Straight pipes backfires - 1988 Yamaha XV 535 Virago DX

I would check if it still has stock jets. you need stage 1 or 2 dyno jet kit. To get best out of that upgrades also look for any vacum leaka

one of the cylinders is missing. It doesn't fire sometimes and when it does, you get the backfire. Check the plugs. It should be obvious which cylinder is at fault.

a wunna be cool engine...best way to fix that is to put a straight pipe on it

* Very hard to brake:
-Check for lose brake booster hose.
*Back fire:
-Check for clog air filter.

mai

Backfiring on throttle-closed decelleration is usually caused by cold air being sucked into a hot exhaust systen. Check for poor seal where the downpipe meets the cylinder head, and leakage at any joints beneath the engine if it has a balance pipe. Hope that helps.

is it a straight thru exhaust, or is it just a head pipe with nothing attached? If it's just a head pipe, you need to get some sort of muffler on it or you'll burn your valves out from a lean condition. The backfire is due to the vaccum fed carbs that yamaha runs. They work wonderfully, but under heavy deceleration, the vaccum still feeds the bowl, and it builds up excess fuel, which eventually burns off as a backfire. If it were fuel injected, you could have the fuel map adjusted to lean it out under deceleration.

carborator needs to be cleaned and the float needs to be reset

If you are running straight pipes they might not give you the right back pressure. This can be reolved by either going back to riginal pipes or instaling a bolt into the pipes about 5 inches in to make back pressure. Another thing? Did you have the bike's electronic ignition reset after you messed with it?

that seems to be what they do, i too have a 650a and have jardines on with baffles, it still pops and cackles when you roll off the gas. are you running no baffels? when i took mine out i noticed a drop in power as i had removed the requierd back pressure for optimum performance. you can get small baffles to slip into straight pipes from jc whitney for about $5 each.
anyway back to the backfire. my local bike shop shrugged their sholders when i asked them about mine saying it's what they do. you will get used to it and you will find a way to kinda not make it do it so much. i actually have grown to like it now, except when there are cops about.

happy safe riding