Write-up: DLE-20 reed valve block mod
02-04-2013, 07:03 AM
#1
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Thread Starter
Write-up: DLE-20 reed valve block mod
Follow up to Write-up: Installing a Bowman ring in a DLE-20
From Frank:
- - -
It is assumed at this point that the engine is removed from the airplane.
1. Remove the back plate bolts
2. Remove the carburetor and back plate from the crankcase.
3. Remove the two bolts that attach the carburetor to the back plate and separate the two components.
4. Remove the reed valve assembly from the carburetor block.
From Frank:
All China engines reed Block Mod.
I found that on the rear intake's there is a Black plastic or Aluminum reed block between engine & carb. It has a flange on it for mounting to flat carb & engine surface and reed part is triangular shaped. The reed block surfaces are not flat and reeds in some cases don't lay perfectly flat against block. The gasket surfaces often times are not flat either and need to be sanded down to flatten. In some reed blocks there are 2 screws that go thru a steel plate that holds reed to surface. On other reed blocks the screws just go through holes in reeds. Remove screws and reeds from block, then file or hone metal plates if supplied flat as 1 side will have burrs from having been punched out and holed not drilled. Next tape down 320 grit sandpaper to edge of really flat surface, table top, edge of thick piece of glass, etc. Because of the lip on plastic block, let that part hang over edge and pull plastic or Aluminum block across paper to flatten. Repeat on other surface until the surface is flat. It won't take much so no need to get carried away. Next deburr the 4 screw holes as screws tend to pull plastic up in screw holes. Remount screws thru plate & reed or just reeds. Make sure reed is totally flat, if not remove screws again and turn reed over and reinstall screws. Screws will strip easily so if you have lock tite you can put a tiny bit on screws to secure & tighten gently. What this affects is idle, engine will be hard starting as if 1 or both reeds are open ever so slightly, fuel won't be drawn up to carb and stay there. If reeds are open it never will pull a vacuum to draw fuel and hold fuel at carb. Thanks Frank
I found that on the rear intake's there is a Black plastic or Aluminum reed block between engine & carb. It has a flange on it for mounting to flat carb & engine surface and reed part is triangular shaped. The reed block surfaces are not flat and reeds in some cases don't lay perfectly flat against block. The gasket surfaces often times are not flat either and need to be sanded down to flatten. In some reed blocks there are 2 screws that go thru a steel plate that holds reed to surface. On other reed blocks the screws just go through holes in reeds. Remove screws and reeds from block, then file or hone metal plates if supplied flat as 1 side will have burrs from having been punched out and holed not drilled. Next tape down 320 grit sandpaper to edge of really flat surface, table top, edge of thick piece of glass, etc. Because of the lip on plastic block, let that part hang over edge and pull plastic or Aluminum block across paper to flatten. Repeat on other surface until the surface is flat. It won't take much so no need to get carried away. Next deburr the 4 screw holes as screws tend to pull plastic up in screw holes. Remount screws thru plate & reed or just reeds. Make sure reed is totally flat, if not remove screws again and turn reed over and reinstall screws. Screws will strip easily so if you have lock tite you can put a tiny bit on screws to secure & tighten gently. What this affects is idle, engine will be hard starting as if 1 or both reeds are open ever so slightly, fuel won't be drawn up to carb and stay there. If reeds are open it never will pull a vacuum to draw fuel and hold fuel at carb. Thanks Frank
It is assumed at this point that the engine is removed from the airplane.
1. Remove the back plate bolts
2. Remove the carburetor and back plate from the crankcase.
3. Remove the two bolts that attach the carburetor to the back plate and separate the two components.
4. Remove the reed valve assembly from the carburetor block.
02-04-2013, 07:15 AM
#2
Senior Member
Thread Starter
RE: Write-up: DLE-20 reed valve block mod
5. Tape a sheet of 320 grit sandpaper to a flat surface
6. Remove the screws that retain the metal plate and reed.
7. Mark the plate and reed for orientation.
8. If there are burrs on the back of the metal plate, sand them off (mine didn't have any).
9. Place the reed valve block on the sandpaper with the lip hanging over the edge and sand back and forth until the surface is uniformly flat. Check often. Note: I cannot believe I neglected to take a picture of the reed valve block on the sandpaper. The drawing will have to do.
A: Reed valve block
B: 320 grit sandpaper
C: Flat surface
10. Clean off the reed valve block.
11. Reassemble the reed and plate on the block.
12. Put a little thread lock on the screws
13. Reinstall the screws through the plate. Tighten gently.
14. Repeat steps 6 to 13 for the other reed.
6. Remove the screws that retain the metal plate and reed.
7. Mark the plate and reed for orientation.
8. If there are burrs on the back of the metal plate, sand them off (mine didn't have any).
9. Place the reed valve block on the sandpaper with the lip hanging over the edge and sand back and forth until the surface is uniformly flat. Check often. Note: I cannot believe I neglected to take a picture of the reed valve block on the sandpaper. The drawing will have to do.
A: Reed valve block
B: 320 grit sandpaper
C: Flat surface
10. Clean off the reed valve block.
11. Reassemble the reed and plate on the block.
12. Put a little thread lock on the screws
13. Reinstall the screws through the plate. Tighten gently.
14. Repeat steps 6 to 13 for the other reed.
02-04-2013, 07:20 AM
#3
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Thread Starter
RE: Write-up: DLE-20 reed valve block mod
15. Remove the gasket from the reed valve assembly
16. Sand the gasket surface of the the reed valve assembly.
Note the darker spots - not sanded flush yet.
There we go.
17. Clean up the reed valve assembly. I used gentle shots of compressed air.
16. Sand the gasket surface of the the reed valve assembly.
Note the darker spots - not sanded flush yet.
There we go.
17. Clean up the reed valve assembly. I used gentle shots of compressed air.
02-04-2013, 07:23 AM
#4
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Thread Starter
RE: Write-up: DLE-20 reed valve block mod
18. Remove the gasket from the back of the carburetor block.
19. Sand the rear gasket surface of the carburetor block.
In progress...
All set.
19. Sand the rear gasket surface of the carburetor block.
In progress...
All set.
02-04-2013, 07:33 AM
#5
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Thread Starter
RE: Write-up: DLE-20 reed valve block mod
20. If you haven't already, remove the carburetor block from the back plate.
21. Repeat the sanding process.
22. Inspect the gasket surface of the carburetor. Mine was very rough.
23. Note that sanding is complicated by the arms at the ends of the throttle shaft. If you plan to sand it smooth, either remove the throttle assembly or find a flat surface narrower than the distance between the two arms. I was able to do the latter.
21. Repeat the sanding process.
22. Inspect the gasket surface of the carburetor. Mine was very rough.
23. Note that sanding is complicated by the arms at the ends of the throttle shaft. If you plan to sand it smooth, either remove the throttle assembly or find a flat surface narrower than the distance between the two arms. I was able to do the latter.
02-04-2013, 07:38 AM
#6
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Thread Starter
RE: Write-up: DLE-20 reed valve block mod
I was able to get the gasket surface of the carburetor much smoother than stock.
24. Time to reassemble the carb and valve block. Put the bolts in through the back.
25. Add the carburetor gasket.
26. Reed valve assembly next.
24. Time to reassemble the carb and valve block. Put the bolts in through the back.
25. Add the carburetor gasket.
26. Reed valve assembly next.
02-04-2013, 07:44 AM
#7
Senior Member
Thread Starter
RE: Write-up: DLE-20 reed valve block mod
27. Follow with the reed valve gasket.
28. Add the carburetor block, gasket and back plate. Apply some thread lock to the bolts and tighten them.
29. Put some thread lock on the four crankcase bolts. Install and tighten them.
All together! Next step: Carburetor equalization mod. Given the position of the engine in the mounts, I will leave the engine off to do that.
28. Add the carburetor block, gasket and back plate. Apply some thread lock to the bolts and tighten them.
29. Put some thread lock on the four crankcase bolts. Install and tighten them.
All together! Next step: Carburetor equalization mod. Given the position of the engine in the mounts, I will leave the engine off to do that.
02-04-2013, 09:41 AM
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RE: Write-up: DLE-20 reed valve block mod
Grosbeak, thanks for the excellent information on how to fix the Chinese carb. Quality control is not one of their strong points. I have a DLE 20 NIB and I intend to fix the carb block and reed valve surface as you have outlined.
Bob
Bob
02-04-2013, 10:09 AM
#9
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Thread Starter
RE: Write-up: DLE-20 reed valve block mod
Hi Bob, much
Hi Bob,
Much appreciated! You may also want to consider a Bowman ring (see the link at the top of the first post in this thread).
ORIGINAL: Oldbob
Grosbeak, thanks for the excellent information on how to fix the Chinese carb. Quality control is not one of their strong points. I have a DLE 20 NIB and I intend to fix the carb block and reed valve surface as you have outlined.
Bob
Grosbeak, thanks for the excellent information on how to fix the Chinese carb. Quality control is not one of their strong points. I have a DLE 20 NIB and I intend to fix the carb block and reed valve surface as you have outlined.
Bob
Much appreciated! You may also want to consider a Bowman ring (see the link at the top of the first post in this thread).
03-01-2013, 12:51 PM
#12
RE: Write-up: DLE-20 reed valve block mod
Is there areason behind doing all this work? was there some issue with the way the motor ran? I understand the ring replacement but why all the reed and carb work.Thanks.
03-01-2013, 03:08 PM
#13
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RE: Write-up: DLE-20 reed valve block mod
A reed that is not properly sealed can cause an engine to run erratic, cause hard starts due to fuel not being drawn up into the carb due to air leaks. Those plastic flaps need to lay flat on the block and seal any air leaks. Hence the refining of the surfaces.
03-01-2013, 03:17 PM
#14
RE: Write-up: DLE-20 reed valve block mod
Would I benefit from this if I'm not having any of these particular issues?Ihave 4 of these engines and they all run pretty much right on, easy start smooth transition, etc. Ihave been thinking about changing the rings. I havea new one not yet mounted so I may take it apart and see what it looks like. Thanks again.
03-02-2013, 02:31 PM
#15
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RE: Write-up: DLE-20 reed valve block mod
ORIGINAL: plaurence
What is the carb equalization mod?
What is the carb equalization mod?
I have two write-ups for carburetor equalization on my website. All of the details about what it is and why to do it are there:
DLE 20: Carburetor equalization
DA 50R: Carburetor equalization
Incidentally, the write-ups for the Bowman ring and the
DLE 20: Bowman ring installation
DLE 20: Gasket and reed surface lapping
05-15-2013, 06:26 AM
#16
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Thread Starter
RE: Write-up: DLE-20 reed valve block mod
ORIGINAL: raptureboy
Would I benefit from this if I'm not having any of these particular issues? I have 4 of these engines and they all run pretty much right on, easy start smooth transition, etc. I have been thinking about changing the rings. I have a new one not yet mounted so I may take it apart and see what it looks like. Thanks again.
Would I benefit from this if I'm not having any of these particular issues? I have 4 of these engines and they all run pretty much right on, easy start smooth transition, etc. I have been thinking about changing the rings. I have a new one not yet mounted so I may take it apart and see what it looks like. Thanks again.
