View Full Version : Extending exhaust

profqwerty - n/a
16-Sep-08, 08:41 PM
I'm trying to reposition my lift exhaust it's gonna hurt when I fall out and crack my knee on it, and it's kinda cr@p looking.

http://img183.imageshack.us/img183/1033/16092008001ip0.jpg (imageshack.us)

http://img183.imageshack.us/img183/16092008001ip0.jpg/1/w640.png (g.imageshack.us/img183/16092008001ip0.jpg/1/)

I'm don't know much about exhausts. I'm guessing this isn't really tuned, just a muffler on a pipe. If that's the case then can I merely add an extension between engine / muffler?

I could cut/weld it a bit, but you always seem to have the gas exit pointing into the middle of the craft!

Notice new handle bars http://hovercraft.org.uk/images/icons/smiley_icons/icon_biggrin.gif

Hovercraft_j3 - n/a
16-Sep-08, 08:52 PM
dosen't scott tilley have that lift engine have you looked at that???

o he has the same as you lolindex.php?t=getfile&id=1808&private=0

team black - n/a
16-Sep-08, 09:52 PM
It's not a stunning design, but there is a definite cone shape, so best not to mess too much. What you CAN do is to cut and rotate sections to change the overall shape, while retaining the centre length of the pipe.

Sean Atterbury - n/a
17-Sep-08, 06:27 AM
What engine is that?

profqwerty - n/a
17-Sep-08, 08:30 AM
Yeah that's about what I thought. Annoyingly the entrance / exit to that expansion chamber are the same side so it always points back towards the engine!

What are the rules on the length of the exit pipe?

It's a Robin EC25PS

nickyd - n/a
17-Sep-08, 01:36 PM
The 'rules' for two stroke exhaust design are fairly substantial!

It's probably best to gain a good understanding of the design principles before getting into chopping them up, so you have a rough idea of the consequences.

I recommend having a look on the net and in some books to give you some insight into how they work.

Failing that, don't fall out and hit your knee on it. Not that I'm one to talk.....


profqwerty - n/a
17-Sep-08, 07:02 PM
Ok I have been doing some reading up. I understand about the tuning / keeping the lengths correct and that now.

I have cut / rotated bits of the pipe between the expansion/muffler bit and the stub to create this: http://hovercraft.org.uk/images/icons/smiley_icons/icon_eek.gif

http://img61.imageshack.us/img61/7445/17092008001qm6.jpg (imageshack.us)

http://img61.imageshack.us/img61/17092008001qm6.jpg/1/w640.png (g.imageshack.us/img61/17092008001qm6.jpg/1/)

It's certainly more out of the way though. This has now left a gaping hole in the guard mesh - I've welded some rod across the gap to give some structural rigidity, but the rest of the hole will have to be filled with cable ties or something...what's recommended here? apart from buying a new mesh?

team black - n/a
17-Sep-08, 09:51 PM
Welding rod

profqwerty - n/a
18-Sep-08, 12:35 PM
OK, I came across a piece of mesh that I've hastily welded on for the moment. It's not ideal (1" sq thick rod) but is certainly strong enough!