OS50-H tunning issue.

[Astronobaldo]

I got a trex 600 from bmfa ads. However, I'm struggling tuning its OS50-H engine.

It starts and idles fine. Done the pinch test ok (it will take about 2-3 secs before the speed rises and then dies off within another 3 secs). However after 25% stick the engine starts to bogging so badly it won't get head speed and it won't take off.

I'm running Magnum 30% / New glow plug (OS #8) / Governor disabled / Throutle curve is 0-50-75-85-100 / Pitch curve 0-25-50-75-100.

At the moment I've got 1 1/4 turn from fully closed (high speed) and 12 o'clock (low speed).

I've moved back and forward between rich needle to lean needle but engine still bogs exactly the same. I went less than 1 turn (high) and 3 o'clock (low) but still bogging. The back plate was still cold though. Should I try leaning it even more?

Here is a quick video I uploaded on youtube so you guys can see it.

[ame=http://www.youtube.com/watch?v=drNabkn9Rsg]YouTube - Trex600 bogging[/ame]

any thought?

cheers.

[tonystevens]

are you sure your pitch curve is correct only it looks as if your exhaust smoke is being sucked up through the blades which would suggest you have negative pitch ,wich would bogg the engine ,it also reminds me of trying to land the heli when in idle up (landing then trying to close throttle in idle up would bogg the engine).is your swash plate working in the correct sense ,blocked filter maybe?just a few ideas

[Astronobaldo]

are you sure your pitch curve is correct only it looks as if your exhaust smoke is being sucked up through the blades which would suggest you have negative pitch ,wich would bogg the engine ,it also reminds me of trying to land the heli when in idle up (landing then trying to close throttle in idle up would bogg the engine).is your swash plate working in the correct sense ,blocked filter maybe?just a few ideas

thanks tony. Swash plate is working in the correct sense. I guess the smoke is getting sucked because at 25% stick I still have some negative pitch. It is because my pitch curve is 0-50-100 and my pitch range is -+11.

I'm going to check the filter. As I've never done it before, is there a easy way for testing it?

cheers

[tonystevens]

i had tuning issues with my os50 which turned out to be the filter and one of the lads down at my club fixed it by elliminating the filter alltogether.just replace the fuel tube between the tank and carb with one continuous length (no filter)and see if it boggs.you will need to make sure your tank has clean fuel in it for this though.hope this helps.

[tonystevens]

thanks tony. Swash plate is working in the correct sense. I guess the smoke is getting sucked because at 25% stick I still have some negative pitch. It is because my pitch curve is 0-50-100 and my pitch range is -+11.

I'm going to check the filter. As I've never done it before, is there a easy way for testing it?

cheers

does your pitch curve in normal mode start at -11 at low throttle, 0 at mid stick? i think the norm is -5 at low stick ,0 at mid stick +11 at high stick,you could have too much negative pitch on spool up bogging the engine before you get to mid stick.

[Astronobaldo]

does your pitch curve in normal mode start at -11 at low throttle, 0 at mid stick? i think the norm is -5 at low stick ,0 at mid stick +11 at high stick,you could have too much negative pitch on spool up bogging the engine before you get to mid stick.

Yes, in normal mode it starts at -11 then 0 at mid stick. I'll changing my pitch curve to start with -5 and also the filter.

thanks mate.

[Janek]

Its too rich.

On an OS50-sxh and Hyper, there are 2 mixture controls, the "high" end needle, which is the big knurled knob, and the "low" end needle, which is the small slotted screw that lies in the "C" shaped, copper coloured, plate.

The Low end needle, on all my OS50 has been a gnats whisker on the lean side. The screw only turns about 0.25 of a turn between the "neutral" point, which is with the screw slot parallel with the "C" shape. therefore slightly lean is with the slot facing very slightly down at the front of the heli from this neutral point (i,e. turned clockwise). Use this as a start point, but beware that small changes to the angle can have quite big effects to the low end turning.

The high end needle needs to start at about 1.5 turns out from fully closed, this will still be rich, but should get you in the air. The fully closed position is with the knurled knob screwed in fully clockwise (leaner), only close it lightly, no gorilla tactics !. Now turn it one and a half turns anticlockwise (richer).

Your aiming for a smooth running tick over, using the low end needle, and a smooth transission between the low and high throttle as you spool up. . . . whilst not allowing it to be lean, which will knacker your engine.

[Bruinbear]

Just a thought.....
Try checking the fuel line from the exhaust and the fuel tank to make sure there are no restrictions. The other thing is that the carb is seated properly, there may be an air leak ? Try a new glow plug.
Good luck,
Mike.

[Astronobaldo]

Just a thought.....
Try checking the fuel line from the exhaust and the fuel tank to make sure there are no restrictions. The other thing is that the carb is seated properly, there may be an air leak ? Try a new glow plug.
Good luck,
Mike.

Thanks mike. I'm using a brand new plug OS #8, I suppose #8 is right for this engine?

Fuel lines are all ok with no restrictions.

the carb seems to be properly seated. I'll remove it and put it back again just in case. Is any test I can run to check if there is any air leak on the carb?

Note: I'm still waiting the rain give me the opportunity to try Janek (engine tuning) and Tony's (filter + pitch curve) suggestions

thanks

[Bruinbear]

The only other thing to test is air leaks on the fuel/header tank ?
An OS No.8 plug is fine, I've always used them in my Hyper 50.
Without being able to physically do anything it's hard to diagnose, sorry.
Mike.

[Astronobaldo]

The only other thing to test is air leaks on the fuel/header tank ?
An OS No.8 plug is fine, I've always used them in my Hyper 50.
Without being able to physically do anything it's hard to diagnose, sorry.
Mike.

Thanks Mike. I have now replaced both tanks and all fuel lines ... still same issue.



Anything else I could try?

cheers,

[Dannyyy]

the clutch isnt aligned? Or the clutch bell?

The clunk is blocked

Put the fuel line on wrong. Should be....... Main tank clunk - to top of the headtank -- Headtank Clunk to carb , Top main tank to Muffler.

Err Cluch the wrong way...

[Astronobaldo]

the clutch isnt aligned? Or the clutch bell?

The clunk is blocked

Put the fuel line on wrong. Should be....... Main tank clunk - to top of the headtank -- Headtank Clunk to carb , Top main tank to Muffler.

Err Cluch the wrong way...

Thanks Danny. fuel lines are ok.

I'll check the clutch. Btw, what is the best way to check if it is aligned?

cheers.

[Dannyyy]

Thanks Danny. fuel lines are ok.

I'll check the clutch. Btw, what is the best way to check if it is aligned?

cheers.

Hmm pass on that one... But mabe just spin the head and just look to see if it wobbles... :S

[Astronobaldo]

It is fixed now!

The problem was the throttle servo connector a little bit loose on the receiver. When adding vibration the servo would start failing. I had a spare servo ... Now it's all good for the weekend

Thanks for your help guys. Have a great weekend.