Backfire out of carbs and dead spot in rpm

[straxcla]

More problems with this crazy bike. About a month (give or take a few weeks) I put a used head on this bike due to valve issues. At that time I also made sure the valve clearances were in spec. The bike ran beautifully for a bit and then started getting a dead spot around 6-8k rpm. The problem is worsened by how much throttle I am giving it, ie when i smash on it it accelerates up to 6k rpm then starts losing all desire to go faster, like it's starving for gas, or bogging out. Then it started backfiring out of the carb when it's hanging out below 3k rpm. The backfiring is slowly getting worse, and the dead spot is just plain annoying. I've put about 2500 miles on it since I put the used head on. I've played with the mixture screws, no difference. Do I need to rebuild my carbs? New jets (I did clean those out awhile ago)? Plugs are pretty new as well. Any input is greatly appreciated.   

[Nocluejoe]

What year is the bike?

Check your carburator hose is out of cross wind and behind the battery box

Check inside your gas tank see if it's rusty

Clean your carbs it's not like you can really ride the bike anyways

Make sure all vacuums are working and no leaks

If you could check your compression on your motor see what your at cold and hot

[MARider]

I had some what of the same issue. it turned out to be the diaphragm on my left carb. PO had used gasket maker to "repair" the torn diaphragm. After i replaced it all seems well..take the caps off your carbs...carefully and take a look for any tears. I got mine from ebay for around 18 shipped.

[nathaniel2910]

also make sure the carb breather is tucked up behind the engine and not sticking out, as this forces air up the pipe and starves the carbs

[MARider]

dito on what nate said. I didnt even have one on mine when I got it and that could have been one of the things causing my issue.

[straxcla]

It's a 2002. So it sounds like I just need to take off the carbs and completely dissect/clean/repair them, and then make sure they're installed correctly.

[MARider]

If it has been sitting yes..I would say tear the carbs apart as that can sometimes cause more harm then good

[straxcla]

Going to try and revive my old thread here. So I cleaned and re-cleaned the carbs, made sure the carbs were synced, checked the petcock coming from the tank, adjusted my valves, and the dead spot is still as present and annoying as ever. I did find that one of my boots coming off the head had worked its way lose so I tightened that which helped a bit with the backfiring. But I still have that dead spot anywhere past about 6-7k rpm, definitely running lean though (plugs are a little white). I'm out of ideas, what's next, new fuel hoses, new jets?

[MARider]

Talk to buddha about getting some jets. I got mine in 3 days from him. also make sure your boots from the air box to the carbs is on there good..not to tight on the clamps. Best thing is loosen the clamps from the carbs to the engine and make sure your air box is one the carbs good then tighten the clamps back down. Did you check to make sure the diaphragms were in perfect condition? I know a million questions but our these carbs need to be pretty much perfect to run right due to the vacuum shazzam. Oh one more thing think about switching to a honda crfx pertock, you will just need to remember to turn it off when you park your bike, gets ride of needed to worry about vacuum though.

[Nakedguy]

I'm putting my money on boot leaks.