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Hi fellow riders. I have a 07 VTX1300 that has an occasional backfire. Doesn't happen a lot but it's a startle when it does. That first fraction of a sec before ya realize no ones actually shooting and its just the bike (again) can be weird to say the least.. I figure it's unspent fuel fumes in the Cobra pipes that eventually ignite sounding like a shot gun blast.
I understand that both the manufacturer and long time riders in the know both recommend 87 octane. This has me questioning that if it's a matter of raw fumes building up in the pipe to a point of explosion would it be perhaps be better to run higher Octane? Like 88 or 89 so that more burns off before having the chance to loiter in the exhaust?
But then I recalled that the higher octane fuels actually burn SLOWER thus perhaps defeating the purpose, I'm also wondering if the higher Octane burning slower that perhaps it's also burning cleaner and thus not as much residual fumes sitting in the "fire area".
Have had this machine couple yrs. now and the R/T ride from Pa. to Fla. went very well. Great cruiser and just enough upgrade from my Virago 1100 to keep me happy, as well as making the Yamaha my back up ride since it's the most trouble free vehicle I have ever owned.
So any advice/suggestion's on the gas issue will be greatly appreciated.
Hope everyone's enjoying the nice fall weather riding...Be Safe, well & Blessed:)
Buster
 

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You misunderstand what "octane" means. It is not an indication of how fast or slow a fuel burns. It is not an indication of how "clean" a fuel burns. Rather, it is ONLY a measure of the autoignition temperature (AIT) of a fuel. This is the temperature at which a fuel spontaneously combusts. A lower octane fuel has a lower AIT and, thus, is more prone to premature ignition/detonation in a high compression hot engine. VTX bikes are not high compression and do not run hot due to being water cooled. Higher octane fuel is not your problem. You need to check the sealing of your header pipes, quality of your header gaskets, do a pair mod, and rejet/tune your carb.
 

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I have a 2007, VTX 1300R. Mine will backfire once every few months. I have Vance & Hines Hot Shots exhaust, I haven't done the pair mod which means I'm adding fresh air to the exhaust, plus my manual choking isn't always perfect. I figure it's that combo. Yes, I only burn 87 octane for the reasons Vinish noted. That being stated, I checked my plugs @ 4K miles and they were perfect. So, basically, I ignore it. I'll likely do the pair mod eventually but right now, it really ain't broke.
 

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I have a 2007, VTX 1300R. Mine will backfire once every few months. I have Vance & Hines Hot Shots exhaust, I haven't done the pair mod which means I'm adding fresh air to the exhaust, plus my manual choking isn't always perfect. I figure it's that combo. Yes, I only burn 87 octane for the reasons Vinish noted. That being stated, I checked my plugs @ 4K miles and they were perfect. So, basically, I ignore it. I'll likely do the pair mod eventually but right now, it really ain't broke.
Any air that gets past the exhaust gaskets, and into the pipes, can cause the backfires too. When changing pipes or just taking them off to work on the bike, many forget they are a 1 time only crush gasket and forget to replace. Also aftermarket pipe flanges are thinner than Honda, and when re-using the acorn exhaust nuts, they do not seat properly UNLESS you either switch to a regular hex nut, or put a couple flat washers under the acorn nuts before torquing to 17 ft./ lbs. Then run for 100 i. and re-torq.
 

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If you do put washers under the acorn nuts, make sure to use only stainless steel washers. Any other type will quickly rust.
 
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