Want to take the nitro plunge...

[Skeezix]

So….after trying to resist, I’m looking at jumping into a Nitro heli after flying electrics for 5 years. As when I began flying electric helis, I figured an Align 700 kit is the best nitro to go with as they seem to just flat out work and are ‘affordable’ in comparison to building a Gaui NX7 or SAB Goblin Nitro. I prefer the 700 class electrics, so thought I’d start out with a 700 class nitro heli vs a 550/600 class.

I’m trying to figure out which engine would be best matched to the 700XN. A friend of mine offered to give me a YS 91 ST and matching pipe he has, however I’ve heard YS engines are notoriously difficult to tune. The major reason I’ve not gotten into nitro sooner, is the difficulty of the motors. I’m not interested in trying to eek every last once of power out of the motor. I need something low maintenance and reliable – I want a Honda, not a Ducati.

Another issue I’m having is the fuel itself. The OS manual for the 1.05 states 15-20% nitro and 18% or more of oil. I currently use Cool Power 15% MV stroke fuel in my planks, and don’t understand why folks are using super expensive ‘heli-only’ fuel. Some of this stuff (VP fuel) is $51/gal! Couldn’t I use a plane fuel with 15% nitro and 18% oil?

-Is the TREX 700XN the best way to get into Nitro? Super combos from Align are hard to beat.
-Can I use an airplane fuel that meets the engine manual requirements?
-What 700 class nitro engine would be best to start out on in terms of ease of use and reliability?
-The OS 1.05H currently comes in two different versions: with or without a regulator. Which one would I need and why?
-Is buying a used heli engine riskier than buying a used airplane engine?
-Any particular brand of pipe I should be looking at?

Not many folks at my club fly helis, and even fewer are flying nitro so I’m on a bit of an island here. Any advice or help would be appreciated.

[ticedoff8]

-Is the TREX 700XN the best way to get into Nitro? Super combos from Align are hard to beat.

IMHO: The Trex 700XN is a rehash of the 700N DFC and the 700N LE.
Nothing really new and they still use a lot of common parts.
But, it is your choice.

If pod and boom is your choice, the Synergy N7 is a better 700-size helicopter.
The N7 flies great with a 91 size engine because of its light weight.

Heck, if you like the 550 size, look at the new Synergy N556
https://synergyrchelicopters.com/

I flew the Trex 700N LE converted to DFC for years and moved to the Goblin 700 Black Nitro.
Not only was the 700N worn out, but the "new" 700N DFC and the "new" 700XN just more of the same, but I was also tired of the "pod and boom" helicopters
That was a huge step up in quality, performance and "presence" in the air.

I flew the Trex 600N Pro for years with the YS 60SR and it also "ok".
But it never "popped"

I bought a Goblin 570 and converted it to nitro as a replacement.
And, it has the YS 96SR-X.
That "pops".

-What 700 class nitro engine would be best to start out on in terms of ease of use and reliability?

I fly the YS 96SR-X (G570 nitro conversion) and the YS 120SR-X (G700BN).
But, it depends on you skill.

No doubt, OS is easy to tune.
The YS engines reward people that understand engines with more power than the OS of the same size.
I have flown nothing but YS motors for the last 7 years
OS is fine too. No one would say otherwise.

The last OS engine I flew was the 91HZ-PSS - that was garbage.

-The OS 1.05H currently comes in two different versions: with or without a regulator. Which one would I need and why?

All YS engines use regulators and backplate pressure to the tank.
The OS engines with "DRS" in the name use a similar regulator and tank pressurization.
Given the option, I would always get the engine with the regulator.
Mainly the tank pressurization is more reliable and higher pressure than the muffler pressurized tank. This results in more consistency through out the flight and more power.

Couldn’t I use a plane fuel with 15% nitro and 18% oil?

OS says "... AT LEAST 18% by volume ... " and it can be caster or synthetic or a blend.
YS states 21%.
I use Rotor Rage 22.5% nitro with 21% pure synthetic in my engines

-Is buying a used heli engine riskier than buying a used airplane engine?

I never bought an airplane engine
I would suggest that they are not any different
Ask questions and get pictures before you buy it.

-Any particular brand of pipe I should be looking at?

That's easy:
Buy the pipe that is sold by the engine manufacturer.
Both YS and OS make pipes for their engines.

[jiminator]

If you're not totally stuck on the 700 size I would consider the Synergy 556 as @ticedoff8 also suggested. Then I'd look for an OS .50 Hyper. This engine has an idle adjustment and one needle which covers both the high and low end. This engine also uses muffler pressure. It would be really easy to tune and help you get used to what it takes to run a nitro. Also, most people either really love nitro or really don't like it and there doesn't seem to be much in between. If you end up not liking it, it wouldn't be to hard to unload and you wouldn't have as much money into it as a 700 size ship. Just a thought.

I only have experience with OS engines so I can't offer anything on how they compare with YS. But I can tell you I have had nothing but good results with OS. Even when I was a complete noob the only issues I ever experienced were self-induced. That said I'd really like to try a YS .96 in a Goblin 570 conversion It must be absolutely a rocket.

For fuel I've been using Torco 30% that I get off of ebay or Amazon. $126 a case delivered was the last price I paid. Runs as good as anything else I've tried. Keep in mind I'm not a hard 3d smack pilot but I've never heard of anyone complaining of this fuel.

[Skeezix]

Originally Posted by jiminator

If you're not totally stuck on the 700 size I would consider the Synergy 556 as @ticedoff8 also suggested. Then I'd look for an OS .50 Hyper. This engine has an idle adjustment and one needle which covers both the high and low end. This engine also uses muffler pressure. It would be really easy to tune and help you get used to what it takes to run a nitro. Also, most people either really love nitro or really don't like it and there doesn't seem to be much in between. If you end up not liking it, it wouldn't be to hard to unload and you wouldn't have as much money into it as a 700 size ship. Just a thought.

I only have experience with OS engines so I can't offer anything on how they compare with YS. But I can tell you I have had nothing but good results with OS. Even when I was a complete noob the only issues I ever experienced were self-induced. That said I'd really like to try a YS .96 in a Goblin 570 conversion It must be absolutely a rocket.

For fuel I've been using Torco 30% that I get off of ebay or Amazon. $126 a case delivered was the last price I paid. Runs as good as anything else I've tried. Keep in mind I'm not a hard 3d smack pilot but I've never heard of anyone complaining of this fuel.

Torco fuel? I've never even heard of that stuff! I'll have to check it out. I live in the Houston Tx area and heli fuel is nearly non-existent. I think a few places have VP but that stuff is very expensive.

[halfcab]

Honda not Ducati, you just made it simple.

I would suggest OS then.
I have NOT seen a night and day difference in power between the two brands.

On the OS the carb and regulator are accessible without pulling the engine.
If ever needed and regulator is in question, in a few minutes your back in the air.

With the YS your pulling the engine to almost do anything.

Nitro is not for everyone.

[Helicrow]

If new to nitro maby you should concider the OS105 HZ (muffler preassure) to keep things easy.

[Skeezix]

Originally Posted by Helicrow

If new to nitro maby you should concider the OS105 HZ (muffler preassure) to keep things easy.

Ok - good to know. What are the noticeable differences and if I don't get a regulated motor, do I need a special pipe/muffler?

Also what about novaRossi heli engines as an option to consider besides YS and OS.
Last I saw Thunder Tiger made a 1.00 heli motor also. Anyone care to comment on thunder tiger?

[thanasi]

Skeezix i was in your shoes lol been flying electric since i started in 2011and never wanted to get into nitro since i work on cars for a living and all the mess to deal with. Now its been a year looking on different nitro options and btw Goblin is king in my area.
After lots and lots of reading and contemplating what to get i ended up with the new 600XN super kit , man o man so happy with it, i have never flown a nitro till just now !!!! Its not a power house but enough to put a grin on your face. A really nice build and AFFORDABLE to maintain, just fed up with the cost of parts so this was a big thing for me.(i push and crash) I have been blinging long enough its time to enjoy flying versus the look at what i got stuff. Lots of support for this kit as you probably already know.
Anyway good luck i know im really enjoying nitro i hope you do to





Tom

[Helicrow]

Originally Posted by Skeezix

Ok - good to know. What are the noticeable differences and if I don't get a regulated motor, do I need a special pipe/muffler?

Also what about novaRossi heli engines as an option to consider besides YS and OS.
Last I saw Thunder Tiger made a 1.00 heli motor also. Anyone care to comment on thunder tiger?

The disadvantage with muffler preassure is that it will run a little richer when tank is full and a little leaner when tank goes towards bottom.

Advantage with muffler preassure is less things that can fail. With my muffler preassure engines its like i allways know it works. Just go fire it up and fly, only mainentrence iw bearing replacement. Pump/regulated engines is better for ppl used to nitro. They run consistent thrue the hole tank just as ritch/lean on full as on allmost empty tank. But more stuff that fail and if your new to nitro you will probably start messing with the needles just to find out the problem was the 1 way valve or diagrafm. Really depend on how much time you wanna spend learning how stuff works

[jiminator]

On your muffler question: most pipes have a threaded hole for the connection to the engine or if you're using a regulated engine just plug the hole with a screw. All of the Hatori and OS pipes I've got came with the necessary hardware.

[Skeezix]

An interesting update. A buddy of mine just gave me an older YS 91 ST motor that hasn't been run in 5 years or so. It came with an OUTRAGE pipe also. Does anyone know anything about the YS 91 ST? I know it's not an OS 1.05H, but it's FREE. I'm thinking about sending it into YS for a rebuild? I don't know anything about the YS heli motors except that the 1.20 vibrates a lot.
Anyway, just trying to figure out of that motor will work with the 700XN.

Again, thanks ahead of time - you guys are a BIG help!

[BrokeDad]

Originally Posted by Skeezix

An interesting update. A buddy of mine just gave me an older YS 91 ST motor that hasn't been run in 5 years or so. It came with an OUTRAGE pipe also. Does anyone know anything about the YS 91 ST? I know it's not an OS 1.05H, but it's FREE. I'm thinking about sending it into YS for a rebuild? I don't know anything about the YS heli motors except that the 1.20 vibrates a lot.
Anyway, just trying to figure out of that motor will work with the 700XN.

Again, thanks ahead of time - you guys are a BIG help!

Clean it up/out and check or just replace the bearings and see how it runs on the bench. I just got and old RJX nitro heli free and I plan on doing the same.

[DCflyer]

Originally Posted by Skeezix

An interesting update. A buddy of mine just gave me an older YS 91 ST motor that hasn't been run in 5 years or so. It came with an OUTRAGE pipe also. Does anyone know anything about the YS 91 ST? I know it's not an OS 1.05H, but it's FREE. I'm thinking about sending it into YS for a rebuild? I don't know anything about the YS heli motors except that the 1.20 vibrates a lot.
Anyway, just trying to figure out of that motor will work with the 700XN.

Again, thanks ahead of time - you guys are a BIG help!

No experience with that engine (its like a circa ~2000ish engine i believe) so they have been around quite some time. But there is nothing to a nitro engine. Take it apart, make sure the internals aren't scarred and rotate freely, replace top/bottom bearing, and piston ring. Replace clunk and fuel plumbing lines. Clean out carb and needle seats, etc. Just give it a good cleaning. I have rebuilt 2 decade old engines for people and they fired right up. Not an issue.

If you don't have the tools/help/support to rebuild it you can send it to Rich at YS motors here in Nevada. He's a great guy and will rebuild the motor and test it out to make sure its running/functioning correctly before shipping it back to you. He will charge you for the parts and a little bit for labor but very reasonable.

http://www.ysengines.us/pages/repairs

I'd say since you're just getting into nitro, a free engine/pipe is a good starting point. Learn on that and make your mistakes there before investing $600+ on a high end motor/pipe combo and then struggling with it.

Just doing a quick search I found this video with the 91 ST engine. Its certainly no slouch and looks to provide good power. Not sure what the difference is however compared to the SR versions (which you'd typically see in heli setups).

Trex 700N YS 91ST (6 min 4 sec)

[Skeezix]

Yes - I have reached out to YS in Nevada. The owner was at an event last week so I’ll call back today. No idea what the difference is between the 91ST that I have and the 91SR - hoping I can get a better picture on that soon.

[DCflyer]

Originally Posted by Skeezix

Yes - I have reached out to YS in Nevada. The owner was at an event last week so I’ll call back today. No idea what the difference is between the 91ST that I have and the 91SR - hoping I can get a better picture on that soon.

The 91 ST manual:
http://www.yspower.co.jp/en/data/pdf/91st.pdf

Just doing bit of research by looking at the manuals......

YS 91 ST:
Bore: 27.7 mm
Stroke: 24.8 mm
Displacement: 14.95cc
Weight: 540g
Practical RPM: 2,000 - 17,000 rpm

YS 91 SR:
Bore: 27 mm
Stroke: 26 mm
Displacement: 14.89cc
Weight: 553g
Practical RPM: 2,000 - 17,000 rpm


By these numbers, the ST has a shorter stroke and a larger bore. Its also about 13g lighter.

Also, upon doing research, I found that the ST's carb opening is 0.5mm smaller than the SR.

From another forum (from 2008):
"Depends what machine you intend using it in and what sort of headspeed you are looking for. The 91 SR loves the lower gear ratios(less than 8.27 to 1) and gives loads of torque. If you are after higher headspeeds and have 8.27 and above then the ST is the better choice.
Both are great engines, the SR is definately more torquey and probably has slightly better spares support"

Based on the quote above and the bore/stroke changes, it sounds to me like the SR was simply a revised ST motor to be more effective in terms of torque delivery for more modern, lower gear ratio'd nitro machines that could take advantage of that.

In summary, with all that being said, for a new-to-nitro pilot such as yourself all of the above is a moot point. You won't notice any difference whatsoever, especially if you're not a 3D pilot. I would say you're safe to use the 91 ST and just get it rebuilt.

The 700XN gear ratio's are designed to take full advantage of high torque motors like the YS 96/120 or OS 105 for maximum 3D performance, but they will run just fine on older engines like the 91 ST.

[Skeezix]

Originally Posted by DCflyer

The 91 ST manual:
http://www.yspower.co.jp/en/data/pdf/91st.pdf

Just doing bit of research by looking at the manuals......

YS 91 ST:
Bore: 27.7 mm
Stroke: 24.8 mm
Displacement: 14.95cc
Weight: 540g
Practical RPM: 2,000 - 17,000 rpm

YS 91 SR:
Bore: 27 mm
Stroke: 26 mm
Displacement: 14.89cc
Weight: 553g
Practical RPM: 2,000 - 17,000 rpm


By these numbers, the ST has a shorter stroke and a larger bore. Its also about 13g lighter.

Also, upon doing research, I found that the ST's carb opening is 0.5mm smaller than the SR.

From another forum (from 2008):
"Depends what machine you intend using it in and what sort of headspeed you are looking for. The 91 SR loves the lower gear ratios(less than 8.27 to 1) and gives loads of torque. If you are after higher headspeeds and have 8.27 and above then the ST is the better choice.
Both are great engines, the SR is definately more torquey and probably has slightly better spares support"

Based on the quote above and the bore/stroke changes, it sounds to me like the SR was simply a revised ST motor to be more effective in terms of torque delivery for more modern, lower gear ratio'd nitro machines that could take advantage of that.

In summary, with all that being said, for a new-to-nitro pilot such as yourself all of the above is a moot point. You won't notice any difference whatsoever, especially if you're not a 3D pilot. I would say you're safe to use the 91 ST and just get it rebuilt.

The 700XN gear ratio's are designed to take full advantage of high torque motors like the YS 96/120 or OS 105 for maximum 3D performance, but they will run just fine on older engines like the 91 ST.

Thank you so much! Now THAT'S great useful information!
I'm very excited about this.

[ticedoff8]

The YS 91ST is a good motor for a light weight helicopter
With the larger bore, shorter stroke and smaller opening, it has better torque output at lower RPM.

They are also easy to rebuild if you wanted to do it yourself.
But, Rich at YS will do an great job if you send it to him. But, he will not send it back to you with the needles preset - so that will still fall to you.

I fly around a guy that flies the YS 91ST in a Synergy N7 and he does some amazing stuff with the combination.

[Skeezix]

Originally Posted by ticedoff8

The YS 91ST is a good motor for a light weight helicopter
With the larger bore, shorter stroke and smaller opening, it has better torque output at lower RPM.

They are also easy to rebuild if you wanted to do it yourself.
But, Rich at YS will do an great job if you send it to him. But, he will not send it back to you with the needles preset - so that will still fall to you.

I fly around a guy that flies the YS 91ST in a Synergy N7 and he does some amazing stuff with the combination.

That's great to hear! I ordered the parts from YS in Nevada yesterday. I bought a back plate gasket (old one was ripped), and a new diaphragm for the fuel pump (figured after 5 years it should be replaced as a safety precaution).

I'm handy enough to replace those parts myself, and figured it wasn't worth the money to send it in to Rich at YS. I'll wait until I can get a good deal on a 700XN super combo (black friday?), but am happy the old YS 91ST will work for the airframe!

[ticedoff8]

Two things:
* The Trex 700XN is not a light weight helicopter. It basically weighs as much as my old Trex 700N LE.
I flew my Trex 700N LE (converted to DFC) with a YS 120SR-X.

* When you are working on the YS motor, do not use a petroleum based oil on anything.
The petroleum based oil attacks the silicon rubber diaphragms that are used in the regulator and 1-way check valve.
While the engine as apart, check the condition of the main bearing (check for a crunchy feel as it is rotated) and the ring (use a micrometer to measure the width of the ring - it should be 0.044" / 0.043". If it is < 0.042", it needs to be replaced)
They swell up and bad things happen.

[Skeezix]

Originally Posted by ticedoff8

Two things:
* The Trex 700XN is not a light weight helicopter. It basically weighs as much as my old Trex 700N LE.
I flew my Trex 700N LE (converted to DFC) with a YS 120SR-X.

* When you are working on the YS motor, do not use a petroleum based oil on anything.
The petroleum based oil attacks the silicon rubber diaphragms that are used in the regulator and 1-way check valve.
While the engine as apart, check the condition of the main bearing (check for a crunchy feel as it is rotated) and the ring (use a micrometer to measure the width of the ring - it should be 0.044" / 0.043". If it is < 0.042", it needs to be replaced)
They swell up and bad things happen.

Roger - no petroleum based oil.
What do you recommend?