CRRC Pro GF26I

[nicetie]

	Quote: Originally Posted by TrikeFlyer
	Nicetie, I also found the initial BTC timing set at 40 degrees and questioned whether that was correct. The factory said for this particular EI it was. The way these ignition modules work (EI) is they do not advance at all. They RETARD the spark by about 26 degrees (depending upon the particular EI) when you first flip and start the engine. Therefore you set the BTC timing at where you want it for when the engine is running max RPM. When you start the engine the EI retards the timing so you can idle the engine down and it will be smooth due to the retarded timing which will be the initial BTC setting minus the degrees retard of the EI which is usually 2 -6 degress.. As you advance the throttle, the EI retards the timing less and less as the RPM increases until the timing is back to the initial BTC timing. Some EI's retard the timing more than others so you have to set the initial timing accordingly to get the BTC you want or that gives to max RPM. Hope this clarifys the timing issue. Trike

Trike,

It's the same thing. Retarding from high RPM to idle is the same as advancing from
idle to high RPM.

HOWEVER there is still something VERY wrong here. If the engine
has to be running to retard the spark for idle, where is it set when it fires the very
first time (while your fingers are turning it through compression?) 40 deg BTDC? OUCH!
Ken

[TrikeFlyer]

Hey...Hey.. Hardtop and BossHoss finally finished the new test stand and ran a couple props with my new tach (GloBee).

Temp 71 F Humidity 62% Dew Point 57 F MSL 640

BTC timing 30 degrees

87 octane Penz ail cooled 40:1


first test Hawk 16 X 8 best smooth idle 1860-1890
lowest Idle 1770-1800

Top RPM 7800


second Test ZOAR 17 X 6 best smooth idle 1680-1700
lowest idle 1480-15-20

Top RPM 7530

Still low time engine and can be tuned a little better, so possibly better number with finer tuning However the transition is immediate and smooth without any hesitation. The spool up is a little slower with the 17 X 6. When I first put the 17X6 on I got a top RPM of 8200 but then I could not duplicate it.

I am manually operating the throttle so could not hold tach, tune carb and operate throttle at same time. When I get a helper I will retune again.

[TrikeFlyer]

Forgot to explain the pictures in last post. With my first stand that had the sheet metal corners with 1/2 plywood just bolted to the angles I got a lot of vibration when I would quickly open the throtle and rev up the engine. Not to bad at idle.

My second Test Stand is 3/4 plywood glued and screwed together. Can barely notice any vibration when idling and at full tilt is realy smooth l with very little vibration.

This engine continues to start better every time. When cold put thumb over carb and flip 3 or 4 times with EI off, turn on EI and flip 2 or 3 times it is running.

When warm or second or more run, put thumb over carb and flip 2 or 3 times with EI off, turn on EI and usually it will start the first flip, but if it doesn't it will always start the 2nd flip. Very user friendly.

I like this engine alot. It starts easier than my glow engines and tuning is very easy and forgiving. I may not have it tuned to the max performance yet, but I am very pleased with how easy it is to start. No fiddling, no adjusting just prime, turn on ignition and flip and it is running and smoothly at that.

Next step is installing the GF26 in my Sea Gull Laser 200. It should be a great match as the Laser is designed for 1.20 -1.50 4 strokes.

[TrikeFlyer]

Sorry guys, the above test numbers were not "wide open throttle" as when I was putting all my stuff away last night after my Test Runs, I discovered I had left the choke on half way so all my test run results are flawed. The choke being half on limited my top RPM as it restricts the amount of air into the carb even though I tuned the high speed needle for best RPM (less 200).

I received a phone call just after I started the engine and it was warming up. When I went back to run my test I forgot I had put the choke on half way to help warm up the engine.

Please disregard the numbers in my earlier post as not true performance results. Will re run again tonight without the choke half on and I am shure we will see better numbers.

Trike

[TrikeFlyer]

Hey Hardtop re-ran my Hawk 16 X 8 prop (Looks just like my XOAR 17X6 only one size smaller) with the choke completely off this time and after a quick retune of the needle got:

best Idle 1800 to 1850 RPM

Top RPM 8150 to 8200

I believe my prop is pulling more air than your MAS plastic prop.

However, unlike your engine mine does not have any noticeable vibration at idle (much less than my OS 4 strokes) and at WOT there is still very little vibration .

This engine really runs smooooooth !!

As far as I am concerned it is broke in and tuned good enough to stick in the Laser to go flying, hopefully this Suday if I can finish assembly of the plane by then.

Trike

[hardtop351]

	Quote: Originally Posted by TrikeFlyer
	Hey Hardtop re-ran my Hawk 16 X 8 prop (Looks just like my XOAR 17X6 only one size smaller) with the choke completely off this time and after a quick retune of the needle got: best Idle 1800 to 1850 RPM Top RPM 8150 to 8200 I believe my prop is pulling more air than your MAS plastic prop. However, unlike your engine mine does not have any noticeable vibration at idle (much less than my OS 4 strokes) and at WOT there is still very little vibration . This engine really runs smooooooth !! As far as I am concerned it is broke in and tuned good enough to stick in the Laser to go flying, hopefully this Suday if I can finish assembly of the plane by then. Trike

lol...i believe it too!!!. the vibration i speak of is at full noise. it seems to be the gold shaft extension and threaded shaft that is causing the vibration....they arent running true.....think that may have something to do with me....will investigate further over the weekend.

i havent done much with my engine this week due to work commitments. one of the things that i WILL be doing is to run it on normal gas not methanol and see what differences i get. that fuel is 25:1 mineral oil.

cheers
craig

[TrikeFlyer]

Hardtop you say you can visibly see your gold colored prop hub is not running true or is out-of-round??? Did you have this off when you dis-assembled the engine??

If so, is there a woodruff key and keyway?? Is the key in proper psition?

My prop hub (gold part) runs as true as on a engine lathe at any RPM.
But then my engine exhibit any excess or abnormal vibration either.

Don't know what is causing your vibration without checking prop balance, shaft/prop hub run out etc.

Hope you get time to find out what is going on.

Trike

[hardtop351]

yeah trike the woodruff key is in its correct position. i have a feeling that its the actual key itself causing the problem. these type of keys should have a small gap to prevent the key riding up on the outer shaft. this is what i think the problem is as i had it happen with my 45cc engine.

as for the props....yes they are balanced correctly. my engine transitions VERY quickly from idle to full noise. i think perhaps it will need propping up to a 18x6 or similar to stop it over speeding in the air. a tacho will tell the truth.

it still likes to run backwards and it does this more than running the right direction. ive never had an engine do this.

cheers
craig

[TrikeFlyer]

That's strange Hardtop. Sounds like your timing isn't set correctly. My GF26 has NEVER started and run backwards. But I think you are on to something with the woodruff key. I don't like the little half moon suckers as every time you push the prop hub on they want to ride up out of the half moon cut slot. Try glueing it in place first.

Guys, here are some more numbers on different props. It leads me to believe you need a good wood prop Hardtop, as you can see from my tests.

Saturday morning 10 am Temp 57 F Humidity 42 % Dew point 34 degrees

Timing still set at 30 BTC Penzoil Air cooled @ 40:1

Master Airscrew "K" series (plastic) 16 X 6
best smooth idle 1550
max RPM 9530

Zinger (wood) 16 X 6-10
best smooth idle 1830
max RPM 7290

Hawk (wood) 17 X 6
best smooth idle 1800
max RPM 8430

Above tests were done by just shutting off engine and switching props, no retuning for each size prop. I am shure the needle setting could be optimized for each size prop.

This concludes my test bench performance tests and now will install the GF26 into my Sea Gull Laser 1.20. Running a little behind due to work commitments so looks like maiden flight will not happen this Sunday. Probably later in the week or even next Saturday.

Trike

[TrikeFlyer]

Correction to my last post

that was a ZOAR 17 X 6 not a Hawk propeller,

the HawK propeller was a 16 X 8 in an earlier post,

Trike

[hardtop351]

hey all...

sorry i havent posted anything lately. ive had a very close family member pass away suddenly. will post more info and thoughts once things have settled here a little.

cheers
craig

[TrikeFlyer]

Bosshoss, we are sorry to hear of your loss and our prayers are with you.

[TrikeFlyer]

Craig, I am deeply sorry for the mix up in names in my last post and are prayers are with you and your family during this time of personal loss.

We look forward to your 26cc posts after your personal affairs are in ordder.

[mattbogy]

Just got the engine today. Really impressed with the quality of the top end. Looks like there is plenty of cooling fins for pushing this motor to the limit. Check out the photos, engine weight with ignition and muffler 2.4 Lbs, 38.4 Oz. One thing I did take advantage of, is the threaded crankshaft for a spinner bolt.

[mattbogy]

Progress photos.