malcolmholt

3136 and EARLWBThank you both for your helpful replies. I really appreciate your advice.

SJN

The pump uses pressure from the crank case.
Block the front crank case vent, so the air pulse is stronger, and the carb membrane will begin to pump fuel into carb.
Problem is that with the case vent open, the little pressure you are making by flipping the prop is not enough to get the membrane in the carb to move.
Once you get fuel in there, unplug the vent, and you will get the engine running

Worked for me anyway.
if it still will not start, and you see the fuel in the line at the carb, then squirt some fuel directly into the carb.
it will fire for sure, and it might take a few times for it to draw the fuel, so just repeat the process.

3136

I forgot to say, if you do it this way peel back the gasket and membrane and slop the petrol actuallyinside, not just on the membrane.

thomber

That's exactly the setup I'm currently building up! At this time I can't give any information on how this combo relay performs but Iexpect enough power and an scale sound. I had to trim the stand-offs deliverd with the engine to 44mm to fit the engine into the given cowl spacing which is 158mm.

Once I've finished building up the Hangar 9 Super Cub and my NGH4 stroker is mounted in front of it (its currently on my test bench) I can provide further information and pictures...

Kind regards,

Tom

MKnutson

thomber,
Pics of your mods to the firewall and or stand offs would be Great!
That dimension was holding me back a little, (engine too long for the cowl).

Mark.

stevelesl

Anyone have a link to a manual, just received my engine but no manual ?. Also, is the front tapped hole in the crank case just a drain ?, no fitting came with mine....

Turk1

That nipple on pic is for drainage.I think you can fit a nipple to add a line to keep model clean.
I guess your engine has 3 rings on piston.So, longer break in and more care.
For the manual: http://www.himodel.com/en/rc_manuals_url.php?id=484
http://www.himodel.com/en/rc_manuals_url.php?id=485

3136

I noticed here http://www.himodel.com/sort.php?brand=228 that they don't make a 2 ring version any more.
So what is the difference between the standard and pro version?

Mikola

the Black one PRO was a 50 pcs limited edition with 3 rings piston, CF engine mount and 4 bolt propeller hub
the Blue one standard version does come now with 3 rings piston. I don't know if early issues have been fixed....

jeffEE

My Feedback: (5)

So the people with the first version, two rings and side mount rails, are out of luck if the thing breaks? Or can it be upgraded to the 3 ring version?

jeffEE

My Feedback: (5)

Here is a video of my first few runs. The first start of the motor is with the choke closed. It ran for a long time. Then the next running is showing what a real paint shaker this motor is. And loud too! And BOY....do I need to work off a few of the winter pounds. LOL
http://www.youtube.com/watch?v=Y2P8h...ature=youtu.be

3136

Hi JeffEE, if that first run was with the choke on you must be sucking air somewhere for it to run like that.
Have you balanced the prop? that shake seems abnormal.

jeffEE

My Feedback: (5)

Yes to both questions. The prop is a XOAR prop, and I did balance it. I think ALL props should be checked before use. The thought of air getting into the engine from some where is my thought also. I have a rod attached to open and close the carb, and I may not have closed it all the way for the choke start. I will make sure it is closed the next time I cold start the thing. The shake is HUGE! I hope it gets better as I get more fuel run thru it. The other thing that may have caused some of the shake is that it was running very low RPM. Lower than I think I will set it at for flying. We shall see. I was just happy it ran so well straight out of the box.

Turk1

HiJeff ,I think you should check the ign.timing also.

jeffEE

My Feedback: (5)

The Timing? Did it sound off to you? Or do you think that would add to the shakes? And then, How would I check it? I am a Nitro guy at heart. I looked at the placment of the magnet and where it hits the pick up. It is spot on as to where the instructions say it should be. Or is there more to it than that?

Turk1

I dont know what ° of advance is given for 38CC 4 stroke NGH but I would play with hall sensor to check if I can have better run.Most probably static advance should be about 28° before TDC like  most other model engines.You should use a degree wheel for it.

SJN

and check the cam timing, as it is pretty easy.

But mine seems to shake just as much as yours when in low idle, and no wings on my plane too

jeffEE

My Feedback: (5)

Well I put in the first flight today. The motor ran just great. And it had more than enough pull for this airplane. It is not that loud at the flying field. But it still shakes a lot. Oh well. So far I am happy as can be with this motor.

Turk1

Great,have fun.But I would not afraid to play with engine to check if I can have a better run.Check valve adjustments,check timing,check plug electrode adjustment(I have best results on 0.8 mm. or greater gaps on 2 stk.).Dont forget your engine has 3 rings and it will take a quite run to break in.

jeffEE

My Feedback: (5)

I wish mine had 3 rings. I have one of the first ones. It only has 2 rings. But it runs nice so no problems.

grossy2

Anybody know what the rocker/valve clearance is??

Cheers

Turk1

According to manual.Valve gap:0.03/0.08 mm.
Manual: http://www.himodel.com/en/rc_manuals_url.php?id=484
http://www.himodel.com/en/rc_manuals_url.php?id=485

stevelesl

Ran mine for the first time at the weekend on regular gas and 25 - 1 synthetic oil, mine appears to be the newer version as it uses standoffs and not a beam mount, wish it was the beam mount as the stand offs interfere with the carb and I dont like the use of the carbon fiber mount plate on the engine. I think I will make an alloy one to prevent these issues.
First run was pretty rough but after getting the low end set i gave it @ 30 minutes at 3000 rpm and it was transitioning well from idle at about 2200rpm to around 5 or 6k as i didnt want to over rev it too much.
Set the valve clearances (which were way out and not keen on the fit between the rocker shaft and rocker arms) to .05 mm.
Ran the engine again for @ 30 minutes and it is now getting a good idle at 1700 rpm, even saw a pretty good 1550 rpm idle but that was really low and some vibration at that level.
Top end was 7050 on an 18 x 8 which is probably on the small end pitch wise, I am probably going to get a 16 x 10 as the engine is going on a Miwest AT-6 1/6 scale so dont want too big a diameter.
So far, very pleased with it other than the rocker shaft as mentioned and I also note a fair bit of play on the crankshaft which is either the big or small end bearings, being needle rollers though I am not too worried at this point.
Going to move to 35 - 1 oil mix and zero Ethenol gas to see what it runs like.
As a side note, i ran it inverted as thats how it will go in the AT-6 and no issues, also noted that there was no build up of oil in the rocker box even with it upside down which I was worried about.
All good so far

malcolmholt

I have had mine for about ten weeks and have had a number of problems but, in fairness to the engine, I am prepared to reserve judgment until I finally get it in the air. It is also only fair to point out that I have no previous experience of model petrol engines. On the other hand I have used model glow and diesel engines for over half a century and am familiar with Walbro carburettors in other contexts.My major unresolved issue is one of vibration. This is so severe that I simply could not contemplate putting the engine in an airframe in its present state. From previous posts here and various short videos on You Tube it appears that some of these engines run smoothly while others display excessive vibration.The most likely explanation of these variations has to be the individual setup in each case though it is also possible that inconsistencies in manufacturing may result in some engines running more smoothly than others. Accordingly, I should be particularly interested to hear from anyone who has encountered vibration problems and managed to overcome them. What is the secret? In addition I would welcome any other advice. The following gives a brief summary of what I have done so far.The engine has been run for about six hours on its stand-offs on a very solid bench. For the first five hours I used 25 : 1 oil and have now changed to 35 : 1 as recommended.The valve clearances are at .04 mm.While I don’t doubt that petrol gurus could do a better job on the high and low needles, I am getting the expected high and idling rpm with a clean pickup and a brown-coloured spark plug so I think am somewhere in the right ball park.I have tried three different propellers, all carefully balanced and all of which run smoothly on other engines. I have also tried the old trick of repositioning the prop.I have replaced the plug with a new NGK.I made a timing wheel and pointer to check the ignition timing which was initially set at 40 degrees btdc. I have moved the Hall sensor to 28 degrees. This has cured a nasty tendency to backfire while starting but has had little effect on the vibration.I am using a new, fully charged 2000mah 4.8 volt nicad. I have a tachometer connected to the ignition module but no other electronic devices which could be a source of problems. (I plan to use an opto kill switch in the model).Any advice anyone would care to share would be much appreciated. Thanks. (Sorry. I did write this with paragraphs. What happens to formatting on this forum?)

kerwin50

It is never good to mount a gasoline engine to a stand. It does not give the flex that it needs like in an airframe. Also always have the wings on the airframe.
I have seen mounting lugs break from this type of mounting as well as over heating.