Mr_Grump

Greetings All

I have three Zenoah engines, a G26EI, a G26 Air, and a G20. I've had really no issues with either. Only one surfaced and I believe it was my fault.

I recently got the G26 Air. It was modified by a well known engine man. An expert in my opinion. I've been running the engine now and have about a half gallon of fuel through it. I use AVGAS and Lawn Boy for my engines during the break in period. I then switch to Bel Ray H1R at 40:1 and I've had no issues.

My G20 was broke in and running great in short order. I've got the usual tan colored plug and has almost no blow-by oil residue. Both of my G26's however, including the new one, leave a substantial amount of oil residue on the aircraft after flight. I've checked the carb setting several times on the new one just to be sure. I've also checked the plug after a half dozen flights or so and have a dark wet plug which to me means to rich.

I really don't believe there's a problem with the new engine. It runs great. I guess I'm looking for some reassurance of that fact.

Will this oil residue clear up over time or is this normal for the G26? What's your experience been?

Thanks for your input....

karolh

A dark wet plug is a fairly good indicator that the engine is running rich, which would also explain the excessive exhaust residue on the model, so some carb tweaking might be necessary here. All engines even of the same brand and size differ one from the other, so just be patient as more than likely with a bit more run time for seating the rings (breaking in) the heavy exhaust goo will disappear.

Karol

apalsson

My Feedback: (1)

+1

I also think that apart from the rich settings, your engine may now be cleaning out the carbon deposits left by the lawn boy oil. I don't think it is necessarily the best choice of oil, break-in or after that.
If you tune your engine to a proper setting, the black residue should disappear in a short while

darrolair

Also still breaking-in. 1/2 gallon isn't enough for break-in.

Lnewqban

What kind of modification?
If that includes port timing, that may be the issue.

Your mix does not have excess of oil.

It means that the combustion is not reaching peak temperature, which can happen due to over-cooling, improper port or spark timing or over-rich mix.

No; unless the cause is corrected.

Tired Old Man

My Feedback: (1)

Define "excessive".

Truckracer

My Feedback: (19)

Don't forget that H1R seems to combust less than other many synthetic oils so more of it will appear on the bottom of your plane than when other oils are used. Not a problem, just the nature of the oil and this will happen at any ratio.

Whistling Death

Yeah, that's what I want to know.

Mr_Grump

Thanks Gents for all the great input.

The engine guy's name I won't mention here. I don't want anyone to get the wrong impression of his work. I will say that he made me a custom carb mount by re-routing the pulse line in the block allowing me to rotate it 90 degrees. If he's monitoring the thread, he can speak up if he wishes.

The engine is running without the cowl in place so over cooling may be a factor.

I'm not using H1R for break-in. I'm using Lawn Boy. It should burn pretty well I'd think. It is early in the break-in period so maybe I'm just rushing the process.

You ask what is "excessive". That's like asking what does a banana taste like. Not a way to describe it. If your familiar with the Hanger 9 Tailorcraft, your aware of the gear bracing. Kind of like a Cub setup if you will. After a few flights, there's a lot of burnt oil on the springs and underside of the landing gear.

I really don't know what else to do for the moment other than run it and see if it clears up some. I was expecting it to be like the G20, pretty much clean after a day of flying. The G20 was the predecessor to the G26 in the same aircraft so it's easy to compare oil residue. With the G20, there was basically none. It to got Lawn Boy and then H1R with AVGAS.

Any other suggestions will be welcome.

Thanks

spaceworm

It does not answer the question, but is the "burnt oil" like an ash? I think that I have read here on RCU that Lawnboy has a high ash content? Have you tried a different break-in oil to see if the problem still exists? Also. even with Pennzoil at 1:32, there will be a period of break-in during which spots of "grunge" will get on the fuselage.[] Good luck.

Sincerely, Richard

HunkaJunk

I can say I have seen that residue with virtually every gasoline engine I own, It stays like that until it's broke in I believe, every new engine I get does it and then it gradually goes away until it's completely gone. I use full synthetic all the way from first run on.

Tip - Pledge furniture polish takes it off the underside of your plane super easy.

Mr_Grump

While I don't have a great deal of experience with 2cycle engines, I do know the difference between oil and ash.

Thanks for the Pledge tip. I'll give that a try. I'll also try the Penzoil though I doubt it'll make a difference. If it does, I'll be sure to post it here.

Thanks to everyone for the opinions and advice.

Tired Old Man

My Feedback: (1)

Lawnboy is pretty messy stuff by itself, and if running rich the problem is compounded. A rich engine is passing more fuel, hence more oil as well, making for a larger oil mess.

First thing I'd do is dispense with the Lawnboy. Who the heck suggested that stuff anyway, DA? No "ashless" oil is good for our air cooled engines. It's designed for use in water cooled engines.

Antique

My Feedback: (4)

If I did it and you are not happy, I can put the stock parts back on and refund the money....A rotated carb will not make black spots on the plane...

Mr_Grump

Thanks T.O.M. I'll try the penzoil. It may do the trick. I've adjusted the carb a couple of times just to be sure it wasn't rich. I can't tell you where I got the Lawn Boy recommendation but it was in an engine forum. As I recall, many used it.

Antique.... you did do the engine and I made it clear up front that I didn't think your work was at fault. I mentioned the rotated carb just to give you the opportunity to respond if desired. I don't have your experience but I am smart enough to know rotating a carb has nothing to do with it. THe engine runs great so no, I won't be returning it even if the oil residue continues.

Tired Old Man

My Feedback: (1)

That's why he's Grumpy #1 I can never remember which Grumpy number I am, but I think it's in the top five or so

karolh

Wether you both are Grumpy #1 or #5 matters not, as we are all just glad that we have you around to help guide us along.

Karol

Mr_Grump

Your right T.O.M. I guess I've earned that #1 spot.... unfortunately. I do spout off occasionally when I should just keep my mouth shut and move on.

Don't know what I'd do without this forum and others. I've gotten a lot of help and good advice.

Again, thanks to all for you input. I'm going to switch to Penzoil for breakin and I'll let you know what happens after a few tanks of run time.


#1Grump..... hummm..... that sounds pretty good!

BTW.... I got Mr Grump from my kids. They had it air brushed on a T-shirt for Fathers Day back in the 80's.....

ahicks

My Feedback: (2)

Maybe I can add something I've noticed. That all else being equal, a newer engine that's still breaking in will throw darker/blacker residue at first? After a while that residue will become lighter in color, possibly making it appear as though there is less of it?

Mr_Grump

Got a point there Ahicks. That is possible I guess.

I did get some Pennzoil 2cyc oil today so we'll see what happens. I plan to run a couple of tanks through this weekend. If there's a noticeable change, I'll let everyone know.

Tired Old Man

My Feedback: (1)

Actually, I was referring to Antique

cuwaert

This is a reply to the thread.
I don't know anything about the American oil brands but I think you can eleminate a few possibilities mentioned here.
Check pre-ignition angle.
If you tune the engine so that it got it's maximum power and a steady idle then it's mixture is ok.
Now ,after some runtime, if the plug is still not "coffee with cream" it's eighter overcooled or the plug is too cold a type or both.
Check Zenoah specifications for what oil brand you should use and ratio.
Port timing seems a long way from home to me unless Zenoah messed up an engine specially for you.
But ofcourse , and you won't believe it, nothing is impossible, there are only more and less probable things.

mighty9

My Feedback: (10)

If ralph worked on this engine all of the above is spot on already. Maybe some redline oil at proper mix and correct needle settings would cure it.

arobatx

Also, the engine isn't overcooled by being uncowled. In fact it may very well be running warmer than if it were properly baffled It IS out of tune, with the plug in the condition yours is in. Make the effort, and take the time to tune it properly right off the bat. Pay close attention to it through the first 5 gallons of gas or so, as the engine breaks in it will require further fine tuning. Engines I have seen at the field, running lawn boy, in the old days, were all a mess. The plugs would easily fowl, and as most would repeat here on the forums, the oil does more harm than good, for our two strokes. There are many better oils to choose from.

Jezmo

It has been my experience that Lawn Girl makes the plug look blacker than other oils. I don't personally use L.G. but have helped others at the field that were using it for break-in. The plugs in those engines were much darker than normal even with the engine tuned good. After putting those engines on either Redline or Stihl UP Ultra the plug cleaned up nicely.

Edited for spelling -