Extra Oomph???

Posted in EggDev with tags , , , , , on March 23, 2011 by eggmotor

23.03.11: Well we finally got to thrust test the Egg with the new head and carburettor combo a couple of weekends ago and things didn’t go to plan. As you can see from the video below, we only peaked 38kg thrust which is 2kg less than with the previous cylinder head and stock carb. I wasn’t sure where the problem might have lay and so doing some quick, rough calculations it appeared we were only getting about 4500rpm.

Any way, I took the spark plug out as I suspected it might be running lean with the stock jet fitted (size about 0.88mm) and after I uploaded an image of the plug to a couple of forums the general concensus was that it was quite lean indeed. I had a spare 1.00mm jet lying around and so I fitted it and did a quick rpm test in the garage and I achieved 4900rpm. Yippee!!! If those previous rpm/thrust calculations are correct then that shows that the Egg should now be pushing about 45kg(99lb) thrust.

I then checked the plug again and it still looks a little lean so I contacted Shane at AGK stating the engine specification and asking what would be the best jet size and he reckons about 1.05-1.1mm. So I’ve ordered and now received some suitably sized drill bits and I will be drilling the jet out to probably 1.1mm either tomorrow or the weekend. I might even squeeze a few more rpms and a smidge more thrust too.

So watch this space, the Eggmotor could soon be exceeding 45kg thrust. Lets hope reliability holds up 🙂 New thrust test will be taking place very shortly.

On Wheels

Posted in EggDev with tags , , , , , on February 22, 2011 by eggmotor

22.02.11: Well I’ve now fitted the new crankcase cover gasket and while I was in the garage I decided to see if the frame dimensions were close enough to the Monster’s specification to see if it would fit on the quad attachment,……. it did.

I just needed to drill a couple of holes for the securing nuts and it was a tight squeeze with the fuel tank cradle but all went well. With the harness connected up I sat in it and performed the starting procedure to have a short, part throttle bash. With the ignition already set to ‘ON’, I reached my left hand behind me and made sure the choke lever was set to ‘CLOSED’. Then while applying half throttle with the control in my left hand I sharply pulled the recoil cord from behind my head, over my left shoulder and down towards my legs. After three or four attempts she roared into life. I then ease open the choke. Now that the prop is back on the throttle response seems very sluggish and tends to bog if quick throttle adjustments are made. Just like the short run previous, the idle is lumpy and it can only be the large GX390 carb causing it. I didn’t rev up in the garage in case debris on the floor got sucked through the prop. Hopefully there will be plenty of power in the top end to give the requisite increase in expected thrust. I have purchased a new GX270 carburettor quite cheaply as according to ‘C-Line‘ in America the GX270 carb produces a significant power increase to a stock degoverned GX200 engine. If the 390 carb is too much trouble then I will swap over and see what happens.

I have also weighed the complete Eggmotor with harness and three litres of fuel and it tops out at 28.5kg.

Alive Again

Posted in EggDev with tags , , , , , on February 5, 2011 by eggmotor

05.01.11: The engine is complete again, albeit with a leaking crankcase gasket. That’s no surprise though as I have re-used it several times now. I’ve a new gasket now and will be fitting it asap. I have had it running as it is and it started fairly easily once I worked out the best choke and throttle settings. I’m still a little concerned about the con-rod bolt torque but we’ll see if she destroys herself with a full power test when the propeller is back on.

I’m still expecting 15-16hp at loaded maximum rpm (~5000rpm) and about 45kg(99lb) thrust if the larger carburettor suits the engine and other mods.

Partial Rebuild

Posted in EggDev with tags , , , , , on January 25, 2011 by eggmotor

25.01.11: While waiting for the new con rod bolts to arrive I thought I may as well build up the top end and figure out a new throttle set up as the gx390 carburettor throttle butterfly turns the opposite way to the gx200 butterfly. The video explains in more detail.

Eggmotor set back

Posted in EggDev with tags , , , , , on January 24, 2011 by eggmotor

24.01.11: In a recent post I mentioned about the improvements I’m wanting to carry out on the little Eggmotor. Well, firstly an update on the blown gasket problem. I think the reason the gasket could have blown is that when I fitted the 18cc GX160 cylinder head on the first time I built up the engine and then also when I swapped to a 14cc head, is that I used ‘thread-lock’ on both occasions and I think this has caused incorrect head bolt torque results. I don’t think re-applying the liquid over caked on thread-lock from a previous time is a good idea. Watching some of ARC Racing’s tutorial videos on the ustream.tv web site I’ve seen that they apply motor oil to all bolt threads to prevent corrosion and to aid correctly torquing the bolts. I suspect the gasket blew due to lack of bolt pressure. I have now in preparation for the new parts re-tapped(cleaned) the block threads and bolts and I can now easily screw the bolts into the block by hand.

'Cleaning' out the threads

'Cleaning' out the threads

Hand tightened with ease

Hand tightened with ease

Also, while using for the first time a new torque wrench with the correct sized drive head (so I don’t need an adaptor which would make getting inside the block impossible) for a borrowed 1/4″ 12pt socket for the billet con-rod I accidentally overtightened the bolts to the point where one of them snapped. The torque wrench was ‘clicking’ as it should while gradually pre-loading the bolts but when I got to the 120in/lb setting there was no ‘click’ and so stupidly I slowly continued to tightened. I’ve ordered a new set of bolts from AGK and currently waiting patiently for them to arrive.

Snapped ARC billet con-rod bolt

Snapped ARC billet con-rod bolt

Monster no more

Posted in EggDev with tags , , , , , on January 24, 2011 by eggmotor

24.01.11: It is with much sadness that I have now sold the GX420 Eggmonster engine. I have been told by it’s new owner that it will have a rich and fulfilling life bolted to a kart and blasting along at high speed. I have kept hold of the frame, quad unit and propellers in case circumstances change in the future and I decide to employ a 4 stroke trike/quad PPG unit for my aviation needs.

Bare Monster Frame

Bare Monster Frame

Goodbye Monster Engine

Goodbye Monster Engine

Goodbye Monster Engine

Goodbye Monster Engine

Blown Gasket

Posted in EggDev with tags , , , , , on January 11, 2011 by eggmotor

11.01.10: In preparation for fitting the upgrade parts (ported & milled 14cc head and gx390 carb) I found upon removing the cylinder head that the gasket seal had failed. Not sure how long it’s been like this and possible oil leak into combustion chamber too as there’s a greasy, sooty (been running rich) residue inside the head chamber and on the valves as the failure section is very close to the oil channel. That could be normal though for running rich but I’m no expert.