Vintage Dirt Bike Q & A

Here's something I found on "Just KDX" site relating to pipe cleaning.. Can be really useful.

Cleaning that pipe :

Step One - Grab a face shield, protective gloves etc and put them on. They aren’t going to protect you if they are sitting on the bench! Wrap a shop rag around the pipe and clamp it in you bench vice. If you don’t have a large enough bench vice place a sand bag on the floor place the pipe on the sand bag and then place a second sand bag on top. Your goal is to immobilize the pipe. Insert the brush into the header section of the pipe. With one hand on the drill and the second on the length of pipe run the brush in and out of the pipe? Use the length of pipe to support the wire rope and prevent it from whipping around. The brush will whip around the inner wall of the pipe and loosen some of the deposits.

Step Two - Install a rubber stopper in the stinger ( silencer ) end of the pipe and spray half a can of non-heat activated oven cleaner into the header end of the pipe. Rotate the pipe to completely coat the all inner surfaces with oven cleaner. Continue to rotate pipe periodically to redistribute the oven cleaner as it pools to the low spot of the pipe. Uses the recommended time on the oven cleaner instruction as a guideline. After the time has elapsed remove the plug and rinse the inside of the pipe using hot water and a high-pressure washer. Repeat step one and two.

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77 MR175, 89 HD Sportster
74 CR125, 00 Kawasaki ZG1000
79 XR185, 56 Cushman Eagle
03 XR650L, 79 Vespa P200E
72 Vespa Super150,
74 HD Z90

an easier and quicker method is to heat up the motor end of the pipe with a torch, get it dull red just after the flange, the spooge in the pipe will be burning well at this point, then turn the torch off, and hold the oxygen lever on and pour the oxy to the same end of the pipe that you heated, be careful to swirl the oxy around as to not create hot spots, the red ring will ravel all the way to the silencer end of the pipe, spewing out lots of black smoke, seems to work well for me.

& it sounds like fun!!! I"ll give it a try next time.. Thanks

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77 MR175, 89 HD Sportster
74 CR125, 00 Kawasaki ZG1000
79 XR185, 56 Cushman Eagle
03 XR650L, 79 Vespa P200E
72 Vespa Super150,
74 HD Z90

it is easy to blow a hole in the side of the pipe if you dont swirl the oxygen!! just keep an eye on the color

Jim,

Did they happen to mention the type of brush used? I've been trying to find a soft stainless ball-end brush w/flexible stem for a while - seems like most of the soft duct-type brushes are fiber type, while the stainless brushes tend to be real stiff and would never make it through the header.

Just FYI - you won't need to clean out the MR175 pipe. The center pass-through tube is about 3/4" diameter and should never clog, and the spark arrestor outlets are easily cleaned from the other end.

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

The way I understood it was that he just unravelled the cable on the end to sort of form a brush. Yeah, my spark arrestor was grudged up in the slots, almost completely clogged..

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77 MR175, 89 HD Sportster
74 CR125, 00 Kawasaki ZG1000
79 XR185, 56 Cushman Eagle
03 XR650L, 79 Vespa P200E
72 Vespa Super150,
74 HD Z90