Idle problems on a tiger pro .46 (2 stroke)

by Rob
(Chandler, AZ, USA)

Hi all,

New to the web site, new to nitro. I have been reading allot of posts here in hopes of resolving my idle problem.

So here it is. I have a 10 year old Thunder Tiger Pro .46 (2 stroke). Although it is an older model, it is a new engine straight out of the box, never used before, but I lost the manual during the 10 years.

Overall problem. I can not get the RPMs low enough at idle so the plane does not move forward (not just a bit but it rolls across the garage floor over). When I trim it more (even by one click) the engine dies.

Facts:

1. New A3 glow plug

2. Hobby store sales guy told me to use 25% nitro fuel by Byron. Is that a bit high on the nitro??? From what I read normal is 15%, but sales guy knows more then me right?

3. High speed needle adjusted correctly. A little bit rich for lubrication. Transition from low power to high power is very smooth without delays, burps, or issues. Pinch test OK.

4. Low power needle. Not sure where it is because I don't have the manual. I'm guessing that it is the only other screw on the back of the carburator. See picture. If so, factory has it turned fully clock wise which seems to work the best. Since I can't turne it any more clock wise, I turned it 1/6, then 1/4, and finally 1/2 turns counter clockwise. With each turn it got wores, more RPMs needed to keep engine from dieing. Returned the needle to factory setting fully clockwise.

5. Used 2 tanks for breake in. 4 more tanks trying to resolve this issue.

One other fact, when I do set the RPMs to the lowest settings and still have the engine running... The engine runs but I can hear it slowing down a bit and after 40 to 50+ seconds it dies on its own. In short the lowest RPM settings ( which are to high and role the plane) are still very unstable and not dependable at their slowest setting.

Next week I'm going to try other fuel with 15% nitro. After that I'm out of ideas. Please help, its an ARF and I have been fighting with it on and off for over a month now. Would like to actually fly it one of these days.

Thank you in advance for any and all help.

Rob

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Idle problems on a tiger pro .46 (2 stroke)

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Jan 18, 2010
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Thank you
by: Rob

Thank you for the info. I shall try the correct screw and tell you how it went. I do think that I will also buy some 15% nitro fule instead of useing 25%.
Once again, thank you.

Jan 17, 2010
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25% nitro seems excessive...
by: Anonymous

I also think 25% nitro is a bit excessive. I would use 10 - 15%. Too much nitro can damage your engine by making it run too hot.

You can actually run an a glow engine with zero nitromethane. The nitro helps the engine idle better and gives you more power because nitromethane requires less oxygen to burn. This means there is more fuel and less air in the combustion chamber.

This also means you burn fuel faster...

But most people use 10-15% nitro.

Jan 17, 2010
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I think you are turning the throttle stop
by: Matt

Hi Rob,

I think I see where you are going wrong.

Here is the manual for your engine.

Manual for Tiger Pro Engine

The very bottom page of the above manual has a picture showing what all the parts on the carb are.

What you are adjusting is the throttle stop. This controls how far closed you can shut the carb barrel.

Item J on that picture is the low speed needle. This is what you need to adjust, but only a TINY bit at a time.

For my attempt at a graphical representation of how the low speed needle works check out the section "Setting the Low-Speed Needle Valve" on the
tuning page. This should give you a better understanding of what is actually happening when you turn the low end valve.

Hope this helps!

Matt