Question for my friends bike????

[blkpitbull]

My friend just bought a 03 sv1000s with only 400 miles on it.

The question is: He says when he barely blips the throttle in nuetral/or clutch pulled in, the motor backfires through the intake. The bikes brand new and is showroom stock. Does anyone have any idea why this occurs???? He says it seems to run fine any other time. I thought plugs but idunno. Any help would be appreciated,

Thanks

[woobie]

Re: Question for my friends bike????

My friend just bought a 03 sv1000s with only 400 miles on it.

I'd head back to the dealer and get it looked at, besides he's almost due for the first service isn't he?

[blkpitbull]

Yeah, the service is really close, but the dealer said that the service consisted of only an oil change and a check of basic things: fluids etc...... i will tell him to call the dealer, but I think he wanted me to ask you guys, because the dealer is almost 2 hours away!!! thanks

[The CyberPoet]

Backfiring through the intake is normally a result of a too-rich fuel mixture, carbon or sulfated ash build-up, and/or a blockage in the exhaust. What's happening is that the exhaust valve opens, the exhaust starts moving out as the piston comes up, then the intake valve opens and fresh fuel-air charge starts moving in; the exhaust valve closes (there's some overlap here), and before the intake valve can close, some of the fresh fuel-air mix ignites, sending an flame-front backwards through the intake tract.

Possibilities:
leaking/dripping fuel injector or bad spray pattern (not atomizing properly)
bad O2 sensor if the bike uses an O2 sensor (or bad wiring to it)
excess carbon or sulfated ash build-up (can be cleaned out with high-detergent fuels and techron)
or
blockage in the exhaust (mouse nest, dirt, condensed water) not permitting proper flow out of the exhaust.

Much more rarely, using an aftermarket filter may induce this issue too (not normally though).

Cheers
=-= The CyberPoet

[TemtnF8]

It does indeed sound like an issue with excessive back pressure in the exhaust. I'd check that route, and definately have him take it to the dealer if he can't figure it out quickly.

[WildKat]

If there was any kind of warranty w/ it, that may help cover the costs.

[KatanaO215]

like has been said, take that thing right back to the shop. they have to make it right and cover it

[BlackB12]

Most likely the borderline too lean factory settings. A power commander will most likely solve this problem. Buells would do the same thing when asked to respond quickly at very low rpm. Got to remember a V-twin at idle has a lot of dead time between firing cycles, and lean EPA mandated fuel calibration doesn't often yeild light switch throttle response at idle.