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Can't start my Webra Speed 35 (Heli) Airboat

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Old 03-21-2017, 08:32 AM
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Airboat72
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Default Can't start my Webra Speed 35 (Heli) Airboat

Bit of a long story on the boat but the engine turns over fires a few times then dies. Priming makes it fire a few more times before it dies again which would indicate fuel starvation. Glow plugs good, blown the carb through needles out all looks clear, high and low set at 1 1/2 and 1 1/4 turns out respectively. Perhaps the carb is leaking air. Any suggestions would be very welcome and much appreciated.
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Old 03-21-2017, 09:41 AM
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Your needle settings are likely too lean. Open them up a couple more turns and try again.
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Old 03-21-2017, 10:11 AM
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This engine has a large bore carb. make sure you run pressure. In a heli model the fuel tank and engine are at the same level.
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Old 03-21-2017, 01:15 PM
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Quote:
Originally Posted by controlliner View Post
This engine has a large bore carb. make sure you run pressure. In a heli model the fuel tank and engine are at the same level.

What is a good method to pressurise? exhaust?
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Old 03-21-2017, 02:11 PM
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Quote:
Originally Posted by Airboat72 View Post
What is a good method to pressurise? exhaust?

At minimum, use muffler pressure. I doubt the carburetor is too big for muffler pressure to be inadequate.
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Old 03-21-2017, 09:18 PM
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is the fuel tank mounted under the engine ? or behind the engine ? if its under the chances are Fuel Draw which means the carby can,t draw and hold fuel in the lines . also is the seal between the carby and engine good ? is the front bearing seal good and not leaking ? the list can go on and on as many issues occur with old or worn engines. start with a richer needles valve setting and also add a pressure fitting from muffler to fuel tank breather. [ 3 turns out on the needles should get the engine running if its only the carby mixtures at fault.
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Old 03-22-2017, 02:24 AM
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Quote:
Originally Posted by 1QwkSport2.5r View Post
At minimum, use muffler pressure. I doubt the carburetor is too big for muffler pressure to be inadequate.
Genius, just the job, Wow that is some power. Thank you very much
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Old 03-22-2017, 02:34 AM
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Thanks everyone.
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Old 03-22-2017, 02:36 AM
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Quote:
Originally Posted by controlliner View Post
This engine has a large bore carb. make sure you run pressure. In a heli model the fuel tank and engine are at the same level.
Genius, Thanks very much. serious power there. s**t myself tbh still here though. What a rush!
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