My engine runs wide open pretty well. I think it may be slightly rich as I can see a slight fuel trail as I fly by. It is very hard to start, even with my electric starter. It doesn't like to idle and will not transition from low speed to high speed without sputtering and it usually dies. I am thinking that my low speed needs adjustment, but I don't know if it's lean or rich. Looking for some advice from you more experienced guys on how to methodically tune this engine., bearing in mind that I am a novice. Any help would be greatly appreciated.

I suspect you'll get a bunch of opinions.

1. With throttle wide open, lean the high-speed needle a click at a time until max rpms (until engine starts to die), then richen the high-speed 4 or 5 clicks.

2. Reduce throttle to idle, let sit untouched for about 30 seconds. If during that time, the engine speeds up and dies, its lean so richen the low-speed. If it bogs down (slows), then its rich and you need to lean the low-speed.


Sounds like your low speed is too rich.

I did notice a lot of fuel coming out of the exhaust during transition. Would that also be an indication of the low end being too rich? Thanks

Yes, a puff of fuel coming out as you transition to WOT is definitely a sign of being too rich. Normally, if the idle is too lean the engine will just die when you advance the throttle.
Usually, setting needle valves is pretty straightforward. I learned after messing with a few cantankerous engines that if it's not, you usually have an air leak, bad fuel, or a bad glow plug.

I have had a similar problem because of old expired fuel. Tweaked everything to no avail. Once I got a fresh can of fuel, engine runs great. Glow engines are pretty forgiving once you give them fresh nitro. I have learned glow fuel lasts about 3-6 months in storage once you open the cap. Hope this helps.
Dean

Do the "pinch test" for the low end:
Get it running and fully warmed up. Bring it down to the lowest idle it will maintain and let it stabilize for a 10 seconds or more.
Pinch closed the fuel line going to the carb. Use a tool (needle nose pliers, whatever) if anywhere near the prop. If it has a remote needle valve, use the line between the needle valve and the carb.
If while pinched it picks up speed, before finally dying, the idle setting is too rich.
If it just dies very quickly, it is too lean.
Find the magic setting where it runs for a little, but barely increases rpm (If at all) before running out of fuel. Releasing the pinch before it dies would result in it continuing to run smoothly.
You may find that you can go even lower for the idle speed than before. Repeat the test if you do lower it, although any further adjustment will be smaller.
Check the fast transition from idle to full speed. It should now respond very quickly, with no hesitation.
As a final check, with it running at full throttle, hold the plane and point the nose straight up for 5-10 seconds, to verify that the high end isn't too lean when pulling fuel against gravity.
Small changes to the high end will have little effect on the low end. You'll likely only have to adjust again if you change props or fuel. The high end may need a few clicks one way or the other if there are big changes in air temps or humidity (as well as fuel or prop).
All that said, if it is a brand new engine, you may have to tweak it on both ends a couple of more times until it is fully broken in, but it won't need big changes.

And I should note - if new and it has a piston ring, continue to run it a bit rich on the high end (smoke trail, not max leaned in rpm) until you have consumed a couple of gallons. It will just get better and better behaving on high/low and starting.
If it does not have a piston ring (ABC or the like) after the first couple of tanks of rich flight, lean the high end in to closer to max rpm. It needs to break in at its normal operating temperature. Too rich means too cold, which may mean parts don't quite mate as well at different temps when later trying to get max power.
In either case, during initial break-in don't stress it with heavy loads like many loops, long vertical climbs, hovering, etc. And give it periods in the air at lower throttle settings to cool things off and vary the temps. You can get more aggressive with each flight.

Thank you so much for all that info. I should be able to tune with confidence now. At lease I know when its rich and when its lean, that's a major accomplishment for me. This is actually an old (ABC) engine, but if and when I buy a new one, I will follow your break-in advice. Thanks again Ted Sander !!