Write-up: Carburetor screw adjustment guides
#1
Senior Member
Thread Starter
Write-up: Carburetor screw adjustment guides
Another mod to my new-to-me 50cc SBach 342. I wanted to have access to the carburetor adjustment screws without removing the cowl. I'd heard of running guides from the screws to the cowl so I thought I'd give it a try.
First, I found some tubing that would work. In my case, the guide sleeve from some 2-56 Sullivan Gold'n'Rod did the trick. Note that this tubing is not intended to rotate the screw, but to guide the screwdriver.
Next step was to make some exit holes in the cowl. There was one there already when I bought the plane so it was a simple matter to make a second.
The grommets that fit the guide tubes had a 19/64" panel mount diameter, so I enlarged both holes to fit.
Grommets in for a test fit.
First, I found some tubing that would work. In my case, the guide sleeve from some 2-56 Sullivan Gold'n'Rod did the trick. Note that this tubing is not intended to rotate the screw, but to guide the screwdriver.
Next step was to make some exit holes in the cowl. There was one there already when I bought the plane so it was a simple matter to make a second.
The grommets that fit the guide tubes had a 19/64" panel mount diameter, so I enlarged both holes to fit.
Grommets in for a test fit.
#2
Senior Member
Thread Starter
RE: Write-up: Carburetor screw adjustment guides
Next, I wanted to see where the tubes come to rest on the cowl when it's put on. In this case, just above the access holes.
I cut the tops off the backs of the grommets and epoxied them in place. And yes, it is a little too much epoxy - thanks for noticing!
Now when the cowl is put on I just need a hook to pop the tubes into the grommets.
There they go!
I cut the tops off the backs of the grommets and epoxied them in place. And yes, it is a little too much epoxy - thanks for noticing!
Now when the cowl is put on I just need a hook to pop the tubes into the grommets.
There they go!
#3
Senior Member
Thread Starter
RE: Write-up: Carburetor screw adjustment guides
Now it's just a matter of finding a long enough screwdriver.
I didn't want the tubes to vibrate off of the screws, so I added some heat shrink near the tips - first on each tube to ensure the proper gap between them was maintained, then on both to prevent them from sliding out of the cowl.
I did the same thing at the back...
Then added another layer for a better hold.
I didn't want the tubes to vibrate off of the screws, so I added some heat shrink near the tips - first on each tube to ensure the proper gap between them was maintained, then on both to prevent them from sliding out of the cowl.
I did the same thing at the back...
Then added another layer for a better hold.
#8
My Feedback: (29)
RE: Write-up: Carburetor screw adjustment guides
I really hope I don't come off as Mr. Poo Poo here but...........I would be very surprised if the tubes do not pull out of the cowl from engine vibration. I also hope your intention is not to make adjustments with the engine running.
#9
Senior Member
My Feedback: (4)
RE: Write-up: Carburetor screw adjustment guides
ORIGINAL: speedracerntrixie
I really hope I don't come off as Mr. Poo Poo here but...........I would be very surprised if the tubes do not pull out of the cowl from engine vibration. I also hope your intention is not to make adjustments with the engine running.
I really hope I don't come off as Mr. Poo Poo here but...........I would be very surprised if the tubes do not pull out of the cowl from engine vibration. I also hope your intention is not to make adjustments with the engine running.
#10
My Feedback: (9)
RE: Write-up: Carburetor screw adjustment guides
You do good work! I do mine only slightly different. I use a straw from soda drink and make a small mount for it at both ends. On the cowl I mount a fuel dot just above where the straws ends. On the carb end I leave the straws about 1/4" short so it does not actually touch the engine. My thinking was If I had to pull it all back apart the straws would still be in place. If someone uses the fuel dot like me. Be sure and tie some string to it and mount the other end of the sting to the female part of the dot inside the cowl. Without a line on it the dot could be lost in the air.
David
David
#11
Join Date: Dec 2001
Location: Upplands Vasby, SWEDEN
Posts: 7,816
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RE: Write-up: Carburetor screw adjustment guides
Hi!
Agree!
All adjustment should be made as the engine is running, in a safe way ofcourse, but with the carb at the rear there is no way you can get your fingers in the prop. It's another matter with the carb up front!
Agree!
All adjustment should be made as the engine is running, in a safe way ofcourse, but with the carb at the rear there is no way you can get your fingers in the prop. It's another matter with the carb up front!
#12
Senior Member
Thread Starter
RE: Write-up: Carburetor screw adjustment guides
ORIGINAL: speedracerntrixie
I really hope I don't come off as Mr. Poo Poo here but...........I would be very surprised if the tubes do not pull out of the cowl from engine vibration.
I really hope I don't come off as Mr. Poo Poo here but...........I would be very surprised if the tubes do not pull out of the cowl from engine vibration.
First, I joined the tubes and secured them to the needle screws with some heat shrink.
Then I bound the tubes together near the tips:
That should hold them.
I also hope your intention is not to make adjustments with the engine running.
#14
My Feedback: (29)
RE: Write-up: Carburetor screw adjustment guides
ORIGINAL: MX240
Running???? The only way to adjust a engine if you want it right!
ORIGINAL: speedracerntrixie
I really hope I don't come off as Mr. Poo Poo here but...........I would be very surprised if the tubes do not pull out of the cowl from engine vibration. I also hope your intention is not to make adjustments with the engine running.
I really hope I don't come off as Mr. Poo Poo here but...........I would be very surprised if the tubes do not pull out of the cowl from engine vibration. I also hope your intention is not to make adjustments with the engine running.