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The fog and the Killer Bee throttled backplate

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The fog and the Killer Bee throttled backplate

Post  balogh on Mon Dec 28, 2015 4:15 am

The fog in may area keeps me in my room not allowing me to fly my planes, and makes me think of how I could further upgrade my favorite reedie.

When measuring the dimensions of the air-intake on its Killer Bee backplate I noted it is tapered at the end, and does not fit the groove in the snorkel pipe of Bernie's throttled carb, that comes on a modified Sure Start backplate. No matter how hard I push the snorkel against the air intake, there still remains some air leakage that would disable to some extent the throttling effect.

So I went back to my toolbox and found a small O-ring that (though born in a SI metrics environment in Europe) fits the groove of the snorkel quite well.

After the O-ring is pushed in the groove, the Killer Bee backplate accommodates the throttled snorkel without any air leakage at the air intake around the groove. Here are the components:



(The snorkel comes from a normal Sure Start as my throttled snorkel serves on my Canary...you will also note that I pushed a mesh screen inside the air intake, though the Killer Bee is made with an enlarged air intake diamater to allow higher airflows...this screen blocks the airflow a tiny little bit but is worth the cleaner engine run..)
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Re: The fog and the Killer Bee throttled backplate

Post  getback on Mon Dec 28, 2015 11:54 am

That's cool up were able to adapt to the killer back plate with just an o-ring , so your not using a throttle ring? getback:cox logo:
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Re: The fog and the Killer Bee throttled backplate

Post  roddie on Mon Dec 28, 2015 12:33 pm

getback wrote:That's cool  up were able to adapt to the killer  back plate with just an o-ring , so your not using a throttle ring? getback:cox logo:  

Even though the o-ring seals the snorkel.. will  Bernie's throttle flow enough air to take advantage of the larger venturi? What size is the bore in the snorkel? Hard to tell from the pics.. but it looks smaller.. and probably matched to the sure-start (grey) back-plate's venturi? Who knows.. it might make for better throttle response.. or maybe increase torque? Only one way to find out.. Eyebrows  I want to resurrect my   dyno for tests like these!

I was also wondering how that high-flow back-plate would work with the throttle-ring.
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Re: The fog and the Killer Bee throttled backplate

Post  balogh on Mon Dec 28, 2015 1:11 pm

The snorkel internal bore is a few maybe 2 mm larger than the Killer Bee venturi bore so the snorkel does not restrict the airflow sensibly.

I have also widened a little  the bore of the throttle body and barrel  with a drill bit. Too wide opening on the throttle barrel will make full closure impossible so if anyone wants to follow this recipe should exert caution.

I went out and flew my Canary  with the throttled KB backplate engine in the fog and it flies and throttles well..
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Re: The fog and the Killer Bee throttled backplate

Post  roddie on Mon Dec 28, 2015 1:24 pm

Did you run the Tee Dee cylinder and high-compression head this time?
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Re: The fog and the Killer Bee throttled backplate

Post  balogh on Mon Dec 28, 2015 2:22 pm

Now this time it was my #1 cylinder
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Re: The fog and the Killer Bee throttled backplate

Post  pkrankow on Mon Dec 28, 2015 2:55 pm

I have been contemplating this. Thanks for the tips!

Phil
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Re: The fog and the Killer Bee throttled backplate

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