New bolt on expansion chamber?

[Rickety4265]

Hey guys. I just found a new bolt on expansion chamber exhaust that seems to be pretty new (all the eBay posts are from early 2023 in their revision history). The dimensions seem pretty similar to the jog scooter expansion chamber that a lot of people seem to like a lot and say is an actual real expansion chamber. I don’t have any welding experience of my own which is why I haven’t gone for the scooter pipe so this new exhaust looks pretty interesting to me. What do y’all think?

CDH67 Colorful Exhaust Expansion Chamber Muffler-2 Stroke Gas Motorized Bicycle

Scooter exhaust:
FLYPIG Exhaust W/ Expansion Chamber For Honda AF18 AF24 AF27 AF28 AF30Dio Exhaust System Muffler Pipe Elite Sym 50

 

[DieselTech]

Hey guys. I just found a new bolt on expansion chamber exhaust that seems to be pretty new (all the eBay posts are from early 2023 in their revision history). The dimensions seem pretty similar to the jog scooter expansion chamber that a lot of people seem to like a lot and say is an actual real expansion chamber. I don’t have any welding experience of my own which is why I haven’t gone for the scooter pipe so this new exhaust looks pretty interesting to me. What do y’all think?

CDH67 Colorful Exhaust Expansion Chamber Muffler-2 Stroke Gas Motorized Bicycle

Scooter exhaust:
FLYPIG Exhaust W/ Expansion Chamber For Honda AF18 AF24 AF27 AF28 AF30Dio Exhaust System Muffler Pipe Elite Sym 50

Nice find on the cdh expansion chamber, is it readily available? Looks decent!

 

[DieselTech]

I think the stinger on the cdh pipe needs to be a bit smaller diameter. It needs to be around 14-16mm opening on the stinger exit. Maybe I'm wrong, but think it would run better with a smaller stinger.

 

[Rickety4265]

Nice find on the cdh expansion chamber, is it readily available? Looks decent!

I think so… there’s quite a few listings for the product on eBay. I haven’t been able to find it on any other websites though.

 

[DieselTech]

I think so… there’s quite a few listings for the product on eBay. I haven’t been able to find it on any other websites though.

Walmart sales it thru their on-line website for 67.99

 

[Rickety4265]

I think the stinger on the cdh pipe needs to be a bit smaller diameter. It needs to be around 14-16mm opening on the stinger exit. Maybe I'm wrong, but think it would run better with a smaller stinger.

Do you know how detrimental that would be for the performance? On some of the expansion chambers other people have retrofitted on their bikes the diameter looks to be around 19mm. Looks like this one has a similar size internal diameter.

 

[DieselTech]

Do you know how detrimental that would be for the performance? On some of the expansion chambers other people have retrofitted on their bikes the diameter looks to be around 19mm. Looks like this one has a similar size internal diameter.

The dio pipe is better, but not a bolt on ordeal. The CDH67 pipe is a bolt on piece, so the stinger outlet size is not ideal but it will work & is a easy fix to make the stinger outlet smaller.

 

[Rickety4265]

The dio pipe is better, but not a bolt on ordeal. The CDH67 pipe is a bolt on piece, so the stinger outlet size is not ideal but it will work & is an easy fix to make the stinger outlet smaller.

How would you go about that? Only thing I could think of is getting a smaller size pipe and jamming it in there to fill in some of the space. Also do you mean the whole length of that section should be smaller or just the outlet?

 

[DieselTech]

How would you go about that? Only thing I could think of is getting a smaller size pipe and jamming it in there to fill in some of the space. Also do you mean the whole length of that section should be smaller or just the outlet?

Really to be correct the stinger/exhaust outlet needs to be roughly 13mm-16mm the full length of the stinger. The easiest way, but not the correct way, would be to cut old stinger off leaving about a 1½" of it on the expansion chamber. Then get some high temp silicone exhaust couplers & hose clamp new stinger to stub of old stinger with hose clamps. But make sure new stinger sticks/or protrudes in the expansion chamber a ½" to 1½" inside the expansion chamber. That's a down & dirty way of doing it, but would not require no welding.

 

[Chainlube]

How would you go about that? Only thing I could think of is getting a smaller size pipe and jamming it in there to fill in some of the space. Also do you mean the whole length of that section should be smaller or just the outlet?

Can you weld?