2005 bruteforce 750i backfiring through rear carb.

[lurzboy]

No matter if it is cold or warm. very hard to startup. It sat for 14 months.
I cleaned the carbs, drained the fuel,refilled with fresh fuel. had to use carb cleaner to get it to fire up. fuel delivery is fine. fresh plugs installed. backfires through the rpm range when accelerating.

Any ideas. Im trying to go riding saturday. I know it was a mistake to let it sit that long with fuel in it. but when I cleaned the carbs, there wasn't any clogs.

[RCW]

I left mine setting with a set of dry carbs while I was in Chile, and it grew fuzz in the small side holes in main jet tube on the rear carb. So, there must have been some residual fuel in there somewhere, and it took a complete disassembly to locate the problem. But, the symptoms were the same as yours.

It is a pain in the donkey to remove and disassemble those carbs, but I know no other way to be sure they are really clean. Also, never use any air from a compressor nozzle to blow out the carbs, or you may find yourself buying a new carb or two. After I clean mine with Honda spray carb cleaner, I take them outside and squirt all the passages out with starting fluid or brake cleaner, and never allow any compressed air near them. Remove the air valve and all the rubber diaphragms before you clean them, or you run the risk of ruining the diaphragms.

Now, I use PRI-G in the fuel and let it set wet for months on end and have zero problems.