[Mordru]

Hi everyone, anyone know about a HISS sound when doing a cold start? Ever since I replaced my carb diaphragms, ive been hearing this sound. Is it some sort of a backfire?

It runs fine otherwise.

Here is my thread with my recent work on the bike. Essentially just a carb cleaning, replaced diaphragms, and a new battery.

Loss of power

Hi everyone, hope you are well if you're reading this. Here's the story: Ran the bike in the morning to work, and on lunch just fine. (Hard start when the engine is cold, but my battery needs replaced. Once it's started it runs great) Went to leave work, bike is giving me a real hard time...

www.ex-500.com

Here is a link to a video with the sound.
Hiss sound when starting

 

[e10_muppet]

Does it continue to hiss when the bike is running or is it just that short sharp pfft on startup? If it's constant then obviously check all of the hoses are seated properly. I have a hiss coming from the back of my petcock when it's running, which i've just taped over.

 

[Mordru]

Just a quick sharp hiss/pfft on startup. Doesnt happen while running. Not sure if its something that needs investigating or not lol

 

[Mordru]

Just noticed this today; I rode the bike out for a bit, parked it for a couple hours. Going to start it again to leave. Switched the kill switch to run. Put the key in, turned on the ignition. At this point there was a puff/backfire type noise!!! I had not touched the starter. Only turned the key.

Anyone know whats going on here?!?!

P.S. side note Im thinking about getting new carbs boots as mine are stock (im assuming) and are really showing their age (bike is a '93).

 

[aneiwck]

Did you ever figure out the cause of the electric snap noise that happened prior to replacing the diaphragms?

I would look at electrical parts first, especially since you said it happened with battery voltage, before cranking.

I took a peek at the wiring diagrams, first inspect fuses and the ic ignitor.

In your video it sounds like the starter cuts out with the hiss sound, can you confirm that?