Holding At 9-10 Grand I Get Backfire And Flames

[doubledscar]

Need help please! Its nice and I want to ride!

I put my 1989 Katana 600 Back together and now its running good at idle and all the way up to about 9 grand but if I hold the throttle at 9 grand or above it backfires and shoots a little flame out of the exhaust.

Could it be bad plugs?

A float stuck open?

Any idea's would be greatly aperciated.

I live in Washington and my nice days are limited! HELP~

[xbubbax]

id go with carbs are not synched correctly.

also did you do an exhaust upgrade? if so you will needs ajetkit

also valve seating/timing. timing is in carb synching and in the internal chain, how taught the chain is

[doubledscar]

I pulled out my plugs and they are BLACK!! Would that cause it? I only have a slip on. Not a full exhaust.

[xbubbax]

carbs are not synched corerectly, check that next, then make chure your airbox is clean. clean out them plugs. mabie running way way toooo lean....

..hoping the cyberpoet will chime in.

[xbubbax]

aahhh its too rich, and causing backfire......too much gas in the A/F mix. also make shure your carbs are clean.