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  1. #276

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    RE: NGH 38CC 4 stroke

    Thanks for the reply. That's a new one on me but I'll give it a go in the airframe to see what happens. However, as a beginner it seemed wise to follow the manufacturer's instructions which recommend a bench break in.

  2. #277

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    RE: NGH 38CC 4 stroke

    I must also agree that the engine does have a fairly high vibration level, my runs have been on a bench which is solid and I ran mine again this weekend on 35-1 and ethanol free gas with a 16 x 10 prop which i intend using on my Midwest AT-6 when it is finished.
    The engine is mounted inverted and I am seeing 7600 to 7800rpm top end but my previous very low idle of down to 1500 has gone due to the 16 x 10 being a light Xoar wood prop, best I can get now is around 2000, vibration is quite high.
    I can however confirm that any larger gas engines I have or have had ranging from DLE-20 up to FPE 55cc and OS 55GT have had pretty bad vibrations on the test stand but when on an air frame they run much smotther, as pointed out above the air frame and in particular the wings operate like a damper and it is amazing how they smooth things out.
    I have not ajusted the timing on mine but have set the valves three times now !, each time they appear to require closing up to meet the 0.003 to 0.006 or so range, i think it's due to the very poor fit of the rockers on the rocker shafts, I dont understand why they are such a poor fit.
    I say mount it in a plane and you will see that it isnt so bad as you think, unfortunately I am about two months away from finishing my AT-6 so wont have any results till then as I dont intend fitting it in any other plane before that.
    Just for interest sake, see attached picture of my 25cc Honda 4 stroke engine, now this one is very smooth ....., only problem is it only produces 1.1 hp and is very heavy.
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  3. #278

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    RE: NGH 38CC 4 stroke

    Another quick story that backs up the mounting in the plane difference.
    A buddy of mine bought his first gas engine a few weeks back (DLE-20) and mounted it in an Aeroworks extra, he ran the engine and called me to say it was vibrating really bad, after I asked him all the normal questions, prop ballanced, low and high needles set etc and he said all was good, i asked him if the wings were on the plane, they were not, I got him to attach the wings and low and behold, it was running very smoothly, again, just shows what the airframe with the wings on does to soak up the vibration.

  4. #279

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    RE: NGH 38CC 4 stroke

    Thanks for the replies. I have now run the engine in the airframe (with wings attached). There is less vibration but still much more than I consider acceptable so I return to my original question. Previous posts here and on YouTube indicate that I am not the only person having vibration problems with this engine. Is there anyone who has had vibration issues and has managed to solve them? If so, would you care to share the secret?

  5. #280
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    RE: NGH 38CC 4 stroke

    Finaly had the day off, and the weather was allright, and the engine and plane was ready to go to the field at last

    Ran about 2 tanks or about an hour at around 3000rpm as stated in the manual, and began fiddleing with the needles to make it transition good enough for flight, and get a peak rpm.


    It went well, but a few small issues.
    One of the blue pushrod tubes is realy loose, so the O-ring holding it in place must be bad. Ill have to take the head off, and see whats up.

    After the first tank, I shut down the engine, refueld, and began flipping the prop. Suddanly, there was no compression at all. I could hear air going backwards throug the carb, so I figgured there was something with the intake valve. Removed the rocker cover, and all looked ok. valve clearance was a bit loose, and I began pressing on the rocker for the intake valve to see how it felt. Then the intake pushrod popped out of it guide, as my engine is hanging down, and the valve was stuck open. I managed to press the valve a little more open, and get the pushrod back in place, and then everthing was fine again, and compression was back. I then adjusted the valve clearance again, and had no further problems. Im pretty sure my valve clearance was too loose, and the pushrod must have been riding on the edge of the cam follower or something.....

    My muffler flange vibrated loose, but once I tightned the bolts while the engine was hot, they have not come loose again.

    It still shakes quite a bit when at low idle, but it has deffinatly helped just running a few tanks through it.
    I expect it to get even smoother.


    Third tank it was running reliable enough to get the plane in the air.
    All went fine, but my cap 232 is tail heavy, and I did not enjoy flying it.
    Power for this 2x2 meter almost 7kg airframe is not great with the 20/8 prop.

    Had 2 long flights, and the engine behaved well.
    I hope with more hours of running, power will get a little better.
    I will try a slightly smaller prop, and more pitch.
    Could not find my tachometer ofcourse, so I have no idea what RPM Im at........pretty annoying

    On the second flight, I installed the cowl, and the engine ran just as well with it on as without.
    It did make the engine sound much more quiet, so that was cool.


    Im pretty satisfied with the engine so far.
    Time will tell if this is a keeper or not


    2 ground run videos:

    [youtube]http://www.youtube.com/watch?v=VUNdTTkwDm8[/youtube]

    [youtube]http://www.youtube.com/watch?v=6wo7Ac3d6sA[/youtube]
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    Sonnich Johannesen

  6. #281

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    RE: NGH 38CC 4 stroke

    very interesting, glad to hear it is going well, on the valve clearances, I found that after each break in run the valve clearances needed adjusted, the fit of the rocker arms on the rocker shaft is very poor, to the extent that I am worried about having the same issues you saw, time will tell.
    Mine is sitting waiting on my AT-6 build to be complete which will be another month or two so will not be able to comment further till i get mine in the airframe.
    Keep us posted on progress.

  7. #282
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    RE: NGH 38CC 4 stroke

    yea, the rockers realy are a poor fit......

    I also forgot to say I moved my ignition iming as close to 28 degrees as possible. It was set atr 40 from the factory, but I just cant see the idea with that.
    I think mine is around 32 degrees, as I cant move it further because of the width of the screws....but it seems to start and run just fine here.
    Sonnich Johannesen

  8. #283

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    RE: NGH 38CC 4 stroke

    i have not changed mine from factory setting as it runs good, I do have the tools to check the RCXL ignition module so will check when I get it ready to run in the airframe and report on the settings I find.

  9. #284
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    RE: NGH 38CC 4 stroke

    well, there is lots of oil inside the engine, so that is good.
    Im running 4% oil in mine at the moment.

    this is how mine looks like on the inside after 4 tanks.
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    Sonnich Johannesen

  10. #285

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    RE: NGH 38CC 4 stroke

    interesting to see the inside of the engine, I am glad to see that the piston top looks like it does because I could see throught the plug hole that it looked un machined which is obviously correct as your is too.
    Are you going to change the bearings or just rebuild as is ?.

  11. #286
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    RE: NGH 38CC 4 stroke

    Are your bearing bad ?

    Mine are fine, so I wont be doing anything.
    I took it apart because of the loose pushrod tube, and just wanted to see how the rest was doing.

    they have machined one of the pushrod tube seats too deep, so I just cut some packing material to a donut shape, and shimmed it up with that.
    Works like a treat.

    I also removed the cylinder, to take a look at the piston, and found the edges quite rough.
    Not realy an issure, but I smoothed them out.

    Also, mine is the 2 ringed version.
    But there is a 3rd lower cutout/groove in the piston, which removes the oil, and the piston has 3 holes inside this groove on each side.
    On one side, there was alot of casting flash inside these holes restricting them. So I opened them up to the intended size.......probably does not have an effect....but anyway
    Sonnich Johannesen

  12. #287

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    RE: NGH 38CC 4 stroke

    no, my bearings are ok I think but I have not stripped the engine, was just asking if you planned to change yours.
    I beleive mine is a three ring version, just going by what I have read but not sure, dont like the sound of the wear or flashing in the groove holes ?, anyway, we will see throu time how they run.
    By the way, I see you live in Denmark, I am a Scott living in Texas, i have been to Copenhagen on business before, very nice city, hope you are getting a nice summer, here the summers are always nice but too hot at 35 to 40 deg C regularly with 100% humidity not uncommon, still, we get many great flying days.

  13. #288
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    RE: NGH 38CC 4 stroke

    I did not take pics of my piston, but you can see the 3 holes in the groove beneith the 2 pistin rings.
    That was where there was casting flash in mine on one side only.

    But everything is so well lubed, I doubt it is an issue.


    Nice to hear that you have been over here
    Copenhagen is a construction mess right now, as they are building a subway under the city, and there is construction stuff everywhere.......not good now, but it will be great when finished.
    Summer has been pretty bad so far, because of the cold/hot weather front seem to be passing us all the time right over Denmark. So we have rain and high humidity, and varying temps.....

    But this weekend, summer should be here they say.......a shame that I will be at work taking care of our 737`s [:@]
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    Sonnich Johannesen

  14. #289
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    RE: NGH 38CC 4 stroke

    One more thing...

    I dis-assembled the intake and carb parts, becuase I could see some fuel spill oil on it.

    In the manual, there are shown gaskets on each side of the white teflon carb/intake isolator. There are none installed on my engine.
    There was lots of fuel/oil in this place, so it can also suck in air. I will make new gaskets for mine, and install them.
    Item 50 in the exploded view:


    Also, the pulse line had quite a bit of oil in it........dont know if this will be a future issue.
    Maybe having the engine inverted, lets oil run into the pulse line and into the carb pump, than when it is installed upright.
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    Sonnich Johannesen

  15. #290
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    RE: NGH 38CC 4 stroke

    made 2 new gaskets.
    Had to get some longer M5 screws. Ideal length would have been 45mm, but I only could get some 50mm.

    This should give me a few thousand rpm more now

    Honestly, It seems to draw fuel better when flipping the prop than before, but it also might be because the engine has seen more run time....
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    Sonnich Johannesen

  16. #291
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    RE: NGH 38CC 4 stroke

    OK....if you dont have gaskets on each side of the white teflon isolator, THEN GET SOME

    Huge difference.
    I had to lean the needles considrably.
    Before throttle response from half throttle to full throttle there was almost no difference.
    Now the throttle has become much more linear, and it actualy throttles in this area
    Smoother running engine in general.

    Found my tach, and it messured 6150rpm with the saito FG 36 muffler and Graupner 20/8 wooden prop.
    Engine flew my cap 232 much stronger today, compared to the last time I was out. But still no match for a 50cc gas engine . It feels slightly weaker than my MVVS 35 gas engine, but the nice torque and instant throttle of the 4 stroke engine is realy nice.
    I also switched from the 25:1 fuel/oil mix to 35:1.
    There is absolutly no mess from the exhaust....It just blows out fine carbon soot i guess, and my plane is 100% clean in that area.
    There is some oil comming from the front breather, as there should be, and it is on the belly of my plane.
    But it is much better now, when I have gone to the 35:1 mix. I was thinking of installing a T on the lube line that comes out of the crank case, and into the intake manifold.
    Then all the spill oil would get back into the engine and burned off.


    Im pleased with the engine, and it is very reliable.

    Very bad of the factory not to install the gaskets.
    That will make a big difference depending on how lucky you are to get a good, or bad mating isolator between the intake manifold, and carb.
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    Sonnich Johannesen

  17. #292

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    RE: NGH 38CC 4 stroke

    great info, I will check mine

  18. #293
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    RE: NGH 38CC 4 stroke

    oh yea...one other mod I did......When I had the intake manifold off, I could see a realy sharp raised mold line inside the intake.
    I took a sharp exacto knife, and removed it, to keep the intake nice and smoothe.

    Probably did nothing....but who knows
    Sonnich Johannesen

  19. #294
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    RE: NGH 38CC 4 stroke

    Tried an APC 18x10 today, and it is quite a bit better than the graupner 20x8

    Got 6900 rpm with it.
    The cap 232 flew with much more authority.
    Guess the extra rpm on the smaller prop will let the engine produce a bit more HP.

    Had my first deadstick with it today......3rd flight without refueling, I guess it ran dry

    I had installed a T on the front crank case vent, and the rear one, so all the oil mess will go into the intake.
    No problems with that setup with the flights today.

    yesterday I drained the pulse line, as it was full of oil.
    I installed a longer tube going up and above the engine, so maybe gravity would not let oil seep into the line.
    Well, after 2 flights, it was completly full again. Strangely enough, it does not seem to have any fuel draw issues even when full of oil.
    I realy hammered the engine with acrobatics to try and kill the engine in flight, but it ran on without a hickup.

    One of my friends has the twin cylinder Roto 85 4 stroke, and it will not do acrobatsics without an electric fuel pump.


    Is your pulse line installed on the center barb on the rear case, or the lower barb ?
    Mine is hooked up to the lower barb.......or it is actualy at the top now when my engine is intalled inverted.


    I admit that Im sort-of a newbie when it comes to gas carbs, but Im learning
    Throttle transition is very good on my engine at the moment, exept if I move the throttle quickly from lets say 60 %to 100% throttle.
    At around 70-80% the engine will stumble a bit, and loose a little rpm, but will be rigt back at full rpm at full throttle.
    But if you move the throttle slowly, then it will not do this.

    I have tried leaning and richening both the low and high end, but cant seem to make any difference.
    It did not do this with the 20x8 prop.......what shoul I do ?


    Here are a few pictures showing my pulse line full of oil, and the T fitting on my vent lines.
    Also my choke setup. And the oil dripping out of the disconnected pulse line.

    Mhhh.....server error right now....will try upload later....
    Sonnich Johannesen

  20. #295

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    RE: NGH 38CC 4 stroke

    SJN
    Very interesting
    I'm waiting your pictures ....
    Best regards

  21. #296
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    RE: NGH 38CC 4 stroke

    Server works again...here are the pictures
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    Sonnich Johannesen

  22. #297

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    RE: NGH 38CC 4 stroke

    Hello
    I just ordered one of theese for a 112 in fieseler storch from black horse models. I hope it will be enugh power

  23. #298

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    RE: NGH 38CC 4 stroke

    From my tests on the bench with the engine you will have more than enough power for a Storch, being a slow speed STOL tyope aircraft you will be good. Check out the guy on You Tube flying his 80" plus P-51 weighing about 20 lbs on this engine, very impressive

  24. #299

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    RE: NGH 38CC 4 stroke

    Thanks for the reply. I will come back with som test data when I got the engine.

    I have seen the video where Affa fly that phoenix p51. He also lives in Norway, And I know he is a very good pilot to That p51 was powered for scale flying with the ngh38 i think.


    Sorry for my bad english, I am not used to write english, just read

  25. #300
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    RE: NGH 38CC 4 stroke

    Got a little video of my cap 232 and NGH today.

    Did not warm up the engine, so it stumbled right after takeoff....but it never quits
    Remember it is a 50cc airframe, so it is a little "underpowered"

    Might get some more video, as the guy filming it was not happy with my camera, and he wanted to use his own.....we will see


    [youtube]http://www.youtube.com/watch?v=OyZwki7Bjkk&feature=c4-overview&list=UUm87T1DR5SdALQ-2tuK4s-A[/youtube]
    Sonnich Johannesen


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