Please read the warnings at the end of article for the 4-stroke!

Well… I decided to spoil myself with one of Miniatures Aircraft's newest kit…. The X-cell Graphite 60 SE. This is my first complete new kit in some time and I must admit…. It was worth waiting for! I am going to go through some of the building process here with some pictures. Pretty much all of Miniature Aircraft kits is built basically the same. So if you don't have Graphite SE kit these steps will still apply. Hopefully by hitting the high lights of this kit will give a good look at what to expect in this X-cell helicopter kit and others. If you buy the SE then you're probably already familiar with building and flying model helicopters. However, don't let the fact that this kit has every thing you would need in the way of a "complete" kit and then some put you off. With this kit you will have plenty of room to grow into it long before you will grow out of it. This kit will do every thing from giving a good platform to learn on all the way to competition, be that FAI or 3-D aerobatics.

Before I begin though, over the many years of flying model helicopters I have always heard that the X-cell's were a great flying kit but there is a lot of building to them…well as far as I am concerned…that's half the fun! Watching a few bag of parts turn into a quality flying machine that YOU built…with your custom craftsmanship thrown in for that personal touch. Knowing that YOU built it and have put loc-tite on all the parts that needed to have it.

The SE kit is about $180 more then the standard graphite 60 kit. You will get a lot for that extra money. First off it comes with a fully metal head that is mostly pre-assembled. It comes with the metal fan, the new metal Anti-rotation / upper main shaft bearing block, the new metal elevator bell crank and quiet a bit more. I will cover more as I go through the building process.

When you first open the box and dwell into it, you see a nice light glass canopy, which has a nice white gel coat. This is Miniatures Sport canopy. You will find a decal sheet with a new style graphics for the new SE helicopter. 2 larger packages of parts, and the tail boom. The parts bags will all have a number ID on the out side. In each you will open multiple bags of parts in for that building sequence. Each will have their own number stamped on the outside. While these numbers do not correlate directly to the building sequence, they will represent each building step. For an example there is 2a, 2b, 2c, 3a, 3b. Just follow in order and you will have the needed parts to build the helicopter. Each building step in the 60 page manual will have the part bag number listed so you can find the corresponding parts. There are 3 large blue print break out style prints that are clearly marked for building. They will have the layout and parts numbers with them. There is a 60 page manual with step by step instructions. There was a special yellow instruction sheet to let you know of some changes you can make if you're going to set the helicopter up for extreme cyclic response.

The first sequence in the building of this kit is to finish out the full metal head. I elected to not do this at this time because the space limitations of my workbench as you can see in the second picture. I figured I would hold off on this till the helicopter was mostly built so I could just add it to the helicopter at that time vs. having it just sitting around and possibly getting the flybar bent. However if you do not have a long 10mm-diameter main shaft for balancing the head, you will probably want to start with this sequence. This way you can use the main shaft in the kit on your high point balance. You can just drop down to that building sequence in this review. However I did take a look at the rotor head and I was really impressed with it. The silky smoothness of the blade holders was really impressive. The blade holders really felt like it was pivoting on glass, it was that smooth.

The next few sequences of steps are to build the upper frame set. During building you will find that the SE has a new style CNC metal elevator bellcrank #0825. This will allow there to be a slight gap now between this and the main shaft, no more riding on the main shaft. Very nice! This combined with the machined CNC elevator swing arm #0826 will give a really smooth and precise movement. This will be connected to the new SE style push / pull elevator arm #0819. This arm is larger then the other push pull arms and will allow a more precise servo set up. It is also pre drilled for different ball locations so you can get the movement you want, either for a normal set up or 3D. Next you will notice the new CNC metal upper main shaft-bearing block with the machined anti-rotation bracket #0823. These two parts fit together very nicely and you not have any of the movement that was possible with the older style anti-rotation bracket. Also the main shaft-bearing block has the mounting holes tapped out so it will allow for the mounting bolts to screw into the bearing block. This will take any chance of compressing the bearing and will make that bearing last much longer. The kit comes with the load free CNC front tail rotor / lower bearing block support #0832. This allows you to run piezo type gyros with out any possibility of stripping the main gear from excessive loads from the tail rotor when you stop during hard tail rotor commands. The tail rotor support block is also set up for longer bearing life do to the fact that the mounting bolts do not squeeze the block together but has the 4 bolts pulling towards there respected side frame.

Before you install the main gear into the side frames I recommend you check the balance of the main gear. I took the main shaft and installed the gear and auto-rotation hub onto my high point. (Excuse the quality of some of these pictures.) If by some chance the balance if off you can rotate the main gear on the hub and recheck it. Get the best spot you can. Then you can bolt the hub and the main gear together. Then after rechecking it, if you need you can take a small drill bit and in the outer ring of the tail rotor teeth you can drill some small balancing holes. This main gear is the machined version and mind did not need any balancing at all. Very impressive! Any moving parts that spin at a high rate of speed should be checked for balancing.

Included is a special instruction sheet (yellow) that will give you detailed instructions for setting up the swashplate and the washout unit for extreme cyclic movement. The added parts are included in the kit. This is nothing more then some shorter machined threaded steel balls. The shorter balls will keep the washout units special links from hitting the ears of the swashplate.

During the assembly of the washout unit you will use very little circlips to keep the pins in the washout unit secure. This can be a slight pain to install and if your not careful they will and can fly, but with a little work you can get them on. Being thoughtful, miniature gave us an extra one just for that reason.

Next is the building of the lower frame set. Nothing special here. All the mounting holes lined up perfectly so it's very easy to get a "true" alignment with these frames.

The metal fan is included with the SE. Before I installed the fan I check the balance of this also on my high point.

The SE kit comes with collets for the OS 61sfn and OS 61sx engines. If you use a different engine you will need to get the collet pack for that particular engine. I put the collets on my high point shaft and check the balance. If you need to balance the fan then you can put some small, not through, holes in the bottom of the fan. Do not go all the way through or in the location of a fan blade. Mine however did not need any balancing. The fan also included new style dampers #0546-16. These are of a one-piece design per side. There is a small hole in them for the clutch shaft. Much nicer then the older style that has the 2 pin style rubber dampers. After installing the fan I check the run out of the fan with a dial indicator. Mine fell with in .001 right off with out any playing with it before hand to find the best spot.

My 1st of 2 deviations from the instructions was on the landing gear. Over the years I have always had the landing gear skids rotate in the struts. So this kit I wanted to try something new and so far so good. It's always been a small pain to heat up the struts and put the skids in place before they get tight again. So what I did was take a drill bit and slightly enlarge the skid holes in the struts. I would only use the drill bit by hand and go 3/4 of the way into the hole. This would allow my to insert the skids will very little effort. Then I "pinned" the skids in place after I mounted them to the lower frame set. I used some small M2.2 cross-tipped screws from the inside edge of the struts. So far they have stayed in place. This is also where one of my 2 minor disappointments came into play. I would have liked to see the #0822 machined aluminum lower frame landing gear attachment plates in the kit. While this is not a big deal these plates are very nice and can really add some low weight strength to the side frames.

Next on the list of things to build is the tail rotor transmission. The SE comes with the non- - dampened tail rotor hub #0541-7. Unlike the other dampened style of hub you defiantly need to use the lighter carbon fiber tail rotor blades. DO not try to use other blades or you will take a chance on breaking the out put shaft of the tail rotor box. After the building of the tail rotor hub with blade holders I checked the balance of this also. Once again I used the high point style balance.

I also installed a grease hole into the upper tail rotor case. This is just a same hole that you can put a 3mm bolt into to seal it up. I cut a small round servo grommet for a seal washer. You can also use a small "O" ring if you can find some. Don't use a long bolt. This hole will be drilled over the tail rotor out put shaft. Make sure that if you do this, your hole is not in line with any bearings or the gear set. Do this at your own risk. There is not much to it but watch out for the location. I also installed a small 3mm bolt and small washer into the tail rotor out put shaft end. This will serve no real purpose but just incase something should happen, it might keep the tail rotor hub onto the shaft.

Now that I have the helicopter mostly built I went a head and finished off the main rotor head. As stated earlier this head came mostly pre-built. I just had to build the paddles and install them with the fly bar. The SE came with the new style metal flybar control arms #0848-8. These already have a lowering sweep to them. This keeps them from hitting the underside of the head when extreme cyclic is used.

For alignment of the flybar control arm this is what I did. I use 2 "L" machine blocks but you can use something like your vise jaws to level them. Lightly tighten both of the flybar arms to the flybar. Make sure you have equal spacing on the flybar. Then set the head between your blocks or vise jaws and rest the arms on the blocks or vise. Only the tips of the arms will touch. By doing this then both arms will have the proper down sweep to them. You can lightly rotate the arms as needed to get both of the arms level to each other. Once you satisfied that the arms are the same, you can finish tightening the set screws in the arms. Install the flybar paddles and align them with the top of the head. The Miniature paddle alignment gages #0510-1 works very well for doing this. Although all the other bolts have been installed and loc-tited I did recheck them just to make sure.

Next I balanced the head on my high point. I use a long 18in x 10mm diameter shaft on my high point to balance the head. I will check the balance in all 4 directions and adjust the paddle weight as needed. If you don't have a long balance shaft you can use the main shaft on your high point before you install it in the first sequence of building. I ended up only needing a small 1/2 in piece of tape on one paddle to balance the head.

The canopy that is included in this kit is the lightweight glass sport canopy #0504 with a new style of decal sheet with it. You can build it with or with out the tinted lexan window. I elected to leave out the lexan window and will paint one on. The canopy comes in a white gel coated. Mine had just one little flaw in it that was hardly noticeable. So you can either paint it or just stick on the great looking decals and go fly.

The tail rotor fins are also new #0588-8 and #0588-9. They are also carbon fiber with a white coating on them. These can be painted also or you can use the special designed matching decals on them. These fins are really light. Lighter then other carbon fins. My vertical fin though did have a small indentation in it. This was probably from shipping. It's not very noticeable but it is there.

You can purchase this kit with no blades or with wood blades or 3D glass blades. If you use the wood blades there are very detailed instructions on finishing them and balancing them. I already have a set of miniature 3D symmetrical blades that I will use.

The rest of the building sequence will be the radio installation and setting up the lengths of the pushrods. The exploded views and instruction manual both will have detailed measurements on them for the lengths. If you follow these you will get a set up that is very close to perfect for a normal or 3D set up. If you have flown R/C helicopters and are experienced with them you probably already have your own touch on setting them up. Between this and different radio's though it can very. If you follow the basic instructions you will be fine in all cases.

The tail rotor push rod was the 2nd place that I wished Miniature had included a different part. The included tail rotor was the stock wire rod. I would have liked to seen the graphite push rod here #0544. It also is not necessary but I would have been nice to have. The wire is just fine though because with the new pro2 style rear mounted tail rotor servo the distance to the tail rotor is minimal and has good support. I had a spare graphite tail rotor pushrod so I installed it. I found in my other xcells that this can tighten up the control surface and eliminate and flexing in the tail rotor pushrod during high loading tail rotor turns.

Well onto the fun part! FLYING!

For my set up I use the Futaba 9z radio with a 501-piezo gyro. I am using YS 61-ST1 engine with a hatori muffler. The blades will be Miniature symmetrical 3D blades. This will be my second YS engine since there release. While my first one rain very well, it seemed to be lacking a little on the power. I really didn't like the performance with the long 690mm symmetrical 3D blades. So we will see what this new YS engine will do.

My set up for the SE is as follows:

All hovering is set for 3/4 throttle stick
+9.5 degrees top end
+5 degrees for hover
-2 degrees for normal negative
-5 degrees for idle up 1
-9.5 degrees for idle up 2
-7 degrees for low autorotations (use -4 to -5 for a normal setup)
+6, -6 degrees of main blade pitch through during full cyclic travel

The first day of flying it was a nice day but windy. The Ys started up just fine with the initial settings specified in the instructions. 2 turns on the larger hovering needle, which you might think of as the main, and the 1.5 turns (factory set) of the sub needle.

I let the engine warm up a bit then spooled up the helicopter. I needed about 2 turns more right tail rotor and 1/2 turns more of right roll. The tail rotor blades are a little longer then what I normally use. The kit comes with 105mm graphite tail rotor blades. Normally I will use about 95mm blades. The longer blades give very good power, however I had my gyro set too high. With the piezo I set it up for stick priority at 100% and this gave me a tail wag. After adjustments I am now down to about 45%. The helicopter was very smooth after that. With the YS and hatori muffler you will get very smooth running engine, good smoke and a lot of quiet! In-between flights I moved my tail rotor control rod take off closer to the center of the tail rotor servo. This allowed my to increase my gyro to about 60%.

I first put about 4 tanks of fuel through the engine before flying around. Just wanted to get it started on a good break in. the YS will take a little bit longer then other engines to break in. after the 4th tank and since it was pretty windy I figured setting the tail rotor mix was out for the most part. I did however have it pretty close by using 20% up and 20% down on the mix. So I decided to try some auto's. Boy was I impressed! Much better then I had expected with this blades. However it was pretty windy. The engine defiantly had much more power then my last YS. It pulled 9.5 degrees of pitch on a climb out to the autos' will no problem.

After about 6 tanks of gas and in-between flights rechecking all my bolts to make sure they were still tight, I tried a few loops and rolls. These were very smooth but not as much authority as I had expected but at a very predicable rate. The metal rotor head has a smoother feel to it then the stock composite head. I really like the way it feels. I was able to put 8 flights on it the first day. As soon as the wind calms down I can get into setting up the helicopter better for 3D.

In conclusion, this is one nice helicopter with just about every upgrade you could possibly want. It hovers very smooth and does the hardest aerobatics you can through at it. The initial set up that was given in the manual is very close and will defiantly get you going. After you fly the SE you can make your own adjustments to suite your needs. I only wished that the machined metal side frame brackets #0822 and the carbon tail rotor pushrod #0544 was included. Although not necessary it would have been a nice added touch. The complete kit took less then a week of nights building to finish, not including the canopy painting. Total hours were less then 25 hours and that was reading all the instructions like a first time builder would do.

I found that the quality of this Miniature kit is to be excellent. Well suited for the beginner to expert alike. I would defiantly purchase another.



The kit will basically build the same as the nitro version of the SE kit. However you will have some parts that are not the same. You get a 12 tooth pinion gear vs. the 10 tooth. This makes the bell larger in diameter also. The clutch is larger to handle the extra power. The clutch is also the "bolt on" style vs. the uniball style. You get a 88 tooth main gear instead of the 90 tooth. This gives you a 7.33:1 main gear ratio. A good majority of people that upgraded there kits to the 4-stroke option are still using the 90 tooth main gear. This gives a 7.5:1 gear ratio. Either seems to work fine. One of the reasons given to leave the 90 tooth gear in, is that they can swap back and forth with a 2 stroke engine and not have to worry about changing out the main gear again. The lower frames are different. The throttle linkage is different for the YS 91. You will install a bellcrank on the engine and a short pushrod that drops down to the carburetor. This is because the carb on the YS 91 is on the backplate of the engine, so when it's installed, the carb will be down between the landing gear. This made me a little nervous because I thought that the engine might suck up some thing. This could be a possibility if you fly off of deep grass. However, so far I have not had a problem. Just put a piece of heavy non-shagged carpet down and you should be fine. The draw of air isn't as much as I thought it would be.

Here is a picture of the top of the engine head, and the airchamber assembly. As you can see it takes up a little more room then a 2 stroke, but fits nicely in place. With the SE I put a header tank on only because the SE canopy has these little lips on the edges of it. This can make seeing the fuel level difficult, not impossible but. However if you set a timer, you can keep track of your fuel that way. I have been getting as much as 18 minutes of mixed flight times with this 4 stroke, and that's with a rich engine mixture.

Before tank pressure

After tank pressure

The YS 91 has its own fuel pump that pressurize the fuel tank. MAKE SURE YOUR TANK HAS NO AIR LEEKS IN IT! What I do is build the tank and put 2 pieces of fuel line on the tank fittings. I then plugged these up and put the tank under water. Then you can squeeze the tank and should not see any air bubbles. Or you can plug one line and "blow" into the other one... pinch off that line and put the tank under water. PLEASE make sure there is no fuel in the tank! After you fly the helicopter you should pull the one way valve. The tank then should release its pressure. Don't point the vent line at any thing you don't want fuel on, nor your self! The YS91 works a little different then the ST-1. The YS91 has a variable pressure system. It will pressurize the tank more during full throttle then at hover, So don't judge the amount of pressure as something being wrong, but there should be some. As you can see, there is A LOT of pressure in the tank. I'm thinking I'm going to change this tank back out to the original one.

After you fly the helicopter a hour or 2 you will need to do a valve adjustment on the engine. You should be able to access the valves while the engine is in the helicopter. I checked them once now and its pretty easy but the engine was out of the helicopter, so after a couple of hours we will see. I purchased a "metric" feeler gage from "Craftsman" and it works fine. About $7 bucks, but I can also use it on my car.

This picture shows the latest hatori muffler (694) that comes with the kit or upgrade. However you can order the upgrade with out the engine and muffler. The 4-stroke is super quiet, even with a pipe! You can see the style of header that comes with it also. This was probably one of the only things that takes a little work to do, getting the header tight on the engine. Its getting a 14mm wrench in the little slot that makes it a little more tough. Also inside the engine head / header hole there will be 2 copper "O" rings that need to go in first. The header will tighten up against these. After you run the engine the first time and it heats up, you can come back and recheck the tightness of the nut on the header. It might have come loose do to heat expansion of the metal. As for the pipe mounting clamp clamp, use the one that comes with the muffler. You do not want to use too soft of a mount or you will break the header. This is because the coupler between the header and pipe is hard and will not give. So far I haven't had a problem but...

Here are a few pictures of the finished 4-Stroke kit. As of this article I have about 2 gallons of fuel through it. I have been running Cool Power 30%. I set the helicopter up for +11, 0, -11 degrees of pitch. It likes to hover about 1450 rpm's for me. That is about 25% throttle opening. Yes...25%... the 4-stroke runs different. I set the idle up rpm at 1650 rpm's.


Not to scare you but the governor is really worth the investment on the 4-Stroke. The YS-91 peaks about 14000 rpm. That's about 1866 - 1900 rpm's, depending upon what gear ratio you end up using, but when this engine unloads you don't want to push it to the max. Even at 1650 rpm's, you might feel you have a safety margin, but its not worth taking a chance.


I have my main needle open about 1.5 turns to start. The low end is open about 1.25 turns. REMEMBER! THE LOW END NEEDLE WORKS BACKWARDS. IN IS RICHER, OUT IS LEANER! Also the low end needle works backwards from most engines. Turning it in will make the engine run richer. Turning it out will make the engine leaner.

These engines are very strong running engines and will last a long time if you take care of them. Don't push the limit. But you will be rewarded with a very smooth running engine that is GREAT on fuel. It will take at least 2 gallons of fuel to break this engine in. DO NOT "LUG" the engine down, especially at the lower head speed. I have found that it doesn't like the full 11 degrees at the lower rpm but at the 1650 it doesn't have a problem pulling it. This is with the Miniature Aircraft 3-D blades.

As you lift off into a hover you will find the helicopter putting out a lot of smoke. Then as you go "upstairs" and fly around, it will still put out great smoke..some times it gets a little thin abut 3/4 throttle. Keep an eye on that 3/4 spot. You don't want it to be lean there. I haven't found it to be as of yet. When you come back in to a hover from forward flight, the smoke will be much thinner for about 5 seconds till the engine settles back down. Then the smoke will pick back up.

The engine likes to use either a OS "F" plug or a Enya #3. However I have heard good things about the new K&B Platinum plug. I'm going to give this a try also and see what happens.

Sooooo...For now... I'm giving the 4-Stroke YS91 version high marks. So far ... So good! I'm liking it better then the YS 61-ST1. I've been hearing good things about the YS61-ST-2, but that's for another day!

Enjoy! I am!


Copyright © 1999 by [Helibuf's World]. All rights reserved.
Revised: 27 Aug 2003 20:33:34 -0700 .