I recently bought a 2003 Honda Shadow VLX 600 for my wife as her first bike. It was a real find . . only 500 original miles on it and it looks like it just came out of the showroom. The problem is, as it’s been sitting unused for years, it was pretty messed up: Carb was all clogged and everything was generally gummed up!
I followed your carb-cleaning advice to the letter and boiled it in Lemon Juice, which seemed to work really well. I re-assembled everything and the bike ran great (kind-of) right off the bat. It starts really easy and idles perfectly. It revs-up just fine in the low-end, but as soon as I start to give it more throttle it starts to bog-down and stalls.
Any idea what might be going on here? It’s a California edition bike with the emission control system, and a vacuum carb, which I hate, but I’m stuck with it.
The jets appear to be completely clean, and the insides of the carb look like new, I just can’t figure it out.
Your symptoms are commonly caused by an air leak. Could be a vacuum diaphragm, a hose, or even just the intake manifolds. I would disassemble and inspect the integrity of all the rubber components.
Also – did you verify that all passages and jets in the carb are clear by spraying fluid or air through them?