Topic: MotoGPWerks Yoshi Exhaust (New Stepped Design)

[eadelacruz91]

**EDIT**

My new exhaust from Chris at MotoGPWerks just came in

It uses a stepped design "for better bottom range and top end so they go from small dia to larger dia (hence the weld ) then to a larger collector"

I've heard amazing things and I trust his work

I got some good advice on cleaning up the lines, I’ll post pictures when it’s installed.

I can’t wait!

[slikwilli420]

I just bought the old design for my racer, but would rather have this one. Captain did a stepped header on his race bike and it made a noticeable difference. I'd be up for a trade if someone wants a mint never run older version.

[Stev-o]

Is the stepped design only on the 550 pipes?

[slikwilli420]

Is the stepped design only on the 550 pipes?

I think it was his latest batch of pipes made and sold. I suspect him to incorporate it into all models of CB pipes.

Really Cal? I would think gains would be unnoticeable on stock engines and it seems like more work for a mod many will not appreciate or understand. What he really should so is incorporate this into a 4-2-1 design and really get the lower end grunt up.

[slikwilli420]

He does make a killer product without a doubt. Its interesting you mention it not being lucrative for him. If you don't make money, either don't make the item, or don't complain about not making money. He has a bit of a martyr attitude regarding stuff like that.

[Don R]

 The stepped design is a proven concept, I've had it on our race car for 10 years.

[Yamahawk]

Just buff the welds with ScotchBrite pads and a stainless steel brush. They will come up shiny and clean and not be visible. You can even use Bar Keeper's Friend as a polish to remove the heat discoloration associated with welding stainless.

You are among the first (2-3 others here) to receive the new design so I don't know if anyone has installed these yet on a running build to determine the gains. He has stated clearly, "If you don't want/like the pipe, please return it and I'll be happy to refund you." He's pretty confident in the design and in my experience, would much rather have his products back then have a customer keep them and not love them.

If you install the pipe, before you fire it up, wipe down the entire pipe with Acetone to remove any oil or grease residue. That will prevent the pipes from tarnishing due to the heat of the exhaust gases.

Some good advice on cleaning those welds! Acetone will eliminate any oil residue for sure. I think his welder did a pretty good freehand TIG weld on the slip joints, looks like he just fused them without filler, but used filler down on the collector to give a good joint weld there. I see some rose color on the fusing, and that's a good sign of proper heat on his TIG torch. The pipes look well designed, and that step up in size will give a better scavenge for the exhaust in each cylinder, kind of like a 2-stroke does. 4 stroke engines work on a similar principle of the pressure wave reflecting back up the pipe into the chamber, which is why some pipes come with a reverse cone installed in the pipe end by the chamber, to reflect it back down the pipe. A lot of math goes into a properly designed pipe for performance.
Charlie

[Yamahawk]

Yeah I see some filler added in spots, but looks like where he could he fused it... makes a nice weld when you can get a nice tight fit, and then fuse the two pieces together. It's nice to know he purges the inside with argon, that makes a very nice quality weld, without 'sugaring' the root inside the tube. Good quality for sure!
Charlie

[PeWe]

Stepped design.... For backpressure?

[Yamahawk]

Stepped design.... For backpressure?

I think it is more for scavenging than back pressure, or the headpiece would be the larger of the two. As the gases are traveling down the pipe, they expand at the larger junction, creating a suction effect into the combustion chamber, purging any burnt and unburnt exhaust, and pulling new mixture into the chamber. More efficient, if that is the design... Now, resonance also play a part, where the sonic wave of the exhaust will reflect back into the head pipe, and stop exhaust from exiting, so the pipes must be 'tuned' for this to be a minimal effect. If you look at some of the V-Twin and 4 cylinder headers, they have a cone, shaped toward the back, and installed into the head pipe where it meets the exhaust port. this reflects the wave back to the exit of the exhaust, minimizing this effect.
Charlie