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HelicopterEngines Plugs Mufflers Fuel › OS 90 C-Spec PS questions.
02-08-2006 06:19 PM  12 years agoPost 1


Southampton, UK

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Just been out running in my new Raptor 90 with OS 90 C-Spec PS. Just have a couple of Questions:

1, It seems that for no apparent reason I was hovering away quite nicely as rich as I could make (lots of smoke and even tail slightly twitching due to being rich), then I landed and the engine went lean. Little smoke!!! I drop the throttle right back opened her back up again and back rich again. Any ideas?

2, It is practically four stroking on idle. Is this ok?

3, Is there anything different about runinng these motors in? I've not used a pumped motor before.

Hope you all can help.


02-08-2006 10:43 PM  12 years agoPost 2



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I have the same set up and am haveing problems with it too i just got a 3rd needle from a friend i will try. The friend said it would help but the real fix is to get an omi carb. He just got the big bore carb and viper head from omi he says it runs so good that he just did it again on the 2nd os91c .It is expencive

Trying to get back in the heli game

02-09-2006 09:41 AM  12 years agoPost 3

rrKey Veteran


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Hey Matt,

If it's four stroking while your running it in it should be fine, BUT with it leaning out that is not good.

I had this with mine, it's very common with the OS 91 C Spec PS, i did'nt start getting lean spots untill the engine was getting some hammer, running in was smooth.

What i did with mine was to add the return needle assembly to the return valve on the engine, sorted!! takes a little tweaking as you have to get it settup according to the fuel/plug etc.. you are using.

It's the mod to have without going to the expense of the cline or other engine modifications.

For the price of the return needle it's worth it.


One Reason For Crashing'Rogue Servo Bent on World Domination'!!
FLP Flight Team

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HelicopterEngines Plugs Mufflers Fuel › OS 90 C-Spec PS questions.
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