[Acadia86]

I realize we're all about VN750s here and mine is doing better than ever with its snazzy new AGM battery this spring! I just took it for my first ride of the season today. I'm in Vulcan heaven.

Meanwhile however, my GF's trusty Shadow VT500 started the season less admirably. It cruises and idles fine but falters something terrible when climbing hills. The front cylinder is putting a bronze sheen on the headpipe too. It always runs on ethanol-free but the carbs were left full during storage. I'm guessing that front carb is crudded up and causing a lean condition that's overheating the pipe.

Is my guess anywhere near accurate?

Like I said, I realize this forum is limited to our particular prides and joys but I've gotten a lot of help and great advice from the folks here. And given how this problem seems universal enough to apply to any bike, I'm hoping for some direction/advice before I offer to help my friend in turn. Would you say the carb is the most likely suspect here or are there other things I should check first?

 

[Spockster]

I realize we're all about VN750s here and mine is doing better than ever with its snazzy new AGM battery this spring! I just took it for my first ride of the season today. I'm in Vulcan heaven.

Meanwhile however, my GF's trusty Shadow VT500 started the season less admirably. It cruises and idles fine but falters something terrible when climbing hills. The front cylinder is putting a bronze sheen on the headpipe too. It always runs on ethanol-free but the carbs were left full during storage. I'm guessing that front carb is crudded up and causing a lean condition that's overheating the pipe.

Is my guess anywhere near accurate?

Like I said, I realize this forum is limited to our particular prides and joys but I've gotten a lot of help and great advice from the folks here. And given how this problem seems universal enough to apply to any bike, I'm hoping for some direction/advice before I offer to help my friend in turn. Would you say the carb is the most likely suspect here or are there other things I should check first?

Not sure how the fuel system is set up, but the carb is the most likely culprit.

Edit.... It appears that some Shadows do have a fuel pump, but that should be the 700/750.

 

[Acadia86]

Thanks Spockster. It helps to have the affirmation of someone with more knowledge and experience. Now it's time to see if those carbs are as hard to get out as mine were!

 

[dirtrack650]

Vacuum leak my guess. Check the rubber carb mount. If there's a manifold, Honda puts a o-ring between the engine and manifold that will leak.

 

[Acadia86]

Quick follow up here for any who, like me, enjoy some nice closure now and then. This mystifying problem turned out to be a missing gasket on the air filter cover. After cleaning the carbs twice, rebuilding the petcock, replacing the intake boots and spark plugs, checking the timing and coils, I finally got desperate to at least ascertain if it was running lean. To test that, I stuffed a clean sock into the intake snorkel. I figured, what the hell, let's see if that slows down some of that airflow a bit. Well by god, that thing ran like a dream with the sock in there!

Remembering that my GF had replaced the air filter, I took it out and examined it for a tight seal. It looked fine, but that's when I also wondered if there ought to be a gasket on the metal cover plate. Sure enough, Clymer showed one. So I fabricated a makeshift one out of EPDM weatherstrip, put it back together and voila! All fixed! I would not have imagined that a bike could be so adversely affected by such a small air leak like that - especially on the upstream side of the air filter - but evidently that Shadow was.