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Having problems getting a Zenoah 25.4 cc engine from a Redmax weedeater to run. During the trouble shooting decided to see about
where the factory timing is set. Verified that the flywheel is positioned with the key in the slot & located TDC using a pencil. I am baffled, because it appears the magnets don't cross under the coil untill several (20+ degrees) ATDC. This is of course when turning the engine in the CCW direction. I'm no expert, but baised on all the good data I've reading in this forum - timing should be about 28 degrees BTDC. If that is true, either this engine runs CW, or the there has been slippage on driveshaft, changing the drive shaft/piston relationship. I even called a local Redmax service/repair tech. who said that it does fire about 25 degrees ATDC. Doesn,t sound logical to me. Can anyone shed some light on this?

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Forgot to tell you this is one of the newer Redmax Stratocharged engines with a clean environment type carburator.

Antique

My Feedback: (4)

Impossible...Spark that far ATDC will not fire the charge in the cylinder, there's no compression left...It must run the other way....
Local repair shop must not know how gas engines run....
Easy enough to check, crank it the other way...

Antique

My Feedback: (4)

RCIGN, Isn't there some way to determine which way a magneto engine is set-up to run based on the prongs of the coil ? Long prong vs short prong ?

Antique

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A G38 has a three prong coil and 2 magnets...At TDC the first magnet is halfway past the left prong of the coil, so when coming up on compression that same magnet is halfway through the right hand prong..Rotating the other way the magnets are not even close...Without measuring it looks like the firing point would be when the left edge of the first magnet is even with left edge of the left prong...
Looking at the engine from the front....

sides7

My Feedback: (9)

RCIGN
Do you know if these Redmax weedie conversions are ever made to run CW. Tried to start by turning in a CW direction but still not starting. Have made spark check and looks good - even got a new plug but looks same as the old plug. Plug gets wet , so I'm concluding timing has got to be the issue. Any ideas?

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Hobbsy

My Feedback: (102)

If it has fan blades on the flywheel, they would tell you which way it is set up to turn, they should be slanted to throw air outward.

sides7

My Feedback: (9)

More information on Zenoah 25.4cc engine that appears to fire ATDC. I assume this is very similar to the G26 and hope someone knows what's going on. I have conclulded that there must be some sort of built in delay in this engine's firing sequence. Before this engine began to give me problems, it was flown in a big SPAD without problems. As I stated earlier, I only checked the timing as I couldn't get it to start. Since it has already run and been flown a plane it MUST BE turning CCW as you look into the prop. I torn the engine down and checked the internals and found nothing wrong or suspect. For the upteenth time, I put the pencil in on top of the piston and verified that TDC is reached before any magnets reach the coil - so it appears to fire before ATDC. I know next to nothing about the coil and it's internals or how they work. Is it possible that there is a built in delay in the firing sequence? Hope some one can shed some light on this perplexing situation. I NEED SOME SLEEP.

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Antique

My Feedback: (4)

Not possible....A G26 has a 2 pole coil and 3 magnets...At TDC the last magnet is about halfway past the end of the pole, so the first two have already passed through the coil and fired the ignition...The timing on a G26 is 28 BTDC....ONLY possibility is the flywheel has rotated on the crank....Send it to me and I'll take it off and re time it..Send it UPS, only about 10 or 12 bucks total for both ways....No charge, I'm curious....
BTW...I was in that B17 many times that used to fly out of Marana, probably flew over your house

sides7

My Feedback: (9)

RCIGN
This engine has a two pole coil, but only has two Magnets. With the engine at TDC, the magnets are already past the coil. The flywheel is keyed to the shaft. As luck would have it, the flywheel got broken during its last removal from the engine. I am presently in WA. state visiting relatives, but will be back to Marana this coming Wednesday. If your offer still stands, I'll ship the engine as soon as I return to AZ. You can still see what happening even though the wheel is damaged.
I am a snow bird between the state of WA and AZ. Fisrt came to Marana about 12 years ago and I can tell you this town is really on the grow. The Marana airport is being planned by the city as a future Corp. jet facility. If you haven't seen it for a while, you would be surprised at all that going on & planned for this facility. Thanks for the response - I'll be happy to have someone evaluate this situation other than myself. Do you still sell Ing. systems?

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Antique

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Yes.......

sides7

My Feedback: (9)

RCIGN
I'll send a PM after I get back to Marana.

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sides7

My Feedback: (9)

Here's the final result on this thread. I sent the engine to RCIGN to evaluate. Ralph had to mill off a portion of the flywheel to balance for a portion that had been broken off the wheel. It has now been determined that this engine (Zenoah's new StratoCharged 25.4 cc) does run CCW, and in fact Ralph reported it is turning 7000 rpm with a 18x6 prop - no performance mods. The existing muffler outlets consists of three 1/2 inch OD Al pipies which may be too constricting. I figured the outlet area at .383 sq. inches. Comments anyone?Anyway, when sent to Ralph the pipes had been shoved into the muffler to aide engine removal from the plane. Ralph stated that "the muffler needs a hole in it to let the exhuast out" I will not hesitate to send any engine to Ralph for evaluation, trouble shooting or repair. He was a big help to me and it is appricited.
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Update: Received a PM fron RCIGN which clears up the muffler statement above,ie There was no hole cut in the muffler to allow the exhaust into the muffler - inother words, I screwd up when making the muffler. DUMB T DUMB DUMB.

Antique

My Feedback: (4)

About the easiest starting magneto gasser I ever saw, but the magnets are PAST the coil when the engine fires...Gotta be a delay in the coil that won't fire the first time the magnets pass the coil legs...The mag coil does look very different from anything else.....Also the carb is a rotary barrel type with 2 inlets, and there are some very different transfer ports and notches in the bottom of the piston...Would be great if it had a little more power....

sides7

My Feedback: (9)

Now that RCIGN has this engine starting & runing so easy, I got to ask the question: Has anyone removed the EPA type carburator and replaced it with a reg. type carb with high & low needles? This "Strato Charged" Zenoah has two hoses from the carb. to the engine - for what ever purpose. With a reg. carb., would you just close off those hose inputs to the engine? Ralph feels the engine should be stronger for its size and I was thinking that riding it of the EPA crap might give a performance boost. Any suggestions would be appriciated.

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Antique

My Feedback: (4)

Might be interesting, but the ports are made to work with the 2 hole carb and funny piston skirt shapes...You could always make some new gaskets to cover up the extra holes..You would need a new carb insulator block and some fittings to get the crankcase pulse to the carb for the pump.....I didn't check the compression, maybe all it needs is the cylinder milled on the bottom to bring up the compression.. I once put a thicker base gasket on a rebuilt Q52 and lost about 700 rpm.....