GeorgiaFlyer

What prop size are you using and how many blades? I know you said you are using a solo prop, Can you judge about what pitch you are running at?

Growler84

My Feedback: (8)

The Corsair setup is a 32 inch 3-blade and the Thunderbolt uses a 30 inch 4-blade. The "pitch" markings on the solo hubs are just a reference point from which we start. Since this is a Thunderbolt thread we'll go with what we did on that one. The 4-blade was set to what solo says (using the chart they supply with the hub) is 16 pitch. If I remember correctly the engine was pushing 4000 RPM on the ground so Mike reset for more pitch twice until he arrived at around 3500 RPM maximum on the ground. In summary, we use the resultant RPM to arrive at a proper pitch setting and don't get wrapped up trying to decipher the Rosetta Stone "pitch" chart.

When we test flew the Thunderbolt it was with a 2-blade Bambula 32 X 18 and the model had sparkling performance, huge 500 ft loops were easy. We thought the 4-blade would result in a significant reduction in performance (and didn't care) but to the contrary, it didn't. The model will still pull huge loops from level flight and has been clocked once, only once, at 125 MPH in level flight. Yes 125 MPH is more than the VNE recommended by CARF, thus only once for the speed run.

Scott Prossen

Very well said! I too run about 3400- 3500 on ground full throttle and have had fantastic performance on all my Moki engines and planes that they fly. Maintenance has been at a minimum I believe in part to keeping the RPM in the lower range. Love to see your advice and experience.

Scott

rbgetz

Greg, This sounds spot on. I'm running a new Moki 300 and they state the motor should be statically propped on the ground between 3600 and max. 4200rpm. I'm running an SL prop, basically a solo with a larger bore for the 300 radial. I'm assuming, based on what you're saying, I should pitch for 3600-3700 on the ground, toward the lower end. I could easily see how setting the static pitch at 4200 rpm that the engine could easily "run through" that in the air. rob

Growler84

My Feedback: (8)

You bet Scott, happy to help. You chiming in made me realize this is the Moki thread, not the CARF P-47 thread, for whatever that's worth.

rbgetz, definitely go for the lower RPM range...3500-3600 because like you said, they unload big time in the air.

Speaking of unloading, I landed Mikes CARF 47 dead stick when his engine shut down coming out of a loop (opti ignition controller failed). When that thing shut down I was confused because the engine was "running" but not making any power. IT WAS WINDMILLING! Yes, the 4- blade spun the engine until the speed dropped down to landing speed. The model was fine by-the-way.

Ragz

Im looking at exhaust tubes for the 250. Any idea what material is ideal for this purpose? Can I use copper tubes?

wphilb

My Feedback: (10)

Yes, I used copper plumbing elbows for my Moki 150 in a Nieuport 28. I just slipped them over and held with a bolt and nut through both, has held up for years.

whit

Ragz

ok thank you

TonyBuilder

My Feedback: (11)

Hi all, I just purchase a Moki 180 for my Meister P-47 build, been reading and most are talking about the 250. Anyone have any info on the 180. I should have mine on Monday and will be mounting it to my 40% super cub for run in and to learn how to use this engine.

I use Pennz oil air cooled 2s oil at 32:1 on all my gassers. Will this be ok for the Moki ?
Thanks

TB

wphilb

My Feedback: (10)

Good move test mounting on a simple to fly plane!

Whit

TonyBuilder

My Feedback: (11)

I learned the hard way, never put a new engine untested and run in, into a scale build

TB

mR JoLLy

I would use a test stand first to get a gallon through the engine before you send it into the air. My 180 had about 6 litres through it and the engine noticeably got smoother during that time. Adjustments were needed also.
I ran at 40:1 with a fully synthetic oil and now it runs at 50:1.

I had some real trouble getting it to start for the very first time. Eventually I stripped and re-built the carb. Could not see anything wrong but it started much easier after that - no idea why. It starts very easily now.

Make sure it is secured. I did not do any modifications to the engine, no pumps etc and it is very sweet with similar cylinder temps. I took a quick video of it on the test stand which was almost pulled over when up to full power, even with a car battery strapped to the back! They really do have bags of power!

https://www.youtube.com/watch?v=ri7xxFr4hIc The engine is waiting for me to build a Laird Turner Special so it is back in it's box.

TonyBuilder

My Feedback: (11)

Thanks for the info, I was planing on starting it on my test stand first to get it tuned and check how all is running. So you say no fuel pump, some say it is a must ( insurance). I guess the test runs will tell.

Here is my stand



TB

mR JoLLy

That's one hell of a test stand.

Yes run it on the ground, check the temperatures of the heads to see if they are all compliant. I may well go with a pump one day, but for now mine is sweet as it is

Nigel

GeorgiaFlyer

I have a Moki 180 that I bought new about year ago and tested on a stand before mounting in the plane. I started with 32:1 penz oil but only for like two runs. It didn't like that mix very rich and was hard to start and would not idle well. I change to Amsoil synthetic 50:1 and it ran much better but was still hard to start and a good idle was never achieved. Also the #3 cylinder was not firing consistently. All this while it was on the test stand for about a gallon or so of gas. I then bought a pump for it. WOW what a difference I saw. It started with ease and the idle was smooth and the #3 cylinder was firing much more consistently with temps on all cylinders much more even. I eventually mounted on the plane and it flies just as good as it ran on the stand with a pump on Amsoil 50:1. I know I have read on this thread many have run without a pump just fine, others found they needed one. Point is each of these Moki motors seem to have their own individual personality, so you just have to test and tweak and fine what works best with yours. Hope this helps.

wphilb

My Feedback: (10)

I was advised not to do much ground running of the Moki radials as it's easy to overheat them. It's another reason I got a big Telemaster to be able to get easy flight/ run time on the engines with minimal risk (vs a N28 or a Meister F4u).

I think as long as you watch your temps and keep it lubed you should be able to get some time in on a stand, it obviously worked for Nigel. Just no prolonged full throttle runs. My apologies if I'm preaching to the choir!

Whit

mick15

I have been radio modelling since 1969 and I have never run an engine on a test stand...........fit it, run it, tweak it, fly it is my philosophy.

m

TonyBuilder

My Feedback: (11)

I think a pump is not a bad investment, and may get one as I don't think it can hurt, I was thinking the test stand just to get it started and see what it does then mount it to my cub and fly it. My test stand is just that, a test stand not a break in stand, the air is the only way to break a new engine in.



TB

GeorgiaFlyer

++1 on the stand usage. Let me know how it goes on the Cub. I have a 40% Cub too. might be something I might try in the future.

TonyBuilder

My Feedback: (11)

Has anyone use an inline digital tac on the ignition like the Rcxel to read rpms on the Moki 180? Also what prop are you all using, thanks

TB

GeorgiaFlyer

Have not tried the tac. I am using a 26x18 prop on the 180.

TonyBuilder

My Feedback: (11)

Thanks, I guess I will have to try one. Also what size four blad prop are you guys using on the 180. Patric at solo props has me down for a 26" is that to big?

TB

Jaketab

My Feedback: (2)

Have a Moki 250 and have always flown it with the 32 x 18 or 19 prop. Conditions permitting, I will soon have the maiden flight with the engine in a new home. (Delro -Turner W4X)
The Turner has a very large diameter cowl. I may want to consider a larger diameter prop for this set up to get more air past the cowl.

Question - can anyone comment on larger diameter props for the 250 - say 34x16 or 36x14? What were your results and did the larger prop overload the engine ?????

Thanks - J Tab

Lormuhl

In my experience a 33-16 sep warbird prop with a wide profile works good and does not overload the engine. The sep 32-18 is a good all around prop, but rpms on my 250 easily hit 5000, and the 30-19 3 blade is also great for warbirds wanting a quieter prop. If you go to a 34" 16 stick with a power tip style and not a wide profile and it should be ok. I also have a 32-16 3 blade fw semi scale prop that has been tached at 4550 on my 250, thats going into my fw190 with fan blade setup. I have been using my yak as a test bed for the engines and it now wears the 33-16 2 blade sep wide blade exclusivly. Good imac and 3d and the 40% throttle flyby sound is incredible. Just remember throttle management with the lower pitched props.

Jaketab

My Feedback: (2)

Lormuhl,

Thanks for the information on props for the Moki. It would be nice to hear from others experience on props matched up on various Moki engines.
I'm getting ready to maiden with a Xoar Wood Laminated 32 x 18. It's a beautiful looking prop with red tips, but on the ground it tach's at 4700 rpm.

Regards - J Tab