YS 61ST2 to a OS 70SZ

[MichaelT1960]

If I switch from a YS 61ST2 to a OS 70SZ will I notice the power increase?

I plan on trying a CY MPII 80/90 exhaust on the OS in my Fury.

Has anyone done this. I like the idea of not having to change gear ratios or engine mounts with the 70 vs adding a 90.

Thanks,

Michael

[Alfred]

Yep
I have got both and both running with MP2's.
I run 20/20 mix and the OS does put out noticeble more power, but requires a Header tank and will go a touch lean at the bottom of the tank.
My OS is 100% reliable and I am not an OS fan. The engine was inside a Fury Expert I bought.
Mine also idle really well, and it's not too lean on the bottom.
By that I mean that I can fly it fairly hard and then select throttle hold and it drops instantly to idle with no hanging on.
It comes with excellent tuning instructions. Follow them to the letter and use Enya3, OS8 or the YS2 Glow plug and you have a reliable workhorse.

[david.read]

Alfred,

If the pipe holds on when you select Throttle Hold, does that mean it's rich or lean?

If it's rich do you just alter the idle mixture setting?

Regards,

David

[Alfred]

It means that it is lean.
I would carefully richen up the idle turning the flat blade screw anti-clockwise 1/8 of a turn at a time.
Take it slowly, doing a couple of autos before doing any more tuning.
Don't go past the point where you have turned the idle screw by more then 90 degrees, as that is the maximum value you can go.
As you richen it up, you will have to re-adjust the throttle courve (bottom end) upwards to compensate for the loss of rpm to keep the engine tick over.
If you can't get anywhere..change the plug.
Enya #3
or
OS #8
reset the idle screw (default is for it to be vertical in the "U" plate) and start again.
I run a MP2 muffler and mine drops to idle in an instant, as fast as I flick the switch, so the OS 70 can do it just fine.

[david.read]

Thanks Alfred,

Can i also ask, i have the 60K card on my OS 70. If the engine is not sharp to spool up is that linked to the high speed needle only or a mixture both needles?

I fly mine with the SB 16 and fly arround on full throttle and return to the ground and see if it idles well, if it does i don't touch the mixture screw if it's slow to pick back up i have been trying the high speed needle.

I think the medium speed needle is for hovering. An i right in thinking that this needle does nothing appart from setting the mixture in the hover???

Thanks in advance.

David

[Alfred]

What is the 60K card?

Not sharp to spool up?
Lean the midrange (clockwise) which is the smaller needle but just 2 clicks at a time.
That's assuming that on full throttle she is still rich enough.

The medium speed needle IS the midrange and will have influence espatially on the transition from low to hover speed.

You really need to get your top end (full throttle) set up correct 1st, as the other 2 needles are slaves to it.

The main needle will influence both the idle + the Midrange

The Midrange will MAINLY influence the lower end transition

The Idle screw will influence the idle and transition up to hover RPM.

If none of that gives you a satisfactury result..change plug Glow plug to another brand..and start again

:roll:

I know it's a pain in the a$$, but that's just what you have to do. Once you got it setup..you should just have to change the Main needle only by 3 clicks leaner or richer to compensate for climatic changes.
If you then can't get it right within 3 clicks..change plug..look for other problems.

[david.read]

Alfred,

Card should have read CARB!

Thanks for the advice on the setup.

Are you guys able to touch the base plate after a tank of fuel? Or is it fairly :smokin:

Regards,

David Read :)

[Alfred]

Never hot enough that I can't keep my finger on it without timelimit and without it being uncomfortable.
I run mine warm only.