Thanks Earl and I concur with the good quality oil, over here you cannot go wrong with Castrol 2T for a start and if you feel up to it you can move on to the more expensive oil but I don't feel it is warranted with this motor.

Glenn

I have been experimenting with running a tuned muffler on the engine for added performance and also seeing if I can set the fuel pump back behind the engine. Note the fuel pump/regulator is loosely affixed to a padded mount using a velcro strip. I have been tinkering with the pump/regulator some and so whether the tuned pipe setup will be useable or not is still questionable. This is for using the engine in a pattern plane I have setup.





I crashed this one, but I have put together another one just like it, and it is getting the little gas engine on it too.

Earl I have no doubt that tuned muffler sounds great, might be a bit of overkill for this motor at present

I have shelved the idea about using the tuned muffler on the engine. It was a test to see what would happen. But there is a big jump in RPMs, speed and power when it comes up on the pipe, and I am uncertain I could richen up the engine enough to handle it and not overheat in the process too. I would have to run the engine really rich off the pipe and then when it jumps up onto pipe I would have to richen it up even more. So it would really need a inflight mixture control setup to work. But then that is getting pretty complicated to do. I used to do that with a Rossi .61 years ago for classic pattern flying though. I just don't feel like trying it at this time with this little gas engine.



So I put on a Tower Hobbies engine muffler I happen to have handy. Then the engine behaves like normal.

In talking about the mods one does, this is a pic showing the 98-3160-7 spring on the left as compared to the OEM spring on the right. Also shown is the steel Walbro metering lever on the left and the OEM soft aluminum lever on the right. The steel lever sits a little higher than the OEM one, but that isn't a problem when in use. The shorter spring allows the fuel inlet valve to open with less pressure on it. So you get more fuel pressure going to the engine's carburetor.





The OEM pump diaphragm may work fine in those locales that don't use our weird, complex formula gasolines with ethanol in them. If you use SEF or Tru-Fuel here in the USA the diaphragm seems to hold up better too. But the USA gasolines seems to soften the rubber and it stretches out then on you.


Depending on your use, the blue plastic diaphragm may work quite well. But it is a little more stiff and doesn't pump fuel as strongly as the white teflon diaphragm does.




Oh yeah, watch out for this pump valve diaphragm in the kits as it DOES NOT WORK with our little engine's pump.

Some engine performance numbers I got with the engine the other day, when I was test running it.

Using a Master Airscrew 11x6 prop.


Master Airscrew 11x7 prop


Master ASirscrew 11x8 prop


Using a APC 11x8 prop


and a Master Airscrew 12x6 prop


engine idle speed with a MA 11x7 prop


Using a MA 11x7 prop shows the engine running pretty decent on temperatures too. Ambient temperature was about 82 degrees F at the time. Not like when it is 110 degrees F ambient temperatures during the summer. This measurement is at the base of the spark plug on the head right there. Off the back of the head of the engine the temps are around 225 degrees F.

I was wondering about the teflon diaphragms, I had fitted the rubber one to my pump/regulator and noticed a big difference.
Earl have you tried a larger prop? say a 12 x 6.
Sorry should have waited until your next post to get my answer

The Teflon diaphragms work really good. But they don't seal around the edge of the pump frame as good, so they can leak if the outer edge isn't really smooth. Same for the blue diaphragm too. I did try the blue diaphragm out and it did work well for me too. But I sorta like the teflon ones more though, they really can draw the fuel really well. But it depends on your use, as it might pump too good in some cases.

have anybody tried to run the engine without the pump and just with pressure from the muffler to the tank?

Suggest using the search thread option but yes is the short answer. Somewhere around the 700 posts I believe. I don't believe it is necessary though as the pump will work fine once it is serviced.

Originally Posted by hawk21

have anybody tried to run the engine without the pump and just with pressure from the muffler to the tank?

Yes. It sort of maybe works. The problem is with glow engines the methanol based glow fuel is used at a much more rich air fuel ratio, plus the air/fuel mixture will ignite over a much greater range. But with gasoline the air fuel ratio is more lean and will only ignite on a much more narrow range. So you could get the carb to work on the high speed needle Ok, but there won't be any throttle to it. Thus it would work Ok for a free flight or control line plane like that. The idle and mid-range won't work due to the air to fuel mixture ratio being too difficult to balance out. The carburetor that comes with the engine was intended to use a fixed fuel pressure level so that it could work correctly. With no pump/regulator you can't maintain a constant fuel pressure level that is suitable for the engine.

Now a Perry pump used with a Cline regulator should work Ok with the OEM carb. The Cline regulator is essentially the fuel regulator part of a Walbro carb or the OEM pump regulator. You cannot use just the Perry pump with the OEM carb as the regulator on the Perry pump is not designed for that level of precision in maintaining a constant fuel pressure.

But it is easier and cheaper too, to just modify the pump/regulator and it'll work fine then. It is only some parts swapping involved, maybe some smoothing needed if it leaks. No fancy machine work is really needed.

NGH 9 CC engine. (1 min 19 sec)

I just saw this, it is in the first pages, it is running fine without the pump and the transition is good

Keep reading and you will learn why we keep the pump on.

Oh, well said,Gary Cee !!!

Originally Posted by hawk21

http://www.youtube.com/watch?v=54DC7...layer_embedded

I just saw this, it is in the first pages, it is running fine without the pump and the transition is good

Yeah it was where I stated it sorta maybe might work OK. In this case it worked on the test stand OK, but when you mount it in a plane it may change entirely the other way, Or somewhere in between. So it depends on your fuel tank location and height in relation to the engine's carburetor. One big issue is with the setup like that, is that the engine starts to run more lean as the tank empties out. That could be a big problem, where the engine is too rich at the beginning and too lean at the end of a flight. Then when you point the nose of the plane up the needle setting changes a lot, so that the engine is too rich level and runs about right nose up. With glow engines they run at a more rich air fuel ratio so it isn't quite as serious of a issue. But it happens with them too.

If a small light EGT probe can be found, a mixture control can be made. Find the optimum EGT (exhaust gas temperature), program a PIC to monitor the EGT and throttle setting then position a servo to adjust the mixture. It has to be done well or can be more problem than help. Probably best for a larger motor and plane. A nice winter project, and a high EGT detection can initiate an alarm that an engine meltdown is on it's way far ahead of the failure.