Drag Specialties Python3 slip-ons

[tsp45acp]

Put Drag Specialties Python3 slip-ons on my 08 1200C last sat (dealership put them on, not me). Bike runs great and sounds great to boot.


Here's my question: bike has always pinged & knocked from day 1 even though I've always run Shell/BP-Amoco/Exxon 93 oct gas. NOT ONE PING OR KNOCK SINCE THE NEW PIPES/SLIP-ONS WERE INSTALLED.

New pipes are 2", old stock pipes are 2 1/4". Smaller pipes with a freer flowing (higher air flow?) baffles which I thought would let more air through making the air/fuel mixture even more lean hasn't happened.


Why did the pinging & knocking stop? Tracy



I really like the slash cut looks too!

 

[NEWHD74FAN]

The smaller pipes with slightly more back pressure closer to the exhaust port in the head, likely improved exhaust tuning, the jist of it is to adjust the "back pressure/fuel scavenging wave". That popping you heard was unburnt fuel combined with higher temperature if the exhaust tuning was not right with the older pipes, along with the other parts of the system already EPA restricted. We also do not know if you had something like an exhaust leak with the existing system, and just sealing the works up would have done the same thing.

In either case, with the new pipe and slipon setup, the sensation of improved torque means that from the saddle you throttle up less and give EFI/ICM time to sync up the A/F & Ignition timing duration time to match the load better and hence less lugging of the engine, then with the old setup, which will bring the onset of pinging and chopping the throttle which would cause backfiring whith the older set. Exactly what changed in your case is purely speculation, but all the above may be a possible explanation.

 

[tsp45acp]

Newhd74fan,

Thanks, it makes sense. Tracy