MOKI 180 LOW END PROBLEM!
 

I tried to adjust the low end disk on my 180 and it hasn't run the same since! The problem I am having is the mid rang is not responding at all, it goes from idle to 1/4 throttle well, but past that there is no increase in rpm until you get to 3/4 throttle and then it just comes alive. But no mid range. All I did was turn the disk no more than 4 tic marks in either direction, (really not a lot). What did I do wrong? Thanks in advance.

Charles

RE: MOKI 180 LOW END PROBLEM!
 

Four tics in either direction on the Moki carb s a considerable amount.

But the thing back in the center and re-adjust your hi speed.

Enjoy,

Jim

RE: MOKI 180 LOW END PROBLEM!
 

What w8ye said!!! DO!!!!

That low-speed disc should not be adjusted more than about 1.5 clicks in either direction, typically even less than 1 click.

RE: MOKI 180 LOW END PROBLEM!
 

When you say clicks, do you mean tic marks, cause it doesn't really click. Also, I have put it back to where it was from the factory and it still isn't running right. I'm concerned that I may done something beyond repair.

RE: MOKI 180 LOW END PROBLEM!
 

What are some of the symptoms? Does it start easy enough? Does it idle farely well. Is it just a transition problem?

Your highspeed neele may need some significant adjustment -- do that with the goal of getting your high-end in an optimal state, about 200rpm below maximum sustainable. Once you have a good high end make minor adjustments to your low-speed wheel to smooth out the idle and transition. Minor adjustments should be no more than 1 1/2 ticks from neutral.

A couple of other things to consider and check:

1) Make sure you fuel system is large-bored, fuel line, klunk, and brass tubing into the fuel tank. The tank should be less than 12" from the engine with its mouth vertically-centered on the carburetor.

2) What kind of muffler are you running. If it is a Bison pitts-style muffler, some of these large engines need more pressure from the exhaust tap. You can increase it by blocking off one of the exhaust tubes.

3) If your fuel system is not set up optimally you may need a regulator or pressure pump. The regulator works off of a crankcase tap for fuel tank pressure. This tap provides significant pressure and should not be used without a regulator.

4) I found that the OS 4-stroke, Type F, plug to be an optimum plug for this engine. I have also found that the Moki is sensitive to good quality glow plug.

5) Probably more important than anything else; is the Moki is a low-compression engine, dessigned to be run on little or no nitro. Unlike the large Super Tigers, this engine should not be run on a low-oil mix. Keep it at the 18-20% range. I run Omega FAI fuel (0% nitro and 18% synth/castor (80/20) oil.) and when that is done I will mix up a batch of Methonal and mix it with 20% Klots. I don't care that my muffler looks old before its time from the burnt-on castor.

The Moki 180 is a ringed engine. If you have somehow damaged it by running it too lean you should be able to see the damage to the sleeve lining and/or ring. Though not free, repairs are much cheaper than buying a new engine.

RE: MOKI 180 LOW END PROBLEM!
 

Jim, I checked all that you have suggested even before I ever flew the plane and all was good. I broke the engine in on 0% (3 gal) with the cowl off then started flying it with the cowl on still slightly rich. I was getting 8400 with a Zinger 18-8 but not quite yet unlimited vert. Everything was working perfect up until I tried a Bambula 20-10 prop and then everything went out of wak. It would spit fuel out of the carb and wouldn't go past 5000 rpm so I started testing and tuning and that's when I adjusted the low end. I even took the High speed needle out all the way to check for debris and all I found was what looked like factory applied thread lock for the banjo fitting assembly. I reasembled everthing and went back to the Zinger 18-8 and things were much better but now I have the transition prob, to make a long story short!

RE: MOKI 180 LOW END PROBLEM!
 

Duplicate post

RE: MOKI 180 LOW END PROBLEM!
 

All things said and done, it appears you should consider sending your engine to an expert. Unfortunately, I think Gerard is out of business and Dave Patrick is on record not accepting Mokis for service (even though the Moki manufacturer said they would.) Try contacting Horizon Hobby and see if they can recommend a repair shop and/or Morris Hobbies. Both Dave Patric and Morris Hobbies now sell Mokis under different brands. Morris' brand is Mark and Dave Patrick is DPM. Dave Patrick even sells a version of the 180 and 210 with high-compression heads (blue head) for use with a higher-level of nitro.

RE: MOKI 180 LOW END PROBLEM!
 

That 20x10 Bambula prop is way too big for that engine. It's almost too much for the 2.10. My 2.10 turns the Bambula 20x8 at 7300 slightly rich, 7600 peak.

Do what Jim said, turn the disk to center tic. It should transition ok, may need a lttle tweaking. If you still have that unusual midrange problem with the disk at center you have some other major problem. Time to take the carb apart and inpect it for dirt or debris. Be sure to inspect the spray bar disk for debris in that fuel jet. Make sure to use a filter on your fuel line.

That paper gasket on the high speed needle can come apart and get inside the carb. You gotta be careful turning that high speed needle assembly when it's still a little tight. It needs to be very loose while turning it or it will tear that gasket. So maybe that's what happened? That was not lock tite you saw it was a paper gasket coming apart? Many people reposition the banjo by loosening that high speed needle assembly.

RE: MOKI 180 LOW END PROBLEM!
 

It must have been something else in there cause The gasket was in tact when I took it apart and also when I put it back together. I may have to see if I can just get a whole new carb assembly.

RE: MOKI 180 LOW END PROBLEM!
 

Ok guys, I figured out the problem, it was the throttle arm on the carb that was loose. Wow I'm glad I did not fly it that way. Now I have a different question. What did everyone with the big Mokis use to make a hole big enough for the tru-turn spinner adapter? I have been everywhere from sears to home depot and I can't seem to find the right size drill bit. Can anyone help? Thanks

RE: MOKI 180 LOW END PROBLEM!
 

what I did for my big Tigers and Saitos, is to buy an imperial drill bit sized just below the size of the engine shaft, and a straight reamer in the metric size of the shaft.... a drill press is required to get the hole accurate... check out your local machine supply house, or maybe Harbor Freight....

[:-]

RE: MOKI 180 LOW END PROBLEM!
 

The spinner backplate must be reamed out to 12mm. The Fox reamer has the right size. The Fox reamer did the complete job for me without a drill. I still used it in a drill press. Also, I found that I had to ream my props for 10mm and ream the back half of them 12mm. I don't know why Moki machined their shaft that way.

RE: MOKI 180 LOW END PROBLEM!
 

I did all that too but I still need to drill/ream the prop for the adapter. What size is it?

RE: MOKI 180 LOW END PROBLEM!
 

It's probably 12mm. Can you measure the adapter in inches or mic it? 12mm = 0.47244 inches (472 thousanths).

RE: MOKI 180 LOW END PROBLEM!
 

The adapter is the tru turn adapter and it has an ID of 12mm so I would guess that the OD is 13mm or 14mm but I can't find those size drill bits anywhere and the body reamers for the cars are tapered so they wouldn't work. What do you think guys?

RE: MOKI 180 LOW END PROBLEM!
 

Is this it?

http://www.truturn.com/cgi-bin/store...adaptprecision

If so just measure the adapter O.D. of the adapter which fits inside the prop. I bet your prop needs to be reamed to 12mm. See post #12 for reamer to use.

RE: MOKI 180 LOW END PROBLEM!
 

It sounds like something is restricting fuel flow. You are using large fuel line through out your fuel system, right? This can make a major difference on large engines.

If you are using the recommended large fuel line, I would disassemble the carburetor and look for a piece of dirt or flashing that could be restricting fuel flow. Good luck.

RE: MOKI 180 LOW END PROBLEM!
 

Thanks ed. I found the problem. It was the throttle arm moving at the carb barrel.