanks!
Wade

84KF
08-02-2008, 06:47 PM
Wade,
I took mine off and now it stays where you leave it. Pull it back to 1500 and it stays there. Same withe 1800, 2000, 2200...etc.

If you have "cables" instead of "wires", give it a try. Just take them off. Cables arn't gonna break (and will be inspected on a regular basis). And lubricate the throttle housing at the panel.

It will make a big difference.

Skybolt
08-04-2008, 01:03 PM
Wade.
I agree. the return to full throttle spring is on the strong side.

But Steve, should the springs be in place, in case there is a cable break or slip?
Maybe to replace the OEM springs with a lesser spring would be a better alternative than removing the springs.

Maybe, we can throw this out, anyone changed to a weaker set of springs on the 912?

Eric.

wadeg
08-04-2008, 10:36 PM
Well I went by ACE and got a few different springs to try. Used a lighter spring that has the same length as the standard and looped ends. Works perfectly now. Silky smooth and not hopping off idle. Can't recall the specific spring number but ACE usually has a rack displaying them all up on a pegboard in the nut/bolt section. Problem solved!

Skybolt
08-05-2008, 11:16 AM
Wade.

Thanks for the feedback.

I assume you have the 912 motor?
What did you do, remove one of the springs (for a pattern) and pick the closest to it in length/shape?

Cheers. Eric.

wadeg
08-06-2008, 10:06 PM
I'll have to drop back into ACE and see which one I got. I bought a few of them that were in the range since they were inexpensive. I got to the hangar, opened em all up and when I went back to check which ones I selected for use, I forgot which bag they came from. Will drop into ACE and see which one I specifically am using and post the number. Also will need to keep a close eye on them for any evidence of wear. The tension is perfect. It is just enough to keep from pulling the throttle forward when at idle (running with vibration). With a little bump it will ease forward but stays in position. No doubt it will toss the throttles to full should the cable break. Happy with my throttle now after plenty of agst.
Just about done! Only thing really on my 'list' for completion is to get my data plate on. Then I will start thinking of more things to do.....

Jerrytex
08-15-2011, 01:59 PM
I found this post in a search. My test pilot flew my Kitfox for the first time ever (yeah!) this past Sunday. I have the Rotax 912 with the dual throttle cable and the friction nut to hold it. He mentioned that he felt the throttle creep was a bit of a safety issue. We talked about it neither one of us can think of a reason that there needs to be return springs. I get and understand the going to wide open throttle theory if the cable breaks but this would only be a real concern on take off and highly unlikely if checked on a regular basis.

I took my return springs off and the throttle works like the Aeronca Champ that I have been flying. It stays were you put it with no creep and no cranking down on the friction nut.

Is there anyone that has had problems from removing the springs? Or the ones that have, any unforseen issues that you have experienced?

Thanks

DesertFox4
08-15-2011, 02:31 PM
780 hours now without the springs in place. No problems. I have Kitfox Aircraft LLC's heavy throttle cable with the friction lock.
You should consider all possibilities before removing them and do what you feel is reasonable and prudent.

Slyfox
08-15-2011, 02:36 PM
seems I hated that on my new 912uls. I opted I believe, to just remove the springs off my old 912ul engine, that fixed mine, works fine. the springs on the old motor were much lighter on springs.

MotReklaw
08-15-2011, 02:47 PM
A friend of mine changed the return springs on his 912U.
Here's a link to what happened to him.

I'm just saying....

http://www.ch601.org/stories/croke_crash.htm

DesertFox4
08-15-2011, 05:23 PM
Big differences in throttle cables. That's why you must choose wisely if you want to remove the springs or not. Some throttle setups used on the Rotax engines rely only on the WOT springs to advance the throttles. You'll find these types more in other makes of aircraft.
The heavy duty throttle cable I and many use from John and Deb do not require them. I can push the throttles open with much more authority than just the WOT springs can deliver. They are much safer than the other types in my opinion.

Jerrytex
08-15-2011, 08:10 PM
I have the thick cable as well. It's hard to bend it with a pair of pliers at a 90 degree angle to it much less pushing it with the throttle handle to make it bend. Thanks for all the info and suggestions.

catz631
08-16-2011, 06:12 AM
You need the springs on the 912. It effects the throttle positioning of each carb(ie: carb sync) in addition to giving full power in case of throttle cable breakage etc
What I did to cure my problem was to install a vernier throttle and a long (about 6 inches) carb return spring that runs from the throttle bell crank to the throttle cable panel at the bottom of the instrument panel(confused)
This counter balances the carb throttle springs and allows me to dial in whatever throttle I want. There is no pressure from the throttle springs at all. Works perfectly ! And if the cables were to malfunction i just pop the counterbalance spring off with my finger and I am back to "ops normal"
Dick

Jerrytex
08-16-2011, 08:14 AM
Dick,

So you have the bellcrank behind the panel that connects the throttle handle to the two smaller thin cables going to the Carbs?

That is how mine was set up originally so I can visualize what you are talking about.

I changed mine out with the dual throttle with the real thick dual cables so there is no bellcrank anymore.

I can definately see that you would need springs on the setup that you are talking about since the cables are small and made to pull rather than push.

Thanks

catz631
08-17-2011, 04:33 AM
Jerry,
I still have the bellcrank and will keep it. It allows me to use to use the "throttle link" I purchased from Highwimg LLC. With it I can pneumatically sync the carbs in about one minute once the "Twin Max" carb sync is set up.I no longer have to shut the engine down to adjust the cable length nuts on each carb. I could even sync the carbs while flying if I wanted to. (It wouldn't be as accurate as with the gage of course)
Dick

HighWing
08-17-2011, 01:27 PM
My new project has the bell crank - Model IV. I will keep it that way. Like Dick, I will put a counter acting spring in the system. I did that early with my first Model IV and it worked fine for 900 hours. I like the simplicity and the $$ savings. I would change out the thin cables from bell crank to carburetor periodically at annual just to be sure.

I have experience with the new split throttle as well, as that is what my friend put in his V. I helped with the install. In my opinion, stiff and heavy with no real overriding advantage and in some respects (with the IV), I believe a step down as the little gizmo won't work and carb syncronization wouild become a two wrench project again.

Lowell

Av8r3400
08-18-2011, 05:57 AM
Lowell - Where are you finding the replacement cables for the bellcrank system? I was in a pickle until a fellow TeamKitfox member sent me his unused set.

catz631
08-18-2011, 06:01 AM
Got my replacement cables @Lockwood. They sell the cable,shielding,end fittings. Just cut the length you need and you are ready to go..no problem!
Dick

HighWing
08-18-2011, 06:31 AM
For the most part, I just replaced the 1/16" SS internal cable. I did once find the sheathe broken from the terminal end. I found cable and ends at a bicycle shop. For the purists among us, I know these cables are not the lubricant impregnated cables from the aircraft houses, but the sheaths are teflon lined and there are no bends in this particular application and replacing them occasionally with local materials was my preferred choice.

Lowell