N7 with 105 tunning issues and run times?

[beans07]

Hi all, I am having some tuning issues with my OS 105 HZR. It feels rich but if I go any leaner than 2 turns on the main it gets too hot. The power is ok but not even remotely close to my mates 120SR. It will pull 12 degree pitch in a climb out but struggles with tic tocs and other moves that load the engine. It doesn't hold a candle to my mates YS120SR that pulls 14 without hesitation and he can be violently rough on the sticks without it even changing notes.

I am running 2 shims on 20% fuel (cool power homebrew based). I am flying about 700ft above sea level. OS 8 plug. I have cleaned the reg and re sealed the pipe (hatori 105 pipe) which allowed me to go in half a turn to 2 turns on the main but it's now running more roughly than before. It is cold on the back plate where you can just feel a bit above ambient on the back plate (86 degrees F yesterday when flying). If I go in 2 more clicks it runs hot to the point hold the finger on the backplate. It seems strange that 2 clicks can be the difference between cold and hot.

Vbar silver log doesn't have anything more than the odd high vibration but it's full of gov is at full throttle so that could be why as it seems to have a bit more vibration than when I ran it in 8 months ago. I really don't think it is over pitched as I set it with VBC at 12 degrees. I have not touched the vbar governor at all.

I am only getting 6 mins of flight time which doesn't sound right to me?

I have only seen and felt glimpses of how good this heli is so any help would be greatly appreciated.

[Rodney Kirstine]

You shouldn't need two shims to run 20%.  You might start there?

[Kevin Dalrymple]

With 20% nitro run the .2mm shim. What is you mid needle set at? The motor sounds rich. When was this motor purchased? Do you know about the high needle seat update?

[Kevin Feil]

The high needle on the left is the correct size, the one on the right is the Wrong Size. OS released a batch of OS 105's that had the wrong needles seen on the right. Look at your high seat and pay attention to the size of the bore, also the ones that were bad are darker in color. See if this helps.

Best Regards,
Kevin

[Kevin Feil]

Well  I have tried 5 times to upload the pictures of the Needle Seats and unfortunately it won't load. Figures right? What is your Email address and I will send you the image to help distinguish which you have?

BR,

Kevin

[Rodney Kirstine]

An easy way to tell if it's the wrong one is to try to insert a 1.5 mm Allen wrench into the orifice at the end. If it can go in, at all, it's no good.  I just got my replacement yesterday and hoping to try it this week.

[beans07]

Thanks for the replies lads. Sorry I am late to get to them I was waiting for an email prompt that someone had replied alas maybe this forum doesn't do that. Not to worry.

The engine was purchased in January this year but may have been a little older stock possibly up to 3 months.

I contacted previously the importer for these engines in Australia and they know nothing about this issue and told me they would enquire with Japan. I even pointed to a forum post on HF. They came back at me saying that OS told them there isn't any issues and no update parts.

I am pretty sure I added a 0.1 shim in it which would make 0.3 I may have to pull the engine out to check but I really don't want to unless I have to.

As a side question when did OS start making their Heli engines in China? My box has a sticker on the side which includes "MADE IN CHINA".

[beans07]

I am exactly 2.0 turns on the main and 1.5 turns on the mid needle.

[Kevin Feil]

Very possible you have the over bored Needle Seat.  pic's sent via Email..

Best Regards,

Kevin

[Mike Spano]

my motor was bought at that same time, if i am not mistaken, it had the incorrect needle seat....

[beans07]

Thanks for the pictures Kevin, I have the one on the left the lighter grey coloured one.

I can insert a 1.5mm MIP tip inside (the shaft of the MIP wont go through).

So I am confused if I have the right or the wrong one now.

We are talking about the main needle seat?

[Rodney Kirstine]

Yes, the main needle seat.  If you were able to get any of that wrench to go in, you have the bad one with the 1.7mm orifice.

[beans07]

I have contacted the place of purchase and see if they can source me one.

So how many and what size shims should I run in this engine? Currently I have 0.3 (0.2 + 0.1)

[Kevin Dalrymple]

Shims for 20% = .2mm.
Contact hobby. Services. They have the seats and will mail one to you. Call them.

[Rodney Kirstine]

I've been running just the .2mm in mine.