2002 VMax 600 backfire on startup

[JeepTherapy]

Freaquently when starting my VMax 600 tripple after riding for an hour or so I got an increadable backfire. I am a little afraid it is going ot blow something apart. Any idea what may cause this? Running too rich? Fuel draining from carbs after shutdown?

any Ideas would be great

 

[SiR X700]

backfire on start up

My wifes 02 V Max 700 does the samething if she does not let it idle for 20 or 30 seconds before she shuts it off. It only happens when she uses her electric start.

 

[larsd]

Better bring an old thread back to life, rather than start a new one?

I have the exact same issue now, my '01 SXR 700 backfires really hard at startup, most often at the gas station when I have been filling it up after a trip. And never when it is cold, and never when it runs. Anyone got a diagnosis? The carburetors probably need a good cleanup, as the idle is not so good anymore. But I had the backfire-issue since before the idle-issue..

 

[Backwoods M Max]

My mountain max will do it too. It happens to me if I forget to pull up the kill switch and pull it over or crank it wih the starter. Just a little fuel collecting in the pipe then going POP

 

[srx700c]

...The carburetors probably need a good cleanup, as the idle is not so good anymore. But I had the backfire-issue since before the idle-issue..

It's a good idea to clean the carbs, especially if they haven't been cleaned this season. Your declining idle quality is usually a very good indicator they need to be cleaned, and whenever I get a backfire I also dig into the carbs since none of the sleds I've had typically backfire.

Some people clean the carbs a couple times a season, or more especially if the sled had been in storage/unused for multiple years. The pilot jets and inlet screens get plugged easily, as well as the small passageways in the carb body, and the little ethanol jelly balls can stick to anything in there. There are good carb cleaning write-ups here on this site, a quick search should provide plenty of good reading.

 

[ClayNation]

My wifes 02 V Max 700 does the samething if she does not let it idle for 20 or 30 seconds before she shuts it off. It only happens when she uses her electric start.

Wondering if anyone has solved this issue -

I bought a 2003 VMAX 600 early this season with 1100 miles on it. It does the exact same thing as listed here. If I don't idle down before hitting the kill switch, I'll get a backfire if started up shortly after shutting down. Also if I crank it over and forget to pull the kill switch up, it will back fire when starting. Runs fine, idles fine, pulls hard, no backfiring while running or idling...plugs look good.

Thanks!

 

[A couple of bucks]

Seeping needle/seat or improperly set float comes to mind.

 

[Jack99]

.

My 1999 600 Triple would "pop" (backfire) during start up as well. One day, it popped so big it actually made 2 muffler springs let go. Definitely, don't want to do that again...

For it, I simply:
- Cleaned all 3 of its carbs using carb cleaner, fine wire strand and air can with small straw blowing.
- Changed oil to Amsoil 2-stroke oil (for snowmobiles) and adjusted its flow rate until their spark plugs are a dark chocolate brown.
- Start and let it warm up 3-5 minutes - before reving it above 3,200 RPM. Now, I start it, put my make up on (LOL!), put my helmet on, adjust its mirrors, plug in my helmet's cord, check my blind spots before revving it up above 3,200 RPMs.
- Before shut-off, let it idle down for 20 seconds as well. Never shut it off when RPM is above 1,800.

Did all of above and it never "popped" (back fired) again.

This might work for your sled as well...