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Main Area => General GS500 Discussion => Topic started by: Derekstix on May 27, 2019, 09:04:16 AM

Title: Help with a search term
Post by: Derekstix on May 27, 2019, 09:04:16 AM
In sure that this has been covered before, but I'll be damned if I can come up with the magic search term. I bought this bike a couple of months ago, and haven't been able to start it. The carbs were supposedly rebuilt and jetted for pods. I put the original intake box back on it.
If I pull off the air filter box, and cover the intakes on the carbs, only the left one sucks air and gets fuel. The right side doesn't even pull air. Any idea about a search term for this?
Title: Re: Help with a search term
Post by: rasusto on May 27, 2019, 02:45:00 PM
Quote from: Derekstix on May 27, 2019, 09:04:16 AM
In sure that this has been covered before, but I'll be damned if I can come up with the magic search term. I bought this bike a couple of months ago, and haven't been able to start it. The carbs were supposedly rebuilt and jetted for pods. I put the original intake box back on it.
If I pull off the air filter box, and cover the intakes on the carbs, only the left one sucks air and gets fuel. The right side doesn't even pull air. Any idea about a search term for this?

If it's not pulling air, I would describe that as a "zero vacuum" condition. That's a bad sign. There's either a massive leak somewhere like a stuck valve or head gasket leak, or the piston isn't moving at all. Try removing the spark plug and see if you can see the cylinder moving up and down.
Title: Re: Help with a search term
Post by: Falken Hawke on May 27, 2019, 09:18:55 PM
A starting point would be "no compression" as that is created on the opposite stroke from vacuum.

Once the spark plug is removed and the engine cranked, one can get an idea if there is an adjustment issue or an overhaul issue.  Basically, if there is a little air moving, the bottom half is probably working.  In that case, checking the top half adjustments and timing should narrow down the issue.

If a borescope is available (cheap ones are available, just get one that has a light and a 90 degree attachment), a quick look at the valves can be done without teardown.
Title: Re: Help with a search term
Post by: Derekstix on May 28, 2019, 07:08:52 AM
Thanks guys. I think I knew what I might have to look for, but my brain didn't want to say it. Hoping for a vacuum leak, but preparing for a tear down. The manual is on the way, regardless.