Vintage Dirt Bike Q & A

What kind of modifications did you have to do to make the MT125 pipe fit properly? I have one that I am thinking about using on the MR.

Also, any suggestions on how to clean out a pipe? The MR pipe is clogged and even water won't flow through. As far as what is clogging it with, I don't know. I was given two spare pipes, and one had a mouse nest in it that I was able to knock out. The other is heavy and won't let water through it.

on cleaning out pipes i use a torch or even a strong heat gun can be used.

in this pic i used a Mapp gas torch and some metered compressed air injected into the pipe.







in this pic i am blowing a good amount of air through the pipe,it had a nice fire built inside.

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(2) 1968 DT1 1970 RT1M,1970 DT1C 1971 RT1B Enduro 1974 MT250 1974 DT250A (2) 1975 DT400B 1974 DT100,1978 DT175
1975 CR250M1 1979 CR250R 1979 Kawasaki KZ400H1 Jesus is Lord!!

Check here:

viewtopic.php?f=21&t=2229&hilit=mt125+pipe+mr175+angle

After this was posted I cut open the pipe and removed both baffles, the spark arrestor, and the tailpipe reducing sleeve. This made the bike feel like a 250, with a hard hit down low and tons of midrange. If you're interested in trying this I have the procedure written up.

Re the MR175 pipe cleaning - on that pipe I actually just heated up the turbine-core section with a propane torch after removing the baffle, then cleaned out the turbine sections with heavy-duty pipe cleaners I got from a pipe/tobacco smoke shop nearby. I also drilled out the center section 5/8" and opened up the baffle's deflector end a bit.

+1 on Dave's suggestions - there's also one in the 'MT250... 5k RPM' thread. If your pipe is really plugged up, be careful using a heat gun - the heat from mine blew back out the pipe and melted the gun's plastic housing.

Dave, can you still get real MAPP gas, as opposed to the MAP Pro low-temp stuff?

Ray

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'74 CR125M (175cc), '75 MR175, '82 RM250Z, '08 YZ250F, '14 Zero FX electric, '14 Zero MX electric, '18 Alta MXR electric

Yeah, I would like to see the write up on what you did to the pipe.

On the mr pipe, will a regular propane torch and air compressor blowing air work? I tried the torch along before and didn't get much of a result.

The pipe write-up is a Word document with pictures - I can E-mail it to you if you'd like. I also sent you a PM on Friday.

I only used the propane torch on the MR pipe to soften up the carbon inside the spark arrestor, then used the pipe cleaners to actually remove it. To burn out the pipe you really need a much hotter setup like the welding rig.

Ray

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'74 CR125M (175cc), '75 MR175, '82 RM250Z, '08 YZ250F, '14 Zero FX electric, '14 Zero MX electric, '18 Alta MXR electric