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Members: Introduce yourself / Re: New Member Harveyo
« Last post by Harveyo on May 29, 2023, 03:33:20 PM »
Thanks Randy - only saw your post now !!!   
General Discussion / Re: 200 MachIII crank rebuild
« Last post by bsracer on May 29, 2023, 03:27:02 PM »
Rotary valve covers. The first set I ran for a long time were done on manual mill and lathe by Rob North. After first couple of races I noticed aluminum bits in the bottom end. The stock rotary valves are too abrasive of the raw aluminum. I then had to repair them and have them hard anodized. The discs still wear thru the hard anodizing after several races. I've had them re-plated once but went back to run the SR cast covers until I decide how I will proceed. I had the ones Rob made copied into CAD so I could have more made (long story of trying to build motors for someone else). They didn't work out and in trying to save some of the samples I modified one set to adapt Kawasaki KE100 steel discs which are considerably thinner. This meant adding material to the face of the inner side of the disc. I was close but again the attempt failed and put aside for now. 

Image 1- rotary valve covers made by Rob North
Image 2- rough CNC version
Image 3- added "slice' to make the face deeper
Image 4-5 again redrawn with thicker face for the Kawasaki thinner discs and 3D printed by Karl Swartout. Still need some modifications to fit.
General Discussion / Re: 200 MachIII crank rebuild
« Last post by bsracer on May 29, 2023, 03:06:41 PM »
ZX-10 vs stock Bridgestone.
General Discussion / Re: 200 MachIII crank rebuild
« Last post by bsracer on May 29, 2023, 03:05:10 PM »
Modified cam gear for the shift drum. I stumbled across two shift drums that the gear is a separate piece. Have never found any reference part# wise or anyone who has seen one. I got a cam from a Kawasaki ZX-10 from a wrecking yard and had the profile copied and redrawn to the 5 seed Bridgestone pattern. I had several profile done and water jet cut. I went with the "tallest" profile that cleared.
General Discussion / Re: 200 MachIII crank rebuild
« Last post by bsracer on May 29, 2023, 02:58:37 PM »
Undercut transmission, I have a couple of sets but they need a minor adjustment to be used. That little step that isn't finished to the teeth is the problem.
General Discussion / Re: 200 MachIII crank rebuild
« Last post by bsracer on May 29, 2023, 02:56:18 PM »
These are the center pins I have modified for the center of the crank. They were pretty inexpensive from Grainger.
General Discussion / Re: 200 MachIII crank rebuild
« Last post by bsracer on May 29, 2023, 02:52:30 PM »
Wow Art,

that all sounds pretty interesting. I have the cylinders Nikasil plated. I'd think the ceramic would be fine but I've never tried it. Just relieving the webs might be an option. I'll have to look at the sample Suzuki rod and see why I strayed from using it. Might have been because I wanted to use the shims and that would have taken more out of the web than I wanted.  I had one Kawasaki (not sure which one) piston for a sample but remember the crown heights were quite different. I think the Kawasaki was much taller. May have had the ring pegs in the wrong position too. Not sure how the KX100 pistons compare. The Wiseco Suzuki RM85 pistons are just a hair shorter if I remember and I use shims under the cylinder anyway. A lot of things can be done especially if you don't have any restrictions. Racing in AHRMA has plenty. If you want to give me a ring I'd be happy to go over some of the stuff. Undercut stock trans helps with keeping it from jumping out of gear or false neutrals. The standard 5 speed isn't the greatest for racing but has got me along for almost 20 years. I've also modified the cam on the shift drum to help this. After seeing a few other bikes over the years I may change the way I do a few things. I attached a photo of the sample Suzuki rod kit.

cheers paul
175 & 200 Talk / Re: silicon replacement of original rectifier on 200RS
« Last post by Old BS Guy on May 29, 2023, 02:35:44 AM »
The banjo fittings for the O.I. lines have a spring loaded check ball in them to prevent gravity flow when the engine is off. many times when you have one cylinder with an oily exhaust, that side will have a sludgy check valve leaking by and accumulating oil in the rotary intake area, or flowing down into the crank cavity where it gets pulled into combustion on start up until it gets evacuated and cleans up. Both of my 200's have this problem. Typical, especially after sitting for extended periods if the o.i. system hasn't been thoroughly purged and cleaned.
General Discussion / Re: 200 MachIII crank rebuild
« Last post by anotheroldtrailrider on May 23, 2023, 08:07:13 PM »
Hi Paul - thank you for the trove of info - as you commented, there's a significant amount of complex machining, so I have some decisions to make before I can really start on the motor.  I suppose if the RM100 rod was wider and needed slight relief on the crank halves, that would be easier than boring the big end pins oversize?  I expect to use single ring coated-skirt KX100 pistons - is the crown height lower than the original?   (I'm a big fan of ceramic coating on piston tops - any reason to avoid it here?)  I haven't decided between ceramic bores and nikasil - my KTM's have survived extreme abuse for years with nickasil.  For the state of tune, it won't be raced but will be used hard on spectacular Ozark back roads - I want upper mid-range and some top end is nice but I don't want to constantly wring it's neck.  I'm spoiled, 15 minutes away there are a couple hundred miles of various loops with no tourist traffic and very little local traffic. 

For the chassis, I re-did the shock mounts and back of the frame and built a swing arm with a slightly larger pivot bolt and bearings instead of the rubber bushings that's slightly longer and stronger than the original to accommodate (rebuilt) adjustable integral-reservoir Marzocchi's from that period.  The forks are 300 Ninja units with cartridge emulators.  I haven't laced them up yet but have slightly wider 18" rims that will be sealed with bicycle rim tape to run tubeless on the original hubs.  (I've done half a dozen sets of wheels with this tape and zero problems, it's available in several widths and very easy to use.)  Obviously, weight reduction is a major goal, and I just finished a one-piece carbon fiber tank/seat/tailpiece.  I'm still on the fence for carb's but since it'll be hidden inside the fairing there's more choices on intake, etc and since I'm not racing it rules aren't an issue.  For the electrics, I have sensors mounted on the original plate to trigger modern coils and a lithium-specific regulator/rectifier for the little lithium battery, and I'll do a LED lighting wiring harness to be truly street legal.  As a Suzuki/Can Am/Vespa dealer in the 70's I loved 2-strokes, but it's been 30 years since I built anything other than 4-strokes so I have a lot to learn.  Once I figure out for sure what I want, I still need to find a machine shop of that caliber - any suggestions there? 
175 & 200 Talk / 200 Mach II RS crankshaft repair
« Last post by anotheroldtrailrider on May 23, 2023, 10:53:05 AM »
I just realized I posted this question in the wrong forum earlier - my apologies.  As the title says, I need to replace both rods on the crankshaft, and want to also replace the step-down center pin that frequently breaks at high rpm.  In the forum for the UK200 racer, Vince mentions the 1977 (he believes) RM100 connecting rods "fit right in" the 200 crankshaft.  If correct, this would be an easy choice because I've found them in stock in several places - can anyone confirm the details?  Lastly, can anyone suggest a crankshaft machine shop with these capabilities.

Thanks, Art Astle
Claremore, OK
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