hey guys

so i still have not taken my Tiger Trainer 40 for its maiden flight yet , but will let my fellow RC'ers know when i eventually work up the courage to do so !!!

anyways ...

So i gave the engine a start today after installing my servos and new reciever and what not , and i wasnt happy with the outcome ....
about 2 weeks ago when i started her up , she ran beautifly .... idle was great, power was great , all was well , and now today when i started her up , it vibrated alot when the throttle was almost closed and on idle , i and i could only get it to stay running if i pushed the throttle past the point of idle where the prop actually starts to pull the airplane !!!! , if i took it any lower ... it would sound as though it was mis-firing and enevtually just die out , then i have to re-prime it , t get it started again

the fuel is fresh , the engine is clean , the tank was raised , the glow plug was new , the glow starter was fully charged and i was constantly adjusting mixtures ..... i cant seem to find what the problem is ,,,,
please help me !!!!

any advice is welcome ,,,, !!!!!

thanks in advance!!

This is a bit of a puzzler, dirt kicker. Any chance your propeller was chipped or damaged at all since the previous engine run. Based on your description, an out-of-balance prop is the only obvious possibility that comes to mind.

If you were running the plane on the ground, it's not impossible that the carburetor could have sucked up a bug or some dust or something. I could see where this could lead to the kind of misfiring you described.

Lastly, it might be worth trying another fresh glow plug. A brand new glow engine will tend to shed some metallic particles in its exhaust while breaking in. These metal particles can foul a glow plug fairly quickly and lead to poor idling. A lot of veteran RC pilots will advise folks to, "always break in a new engine with an old glow plug" for just this reason.

Based on these possibilities:

1) Check your propeller and verify that it is still balanced and undamaged. Spinners can also be out of balance, so if you've added a plastic spinner since you last ran the engine, this too might require some checking.

2) Verify there is nothing plugging up the carburetor or needle valve assembly, you can visually inspect and also flush the engine out by pumping a little fuel backwards through the carb and the needle valve

3) If neither of these issues seem to be causing your problem, go ahead and try another glow plug. Start with another used plug if you have one that is trustworthy, or use another new one if you don't have an old one that you know should work.

Good luck!

thanks bigedmustafa for the reply !!! .... i replaced the glow plug this morning ! and cleaned the metal filings out the exhaust ... but i did respray my prop .... could that unbalence it though ????

Two weeks ago it was likely cooler, if so then it will run richer in warm weather.  Try turning the idle mixture in about 1/8 th of a turn.

Hi!
??? Metal filings out the exhaust ????

?????????????????????????? Me too!! Yes, spraying or painting will throw the prop off balance. Mater of fact I use clear lacquer to balance my props quite often, depending on how you did it the prop could have been way out of balance!! You mentioned twisting screws, now you can also be way out of tune too. You first tune the top end, bring it up to full rpm then back it down 300 to 500 RPM, now you adjust the low end so you can get the RPM down to what the manual states as the low end RPM, usually around 2000. Just because the engine can pull your plane around at idle doesn't mean it's an engine problem. When I have an idle set on a plane and it's getting pulled I will put a bit of tension on the wheels using fuel line, a washer and my wheel collar.

i like the idea with the tension on the wheels .... could work well ... also the engine is new , a new engine has to be 'Broken in' so while it runs thers pices of filings from the cylender and ports which gets extracted out the exhaust ,,, and as well , my "IDLE" cant drop below 2500 RPM else she dies out ...

mid range, midrange, midrange its that small slotted screw head inside the throttle barrell/arm on the right hand side likely too rich adjust eighth of a turn at a time.

John

thanks john ! will try as soon as i get nitro again .... im using 10% should i try 15% maybe or keep it at 10 ?

There is no real need for higher than 10% nitro except perhaps you are flying at higher elevation and density altitudes.

John

Does it idle better with the glow driver on? If so, that's a dead giveaway for a rich low end. The other way to tell is listen for it to slowly drop in RPM until it starts to miss and then eventually die. A lean idle will run fine for a few seconds and then die suddenly, and also will hesitate when you gun the throttle open. That said, 2500 rpm is a decent idle. I run my Thunder Tiger .46 pro around 2500 and it won't pull my Kaos at all on level ground. With perfect tuning I can get 2200, but there's no need.

no it idles the same with glow driver on / off ..... i noticed yesterday when i took off the backplate .... there is some kind of Rust like discoloration on the cam ... almost like a brown varnish type color ..... what does this mean ????? is it bad news ??????

The brown varnish type color...is castor oil. It means the engine is being lubricated, cooled and preserved. Pretty much in that order and nope its not bad news.

John

Just so we are using the right terms, a 2 stroke engine doesn't have a cam. I think you are referring to the crankshaft which turns brown in any engine ran with some natural castor.

So back to the troubleshooting, you know you aren't running rich since the glow driver doesn't affect the idle RPM, so it's possible you are running lean. But if I understand you correctly, you have tried tweaking the low speed needle and didn't get it any better? If that's the case, I suspect a blockage. The fuel passage in the carb is small, so it doesn't take much to restrict the fuel flow. Occasionally there is something in the new tank that can get in there, or if you laid the fuel lines down on your workbench a piece of dust can get in them and make its way to the spraybar. A quick and dirty method to clean in out is to run the engine up to full throttle and seal your finger over the carb barrel. That sucks a lot of fuel through the spraybar which can dislodge the offending particle. Just be really careful of your fingers when you do it. If that doesn't work, check all of the bolts to be sure they are tight on the engine (they can work loose during the initial thermal cycling on a new one) and then re-plumb the tank in case there is an air leak in the lines.

okay jester ! THANKS for setting me strait .... i meant the crank shaft , just couldnt find the word at the time ! haha
thanx for all the input will give it a try!

Hi!
Brown colour means RUST! And steel rust!
If it's comming from the ball bearing it's bad news!
Third picture shows how it shoudn't look like!

@ jaka

thanx alot for the pics ! very informative ! and yes that is what it looks like! thanks

Great Photos Jaka!!!!!!!!!!!!!! Outstanding, nice and clear. A point of my own, I have opened up engines and most all of them have a coating of rust on the back of the crank, not as bad as Jaka is showing. Don't over think or worry about it, just the nature of the beast and something I clean up in the rebuild. However, the bearings are another story and if there is rust in them then I replace them.
Really good photos!!

thanks guys ! , so back to the point .... if my engines idle problems are not somehow user related ... which i dont see why they wouldnt be !!!!!!!!!!!!!!!!!!!!!!!!!!!!!! what else should i start looking put for ?

P.S i stripped my propeller's spray paint job that i gave it .... its now back to stock grey , like it was the day my idle ran so sweetly !

hopefully she'll idle better now !!!

say ... would an electric starter help my issue of turning the prop over so many times ,,,, and possibly the idling problem ?? my hobby informer and next door neighbor said i should invest in an electric starter , instead of using the trusty old chicken stick !!

Do you have anyone helping you at all with getting into the hobby?? Perhaps this neighbor?? Doing tuning or repairing on line is only good up to a point. Has anyone even mentioned a prop balancer to you, do you know what one is? It's the simple things you ask that makes me think you could really use a mentor that can do hands on helping.
Just wondering. seems to me this has been brought up in another post.

yeah ... infact ... this is my only my 2nd plane and 1st nitro one at that .... so i do apollogise for the noob questions ... but we all have to start somewhere ....

and to answer the question on the mentor .... my neighbor has 6 planes , 3 of which are nitro .... so he does help me out from time to time ....

i have heard of a prop balencer ... just havnt really seen the need to invest in one ....

Try to get the TT instructions on how to run in an ABC type engine. Do not attempt to find an 'idle' until the engine has a hour or so running, the carb does not have an 'idle adjust' control, just mid range and full power mixture controls. The idle speed will depend on the prop fitted, and will change with different props. It will be what it is. Do not rely on the 'electric finger', TT engines start within 3 flicks if there is nothing wrong. More than that and you need to start looking at fuel and plugs, cause something is wrong. Invest in a prop balancer and use it. Make sure that your engine mounting screws/bolts are tight. There should be no metal bits leaving the exhaust, otherwise something is wrong. Any dark staining in the exhaust muck, muffler/engine joint or around any engine bolts is a sign of fretting aluminium, and you need to check bolt tightness. Find your local club, get help, these are good engines, but you need to treat them with care (as with all engines, of course) and given that care will outlast your airframe.
Evan, WB #12.

In theory I agree that the electric starter shouldn't be needed, but it makes life so much easier. Hand starting requires either a lot of trial and error to get a feel for it, or it requires having someone to show you how to do it. A wireless setup with either a 10 cell NiCd pack or a 4 cell lipo is best, assuming you have the charger for it. Wiring to a 12 volt lead battery works too if that's what you have. Harbor Freight sells a drill battery and charger than many have wired up with good results. Resist the urge to rig up an electric drill for it though, as your wrist doesn't have the right kind of strength that way to resist the torque.

Back to your engine issues: Do your bearings feel smooth and slick? If not, that is likely the cause of your idling problems. I was assuming a new engine in your original post but if it's old and been sitting up for a long time the bearings could be rusty or gummed up with old castor. Both will cause increased friction which kills your idle and reduces top end RPM.

Hi!
Agree that an electric starter is must!

Todays ABN /ABC engines don't need any lenghty running in!
Your TT..46 PRO SE should idle just perfect from the moment you start it...provided you use the right fuel (5-15% nitro), use the right glow-plug (Many...OS 8 or Enya 3 are the old stand byes) Use the correct tank size(6-10oz)..mounted correctly (according to the tank mounting rule), use the correct propeller size (10x7, 11x6, 12x4, 12x5 for sport flying) and have adjust the needles correctly! Andf ofcourse,most important; Have a god engine to start, with with no faulty ballbearings or worn out cylinder liner/piston.

That simple!

thanx for the replys and jaka for the pictures (agan) lol !!

now that you guys mention , if the motor is warm , say i put a hair dryer on it , to warm it up , or its been running .... it turns smooth ! the prop does a full 360 degree rotation if i just flick it with ,my finger , but if its cold and i flick it , it feels sticky and only does a 170 degree rotation , before i start ripping my engine apart ,,,, which i REALLY dont want to do ... what oils or sprays such as Q20 , fluidfilm or WD40 can i use to spray on the bearing ?? i knw i sound so stupid askiing these questions ,,,, but its my 1st nitro engine