YS engine with OS 61G Carb

[ticedoff8]

In the YT video, at timestamp 1:02, it looks like you are adding an O-ring or washer under the plate that blocks off the YS regulator.
Any idea on the specifications on that (material, diameter - etc)?

About the 120SR-X:
Is the Velocity Stack "nice to have" (aka: Bling) or is it mandatory?
If one decides to leave off the velocity stack, does it effect performance?
And, if leaving off the velocity stack has no effect on performance, does the crankcase still need to be machined so deeply?

Also, in picture IMG_5296, it looks like you machined off the bell-opening on the top of the velocity stack.

Is that because the fluted end of the bell is too large a diameter and would require deeper cuts into the crankcase?

[Sky_]

Hello,

yes it is a washer and O-ring. But it is not necessary.
It was only a test.

All other YS of mine are without washer an O-ring.

The Velocity at last are not necessary. Works without also pretty.
I cut the Velocity and use it with a filter.

No cuts on the Crankcase. It is outside original. Only inside porcessed.

Plug and Play.

A YS-120SR/X works out of the box with this adapter (only cylinder head processed).
Original YS120SR Out Of The Box with this adapter.

I processed the Crankshaft and inside Crankcase.

My Align T-Rex 760XN is the Devil himself with my YS

P.S.: The YS120SRX Silver Surfer is with shortened Head on the top. To use with Diabolo Nitro

[ticedoff8]

Only inside porcessed.

(only cylinder head processed)

I processed the Crankshaft and inside Crankcase

May I ask you: Is the increase in power due to internal changes (porting, polishing, changing the transfer port's sizes) and not so much about the OS 61G carb??

[Sky_]

Hi,

each YS has only with the OS Carb more power.
Because the Carb. has more fuel and more efficient mixture.

You can also see, when you plug the os 61G on a normal OS 91HZ.
Runs stronger....


One mod. on the YS120 is really useful and easy to make.
The inlet on the crankshaft.

[Sky_]

Testflight with Align T-Rex 760XN

[ticedoff8]

Finished mine.

For anyone that is planning on this, there are some areas that you may want to be aware of.
It isn't hard.
I'll post more details

[Sky_]

Good job! Yes, one more Powerhouse.

YS2 Glow Plug is the best in my opinion.

I have also a YS 120 SRX Performance with Venturi on it.

[ticedoff8]

I finished my conversion, but have not flown it yet. I can update on that part later.
I started this with the idea that I could revert to the stock configuration if this didn't work out. I wanted to avoid any machining of the crankcase or head that would prevent that. The only machining that was really needed was to cut one cooling fin on the head to clear the OS carb's inlet.
I would say this worked out pretty well.

There are 3 minor issues that showed up during the conversion:
- The adapter plate for the carb needs a little work to get it to fit perfectly on the crankcase's carb mounting boss. This may vary from crankcase to crankcase. But, it was a problem on my crank
- The head needs some modifications for the one of the cooling fins to clear the ventury of the OS 61G carb. This is not a problem and should not affect cooling. The mill work does not prevent going back to the stock YS carb.

[EDIT]
- The carb's fuel nipple obstructs the mounting screw on the left front of the engine (see pics). I am mounting this in my Goblin 700BN, and I cannot use the SAB supplied 4 x .7 cap-head screw in that spot. I can get a shorter screw to fit, but I cannot get my hex-driver to engage the screw's head to torque it down. The worst case is that I will have to remove the head, remove the carb, torque down that screw and then reassemble the carb & head.

The pics are included.

Also, keep in mind that the 4 screws that hold the YS regulator are 2.5mm diameter - not 2.0. This is important because typical 2.0 screw will thread into the crankcase, but you cannot torque them down.
If you do decide to cut the YS regulator screws to hold the new cover plate, you cannot go back to the stock configuration without buying new screws. Besides, the YS screws are flathead - they will not seat properly on the new plate without you adding a counter-sink to the plate.
Side Note: The supplied plate to block the YS regulator mount seems to have 4 holes drilled for 2mm screws. To get the 2.5mm screws through the holes on the plate, I had to chase them with a #39 bit.

I added the OS velocity stack - because it looks cool. I don't think its needed for performance. But... it does look cool.

In general, the cost of the adapter plates is less than I would expect for the quality of the parts (Thank you Mr. azfishguy76 !!)
If there wasn't a need to machine the fins, this conversion is almost "bolt-on" ready and shouldn't take more than an hour or so.
If you are careful removing the YS carb and regulator, you can reuse the gaskets. I bought a new regulator gasket and made a new gasket for the carb adapter plate.

The donor crankcase came as a "short block" with no carb - so that was a huge benefit. It needed a new rear bearing and the glowplug hole was cross threaded, but those were easy to fix.

[smwht]

You can pull the high needle seat to get to that bolt, easier than pulling the carb anyways.

[Sky_]

I'm so proudly to see, how lucky this guy is with the YS modification.

He can't beleave the constant power of this mod.

When the owner would know, what the hell of power has the YS120SRX (or YS120SR) with this mod..

[Baedarlboo]

Originally Posted by Sky_

I'm so proudly to see, how lucky this guy is with the YS modification.

He can't beleave the constant power of this mod.

When the owner would know, what the hell of power has the YS120SRX (or YS120SR) with this mod..

Seems to be working well for him.

[ticedoff8]

Working for me too.
I have not had a chance to lean it out for maximum power yet (only two flights so far), but it does show promise.

I talked to someone else that did this mod. They said the power gain is really noticeable.
Since we are both using the mod on the 120SR-X, I hope to see that kind of gain too.

Personally, I never had too much trouble with the YS carb, but I see now how much easier it is to set the needles on the OS carb.
It is really just a 1 needle carb.
The idle needle really doesn't need to be changed from the factory default - you just open or close the barrel to get the best idle
The "mid" needle only makes minor changes in how smoothly the engine transitions from idle to "idle up" (hover headspeed).

It is only the high speed needle that needs all the adjusting.

[Sky_]

Yes, the YS is so easy to tune with th OS Carb and runs so powerful constantly.

I am so happy...

[flysti06]

I have a set for sale $50 shipped

[Edge67]

Does anyone have an extra kit they will sell?

[ticedoff8]

I would have to guess that OS is being swamped by orders for a 61G carb.

I ordered the 61G and some other parts from RC Japan on 04/09 and received the parts yesterday (06/08).
And, this was not RC Japan's fault, they had to wait for OS. RC Japan replied to all my email questions and always gave me the best information they had at the time.

RC Japan asked if I wanted a partial shipment and they'd send the carb later - I just decided to wait for 1 complete shipment.
When they finally got the carb from OS, RC Japan shipped it FedEx (shipped 06/05) for a 3 day delivery at no extra charge.

I think we wiped out OS' inventory of spare 61G carbs and it took them 6 or 7 weeks to make a batch.
To be fair to OS, I'm sure COVID-19 delays were a factor in their factory too.

[Sky_]

Thanks for the PNs.

But here is the Link of the Shop: https://rc-carbonstore.com/OS-61-Car...120-Conversion

Works great.