H9 15cc Carbon Cub

[AKNick]

Ya. He might need to build a fire to warm it up!

ha ha! I'm kind of wondering if they say to do a long ground run like this because it will accelerate the break-in time exponentially for this little twin for a more reliable idle? I've ran an 8oz tank through it pretty rich, and it's producing a lot of black sludge... It seems to have improved the idle. I'm going to run another tank through it, before I take it up I think. I just want a reliable idle that will make the plane landable in my runway surrounded by hemlock and spruce, and alder trees!!

 

[pawnshopmike]

A couple guys at my local field bought the Evo 10GX when it first came out. They said they had to run a gallon or more though them before they started running right.

 

[AKNick]

oh boy... just what I need... 1gal = 8oz/10min at a time = 16 tanks and 2.5hours of flying later.... wow.

 

[pawnshopmike]

oh boy... just what I need... 1gal = 8oz/10min at a time = 16 tanks and 2.5hours of flying later.... wow.

Yup.

But hey, this is a different engine so maybe I'm way off base.

 

[AKNick]

No I believe you! Why else would the mfgr say do a 20 min ground run!?!? It must be unique to this size of gas engine. As long as it's running rich with a higher oil content, and it's not scorching outside... I'd rather do a long ground run, then have an unreliable idle to land/fly my airplane safely. Look at my avatar, that little gap in the trees is pretty much my approach, and those trees go all the way around the field. So if my engine quits, it's alot like landing on an aircraft carrier, no open fields or corn to stall it into. I have a linemen friend that has put his cleats of to rescue a model or two from them tree tops.

 

[WMcNabb]

Found this on the web, thought you might enjoy...

 

[AKNick]

Ok, so after another unwanted extensive ground run it transitions much smother and much more power. However it still does not want to idle. So I started looking into it... Timing was pretty retarded, maybe 36btdc. So I adjusted it to about 28-30btdc. Each cylinder is about 2-3 degrees different so I made sure it didn't go below 28. While doing that I was looking at the 1/4-20 plugs and hmmmm. The RH cylinder plug looked like the electrode was recessed and the tang depressed. I honestly didn't look at it before, but this looks like it was done by the factory. It still sparks just fine though. Plug in the middle is new in the picture. I also noticed more black breakin residue on the LH exhaust side the the RH with the plug in better condition. Could just be the prop wash, or coincidence, but just a thought. I just need to find the plug gap for these little plugs now. Then I'll give her a run and see how she does. Fingers crossed!

 

[pawnshopmike]

 

[AKNick]

Good news, I sanded the reed block, replaced the plugs with new ones from VVRC and re-timed the engine to 28-30btdc. The engine runs much better. It will still die 96% of the time from WOT to idle, but a gradual decrease is fine. Transition is great from idle to WOT, maybe a tad on the rich side, but should work out great for flying around breaking in the engine. I was getting excited for a maiden when I noticed that my LH flap servo was twitching randomly.... I still need to investigate... It's always somthin!!

 

[Dirt]

Your description of the idle behavior sounds to me like it is a bit lean on the bottom end. Try richening it a bit.