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DL-50 Reed Valve Wear Question

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Old 07-24-2011, 08:46 PM
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sgillmore
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Default DL-50 Reed Valve Wear Question

I have an original DL-50 that I purchased from DLUSA a couple years back. I haven't flown it a ton...about 7 gallons. It's been a great engine from day one: starts easy, runs strong and been just about perfect in every way...until last weekend. I was flying my 30% Yak at the AMA 75th Anniversary fly-in. Several flights on Thursday and most of the day Friday when late afternoon it happeneddead stick about five minutes into the flight. After some basic checks on the ignition, ign battery, fuel system, etc... I went back up. Engine ran great for about five minutes, then quit like the fuel was shut off. I flew it one more time and the exact same thing...a dead stick about five minutes into the flight.

It seems to be heat-related, but whatever it was started all the sudden. I flew 10-12 minutes flights in the same weather/temperature with no issue for two days straight before this started happening.

When I got home pulled the engine and started looking through the engine. The only thing I've found so far is this odd wear on the reed valves (see pics).

1. Has anyone seen this before?
2. What causes it?
3. Could it possibly cause the problems I'm having?
4. Does anyone have torque specs for these engines? I have a tendency to over-tighten everything I touch. If I could torque the carb/insulator block bolts with a torque wrench it sure would make me feel better.

Thanks!
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Old 07-24-2011, 11:05 PM
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Default RE: DL-50 Reed Valve Wear Question

The noted wear is typical of aging reeds, but not the engine stop problem. Look towards the ignition. It does indeed sound heat related, but related to hot electrical components. 45-50 inch pounds will do for the screw torque on the carb.
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Old 07-24-2011, 11:31 PM
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Default RE: DL-50 Reed Valve Wear Question

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ORIGINAL: Tired Old Man

The noted wear is typical of aging reeds, but not the engine stop problem. Look towards the ignition. It does indeed sound heat related, but related to hot electrical components. 45-50 inch pounds will do for the screw torque on the carb.
Thanks for the reply. I'm assuming I should go ahead and replace these?
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Old 07-25-2011, 06:20 AM
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Default RE: DL-50 Reed Valve Wear Question

Wouldn't hurt. One other item to check while things are open that could be causing the 5 minute run problem. Open up the carb and clean the carb screen.
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Old 07-25-2011, 07:50 AM
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Default RE: DL-50 Reed Valve Wear Question


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ORIGINAL: Tired Old Man

Wouldn't hurt. One other item to check while things are open that could be causing the 5 minute run problem. Open up the carb and clean the carb screen.
Thanks for the suggestion, but that was one of the first things I checked. The screen was amazingly clean.

I'm going to order a new gasket set when I order the reed valve assembly. Just curious, if I pull the jug on the DL-50 will I have any trouble getting it back together without a ring compressor? What would you recommend for torque on the head bolts?

Thanks again for your help.
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Old 07-25-2011, 08:07 AM
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Default RE: DL-50 Reed Valve Wear Question

I've managed to nudge the ring into place with a popsicle stick on a DLE. On a 79cc Mahle, I used a big electrical tie wrap around the ring. When the piston went in the cylinder, the tie wrap fell down around the connecting rod and I cut it off.
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Old 07-25-2011, 08:17 AM
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Default RE: DL-50 Reed Valve Wear Question


Quote:
ORIGINAL: w8ye

I've managed to nudge the ring into place with a popsicle stick on a DLE. On a 79cc Mahle, I used a big electrical tie wrap around the ring. When the piston went in the cylinder, the tie wrap fell down around the connecting rod and I cut it off.
Good tip .... large wire ties work well as ring compressors.
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