>>> Eggmotor - Engine

The four videos above demonstrate the dis-assembly of the engine and removal of the governor unit which is necessary in order to get the required rpms. After you have removed the governor unit, the long spring on the governor arm can be then used as a throttle return spring. The videos also demonstrates this procedure.

When you have taken out the governor it would be a good idea to remove the low-oil sensor. It’s the black module that sits under the crank. Just unbolt it and snip the wire which goes to the master switch. Feed the remaining wire from the sensor out of the black rubber nut/fitting on the outside of the block, pull it out of the bullet connector and discard. This empty connector can now be used for your kill switch. Fill the small hole where the sensor wire went with either some epoxy glue or a small/short self-tapping screw.

If you have or about to order some or all of the upgrade parts (listed below) then don’t rebuild your engine just yet. Take a look at affordablegokarts web page on the performance basics that are possible on your engine. When rebuilding it is important to correctly torque all the nuts to ensure nothing falls off. When you are fitting the flywheel nut (flywheel needs to be removed when following the governor removal procedure in the video and if replacing standard steel flywheel with an aluminium billet one) you really need to ensure correct torque. Go to affordablegokarts torque values page for more info.

Below I have listed the bare minimum of parts required to achieve around 14hp and upto 40kg thrust (with the correct propellor specified later on). These parts and prices are taken from affordablegokarts own site and were correct as of February 2009. The following parts are all fitted to the original prototype (except the cam which is a slightly different specification).

So hopefully, all being well you now have a potent 4 stroke. Bolt it to a workbench or table if possible so it doesn’t bounce around while testing. Add some 10w - 30 motor oil(approx. upto the edge of the filler tube). Fill the fuel tank, turn fuel tap on, almost close the choke, add some throttle (use the adjusting screw if you haven’t set up a throttle mechanism yet to turn the throttle to about 1/3) and pull the starter cord. You may need to adjust the choke and throttle a little in order to start the engine. Don’t run at full throttle yet as the engine will be ‘tight’ until it’s run-in and also because there is no load on the engine you could possibly destroy it. Here is my video of the first engine run after re-assembly.

So there you have it, approximately 14hp for not a lot of money. Not too bad so far, eh????

While I remember, now that the standard airbox has been thrown the choke lever has a tendancy to fly off ever time you start the engine. You will ideally need to fabricate a ‘choke hold’ of some discription to prevent this. I have bent a length of 4mm rod and screwed it to the spare bolt hole on the cylinder near the throttle and it terminates just above the choke lever. I’m sure you can think of something. ARC Racing have a choke hold on their shop page. I’m not sure if the AGK filter adaptor will allow the fitment of this part.

Propellor Hub...

In order to fit the prop to the engine, you are going to need a hub. The one I found most suitable was from Zero Error Racing in the USA (see below). Currently it is just shy of $30.00 and you can purchase it thru PayPal. Most engines don’t come with a key fitted to the output shaft so you will need about an inch length of 3/16 inch square rod to lock the drive between shaft and hub. The bolt circle is 1.687 inch across and you will need this information in order to get the propellor correctly drilled. Below is an image of the dimensions I sent off for the prop fabrication. UK source for prop hub now available.

When fitting the prop to the hub it would be wise to fabricate a face plate in order to distribute the bolt loadings evenly over the prop surface as oppose to just using large washers on each of the 3 bolts to press against the wood. It will help improve the strength of the fixing and reduce any deformation of the relatively fragile wood. Just use the hub as a template for the diameter and bolt hole locations.

Use 6mm diameter bolts which should be long enough to pass through prop, hub and maybe 20mm spare to allow ‘double-nutting’. The thread on the inside of the hub I guess is of an imperial size and a 6mm diameter bolt thread doesn’t quite provide a secure fixing (you might find it tricky to thread through it too). So, if you thread the bolts from the front (through the face plate first, prop and then hub) and then secure with a standard 6mm nut and then immediately with a 6mm nylon locking nut behind the hub to make absolutely sure the bolts don’t work loose. The bolt circle diameter needs to be 42.85mm (1.687inch).

Right, we are getting somewhere now.

I will tell you now that I have only tried one size prop with the engine configuration and I don’t think it is far off in terms of correctly matching the power/rpm. If you wish to experiment to gain more thrust then that is up to you. I chose a 34" x 10" large-scale model radio-controlled aircraft propellor from Xoar International. The prop is a PJD-P (pusher) type. Again, PayPal accepted and the price including UK shipping was $160 back in the Autumn of 2008. Just send them the drilling dimension image and you will get a reply back from Matt and/or Kevin. Expect a 2-4 week wait as I believe they are made to order and not ‘off the shelf’. Now available is the Thrust Data Sheet for this prop. Using a digital tacho (e.g. 'tiny-tach') or a non-contact laser tachograph device you can now get an accurate thrust output figure just by testing the rpm alone :o) One of the cheapest non-contact versions I found was on ebay for around £10.00 (still need to test it though as it is still on order from Hong Kong).

Well that’s it really for the power upgrade, hub and prop. The next page delves into fabricating a useable throttle/kill switch unit.

Click here for the Throttle page.

Honda GX200s are quite expensive but luckily for us, many Far Eastern countries clone the Honda design and sell them dirt cheap. If you do a search on ebay for ‘6.5hp’ or ‘GX200' then you will usually come across a variety of different clones.

To order these parts, the propellor and engine hub from the various suppliers then ideally you will need a PayPal account. Your contact at AGK will probably be Shane, he really is a nice chap and has always helped me with queries and parts orders. For international orders you don’t need to set up an account on the AGK web site. Just send Shane a list of your requirements and he will reply with a PayPal invoice. Pay up and wait for the postman ;o) Please Note: You may be subject to additional shipping charges and VAT/import taxes when ordering parts from outside the UK.

When it comes to fitting the parts, AGK has a few pages of tutorials to help you out. Or you can get some of the info from the previously added videos. Also, ARC Racing’s blog has a wealth of knowledge to help you out, plus a good selection of parts.

Things to note:

Make sure when you fit the air filter adaptor that it is not upside down. The two holes on either side of the carb bore are not quite directly opposite and putting the adaptor on upside down will cause the cuts outs to not properly match up. Click here for example.
The carb main jet is accessed by the nut on the bottom of the float bowl and then using a smallish flat blade driver to screw out the jet. If you are feeling confident you could drill the hole out bigger with a 0.9mm drill bit rather than ordering a 90# jet. Make sure you drill it dead centre though.
The aluminium billet flywheel can be fitted as per the video but make sure you have the correct gap between magneto and coil.
Make sure you adjust the valve lash (the gap between the valve cap and the rocker arm correctly) when swapping the cylinder head over. Again, AGK and/or ARC Racing have info on this procedure. I refitted the original head gasket when I changed the head over and I don’t appear to have any compression leakage. You may decide to order a new one.
While you are doing the head it would be wise to fit the stronger valve springs too if you’ve ordered them. Valve float is probably not an issue with the ~5,000 max rpm the engine will be giving under load and so you may decide to not bother with the springs at all.
The cam is an easy job while the engine cover is off. Just make sure you line up the dimples with the crankshaft to ensure the timing is correct. Click here for more info. This link to AGK’s cam installation guide covers the topic of grinding the engine block to ensure clearance. This procedure is not neccessary with the cam size I’ve listed and so you can ignore most of the tutorial.

New Parts Update...

I have recently been in contact with Shane at affordablegokarts regarding two of their bolt-on kits available for the engine.

The 'Best Bang for your Buck' kit ($380.00) and the 'Bolt-On Kit #10' ($820.00) offer upto 15hp and 18hp respectively. Using the newly acquired thrust data from Xoar Props means that the 'BBfyB' kit should still give you 40kg thrust and the 'Bolt-On Kit #10' should theoretically produce 47kg thrust @ 5600rpm which is enough for a 95kg pilot.

Tim Kerr at GX160Parts.com has recently updated his web site with new stock which will ultimately help the UK Eggmotor builder enormously.

There are complete tuning kits and upgraded engines available now. Obviously this will save any UK builder a small fortune on expensive shipping and import duty charges.

Individual parts are still available such as aluminium flywheels, cams, heads, carbs. etc. Click here for more information.

Also available are paramotor engine/prop hubs. Custom manufactured, these retail for £24.99 +VAT. Ideal for 'Eggmotor' project or any other GX160-GX200 based direct-drive paramotor with a 3/4inch output shaft.

There are a range of kits and engines available for the GX160 and GX200 models from the GX160Parts.com website but the best two in terms of power output are stated below.

Optimum kit is the Performance Upgrade Stage 3 option for £384.99.

Optimum engine specification is the GX200 Stage 3 option for £674.99.

I can only speculate at the moment that +15hp and >45kg thrust with a 'standard' size 34"x10" Eggmotor propeller should be feasible.

The comprehensive list of parts in the above two options will give sufficient power and reliability to build a successful paramotor for a lightweight pilot. The engine option will also give piece of mind to anyone daunted at the thought of tackling an upgrade task themselves.

GX160Parts offers free delivery on all orders over £100.00.

Please note: While building Sam's 'Egg' with the blue/black Wiltec engine, I found that I have had to machine the inside of the hub a little bit in order to fit it onto the output shaft. The Loncin engine on the prototype has a 3/4inch shaft and I had no problems with the hub, while the Wiltec appears to have a 20mm diameter shaft. Also worth pointing out is that the Wiltec's output shaft is about 10mm shorter than the Loncin engine too.

Please Note: The 'Bolt-On Kit #10' has a different carburettor and will require a different throttle cable set up compared to the 'standard' option. Also, this means that a carb adaptor manifold is required (included with kit) which may cause air filter clearance issues with a standard Eggmotor frame. On the plus side, it has a 'pulse' fitting which can be used in conjuction with a pulse pump (UK source) to draw fuel up from a larger tank positioned under the engine rather than using the 3.6 litre metal tank above the engine.

Addition...

A fellow 'Egg' builder and myself have now had prop bolt failures using 'normal' bolts purchased from local hardware stores. This has unfortunately resulted in damaged/destroyed props. I have now fitted both Eggmotor prototypes with high tensile bolts which should eleviate the problem. Also, as the thread inside the hub doesn't quite 'grip' the bolt threads I have drilled the thread out with a 6mm bit and continued to use the 'double-nutting' method of secure fixing.

Addition...

Sorry, I forgot to mention that the exhaust headers that come with these two kits might extend beyond the 'prop' circle which will obviously prohibit the rotation of the prop. This can be remedied by cutting/re-welding the header on the flange or by asking Shane to swap the header in the kit with a RLV type (just like our prototypes). If you ask him nicely he might do a free upgrade to the RLV type.

One or two 'egg' experimenters are having fuel leakage issues with the Mikuni carb in the 'Bolt-On Kit#10'. Possibly due to the tilting/twisting motion of ground handing. Purchase at own risk or try asking Shane to swap to a bored GX200 carb or GX390 carb (plus the relevant adaptor).