Baffles Finally Explained!

Need To Send Me Something?
Paul Van Gaans
1201 Howitt Street
Suite 27
Wendouree, VIC 3355
Australia

[stephencox]

It is all about tuning the different lengths of the parts that make up the exhaust system, For instance in the early 1970's with Yamaha TZ 350's one trick that helped both power and noise was to make the stinger section extend between two to three inches past the visible weld joining it to the convergent cone into the expansion chamber.
In a similar way I have made V rod straight thru looking two and a quarter inch OD pipes that had an absorbtion type baffle about a third of the way down the pipe where my math said it would meet the reverse sonic waves at the optimal point worked great made good even power on the dyno was not too loud and looked the part bike tech since 1972 you hopefully learn some things in that time

[BarnettSpeedSuzukiThou]

The fun stuff starts when one calculates the exhaust length taking into consideration the cam lift, duration and overlap, not. Lol.

[saddlebag]

Pipes involve physics that flies above the heads of us shade tree mechanics. Power delivery at the lower rpms is not about restriction at the lower rpms, it's about reflecting the sonic wave so that they can scavenge the cylinders more effectively. It's the same reason twins typically use crossover designs these days. There was an exhaust maker who used to have some excellent vids on Youtube on this, but I can't find him anymore. He could make far and away the most top end power with straight pipes, but there was no way he could tune out the power dip at lower/mid range.
You would think that removing the pipe altogether would be the least "restrictive, " right? Actually, the bike would run terrible if at all at lower rpms w/o them because there's 14.7 psi of air pressure sitting there at the port blocking the exit.
The idea behind reflecting the wave is it creates a vacuum at the port when it's tuned right (mechanical placement of the impediment) to make the engine better clear the cylinders at lower rpms.
Your adding the lollipop is effectively creating an impediment that creates the reflected sonic wave. Thing is, you're not engineering it with any mathematical precision, you're just putting it on the end where you have access. As long as it works better w/o it then, what the hell, take the win.
There was a guy on a Victory site years ago and he did that lollipop thing. I don't remember if it improved the power delivery any, but it sounded magnificent at idle like that. Had that lopey cam sound. Of course Indian does that pretty well as it is, but Vics didn't.

[dakkanTM]

Exhaust Reversion, its the moment where the pressure of the exhaust gasses in the pipe drops to the point where the outside air pressure causes the exhaust to reverse and you catch volume of waste air in your cylinder before the exhaust valve has a chance to close. This causes a lower volume of charged air to be pulled through the intake valve and lowers your toque and power.

Thats my understanding of it. Baffles etc help slow the reversion air to lower this problem.

[Idontalways]

With the slip on’s installed, did you have the stage 1 fuel map installed from Indian? The increased flow from the mufflers may require different fuel inputs to retain power across all parts of the RPM range.

[hughmac]

Interesting, the Pan America that I have, when fitted with a Vance and Hines muffler improves the power significantly below 5, 000rpm and above, then they advertise with a dyno curve comparing the V&H muffler to a standard muffler, and there is a significant jump in the low end and upper end power, that is noticeable when riding, in fact fitting the standard muffler, I notice I was revving 500rpm high to get the same feel in acceleration. Then the Pan Am is quite a different bike from yours.
I also have a 1988 Lowrider with hot cam, big replacement carb and some V&H shotgun style pipes (they have a cleaver tube like baffle in the pipe, so it looks like a straight out pipe), I know when I fit the standard pipes and muffler, it kills the power and torque on that bike. Then it is an old bike with a sidecar and it gets the same economy as my old Commodore. Doesn't compare to your bike either really.

[losadadeveloper]

Could not see the link to the other video you mentioned, thanks

[furocity]

Paul, off topic but did you ever test ride the 101 scout? Video?

[griff]

Was a fuel mix adjustment necessary when you installed the Rineharts mate? I’m researching new slip ons for my ‘23 CDH and am leaning toward Rineharts just based on your experience. Is there another type of slip on you would recommend alongside your Rinehart setup?

[NateDS]

Do you experience high idling on your bike before putting on the lollipop?