High Speed Engine Death Part 2: Fuel or Vacuum Lines?

petcock-closeup-honda-nighthawkAfter pondering and hemming and hawing about this expressway stalling issue, I started a new thread on the Nighthawk Forums, where other people are helping me figure this issue out. The consensus has generally been the same, minus a few outliers – there’s most likely an issue with the vacuum on the petcock. The vacuum and fuel lines are the easiest to fix out of these, so those are first. It’s starving for air and that’s causing it to die.

As long as I stay going under the 65mph doom line then it’s riding just fine!


My new challenge is whether or not I want to go with steel braided line or not! Look at those old lines on there. Nasty business. Just nasty.

Thankfully there’s a Walneck Swap meet happening today, but it only goes on till three, so I’ve gotta leave now!

4 thoughts on “High Speed Engine Death Part 2: Fuel or Vacuum Lines?

  1. Steve

    DUDE! thanks for tackling this issue with no power and stall at 65… that is the same issue I had, and hadn’t had any luck finding any info! new line, new petcock parts and even synched the carbs while everything was apart… Bingo no issues! Thanks. Steve

    • Dang you put in a lot more work than I did for it! I should definitely do some carb work and rebuild my petcock, it’s really stiff, but I’ve been thinking that I might be able to use a 2000s Shadow petcock – I’ve got a friend with one and it’s a quick flip of a switch, and that makes me crazy jealous!

      Glad you’ve got that running well. What are you riding?

      • Andrew

        Hey Charlie,

        I hope you are still using your site! I recently bought a 1985 Nighthawk 700 and I am having the same issues with stalling at 65mph+ however mine has been very sporadic. Some days it will go more than 50 miles without stalling but then it will suddenly happen. Do you still think this is a Vacuum/fuel line issue? I greatly appreciate any feedback because this is awfully frustrating when I am trying to get to work.


        • Hey Andrew, sorry for taking so long responding, I hope you were able to get running since then. But!! Vacuum lines are so cheap that I’d definitely just replace them instead of looking for anything else that might be wrong. That’s how mine was stalling for a little bit. You can get the tubing from any hardware store I believe. Just bring in a piece of it (or take it off the bike while you’re in the parking lot, it’s easy enough).

          Did you get it fixed?

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