Backfiring and WOT problems

My 2007 660 started coughing and spitting as i approach max speed (this is not the rev limiter, I know what that is), also backfiring as I let off the gas. then it would slow down and could only go around 10
miles per hour, eventually stall and would not start again unless I waited about 3 to 5 minutes. Then it would run fine as long as I did not push it hard, but it did backfire still. Later I heard a metal on metal sound like my muffler was rubbing the frame. Today I see there is a crack in the front of the muffler where the pipe attaches. I have heard these are related, has anyone heard of this or have any suggestions?


Rob
2007 660 Special Edition

Could be running lean from the exhaust leak if it's a big crack. I would bet that's it.

My 07 660 did that when my fuel pump was getting weak. Cough at WOT, stall and then not start for 10min. Was commonly called vapor lock. The exhaust leak will cause it to run lean. Is it where the pipe meets the muffler or where the two pipes connect ?

The 660's exhaust are prone to cracking just past the head, And your runing problem is your carb, it needs to be disasembled and deep cleaned properly, ie not just spraying it with a can of carb cleaner, but using the proper chemical cleaners and checking all the internal passage ways. And the diaphram for cracks or tears.

Thanks for the advise. Firefighter, the crack is where the pipe meets the muffler.

check your fuel also is it older, had similar problems with bad gas

Thanks Madmax, it is new fuel with stabilizer in it.