Very bad backfiring problem

[smokingness69]

ive got a 00 busa. mods are small airbox mod, k&n filter, pcII, clutch mod and cushion kit, ram air scoops, and pair removed. i had an akro evo full exhaust with akro map before and the bike only backfired when i was in the 9k rpm ranged and snapped the throttle shut. even then it would only backfire once or twice in a row. i have now since changed to the brock gen3 pipe and BDE-014-G3 map and im getting backfire like crazy even when shutting the throttle at low rpm's. like around 5k and even when closing the throttle slowly. if i do it a 9 or 10k rpms it backfires about 6-8 times in a row. any help is appreciated. it doesnt feel like im loosing any power but its annoying as hell. dont know if this helps but it has a very poor throttle response from a 1st gear roll on at about 5-7 mph. id expect it to break the tire loose like crazy but it stumbles at first and then picks up like its suppose to. i have adjusted the tps sensor...could the exhaust bolts be loose causing it to suck air (i reused exhaust gaskets), or could the throttle bodies be out of sync? its got 18000 miles and they've never been synced.

 

[stlbusarider]

Have you ever had the valves adjusted? I have an 04 with a simaller problem. At high rpm when throttle is released it will shoot small flames out of the pipes. I have no mods other than yoshi slipons, and adjusting the vales helped.

 

[smokingness69]

havent adjusted the valves but they arent making any weird noises. ive heard of people on here going tens of thousands of miles without adjusting the valves.

 

[Burger King]

Definetly sounds like it's sucking air. Since you just changed the pipe I would guess that it would be in that area. At 18K miles I would put on new exhaust gaskets. A cheap start. I would also check all the joint locations of your new pipe. Make sure they are seated properly with no bent areas at the joint locations. Also make sure your PAIR "covers" are sealed. Did you use new gaskets when you added the cover plates? Are the cover plates warped allowing air to be sucked in to the exhaust ports? You can buy new gasket material from an auto parts store and cut it to fit.

At 18K your bike definitely needs a carb sync. Simple to do or have done and can make a world of difference on throttle response. If you are mechanically inclined I would encourage you to buy some carb stix so that you can do the sync as aften as you like. It is a no cost, other than the carb stix, way of making sure your bike will run its smoothest and have it's best throttle response.

 

[moondog]

I'll bet it's at the head pipe, don't re-use the old gasket, just asking for trouble. You've got a major cold air leak somewhere and if changing the pipe was the last thing you did, there ya go....

 

[BusaWhipped]

havent adjusted the valves but they arent making any weird noises. ive heard of people on here going tens of thousands of miles without adjusting the valves.

The valve clearence needs to be checked at 15,000 miles. The Busa doesn't seem to need valve adjustments as much as other bikes, but if you don't check, you don't know.

 

[smokingness69]

thanks for the help guys. ill put on new gaskets and do a carb sync. ill get back to you and let you know if it worked.

 

[smokingness69]

ok guys, here's the update. i bought new header gaskets to install on the exhaust ports. when i took the head pipes off i found that each port had two exhaust gaskets in it. obviously my dumb ass f'd up. it appears that when i installed the akropovic exhaust a few years ago i didnt take out the old exhuast gaskets and instead put the new gaskets for the akro pipe on top of the stock gaskets. i never noticed because it must have sealed good enough to not suck in outside air. so recently when i took off the akro pipe and installed the brock pipe, i thought i was just reusing the gaskets from the akro when in fact there were two sets of gaskets in it. the seal must have broke loose when i installed the brock pipe and started sucking in outside air. so i ended up having to take the brock pipe back off and removing the two sets of gaskets and then i installed a brand new set of gaskets. guess what....bike doesnt backfire anymore. the lesson learned today is dont screw up like i did and put one set of gaskets on top of another and remember to use new gaskets when changing exhaust.

thanks for the help guys.