Zenoah flywheel tool

Fuel Inlet fitting - includes mounting hardware. Fuel Vent fitting - includes mounting hardware. Air deflector for Zenoah G2xx engines. Gas Fuel Tank Plumbing Kit. Fully adjustable! Everything you need to setup and support your gas helicopter. Tired of measuring just the right amount of oil to mix with fuel for you gas helicopter or car?

Premix oil for your gas helicopter! High volume air filter and velocity stack for Zenoah engines. Custom made clutch base for Zenoah RC Engines. Spool to wrap fuel vent lines into a perfect coil Can be installed over a frame spacer or bolted to the frame Fully fuel proof.

Pics 6 and 7: Unplug the red wire between the red and grey coils. Hold both sides of the connector firmly when pulling to seperate them in order to prevent pulling the wire out of the connectors.

Pic 8: Remove the two screws holding the grey coil to the side of the crankcase. Stock screws are Phillips head screws. Remove the grey coil. Pics 11 and Remove the three screws that hold the motor's backplate.

On stock motors these are also Phillips head screws. It is sometimes fairly difficult to remove these, and the head can strip easilly so be careful. If you do strip one been there use a rotary tool with a cutting disc and cut a flat slot in the head and remove the screw with a good flat tip screwdriver. Notice that the backplate pictured here has been modified somewhat. I had to make some emergency mounts for a race and actually kept them. I don't use them anymore but still keep them as backups.

Pics 14 and This is how I hold the flywheel in order to remove the pulley that holds it on the crank. There are different methods of doing this, including stuffing small rope in the cylinder or using a piston stop tool, but these methods rely on the piston to hold the crank in place when you are applying force on the pulley to remove it.

Doing this can actually lead to the crank being forced out of allignment. I simply insert a 6mm allan bolt into one of the puller holes in the flywheel and position the flywheel as pictured. The bolt has to be long enough to go through the flywheel and protrude in the back. The bolts I use are 30mm long from under the head to the tip of the thread, and fully threaded.

As you try to turn the flywheel counter clockwise, the screw will butt up against the crankcase casting behind the flywheel and hold it enough for you to remove the pulley. This same method is used to re-install the pulley later on. Pics 16 and Shows what I use to remove and install the pulley. You can actually purchase a tool for this from Zenoah, but this works just fine.

One of the ears of the pulley fits into the slot and the side of the bar rests against the other ear providing ample grip to unscrew the pulley. In future "Hobby Machinist" articles I will try to illustrate methods of making a few handy tools for engine work, including a tool similar to this one but nicer and a flywheel puller.

Pics 19 and Remove the two screws holding the pickup coil red in place over the flywheel. The stock bolts are Phillips head screws. Pics 21 and Shows the "puller" I use to remove the flywheel. Its simple and effective. Spacing the two 7mm diameter holes 47mm center to center will do the trick. Insert the bolts in the plate and thread them into the two matching holes in the flywheel.

Thread them in slowly and evenly until the plate butts up against the crankshaft end. Hold the plate with one hand and tighten each bolt a little at a time so the pulling force is even on both sides.

You will have to hold the plate firmly and apply sufficient force on the bolts. You will hear and feel a sudden "pop" when the flywheel comes off the cranshaft taper.

Then simply pull it off by hand and remove the puller. Pics 23 and Using the side cutter pliers, grip the flywheel key and pry up to pull it out of its keyway. The key is made of fairly soft metal, special care should be taken to try not damaging it.

If you damage it burrs file it clean before re-assembly. Pics 25 and Removing the clyinder. Loosen and remove the four allan bolts holding the cylinder down. Genlty remove the cylinder from the base. You might have to pry a bit to loosen the cylinder off the base if the gasket is "stuck".

Once you feel it let go, lift straight up. Grab hold of the piston as soon as the cylinder is high enough to do so to avoid letting the piston drop out. I did not remove the piston when I did this rebuild, but this is a fairly straight forward task that I will try to explain. There are two snap rings one on either side holding the wristpin in the piston. To remove the piston you must remove the wristpin.

To remove the wristpin you remove the snap rings only have to remove one actually and push out the wristpin. Hold the piston while doing this. Then you carefully lift the piston off the connecting rod and lay it aside. The bearings in the connecting rod piston end are now free to be removed, or fall out! Carefully remove the two spacer washers one on either side of the bearing and slide the needle bearing out of the connecting rod.

You have to take them out or they will fall out. Happilly the needle bearing is a caged type! To remove the ring from the piston find the break in the ring, at the retaining pin and spread the ring open enough to lift it over the piston crown top.

DO NOT pry! It must be out of the ring groove, all the way around before lifting. If you pry, it WILL break. If you spread it too much, it will also break! If you are going to remove the ring, have at least 1 spare one handy just in case. Pic Remove the four allan bolt that hold the crankcase halves together. These are at the flywheel end of the motor. Pic Shows the crankshaft still inside one of the crankcase halves. Pics 29 and Crankcase halves and crankshaft removed. Pics 31 and Removing the large oil seal output end.

I pry it out part way with a flat head screwdriver then push it out from the other side using the same screwdriver. There are so many different way of doing this, but this works for me. I almost always destroy the seals taking them out this way though, but I would never re-install old seals in a motor anyway, so I don't take any special care in removing them.

Worth noting however is to take special care not to damage the seal seat in the crankcases however. It is easy to burr the inside of the crankcases when removing the seals so be carefull. If you do happen to damage them, carefully file them smooth using whatever you can to do so. Do not modify the bore. You want the new seals to fit in properly and seal the way they should: they not only seal on the crankshaft, but also in the crankcases.

Below is explained using a small propane torch. Carlo uses a much safer and more controlled method with incorporates the use of a small toaster oven. Pics 33, 34 and Dropping the bearings. Setup the case with oil seal removed on a fireproof surface with bearing side down. With a propane torch, heat case evenly around the bearing, taking care not to stay in one place long and not heating directly on the bearing.

You want to heat the aluminum around the bearing enough for it to expand. The aluminum will expand faster than the steel bearings especially if you do it right and don't direct the heat on the bearing itself and the bearing will simply fall out.

Notice the cirlclip or snapring in the output side case. This serves as a stopper for the bearing. Pics 38,39 and Removing the small oil seal flywheel end. Notice there is no snapring stopping the bearing in this case. The case itself has a lip for the bearing to butt up against. Thus the reason for the smaller oil seal since the bore is smaller on that side.

Pics 41 and Drop the bearing, same method as the other bearing, by resting the case bearing side down on a fireproof surface and heating it with a torch. Aluminum can easilly be melted, so a propane torch is the most heat you would want to use, and avoid heating the same area consistently. Basically do everything in reverse order! I will cover most steps briefly and only point out important aspects! Most of the pictures are self explanatory, escpecially now that you know how everything came apart!

Pics 45 and Installing the new bearings. If you removed the snap ring in the output side case, make sure to re-install it prior to installing the bearing. Setup your case halves on a fire proof surface, this time bearing side up. Heat the cases with the propane torch to expand the metal. Without using heat measuring tools, there is no way of determining the exact amount of heat and time required.

There are heat indicating pencils availlable that will melt when rubbed on a hot surface when the surface gets hot enough. You can equally use infra red heat guns, or heat controlled ovens. There are a multitude of ways of doing this. I have an infra red heat sensor gun, but don't actually use it for this.

To be totally honest, I usually heat the case for about the same time as it took to drop the bearing. This is far from scentific, but seems to work just about everytime! Do it however you feel is best for you.