Having issues with a 2 liter boxer engine.

H. Paul Shuch is a Light Sport Repairman with Maintenance ratings for airplanes, gliders, weight shift control, and powered parachutes, as well as an independent Rotax Maintenance Technician at the Heavy Maintenance level. He holds a PhD in Air Transportation Engineering from the University of California, and serves as Director of Maintenance for AvSport of Lock Haven.

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914Driver
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Joined: Thu Nov 17, 2016 4:42 pm
Location: Saratoga, NY

Having issues with a 2 liter boxer engine.

Postby 914Driver » Fri Aug 10, 2018 1:09 pm

Limbach L-2000a with Stromberg-Zenith 150CD3 carbs. The plane's been sitting for a while before I bought it, I'm concerned that the logbook showed the valves being adjusted at 5 - 10 hour intervals. Compression was low so I adjusted the valves correctly (had to back the adjuster out 2 turns just to get them to relax). Ran it a bit, checked compression, ran it some more, check adjustment and the compression is now 120-140.

Timing is spot on, so what's the problem? It won't rev higher than 2500 RPM. Red line is 3k, but run up instructions are to go to 2750 for 30 seconds. The only other variable is the carb. perhaps some schmegma is lodged in the main jet? I put some Save the Baby type cleaner in the fuel tank, but that takes time to work.

Removing the carbs is a real pain, I guess I'm looking for an easier solution before going through all that. When I rebuild this type of carb for a 1966 Datsun I had, the kit came with a 45 minute video, not a good sign.....

Suggestions greatly appreciated.

Dan

914Driver
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Joined: Thu Nov 17, 2016 4:42 pm
Location: Saratoga, NY

Re: Having issues with a 2 liter boxer engine.

Postby 914Driver » Fri Aug 17, 2018 6:48 am

Carbs were pulled and cleaned. Kinda. More of a wipe down, the jets and orafices were clear.

Rats. More befuddled than ever.

chicagorandy
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Joined: Fri Sep 08, 2017 2:39 pm

Re: Having issues with a 2 liter boxer engine.

Postby chicagorandy » Fri Aug 17, 2018 7:29 am

You probably already have this in your files, but just in case:

http://constructeur-amateur-aviation-lo ... -carbs.pdf

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joey4420
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Location: Cincinnati Ohio

Re: Having issues with a 2 liter boxer engine.

Postby joey4420 » Fri Aug 17, 2018 12:33 pm

Not that I am that knowledgeable on these things; but if the engine is running good at full throttle but just doesn't get to the RPM you want, could it not be the prop? Either too long or pitch is wrong?
Joey
Cincinnati OH
Sport Pilot
Ercoupe N99773

914Driver
Posts: 44
Joined: Thu Nov 17, 2016 4:42 pm
Location: Saratoga, NY

Re: Having issues with a 2 liter boxer engine.

Postby 914Driver » Sun Aug 19, 2018 7:39 am

I thought of that but dismissed it because the ship flew in its current setting under the previous owner.

Wm.Ince
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Re: Having issues with a 2 liter boxer engine.

Postby Wm.Ince » Sun Aug 19, 2018 11:27 am

914Driver wrote:I thought of that but dismissed it because the ship flew in its current setting under the previous owner.

What is acceptable to previous owners may not be acceptable for the rest of us.
Bill Ince
CTSW
Retired Heavy Equipment Operator

chicagorandy
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Joined: Fri Sep 08, 2017 2:39 pm

Re: Having issues with a 2 liter boxer engine.

Postby chicagorandy » Sun Aug 19, 2018 12:34 pm

Agree, how do you know if the 2700rpm number was ever actually met in the past? Still could be the wrong size prop?

914Driver
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Joined: Thu Nov 17, 2016 4:42 pm
Location: Saratoga, NY

Re: Having issues with a 2 liter boxer engine.

Postby 914Driver » Mon Aug 20, 2018 7:45 am

"Seat of the pants" feeling. During a high speed taxi down the runway at 2500 rpm, it danced on the tires and felt like it wanted to fly; but if I needed a little oomph to cleat the trees, I didn't have it.

Dan

3Dreaming
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Location: noble, IL USA

Re: Having issues with a 2 liter boxer engine.

Postby 3Dreaming » Mon Aug 20, 2018 8:56 am

Just curious, but what aircraft are you trying to fly with this engine?

chicagorandy
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Re: Having issues with a 2 liter boxer engine.

Postby chicagorandy » Mon Aug 20, 2018 10:06 am

Do the current plane and pilot weigh the same as flown by the previous owner?

914Driver
Posts: 44
Joined: Thu Nov 17, 2016 4:42 pm
Location: Saratoga, NY

Re: Having issues with a 2 liter boxer engine.

Postby 914Driver » Tue Aug 21, 2018 3:54 pm

Yep, no changes in the plane and I weigh within 10 lbs. of the previous owner.

Aircraft is a Grob 109 motorglider. I pulled the carbs, cleaned and reinstalled them. Only went to 1500 RPM! I pulled the spark plugs and the two on the port side are not firing at all. Time to learn about magnetos. (magnetoes?)
Image

3Dreaming
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Location: noble, IL USA

Re: Having issues with a 2 liter boxer engine.

Postby 3Dreaming » Tue Aug 21, 2018 7:40 pm

Is this the one that sold at auction recently?

914Driver
Posts: 44
Joined: Thu Nov 17, 2016 4:42 pm
Location: Saratoga, NY

Re: Having issues with a 2 liter boxer engine.

Postby 914Driver » Wed Aug 22, 2018 7:13 am

No. That one was kinda rough for the money, mine came from the San Francisco area.

Link to a video: https://www.dropbox.com/s/h85rh8znh21vbu5/California%20Heavens%20%28low%20res%29.m4v?dl=0

914Driver
Posts: 44
Joined: Thu Nov 17, 2016 4:42 pm
Location: Saratoga, NY

Re: Having issues with a 2 liter boxer engine.

Postby 914Driver » Sat Aug 25, 2018 8:29 am

Update:
I pulled the plugs, the ones on the starboard side were slightly sooty; the port side two had raw gas. No fire. I turned on the ignition and rotated the prop while grounding one plug at a time. The two on the starboard side showed a blue-ish spark, port side did indeed fire but it was orange - yellow. New Slick 4330 will be here next week. Fingers crossed ....

Looking through the logbook, the valves were adjusted at 5-10 hour intervals recently. I looked at them when it first arrived and found all had to be loosened at least 1/2 turn to make the valve fully close. I wonder if it was the Mag the whole time. It was changed at 500 hours as it should be, but now with almost 1400 hours on it, hasn't been changed since; that's almost double it expected life.

Dan


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