Gasket and reed surface lapping

Hangar > Engines > DLE 30 > Gasket and Reed Surface Lapping


Like I've done with my DLE 20 and RCGF 32 before, I followed Frank Bowman's advice for all Chinese-built gas engines by lapping the carburetor and reed valve mating surfaces in my DLE 30.


Carburetor to rear crankcase

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For the purposes of this modification I will refer to the above components jointly as the intake assembly.

Lapping is the process of smoothing a flat surface remove undulations and imperfections. According to Frank, many Chinese engines suffer from a lack of quality in this area resulting in hard starting and rough running. To the shop!


The first step is to remove the carburetor and reed valve block assembly from the rear of the crankcase. I had no trouble separating the carburetor from the reed valve cage but the heat block was stuck fast to the rear crankcase and I had to use a fair bit of force (hands only) to break it loose. The gasket didn't survive intact so I ordered a new set and moved along with the lapping.

Heat block to crankcase gasket fail

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Lapping started with the rear crankcase.

Lapping the crankcase mating surface - 01

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With a sheet of 320 grit sandpaper taped to my glass surface, I lapped the rear crankcase mating surface while it was still attached to the engine.

Lapping the crankcase mating surface - 02

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That's better.

Crankcase mating surface lapping complete

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Moving along the intake assembly, the next part is the reed valve cage. Here's the reed valve mating surface before lapping...

Reed block reed surface - rough

And after lapping.

Reed block reed mating surface - smooth

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And the carburetor mating surface before...

Reed block to carb mating surface rough

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And after.

Smoothing reed block to carb mating surface - 05

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Heat block mating surface before...

Heat block to reed valve block mating surface - rough

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After.

Smoothing the heat block to reed valve block mating surface - 0102

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Carburetor mating surface before...

Carburetor to heat block mating surface - before

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Holding the throttle closed to keep debris out.

Throttle plate held closed

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Carburetor mating surface after.

Carburetor to heat block mating surface - after

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While I had the carb off the plane I removed the cover to check the filter screen. What a mess!

Dirty carb screen

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That's better.

All clean

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New gasket set.

DLE 30 gaskets

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Putting it all back together.

Thread lock on the bolts, new gaskets throughout the carb

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