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New to carbs - 1980 GT80 bogging out and not starting

05 Jul 2020 12:13 05 Jul 2020 12:15 by TastyChevelle.
TastyChevelle
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New to carbs - 1980 GT80 bogging out and not starting #1
Hello,

So my GT80 is missing the air screw from the carb. Would that make it run way too rich? Right now I put duct tape over that hole so dirt doesn't get in. :Ugh

Here are the symptoms: It runs for 5 minute spurts at a time just fine, plenty of power. I do maybe 2 or 3 of those and then did other things and let it sit for an hour. I come back, starts right up, then ride for about 15 seconds, it starts to bog down, not fire every cycle, and can't get any power down without it dying. Then it stops, I kick and I kick and I can't get it to start.

The first time this happened I cleaned out the carb thoroughly, taking out jets, the needle, carb cleaner and air compressor in every orifice. Still doesn't start.

Then I took out the spark plug and it was wet, but oily wet from the pre-mix gas I think. Clean that off with brake cleaner, air compressor. It fires for a split second, then no amount of kicks got it to start.

Then I said what the heck and shot brake cleaner down the cylinder, kicked it over a few times to blow out the oil or whatevers in the cylinder, blew air in there, cleaned off the spark plug. Starts after a few kicks and back to square one, runs great for 5 minute sessions, plenty of power, do those 2-3 more times, seems to kind of slowly bog on the later runs, let it sit, and I clean out the cylinder again and it runs like new. Also let me know if this is a major no no. It worked multiple times and it seems ok still.

:silly: HUH?

Like I said, I'm new to carbs and what the symptoms are if it runs too rich or too lean, but my guess is its running so rich that the cylinder gets slowly flooded. But I don't know.

About to buy a Mikuni carb replacement because this one is missing the air screw and is all pitted out on the inside, and we'll see if thats the issue.

But what are your thoughts?

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10 Jul 2020 16:35
mryan
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New to carbs - 1980 GT80 bogging out and not starting #2
When you first start it that day the engine is cold. Your letting it suck in as much gas as possible. After it gets warm, it is to rick and can't get enough air. Try to find a screw. Maybe from a lawn mower, they might be the correct size? If not, you will need a screw to correct your problem.

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10 Jul 2020 17:13
Swoop56
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New to carbs - 1980 GT80 bogging out and not starting #3
You could buy a carb kit . They usually include the air screw and spring ( check first ) .
If you can't find an OEM part , it will do the job . Don't use any of the other parts , other than bowl
gasket , or float valve .

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