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Old 01-09-2009, 12:09 PM
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Re: Moki 210 questions/issues

Joe AP,
I fly at 7,000 ' elevation, every Moki I broke in at No nitro but it run best with 10% Powermaster. Dont know why , dut it did.
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Old 01-09-2009, 12:20 PM
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Re: Moki 210 questions/issues

Well there you go. At elevation the higher nitro might run better because the compression ratio might be lower. It is less dense air. First time I ever thought about that. My field is about 800 feet ASL.
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Old 01-09-2009, 11:18 PM
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Re: Moki 210 questions/issues

Static compression ratio won't change regardless of whether your at the beach or on the moon as it is the mechanical/volumetric relationship between bore/stroke/compression height, chamber volume, ring height, and head gasket thickness. It also means little because dynamic compression is what makes an engine run as it factors in the actual physical exertion placed on the intake charge during the compression stroke of the engine.

Air thins out at altitude and this lowers power output. We all know this. Nitromethane is 56% oxygen by volume so it effectively becomes a "chemical supercharger" much in the same way nitrous oxide does. (excluding the -120F temps that nitrous boils at when it hits the atmosphere)

So, on paper it stands to reason that if an engine makes "X" power at sea level, it will take a dosage of nitro to make the same power at high elevation. The nitro essentially just brings the engine back to sea level.

Hope this helped someone a little.
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Old 01-11-2009, 06:18 PM
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Re: Moki 210 questions/issues

Except this engine was not designed to run on nitro. It was never in the equation when they designed it in Hungary. So all it does is gobble fuel and create heat. Also it may change the timing and cause it to perform less than optimal. 0% nitro ran great. I used to like not having to buy 15+ a gallon fuel. I could get it for just over $9 a gallon and it used less fuel. Ran awesome. Can't see where you can lose with that fuel. I used to love the K&B 1L plugs too. $2.75 a piece. It was a cheap engine to keep running for me.
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Old 01-11-2009, 11:23 PM
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Re: Moki 210 questions/issues

I never did tach mine, but it did have more power with a little nitro. I ran it on zero % nitro and it ran great, but had a little more zip on it with 10%. Ofcourse that was before anything with nitro went sky high in price. Either way it's a great running engine.
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Old 01-12-2009, 01:07 AM
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Re: Moki 210 questions/issues

I ran mine on 10% red max with a fox idle bar long plug. Liked to be wet to start and ran perfectly for hundreds of flights. Only time it ever quit was when I was having too much fun and ran the tank dry.
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Old 01-12-2009, 03:31 AM
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Re: Moki 210 questions/issues

What WangoTango and flatspinjim said!!!
Loved my Moki 210, but I ultimately went to gas engines. I kept it simple with manufactured recommended fuel setup and K&B 1L glow plug. Was difficult to find fuel with no nitro, so ran it on 5%, and 10% when I couldn't get 5%. It ran great!! (once broken-in and leaned out) Quick response and low idle. Took about 2 gallons in break-in before it was running really well, that is, to fly, and better than 5 gallons to where it was super smooth. It would then just start and run using the grab-the-spinner, rotate-forward-to-compression, and then spin-it-backwards technique. It would bounce off the back compression and start right up. Of course it had to be almost flooded with fuel, ...and I did flood it a few sometimes to where it wouldn't start, such as on some hot days. It definitely liked to be wet to start. I had it in a Midwest Extra 300L (80" at ~16 lbs), which was designed by Mike McConville many years ago for the Moki 1.80. I developed a technique of placing a piece of tapered pipe insulation foam into the inlet to seal the inlet, then rotating the prop forward about 6 or 8 full rotations (no glo power during this, just to choke it). I used the foam plug because, with the cowl in place, I could not put my finger over the inlet to choke it. When the foam plug was pulled I would check to see how wet it was, or if it was even wet. If it was, and/or if fuel dripped out of the carb, then I knew it was good to go.

I ran that engine and plane with a 20x8 wood prop. Vertical climb was no problem, on this 16 lb plane, but downlines were too fast compared to the gas planes I was competing against. Downlines were too rushed, and I noticed that the gas planes got some breaking off the prop. I went to gas when I stepped up to a used BME 102cc powered Radiocraft Extra 330LX (35% at 27 lbs). The BME was pretty fuel efficient, and I found that it didn't use much more in the volume amount of gas as the Moki 2.10 used in volume amount of methane fuel on a flight. Of course the Moki 2.10 uses a lot more fuel than the Moki 1.80. I retired the Moki, but it is one great glo engine. The best glo engine I have ever owned.
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Old 01-12-2009, 03:40 AM
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Re: Moki 210 questions/issues

Slight correction in my last. The Moki 2.10 is the best 2-cycle glo engine I have ever owned. For 4-cycles I love my YS-91FZ and YS-110FZ.
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Old 01-12-2009, 08:10 AM
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Re: Moki 210 questions/issues

I have to admit being "attached" to mine also. I've never heard anyone gripe about them or a YS.

Cool stuff.
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Old 07-12-2019, 10:53 PM
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What is the best muffler for the 2.10...I want to use one on a 30cc Profile model. I'd like to use a regular "Sport" style like the Bisson or a OS 855.
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Old 07-13-2019, 06:20 AM
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They're get'n lower mate.....
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PM sent John
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Old 06-02-2020, 07:55 AM
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I took a 7 year break from RC, but I recently dove back in. I just bought a NIB Sundowner 80 and a Moki210 to recreate my race plane from years ago.

I own a machine shop. 7 years ago I went down a deep rabbit hole to wring out a Moki for all it was worth.

The prop was a 17x12 APC. When I started it was a 7200rpm ceiling using 15% and Pitts muffler.

Tearing into the motor I first raised the X port roughly .035". Then I began machining my own pucks for the head. I played with various squish rings and chamber volumes. I studied the cylinder to mitigate stripping out a thread.

Next was the ring. Ended up buying a bunch of rings from Bowman and playing around with them as well.

Onto pistons. I tried altering the edge prep on the ring land to "advance" the exhaust timing a bit. That was a bad move. Keeping the squish ring unmolested proved better. I rigged up a set of fixtures to weigh and balance the piston, ring, pin, and rod using a reloading scale. I dont recall the bobweights.

Somewhere in here I monkey's with the transfer ports and I stuffed the crankcase with gobs of JB weld as well. I'd file stuff back with a dremel to where there was just enough clearance for it to work. -fully expecting a bomb at some point.

Bearings were also swapped out. Boca makes a ceramic conversion.

Next, carb. Because this was a race motor I just wanted air. ID bored the throat and the barrel to where it would not shut off. Not a problem as I dead stocked the landings anyway. I also had to widen the groove of the idle circuit. Only way to get the transition right on 40% nitro. (more on that in a sec)

Next. Pipe. Mac took care of this. Told him what I did and what I wanted. Paid and waited. It was worth it.

Fuel. Once I had this thing together with the pipe it would run upwards of 11,500rpm. No joke. This was tested and verified on the ground. I figured another 500-700 in the air with the blades eating clean air.


Torque was the problem. The motor would fall off the pipe too easily. I prolly needed a 16x14 prop, but I tried spiking the nitro content to get it to stay there. This worked. I bought 5 gallons of nitromethane, quarts of Klots Techniplate oil, and methanol to start blending my own fuel. I also purchased a mercury based specific gravity bulb for testing nitro content.

I eventually worked my way up to 40% nitro. Plugs got changed along with head pucks to get the compression right. The issue became heat. I noticed right away a huge spike in rpm upon cold start. Within 60 seconds I would lose roughly 1200 rpm. The head was getting too hot.

So..we go fringe. I made a small heat exchanger and wound a copper coil around the motor. I soldered that in place in a few spots along the coil. A shaker perry pump circulated the water.

It worked! The weight gain was pretty small, but it kept the rpm up on the stand.

Last was fuel delivery and consumption. A stock Moki on a Pitts and 17x12 burns through around 3 to 4 ounces of 10% per minute at WOT. I was using over 6 on 40%. I went to a bladder tank from Tetra and I added a crankcase pressure actuated perry pump to supplement delivery. That solved lean spots while cornering.

When done I could knock on 12,000 rpm with a 17x12 APC. This was on the ground. The plane was shot on a police radar at around 125 to 130mph straight and level passes. 160+ was pretty easy in a power dive.

Should also be said that this plane had glasses wings and all the trailing edges were almost knife blade sharp. It was a pretty slippery turd of a plane.

If your into rodding up a Moki, this is one pathway to do it. Fun stuff. My 2.0 version is going to hopefully be even more ridiculous.

Fun stuff.
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Old 06-02-2020, 11:15 PM
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I love rabbit holes. It's just a hobby anyway.
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Old 06-02-2020, 11:55 PM
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Ran my Mokis for years with 10% red max from FHS.. always ran perfect out of the box. No need for regulators etc.. just tune it and fly. They did like to be wet to start and just a bump of the spinner with 2 fingers would make it start.
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Old 06-03-2020, 05:52 AM
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Love fast engines and planes,keep the updates coming.
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