Help from Older&Wiser Mechanics? (1985 VF500F Interceptor)

Hey everyone!

This is my first bike, and I'm having a bit of trouble diagnosing how to fix a problem with my VF500 Interceptor. Revving the throttle when the bike idles below 1500 RPMs causes the engine to shut off, but it runs fine when revved from anywhere above that.

Here's what we've worked on already.
- The carbs have been rebuild with new gaskets.
- Coolant has been flushed.
- Verified that there's fuel and that the fuel pump is working
- Sparkplugs are firing and battery is charged
- New air filter installed
- We've adjusted the mixture up to both a full turn leaner and richer at quarter turn intervals

Strange note as well: it seemed like only three cylinders were firing until we moved the choke to full, and the fourth started to fire. After this, all four seemed to fire from the start, no matter where the choke is. I'm unsure of what caused the fourth to start. We guessed this change by sound and temperature of the fourth cylinder.

I'm guessing there's an air leak with the carb boots? One was a little cracked and we greased them before reinstalling the carbs. How do you test for that? I ordered new ones anyway, but if that doesn't work, I'm not sure how to move forward. Thanks for your time and reading!

 

Try some duct tape on the cracked boot(s) to seal it.
It leaves a bunch of sticky residue, but you will be replacing them anyway.

 

seems like you need to clean the carbs again, but better.

 

I'd also suggest that your idle jets are probably plugged and / or idle circuit is gummed up.

 

If you're interested, i'm offering to professionally inspect, clean, adjust and leak-test your 500 carbs for just $220. I also have some spare, hard-to-find carb parts for VF500s. turn-around time 12 days max. guaranteed results.

 

Spray some carb cleaner near the crack, if rpms go up you need to replace them

Sent from my SM-G900P using Tapatalk

 

Can also spray WD-40 - the rpms will change if air leak

 

My condolences on this being your first bike BUT they are fun when running right. Your pilots jets are clogged, get a brand new EBC set from ebay, they're only about $15 bucks for the set. Easy. They're #38 Keihin (type) series 21. Easy.