Basic engine tuning.

[ericb]

Great write up Terry. Thanks.

 

[49dimes]

So you cut the header the same length as the prop?

No. With a prop that you are running....the header is getting cut to achieve peak rpm (usually 1/2" increments) .
Change the prop (load) and peak rpm will not be the same as if you cut another header for that prop.

Example....(Figures are fictional but typical of 50/60cc class engines)

Prop 23x8. 7400 max rpm peak 11.5 inch header length.

Prop24x8 7200 max rpm peak 10.5 inch header length.

Prop 24x8 7000 max rpm 11.5 inch header length.

SO...You are basically matching the prop to your header for your engine will run a variety of props for the desired performance you may choose.

Yes atmospheric conditions play a role in peak performance but the results are the same when cutting the header for the prop.
You are obtaining max peak rpm for the atmospheric conditions you are in .You are cutting for max peak rpm for the prop you are using.

 

[Naughty Monkey]

So you cut the header the same length as the prop?

No, he cuts it WITH the prop!

 

[49dimes]

No, he cuts it WITH the prop!

That MORONALIZER really works.

 

[Knife-Edge]

Terry I have my idle set to around 1600 rpm on my DLE 120. The landing idle I have set to 1200 and I activate it with a switch. So when tuning the low needle do I do it in the landing idle mode at 1200? Sorry for the silly question but just wanted to be clear.

 

[Terryscustom]

Terry I have my idle set to around 1600 rpm on my DLE 120. The landing idle I have set to 1200 and I activate it with a switch. So when tuning the low needle do I do it in the landing idle mode at 1200? Sorry for the silly question but just wanted to be clear.

Low idle. One good point to note is to set that low idle after you fly and the engine is hot. It will idle lower after the engine is hot. Don't worry so much about the actual RPM as to set it at a reliable low RPM. Personally I only use a tach if I'm looking for info to post for someone.

 

[Madinpensacola]

Split ailerons. I knew I had forgotten a mod I wanted to make. Thanks.

 

[Knife-Edge]

Low idle. One good point to note is to set that low idle after you fly and the engine is hot. It will idle lower after the engine is hot. Don't worry so much about the actual RPM as to set it at a reliable low RPM. Personally I only use a tach if I'm looking for info to post for someone.

Thanks terry!

 

[Bipeguy03]

Ok Terry maybe you can help me out with this one. I'm usually pretty good at getting my engines tuned but this one has got me stumped.

It is also a DLE 120, On the low end it loads up and if I try to clear it, it stumbles and quits but if I jab the throttle it acts lean and dies instantly.

On the High end it act lean, if I go wide open for a few seconds and bring it to idle it stays at a high idle for almost a minute then loads up slows way down and quits. If I even let it start to load up, the instant I give it throttle it dies whether I do it slowly or nail it.

One more weird thing it did, I was straddling it to hold it back and I took a step forward and the plane lunged a bit. When the stabs hit the back of my legs and the plane stopped the engine stumbled to the point it almost quit.

I've always done it the way you describe and start on the low end, but I can't seem to get a reliable idle to start with and I know that has to be what is throwing off the high adjustments.

I had the idea to just get everything rich and then just slowly lean it back, but just wondering if you had any different ideas. I know it's difficult to diagnose engine issues through a keyboard but thought I'd ask lol

 

[jhelber08]

Ok Terry maybe you can help me out with this one. I'm usually pretty good at getting my engines tuned but this one has got me stumped.

It is also a DLE 120, On the low end it loads up and if I try to clear it, it stumbles and quits but if I jab the throttle it acts lean and dies instantly.

On the High end it act lean, if I go wide open for a few seconds and bring it to idle it stays at a high idle for almost a minute then loads up slows way down and quits. If I even let it start to load up, the instant I give it throttle it dies whether I do it slowly or nail it.

One more weird thing it did, I was straddling it to hold it back and I took a step forward and the plane lunged a bit. When the stabs hit the back of my legs and the plane stopped the engine stumbled to the point it almost quit.

I've always done it the way you describe and start on the low end, but I can't seem to get a reliable idle to start with and I know that has to be what is throwing off the high adjustments.

I had the idea to just get everything rich and then just slowly lean it back, but just wondering if you had any different ideas. I know it's difficult to diagnose engine issues through a keyboard but thought I'd ask lol

I'd maybe take a look at cleaning the carb.