CRF 50 Exhaust on ATC 70 (pics)

[JohnR.]

I've made some progress with my ATC70 project. I've painted the engine cases and side covers, primed the forks, ordered most of the parts I'll need to finish it, and best of all I've tweaked a White Brother's R4 exhaust for a CRF50 dirtbike to fit. The frame needs to be prepped and painted along with about a dozen other parts but if we get some decent (sunny) weather here tomorrow I can make some progress on the small parts at least. I can't wait to hear the little 70 thumping through that exhaust system.

John

[blue27]

I LIKE THAT EXHAUST , keep the pics coming.

[65TremecGT]

how much "tweaking" was neccessary and where did the "tweaking" occure!?! I just got my second 70 running last night and put it back together tonight, want to take it for a spin but the garage is too full of junk, maybe on my day off!

[BigGreenMachine]

Those bends in the head pipe look "tight," know what I mean? Wouldn't it have been better to use the headpipe section with those bends already in it then weld the two head pipes together?

[JohnR.]

Believe it or not that 90* bend that looks a little crimped was actually like that before I started bending it. I have never seen this exhaust in person before so I can't say for sure if it was damaged by teh previous owner or it just comes that way from the factory. If I like the way everything works I can always buy a small stainless 90* and have that section replaced. I didn't have to bend it so much as I had to straighten it if you know what I mean. It literally took me about 30 minutes with the frame next to the vice so I could go back and forth test fitting it quickly. Mainly, the muffler was way too high so I gradually tweaked the long piece of pipe until it was at the right height, then I realized that the muffler was aimed a little down. To fix that I tweaked it until the muffler was a couple of inches too low then I clamped the pipe in the vice right up against where the pipe ends and cones into the piece the muffler slides over. That allowed me to aim the muffler up but still have the rest of the pipe in the correct position. I don't have a TIG here so I can't weld stainless properly. Even if I did I can't see any reason to cut and weld when all it needed was a slight tweak.

John

[BigGreenMachine]

I was only speaking about the 90* bend, looks restrictive. Everything else looks spot on, I really like it! Keep us posted.

[aquapunk]

yeah, it does look crimped, maybe its just the angle of the pic?

[JohnR.]

Nope, its a bit crimped there but that's how it was when it arrived here. I'm not too worried about it, if it works out well I'll start watching ebay for another and put that one on my daughter's. I only paid $75 for it so I can't complain.

John

[super90]

When i put a stock 50 exhaust on my old 90 I used a pipe bender. I filled the header with fine sand and plugged the ends with some rubber stoppers. So when you bend it theres no kinks.

[JohnR.]

That's a good idea!! I'll do that next time but I wonder if the guy I bought this system from crashed and bent it somehow or if that's just the way it is. I'm going to disassemble it today so I can paint the frame and once the pipe is off I'll try to "uncrimp" that section a little by squeezing the sides in the vice. Its worth a shot I guess.

John

[super90]

Sometimes with thoes pipes they dont align up the greates and the previous owner could have tried forcing it down to fit and it could have bent. If you want to bend it back i would heat it up and put it in the vice. If that didnt work i would try heating it up and tapping it out.