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SBJ needle insert--removable??

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SBJ needle insert--removable??

Post  Robbasdog on Thu Mar 03, 2016 11:19 am

Hi folks,
 I think I know what the answer to this question will be, but I'm gonna ask anyway! Has anyone tried to remove and re-fit the threaded insert for the needle in the tank backplate on a Space Bug Junior? The reason I ask is that on my SBJ the insert is visibly dirty or rusty through the clear-ish nylon, and looks terrible. I am going to experiment with my ultrasonic cleaner to see if it will shift the crud, but I'm not holding my breath waiting for that to be successful. I would guess the insert is pressed in, not moulded in, but how tight is it? I don't mind being the first to try it, but if someone already has, so much the better; after all, it's said that it's smart to learn from your mistakes--so learning from someone else's has to be even smarter, right?
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Re: SBJ needle insert--removable??

Post  Mudhen on Thu Mar 03, 2016 5:01 pm

You can remove the insert, but you’ll need an expendable Babe Bee needle valve.
You’ll also need plyers and a rag handy.
Make sure the threads are clean enough to smoothly thread the needle valve into the tank back.
Then remove the needle valve.
Drop the tank back into warm/hot water, but not boiling.
After about 10 minutes, remove the back from the water and thread the needle valve all the way into the insert. Grab the tank back with the rag, and the needle valve with the plyers and PULL.
Once removed, you can clean the insert and the tank back with rubbing alcohol, Q-tips, and computer air..
When ready to reinstall the insert, first lightly coat it with Vaseline. Thread the needle valve into the insert. When you’re ready to press it into place, make certain the fuel jet drilled into the insert will line up with the nylon jet on the tank back. You’ll have to feel it carefully so as not to install it against the mold lines. Once it’s lined up, it takes very little pressure to push it all the way in.
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Re: SBJ needle insert--removable??

Post  pkrankow on Thu Mar 03, 2016 5:14 pm

Is Vaseline the best choice? It does tend to eat into many plastics over time.

Phil
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Re: SBJ needle insert--removable??

Post  Mudhen on Thu Mar 03, 2016 10:53 pm

pkrankow wrote:Is Vaseline the best choice?  It does tend to eat into many plastics over time. Phil
I've never had that experience.
Vaseline is petroleum based, so it will prevent corrosion. If he decides to run the engine it will cleanly burn out after one tank full.
I have used it on polystyrene, polypropylene, and nylon threads, (Mostly Cox restorations.) I've not seen any side effects.
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Re: SBJ needle insert--removable??

Post  Robbasdog on Fri Mar 04, 2016 8:49 am

Well I was wrong, thats not the answer I was expecting. Thanks Mudhen, useful tips indeed, and pretty much how I was going to tackle it too. Great to have the voice of experience confirm my own thoughts. The ultrasonics didn't do much, but it's only a low powered thing anyway, just a toy compared to the ones I used at work a while ago. I've got some silicone-based o-ring grease leftover from my scuba diving days that should be just the thing for reassembly, totally inert stuff used to lube regulators. Fuel-compatibility is not an issue, the wee beastie is officially retired from active service now that its compression is a bit meagre, and is being restored as a show-piece. Got a few Babe Bees to take over the flying duties.
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