Goblin black nitro -- size and engine

[Jotto]

I'm considering a Goblin black nitro.

So... 650 or 700?

Which engine? I see that YS 96 and OS 105 are popular choices.

Any thoughts?

[Locktite]

I had a 650 and now have 2 700’s.. I prefer the flight characteristics of a 700 over the 650.. you also have a ton of blade selections with a 700 size machine.. For me OS will always be my choice of engine.. Great power and reliable engine

[jsbach#1]

I only have 6 gallons through my 700. The airframe works great no problems at all. Belt tensions are not an issue as I feared they would be, I have actually played less with belt tension on this bird than on my electric 700's after the same amount of flights. Probably because the power is less.

I am using the YS 96. No problems. I have not had an unexpected shut down yet, and I have done many auto's through the flights so the engine has demonstrated it can idle, fast idle, spool up, spool down, cut throttle and over again without dying.

I have said if I did it again I would probably do 650 but the 700 is great I have no interest in changing the size.

[Jotto]

Originally Posted by jsbach#1

I only have 6 gallons through my 700. The airframe works great no problems at all. Belt tensions are not an issue as I feared they would be, I have actually played less with belt tension on this bird than on my electric 700's after the same amount of flights. Probably because the power is less.

I am using the YS 96. No problems. I have not had an unexpected shut down yet, and I have done many auto's through the flights so the engine has demonstrated it can idle, fast idle, spool up, spool down, cut throttle and over again without dying.

I have said if I did it again I would probably do 650 but the 700 is great I have no interest in changing the size.

Thanks for sharing your experience! Would would you go for a 650 instead if you did it again?

[ticedoff8]

Originally Posted by Jotto

Thanks for sharing your experience! Would would you go for a 650 instead if you did it again?

I was planning to do a "Big Block" conversion on my Trex 600N and use a YS 96SR-X
I like the idea of a lightweight machine that has way too much motor for the power to weight ratio

I found a great deal on a SG651 kit (Goblin 650 Black Nitro) and built it with the YS 96SR-X.
The only "upgrade" I used was the aluminum fuel tank rails

The dry-weight of the G650N is 10.5lbs (YS 96SR-X)
The dry-weight of the T600N is 9lbs (YS 60SR)
(both weighed on my typical Gerber baby scale)

I cannot find the peak-power specs for any YS engine, but I assume the 96SR-X is going to be more powerful than the 60SR (by a lot)

I have not flown it yet.
But, I think this will be a kick-ass combination.

And, I can always add the 700 upgrade parts to the 650 airframe at anytime.
But, I would expect the 700 kit to weight around 11 to 11.5lbs (heavier tailboom and blades) and you may need to add lead to the nose to keep the CG correct (tailrotor 5cm farther out).

I have an MSH Protos Max Nitro (700mm) in mind as a replacement for my T600N.
And, I have a YS 120SR-X on the shelf waiting for a new project.
So I doubt I'll be stretch thing the G650N.

[jsbach#1]

The protos nitro looks really sweet !

The 650 and 700 goblin nitro are closer in weight than that. That short carbon cross section of boom at the end which is longer in the 700 is negligible mass. The only difference in mass that's significant is the blades and that's also negligible in flight. I didn't have enough hands to take a pic for you showing the balance is right on. With a 2s pulse pack. The weight is 10.2 lbs with about 1/5 or 1/6 fuel level. Fully fuelled up it just breaks 11 lbs on 2 different low mass scales I tried.

I know these luggage scales aren't the most accurate but it's consistent with Sab published numbers.

Just finished putting her back together slight tip over on landing was trying different autos. Dying to fly !!

[jsbach#1]

Originally Posted by Jotto

Thanks for sharing your experience! Would would you go for a 650 instead if you did it again?

Been thinking about this and I don't have an answer. I really like the way mine flies it's just so fun the light disc load and autos are great on this machine. Every time I fly my friends 650 I really enjoy it too. I think at the end of the day I like the black green too much and that over rides any slight differences at the fingers.

[Jotto]

Any reason not to go for the YS 120? Isn't bigger better...?

[jsbach#1]

Its safe to say the 96 is their best engine.

[ticedoff8]

Originally Posted by jsbach#1

Its safe to say the 96 is their best engine.

Safe...
But wrong.

I was going to put my YS 120SR-X into the G650N.
But I think the 120SR-X has too much power for the 650mm blades on the G650N.
I doubt I could run enough collective pitch on the 650mm blade to keep the 120SR-X in its power band.

The 96SR-X has the advantage of running a higher RPM than the 120SR-X which is a better match for the 650mm blades.

The 120SR-X will be a better fit for 700mm blades (if you decide to start with the Black Nitro 700 instead).

I will be using the 120SR-X on the Protos Max (when it comes on the market) with the longer VTX 717.

[jsbach#1]

I dunno man, I don't deny the 120 srx will be a beast but I flew today , the 96 was singing beautiful in the 700, virtually no bog except on the ugliest collective mismanagement power moves.

I suppose you'd have to run one tooth larger pinion with 120 motor if the rpms are lower on it.

[crashagain]

I have 2 700's with 120sr's in them with the new hitori pipes and and they fly great.
Gobb's of power and a good flight time. I can flog them and get almost 7 minutes out of a tank of fuel.
running the 26t pinion and curves.

[husafreak]

I have a first run YS120 in my new Goblin 700. It was in a Rave ENV previously. The engine has been a real sweatheart, good power and reliable. In the Rave I used a header tank but I left it off the Goblin as the body doesn't really accomodate the header tank very well. Are most guys still using header tanks? I always thought it was an important part of a reliable fuel system...

[husafreak]

What motor rpm and headspeed is ideal for my 700/YS120? It ran so well in my Rave I never thought about it. Rpm on the Rave was 1900. I?m not quite as happy with the way it?s running on the Goblin.

[husafreak]

And finally I?m out of Enya 4 plugs. But I still have Enya 3 and 5 plugs, and OS8?s. Do you think the plugs I have are Fine or should I get more Enya 4?s? YS120

[crashagain]

My head speed is about 1950 to 2000. I run curves so I have to guess.
I run OS8's and 7's.
No need for a header tank the clunk in the goblin works great. Power is smooth from start to end..

[ticedoff8]

Originally Posted by husafreak

What motor rpm and headspeed is ideal for my 700/YS120? It ran so well in my Rave I never thought about it. Rpm on the Rave was 1900. I?m not quite as happy with the way it?s running on the Goblin.

The YS 120SR-X engine has a max RPM of 16,000.

I personally believe that a 700 size heli should have a 2000 RPM headspeed maximum.
The only real reason to go higher than 2k RPM is to make a lot of noise and waste power.

So, to get the head to run 2000 RPM with a 16,000 RPM engine "redline", you want to use the 27T motor pulley (7.95:1 gear ratio)
Then run a governor and set the headspeed to 2000.
This will run the motor at around 15,900.

If you believe that 1950 RPM is the better headspeed, then using the 26T motor pulley (8.23:1) is a little better. This will run the motor at around 16,050.

Either 16,050 or 15,900 are good RPM ranges for the YS 120SR-X
This will keep the carb barrel open to around 80% and then open to 100% when needed.
This makes it much easier to tune.

If you use the 27T motor pulley and run the headspeed at 1950, the motor is only turning at 15,500 - and that can actually bog the motor and makes it a little harder to tune.

Unlike the 91 size motors, the 96SR-X and the 120SR-X do not need to be run at a higher RPM than they are designed.
They do not "bog into the power band" the way the .91 size engines do.

[jsbach#1]

80% throttle opening would that be at a hover ? That seems like too much ?

I have been thinking about this. Where do you set your motors needles at to achieve hover at where abouts throttle opening.


This is something I have been trying to explain to people. The governor will open the carb to where it needs to achieve the requested rpms. If you're running richer or leaner (within a reasonably small window) the carb will be hovering with a little less or a little more throttle opening.

This will affect performance during transitions and affect the rest of your tuning. That is governor tuning and engine tuning.

I'm with you I prefer to use a little more carb opening than what YS indicates on the carb and get both needles into the equation. Then nice and fat at WOT to keep everything safe and happy.

I get good flight time, and heaps of power. YS96.

Now you got me so curious about 120

[husafreak]

I was pulling my hair out this morning trying to figure out these gear ratios. Hello! I just found out the gear ratios in my Goblin 700N manual are reversed. I measured my blades and checked the box label, stopped short of pulling the clutch bell to count teeth, Google is your friend I've reset the gear ratio in my VBC Tx to 8.23. I'll try 1940 to get close to 16.000 rpm. I imagine having the right gear ratio programmed will have my engine sounding much better. Thanks!
I'll fly it without a header tank as long as it runs well.
I'll try the OS8 plugs I have on hand. The manual for my 120SR says OS 8/7 or Enya 3/4/5.
When the YS120SR first came out a lot of guys struggled with it so we were very concerned with what plug to use and header tanks for instance. I honestly think the reason I had no troubles with mine was because I flew YS two strokes for many years and they just ran better on the rich side, so I never tried to squeeze the last bit of power out of it, and it (they) ran well.
But they could be finicky, hopefully changing plugs and dropping the header won't create issues.
I have never run my 700's over 2000 rpm head speed. 1900-1950 always just sounded and felt right.

[jsbach#1]

Where do we get the header pipe for the ys120 now