LT80 turns over but won't start

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Dec 28, 2025 | 04:02 AM

#51

Fahnone91

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Joined: Dec 2025

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Quote:

Originally Posted by merryman

There should be a steady flow on PRIme. Also, if you spin the engine over on the starter with pipe disconnected there should be a steady flow when tap is ON. Have you put enough fuel in? As it takes fuel from about 30mm above the bottom, except when on REServe. Anyway, I find they can be bad to get going after a lay up and generally start them with a sniff of gas from a gas blowlamp, surprising how effective this is on two strokes. Plug has to be dry when you do this as spinning over on petrol until you have "wet the plug" ensures no spark, so no start. Advantage of gas is it can't wet the plug and if the mix of gas and petrol is too rich, when on gas it will weaken as the gas disperses when you turn the gas off, until it is "right" to fire.

Hello merryman, thanks already for your answer.

So with the new petcock there is no flow what so ever on prime, neither on ON only if i take the vaccum hose of an im sucking on it....
would it be better to try and get a Banshee petcock to get rid of the vaccum operated petcock?
also i stil have the oil injection pump installed without being sure it's working.

Greetings

Stephan

Dec 28, 2025 | 04:34 AM

#52

merryman

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Joined: Oct 2013

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From: Lancaster England

Jack (LT80) was the expert and used to run his on fuel/oil mixture. He also used to fit the Banshee tap. I prefer to leave both standard, a bit too easy for someone to fill up with neat fuel, either because they don't know two strokes should have a mix, or because they think the oiler is still working. If you want to test it, when the fuel level is low, put a small quantity of two stroke oil in the fuel tank, slosh to mix and start up, run for 5 min then disconnect the oil line at the carb. When running, the mixture will keep the engine lubed and oil should dribble from the pipe if the oil pump is working. Same for the tap, all to easy to forget to turn it off after use, I was brought up on British motorcycles which always dribbled if the tap was left on, but most people are not used to having to turn off. I do use Chinese taps, as with many Chinese spares they are not quite right, I find the labels for on, res and prime are wrong, you have to work out which is which by putting a small amount of fuel in, and seeing which way it needs to be for res, then more fuel in and see which is prime and which on. I then marker pen this on the tank above the tap, otherwise I forget.