saving a 1980 KZ750 twin

When I worked offshore in the instrumentation world the majority of what I did when I started out was bending tubing for process and utility connections. We did mainly from 1/8th inch up to 1-1/4 inch stainless 316, 317L, monel, inconel, 2507...Thousands of feet and the bender makes all the difference. You need a shoe with the diameter desired that is rounded out to hold the tube then a shoe to pass around the outside with the same diameter as the tube, rollers on the outside give the best bend without flattening. Most benders that I've used without rollers on the shoe flatten the tube to some degree. With all of that nonsense I just laid out you're on the right track with just buying pre-bent pieces. It'll be less headache since you don't have access to a bender.

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teazer said:
Check with Megs/Cone engineering. According to a table I downloaded a while ago, 2 into 1 collectors require an outlet of 150 to 175% area of the primary pipes. That works out to 1.875 to 2" and use the smaller size for a more torquey motor.
yeah i wondered if that would be too big. Ill drop down to 2" and buy one of the pre-made collectors from cone engineering.
 
Back in the early 80's I built a scrambler type 2n1 exhaust system for a Kaw 750 twin. I used mandrel bent and straight pieces from Summit.
 
jpmobius said:
Right! I've tried that long ago with much smaller tubing - both inside and outside but no heat. Total failure. I'd expect an internal spring to lose all its support strength heating the tubing sufficiently, and be impossible to remove, but it is just a guess. I would expect the bending to seriously clamp the spring, and then contracting when cool to make it a permanent assembly! Sand,compacting, caps, and heat definitely works though, but you need a seriously big torch!
U waz prob holdin it wrongz
 
clem said:
When I worked offshore in the instrumentation world the majority of what I did when I started out was bending tubing for process and utility connections. We did mainly from 1/8th inch up to 1-1/4 inch stainless 316, 317L, monel, inconel, 2507...Thousands of feet and the bender makes all the difference. You need a shoe with the diameter desired that is rounded out to hold the tube then a shoe to pass around the outside with the same diameter as the tube, rollers on the outside give the best bend without flattening. Most benders that I've used without rollers on the shoe flatten the tube to some degree. With all of that nonsense I just laid out you're on the right track with just buying pre-bent pieces. It'll be less headache since you don't have access to a bender.

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Yes those are the nicest, did a lot of stainless piping with hydraulic benders at the nuke plant last year. Lots of bends since they try to avoid unnecessary welding.
 
Key to perfect mandrel bends is clean pipe inside and out and a well cared for wiper die, the balls and wiper need a puff or two of graphite every 10 or so bends. a cnc bender can bend a compound radius just not 100% continuous it needs to let go and rotate then re clamp several times. I bent many miles of 4" stainless for Dodge Cummins trucks and QC would not let a wrinkle go by.

I don't think Yosh is using anything inside the pipe, it's Ninja bending skill and heat ::)
 
Rider52 said:
Back in the early 80's I built a scrambler type 2n1 exhaust system for a Kaw 750 twin. I used mandrel bent and straight pieces from Summit.

pics?
 
teazer said:
Check with Megs/Cone engineering. According to a table I downloaded a while ago, 2 into 1 collectors require an outlet of 150 to 175% area of the primary pipes. That works out to 1.875 to 2" and use the smaller size for a more torquey motor.

I have a pair of these: if you need one!

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I ordered some bends from Cone Engineering and was kinda disappointed in the quality. Not much better than my crushed sand bent radius. and they had creases on the outside of the bend. The first bend of the header is very visible so I bought some bends from Colombia Mandrel and the quality was much nicer and 7 bucks cheaper a piece to boot!

My buddy Eric thought 2" would be too big for the collector so I dropped that down to 1.875". This meant there were no cheap collectors to be bought so i had a go at making my own.

I hammered open the ends of the primaries and then faced them on the disk sander before welding them together to try and keep stress out of the welds. It still took a good amount of bashing after to get it to fit up.I also ovaled the big tube slightly to help out the transition. I was super shaky welding this up for some reason so the welds arent my best, I probably should have done some practice beads first to get in the groove but you will never see these welds when the pipe is on the bike, so whatever. I also compressed the fork to make sure there would be plenty of clearance. next up is sand bending the second bends.
 

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Nice work on the collector. I used a 2-1 collector from cone eng on the 360 headers and they neglected to tell me about the little triangle filler pieces. I ended up welding it to the headers once, removing it and rewarding between the two header pipes from the inside since it was impossible to fill the voids. I'll just make my own next time.


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Guess they were worried about vibrations.
 

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Very important for the battery! (somewhat less so for some of the new tech batteries) Be glad you have all the bits - some are a pain to find and put everything back proper!
 
doc_rot said:
Guess they were worried about vibrations.

Try soaking those rubber bits in DOT3 brake fluid overnight. I had some pretty good results on the XL rubber parts. It doesn't make them look new but it gives them back some of their flexibility.
 
good idea, but have a care. Soaking any rubber parts in brake fluid (methyl salicylate (wintergreen oil) and acetone is better) can do wonders, but pretty easy to overdo, so keep a close eye on how long you soak. Some parts can seem fairly immune, but some can expand and become ruined unexpectedly. Methyl salicylate is better IMHO and does not eat paint like brake fluid. Go cart guys use it to prep their tires so check out cart suppliers if you want some. Can also be had at drug stores slightly altered and way more expensive but it still works.
 
I have used wintergreen oil on carb boots before and it works pretty good. Only the 4 bushings that hold the battery to the frame are in bad shape and they are still available from Kawasaki for a little over a dollar a piece. I looked up the bikes that use these bushings and its well over 100 models all the way to 2016. guess Kawasaki got their moneys worth out of those molds.
 
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