Setting the Needle Valves

[JanFloris]

Hi.

I have a Kyoho Caliber 3 heli with an Irvine .39 engine. I am very happy with the heli. The only thing I'm not 100% sure of is the correct way of going about setting the low-end and top-end needle valves on a heli. With airplanes you just open the throttle completely and listen to the sound of the engine to set the needle. Is there any tips to set the low end and the high end values of a heli? And also, if you are in a hover and you give a fair amount of + collective quickly, should the engine revs drop as the heli climbs?
Thank you

[marktigere1]

Hi

For top end needle, fly for about a minute, land and feel the backplate of the Heli. If you can hold your finger on it for more than around 5 seconds, then the needle is too rich turn it in a couple of clicks and fly again. If its too hot to touch, richen the needle. When you can comfortably hold your finger on the back plate then you are about right.

For the idle needle, pinch the fuel tube leading to the carb. The engine should rev up for about 5 seconds and then die. If it dies quickly, then the needle is too lean, if it runs on for around 10 seconds then the low end needle is too rich.

I did this for my Irvine 36 and it ran a treat although I never needed to adjust the idle needle.

Do be aware that the amount of Nitro has an effect on the backplate temperature. More Nitro means cooler running, less Nitro leads to hotter running.

BobJ told me in a thread that Irvine's were high compression engines and that upping the Nitro content can reduce temperatures if required or fit shims to the head to lower compression.

Never needed to do this myself.

Hope this helps.

Cheers

Mark

PS. If the rotor speed drops on a climb out, it may be too rich. Check the backplate temp.

[JanFloris]

Hi marktigere1. This is exactly the sort of info I needed. Thank you!