XR50 undertail exhaust mod

[762SPR]

I was riding the fiddy the other day and I got pretty tired of burning my leg on the exhaust and standing all funny on the rear pegs. I saw a picture someone posted in another thread of their bike with an under tail exhaust that he had done, so I asked myself "... How hard could it be?"

Of course, here is is in it's stock form:



The first cut was... here ish. This is just about where the pipe will bend in around the subframe.



Next, I hacked the rest off of the silencer. Taking note of how much of the tube was protruding into the silencer.



I just happened to have this piece of 4130 leftover from my frame build. It's 1" OD and thinner wall than the frame, but it slipped right over the exhaust pipe so it was perfect!



Then I cut off the rest of the brackets, bead blasted, and welded on the "mount". I took one nut, and drilled out the threads, then stacked a normal nut on it and tacked them together, then welded them on to the silencer with the "hollow" nut on the bottom. This is just a ghetto way to stand off the threaded part to give some compliance with the mount screw...

[762SPR]

To mount it to the frame, I simply drilled a hole where the seat bolts on and ran a set screw through it. Simple and easy!



Here I have the new section of the pipe in place. You can see I cut the bend, and then spliced on a straight piece that will partially protrude into the silencer. You can also see where I have marked to drill a hole for sed protrusion... It's all starting to take shape!



Here's the pipe's fit to the frame:



And with the silencer attached:



Pipes welded and hole capped. I love this little bike. I just picked it up and put the whole thing on the welding bench, arranged the parts on the bike and tacked them right there! Alignment made easy.

[buddy lenzin]

Very nice!

I wish I had the tools so I could do the same.

[762SPR]

Hit it with some header paint, and DONE!



With the seat on:



Since this is an XR, not a CRF, The side plastics and rear fender are all one piece. Looks like I'll be needing a CRF rear fender and just run it without the side panels, but I totally dig the way it looks!

I didn't think it would change riding that much, other than making it more comfortable, but it really does! It's so much easier to balance, circles on the pegs are cake now. I was never really good before, I could do 3 or 4 and then set it down... but right off the bat I hopped on and did like 10 good ones, then straightened out and rode around in the same wheelie, and I've never been able to do that before!

The one and only problem so far is I have to put my sitdowns on hold because I'm still running the stock suspension, it bottoms out and the back wheel rubs on it. Looks like I'll be getting that boinger kit from 50Stunt pretty soon!

This was a pretty easy mod to do, it's super cheap, and makes back pegs a lot more comfortable. I mean, It wasn't horrible before, but now that I've tried it like this, I never want to go back to a regular 50!

[762SPR]

Quote:

Originally Posted by buddy lenzin Very nice! I wish I had the tools so I could do the same.

Thanks!

All of the tools I used were actually pretty common. Hacksaw, dremel, angle grinder, power drill, and of course the welder. If you have those, you can probably manage this mod! Even if you don't have the means to bend the extra piece of pipe, you could probably get a piece at a fabrication shop, or exhaust shop... Or do it with angle miters.

[buddy lenzin]

You got me there...

What's the angle you bent the tube at?

If I can get it bent and go to a buddy's to use his welder.

[Larse]

Quote:

Originally Posted by buddy lenzin You got me there... What's the angle you bent the tube at? If I can get it bent and go to a buddy's to use his welder.

if you got a shorter silencer or want it a bit further out you can just make two 90 degre-ish bends, so the pipe will have an S shape

[762SPR]

The tube was bent 90 degrees with a 3" radius. I didn't measure the angle I cut it at, but you can see in the pictures the cut almost touched the back of the can, so a quick mock up should be all you need.