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Discussion Starter · #22 ·
Ok so..
Saturday,
Started carb... Moved the slider in the mouth of the carb up and down... Engine roars into life accelerating and revving up properly...

Turn off.... Open carburettor clean all jets holes etc ...
Checked compensator diaphragm.(seems like compensator nozzle (the little spray, is blocked)

Cleaned out float bowl.
Cleaned out accelerator diaphragm (the one that slides up and down in the carburettor mouth )
Cleaned out channels for auto choke...

Put together ...

Put on quad .... No start ....
Check fuel lines... No start still ...
Got frustrated and stopped for the day....
Any ideas??

Could it be something else besides the carburettor??
I must also check the vaccum lines... As the slider diaphragm is controlled by the vaccum 馃し馃し

But a new carburettor?
Take it to a mechanic??
 

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I'd say its a fuel or carb issue for sure. Question... Does your carburetor have a diaphragm slide ?
A rubber diaphragm up top that uses vacuum to lift the throttle slide ? Since you said it ran when you
manually lifted the slide I'm wondering if it has a tear in it or isn't seated in its groove. If you can see into the carb throat,
you should see the slide move up when you give it throttle. As for replacement carbs , that's an option. I have a Chinese carb on my Yamaha. Keep in mind that they are made for many different vehicles and you'll probably need to fine tune the jetting.

Mad
 

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Discussion Starter · #24 ·
I'd say its a fuel or carb issue for sure. Question... Does your carburetor have a diaphragm slide ?
A rubber diaphragm up top that uses vacuum to lift the throttle slide ? Since you said it ran when you
manually lifted the slide I'm wondering if it has a tear in it or isn't seated in its groove. If you can see into the carb throat,
you should see the slide move up when you give it throttle. As for replacement carbs , that's an option. I have a Chinese carb on my Yamaha. Keep in mind that they are made for many different vehicles and you'll probably need to fine tune the jetting.

Mad
It's got a brand new throttle slide...
And yes it slides. Up about 1/2 cm when I give it throttle (when it's running) ... But it also bounces up and down between, the 1/2cm an all the way down... While running.... Seems to be bouncing up and down with the explosions...
But nowhere near as much as I've seen it slide in ur videos.....
 

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I don't know if I already asked this, is that quad a 2 stroke or 4 stroke ?
If 2 stroke, check your reed valves. They can break.
If 4 stroke, have you checked valve clearance ?

Mad
 

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Absolutely. If its a 4 stroke and the valves haven't been checked in a long time, it can drastically affect
the way it runs. Tight valves can burn. A tight intake valve that's hanging open can allow air to be pushed
back out of the cylinder head and through the carb, where more fuel is introduced causing a super rich
mixture. You really can't do any trouble shooting on carb or electrical issues until you know the
motor is mechanically sound.

Mad
 

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Discussion Starter · #28 ·
Absolutely. If its a 4 stroke and the valves haven't been checked in a long time, it can drastically affect
the way it runs. Tight valves can burn. A tight intake valve that's hanging open can allow air to be pushed
back out of the cylinder head and through the carb, where more fuel is introduced causing a super rich
mixture. You really can't do any trouble shooting on carb or electrical issues until you know the
motor is mechanically sound.

Mad
Hmmm. I was getting a ton of air coming back up through the carb...
 

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Discussion Starter · #29 ·
Absolutely. If its a 4 stroke and the valves haven't been checked in a long time, it can drastically affect
the way it runs. Tight valves can burn. A tight intake valve that's hanging open can allow air to be pushed
back out of the cylinder head and through the carb, where more fuel is introduced causing a super rich
mixture. You really can't do any trouble shooting on carb or electrical issues until you know the
motor is mechanically sound.

Mad
Any words of wisdom, or cautions before I go about setting the valve clearance?
 

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Sure. Make CERTAIN you adjust the valves with the subway Top Dead Center on the COMPRESSION stroke. 2 ways to check this.
Remove spark plug
Take stator cover off
With your finger over the spark plug hole, rotate the engine in normal direction until you feel air coming out
of the spark plug hole. Use a plastic zip tie and insert it in the spark plug hole and slowly rotate the engine. When the
zip tie stops rising ( its sitting on the piston) that's TDC compression stroke. Do NOT use a small zip tie that can fall in the cylinder head.
OR
Remove the valve cover. Slowly rotate the engine until you see the intake valve ( the one closest to the carb) start
to open the valve. Continue as it opens then closes. Now watch the cam lobes. When both rocker arms are sitting
AWAY from the cam lobes kinda equally, adjust there. Before you start, both rockers should be a bit loose. You should be able to wiggle them. If one is tight, double check your cam settings and go ahead and adjust.
Sometimes people adjust their valves on the exhaust stroke. You end up with an incredibly noisy engine and not
much power. Don't do that

Mad
 
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