jeffie8696

Ialways backflip my 4S engines, once they are well broke in and tuned correctly it is a snap.

FNQFLYER

Starters help preserve fingers and hands

blw

My Feedback: (3)

I just watch the fuel line for fuel to reach the carb. I turn the prop over a few turns to check for hydrolock. If the Saito is warm I just bump the starter a little to crank.

rowdyjoe

My Feedback: (9)

Hey Guys,
I'm having a bit of trouble with overheating. Ihave an FA-80 mounted inside the cowl of a Hangar 9 Fokker DVII. The engine runs great but, while attempting to tune the HSneedle it will overheat to the point of dying no matter how rich Imake it. So, Iassume the issue is lack of cooling air or ?????. I've opened up almost the entire bottom of the cowl so the heat can exit but, it doesn't appear to be enough.

I have installed a Turboheader exhaust and put an exhaust deflector on the end of it to make sure the exhaust mess makes it out of the cowled area. The deflector is slightly pinched by a zip-tie that holds it in position. Will a slightly restricted exhaust cause overheating?
Any advice will be appreciated.

Thanks,
RJ

smkrcflyer

I got a real good deal on an almost new Saito 450r3. Now I need to find a plane for it. I’m not a 3D flyer I was thinking about a bi-plane. Anyone have a suggestion?

SrTelemaster150

Top Flite Giant F4-U Corsair ARF or kit

Don Smith FW 190A-8 (plans or pre cut)

The 450R3 is probably going to be my next engine purchase & it will go in one or the pother of those planes.

I'll be running C&H electronic ignition lighting off 15% Cool Power glow fuel too.

smkrcflyer

Can you give me some information on the C&H electronic ignition? I have the Top Flite Giant F4-U Corsair kit still in the box but it looks like this engine is a bit big to fit in the cowl. I will check that tonight.

SrTelemaster150

A 3 cyl radial is relatively easy to set up for EI. You mount a hall sensor on each cam housing (3 total) W/1 trigger magnet in the prop hub ring. You then utilize 3 single cylinder modules, 1 for each hall sensor.

C&H is looking for a 450R3 to develope a single module to fire all 3 cylinders. I had planned to pick one up & send it to them for that, but my finances would not allow me to make the purchase.

The 450R3 will fit into the Don Smith FW 190 A cowl. It also fits into the Black Horse Corsair ARF cowl.

Correction.: The 450R3 is 237mm That's just over 9.33" A 9 1/2" ID would be minimum.

jeffie8696

Iwear a heavy leather glove, one little flip of the finger backwards against the compression and Put Put Put Put Put Put.

And it really impresses the crowd in the pits.

lopflyers

My Feedback: (12)

I chicken stick all my engines, if they are adequately primed they will start w the chicken stick, if they don't then I use the starter.

treehanger

Compression problem? I have a FA-56 that I acquired used and I have no idea of its history. I think it is a fairly high time engine. The outside looks really great. I mounted it in a plane and took it to the field today for a test run up. With the throttle 1/4 open and finger over the muffler, it did draw in fuel.

I got the engine home and removed the carburetor. The connecting rod, piston movement, etc. looks okay. No metal chips or visual defects. I then turned my attention to the valves. They seem to be working okay but I loosened the adjustment gap to be sure they are closing. Seems okay visually but still I don’t feel the compression stroke. It’s like the glow plug has been removed!

Maybe I should use an electric starter and not worry about that expensive shiny spinner. Ha. Any suggestions? (I did a thread search but didn’t find anything like this symptom.) Bob

Am I chasing something that’s normal? I’m use to 2 strokes that have the distinct compression “pop�.

I connected the glow starter and used a “Chicken stick� to flip the prop but there was no life. I then noticed that I can turn the prop with one finger (no glow battery) and I do not feel any compression “pop�. Is this normal?

treehanger

Sorry about the extra line spaces, I pasted from WORD and it should not have displayed that way! Bob

SrTelemaster150

You can go back & edit the last post. Just backspace the gaps out & re-post.

You should definately feel compression if it is an engine W/time on it. When they are brand spankin' new they don't have a lot of compresssion but after a very short time it will increase.

Could be that the valves aren't closing. Some varnish or carbon could be keeping the valves springs from seating the valves completely. Get the engine on TDC of the compression stroke & back off the valve adjustment. Spray some PB Blaster or some such penetrating oil into the ports & valve springs. Work the valves W/your fingers to see if they are sticking & perhaps that will loosen them up.

If you can't remedy the problem that way my suggestion would be to pull the cylinder & see what the ring/piston/bore looks like. You could then also have a closer look to see if the valves are seating

The Raven

When rebuilding some second hand 45's the previous owner said they were worn out, it turned out to be nothing more than a gummed up rings.

Strip and clean the engine, maybe put in new bearings and glow plug, reassembly and fly.

Don't over analyse it. It's a slippery slope that generally yields little to no improvement over a basic rebuild and tune.

Cougar429

My Feedback: (3)

Treehanger, if you go as far as pulling the jug it is not too much more to drop the valves and have a look at the valve faces and seats. There are only a few places that you will lose compression, bypassing the ring/piston/cylinder wall sealing and either or both valves. One easy test is to listen at either the carb throat or exhaust when rotating the crank around to TDC. If either valve is leaking you will hear the hissing sound. If there is serious blow by on the ring you may be able to hear it at the case vent if on the rear cover.

One other check would be to put a few drops of oil down the plug hole and then reinstall the plug and rotate the motor. If you have a good seal now then the ring seal is the most likely culprit.

Worst case scenario is a broken ring, burned piston or valve and seat and a teardown is about the only way to ensure you are mechanically sound. You can do this and leave the rest of the motor intact so if the bearings and cam are good they can be left undisturbed.

Another boo can be had at the bottom of the lifters. Any unusual wear there should be addressed before the motor is repaired and reassembled. Normally easy to fix with a new cam and lifters all that is required if there are no other serious problems buried deeper in the motor. The first would be corrosion and likely to show up in the bearings.


Rowdyjoe, your description is exactly what will happen with a cowled engine if the air is not directed over the cylinder with enough volume to remove the heat created. Even if you follow the rule of thumb in that the exit area for the heated air is 3X the size of the entry that air will always find the path of least resistance, in most cases around the bottom of the case. Not having enough exit area is nearly as bad as the air can stagnate within the cowl and not remove any heat at all.


Here are some pics of my own solutions. They have been posted before, but I cannot seem to access them.

NOTE: The theory is identical to what is used on full size aircraft.


First is the Skybolt. This was my introduction to cowled 4-strokes and initially I did everything wrong. The first flight cowled the motor overheated and seized as it was an open installation. Since the cowl mod it had never overheated again. Even though freed up and with appox 300 cowled flights it came back to bite me recently, requiring a new rod.

The same idea was applied to the Harvard and again, the OS 90 has not had any problems.

The last is the Saito 125 installed in Rare Bear. Only the one maiden flight recently with the cowl off, but I am equally confident it will be fine once installed.

treehanger

Sr Telemaster- I can feel the exhaust valve sticking when I press the rocker arm. So that's one clue. I'll go down to the barn and try the PB Blaster tomorrow. (It's raining now.) Maybe put it in the cylinder too.
Wow, I just noticed, somehow my paragraphs got out of order when I pasted it in!.

Raven- As a retired engineer, I do tend to over analyse!

Cougar- I think I see a teardown in my future. Oil down the plug hole did not do anything. Good thought though.

Bob
Thanks everyone for the suggestions. Very helpful.

lopflyers

My Feedback: (12)

I had the same compression problem in my Magnun 91. When you flip the prop it was like a bicycle [:'(].

Cougar429

My Feedback: (3)

Keep us informed.

Don't forget overnight in a crock pot filled with glycol will cure a lot of ills, (and make the motor come out OOOOH SHINY!)

SrTelemaster150

No compression improvement W/oil squirted in the cylinders is a definate indication that your problrm is valve related.


That is compression troubleshooting 101. If compression had been restored by squirting oil into the cylinder it would have been due to the oil (temporarily) sealing faulty rings.

SrTelemaster150

This is just an educated guess considering your symtoms.

First rule of trouble shooting: Always assume that it is the easy fixes & try them 1st.

Since your engine is making pressure to the tank & drawing fuel to the crab, it looks to me that the engine is making some compression when you place your finger over the muffler.

You finger is likely blocking (sealing) the compression that is leaking by a partially open exhaust valve thereby pressurising the tank. In order to do that, the intake valve must be sealing at least some.

Remove the rocker covers, intake manifold, exhaust, valve adjustment screws & glow plug from the engine & soak the valve train well in some sort of penetrating oil. Squirt penetrant into the ports & cylinder. Work the valves W/your fingers until they are free.

(since you already have the carb/manifold removed, it would be a good time to remove the backplate & inspect the rear bearing for rust)

Assuming that you found the rear bearing in good order, blow off/out the valve springs & ports W/compressed air. Do the ports W/the valves depressed & the glow plug removed. That should help clear the seats. Now, before you turn the crank over, flush the cylinder out W/lots of penetrant/solvent & then turn the crank over to flush the solvent out through the glow plug hole.

(if the rear bearing was rusted you need to do a complete tear down)

After you get it all freed up, adjust the valve lash to .0015" to .002". Oil up the valve train including some down the pushrod tubes. Drop 1 or 2 drops (only) of oil into the combustion chamber & replace the glow plug.

Before you even replace the intake manifold/exhaust, check to see if you have compression.

If you now have compression, finish assembling the engine & fire it up.

rowdyjoe

My Feedback: (9)

Thanks Cougar,
     I can adjust the intake air pretty easily on this bird and resolve that problem.  I can also open up more exit are if needed.  I'll try directing the intake air to flow directly over the cylinder first. 
     I really appreciate the pictures.  I didn't realize it was OK to squeeze the intake air down that tight.  I haven't had an airplane with a cowl that fully encloses the engine like this one does and cooling has never been a problem.  The pictures are worth a thousand words. 

RJ

Ernie Misner

Perhaps not your problem at all but keep in mind that on a 4-stroke, if the carb is closed all the way it won't have any compression when you turn it over.......

Ernie Misner

SrTelemaster150

If you are refering to treehanger's issues he did state that the throttle was opend 1/4.

Hobbsy

My Feedback: (102)

Bob, I tried to EDIT that post for you but when it goes into the EDIT format it becomes a jumbled up mess that I can't figure out.

lopflyers

My Feedback: (12)

[:-]No worries, it can be read