pmk

Was the Beta a wired or wireless computer. Do you recall what brand?

Since the Department of Motor Vehicles allowed me to get a street legal tag for my Resto Mod 73 OSSA MAR, it just seems correct to have a speedometer. I do not have the wheel driven type that mounts to the fork leg. I do have on hand an ICO Checkmate enduro computer, but consider it may be a bit cumbersome and is overkill on functions. Considering using a bicycle computer. Curious what brands and models others may have used. Is it possible to use a wieless type, or will the ignition cause issues?

I need to replace the O rings on the fork caps of my 73 MAR with Betor forks. The measurements seem to be 3mm x 31mm. Here in the USA metric Orings are not locally common. Also, before I order them, I was hoping someone knew the proper size. Thanks

Not on my OSSA, but my riding buddies 72 250 MAR, he had issues with the clutch pushrod. As mentioned the single steel ball had fallen between the seal and shaft. The ball had been displaced by the previous owner that had rebuilt the engine himself. This placed a slight groove into the clutch pushrod. To resolve the problem, the right side cover was removed. The short rod was withdrawn from the countershaft and as you mentioned, a small magnet found the steel ball. Using a dab of grease, and the bike laid onto its side, the ball and rod were installed, followed by the side cover. Not sure if you are aware, but there is an adjuster on the clutch pressure plate if you find all the parts are properly installed. Possibly the adjuster is not set properly.

The link I posted does have your number on it. Shows it as a 76 350. Not sure why it is green and not red as the list photo shows.

Always solid advice. Thank you for correcting my mis statement about swapping cylinders and crank. As much as I learn about OSSAs, seems the learning curve continues. Thanks for being here, you are a true resource with great info.

I have not done this yet, but was considering it. Costly, though. Has anyone run ARC levers and perches on a vintage bike? These would be the folding style brake or clutch levers with the slipper style perch. Was also considering the hotstart type lever for the perch clamp to be for the compression release. I know, expensive, but seems kind of a sweet setup if it is known to work.

Looks as if the slot for the rear axle was modified as it seems very long. I did notice the wires for the ignition are possible very close to the exhaust by the tank / seat area. Again, neat bike.

I did not see where you posted the frame and engine number. Possibly this was sold as a 250 and later had a 350 crank and cylinder installed. This link is one of the more complete list to ID the OSSA. You need to scroll down through the entire list to see the various 250 and 350 models. http://ossa.2y.net/ossa/bilder/modelos/index.html What is the frame / engine number if you don't mind sharing. Nice looking OSSA. Appears very complete. I think if I were to offer one tip, from my short OSSA experience, immediately and continually lube the spoke nipples with a quality penetrating oil. If the aluminum nipples are seized onto the stainless spokes, they need every bit of help to prevent breaking the spokes.

Not the OSSA tank, aftermarket plastic tank.

Scot, thanks. The fuel tank, one detail not visible or apparent in the photos is to drain the fuel, to prevent the tank from yellowing, I made it so you simply disconnect the fuel line, and then one nut secures the tank. No removal of anything else, fuel can be drained in a minute. Plus, no issues with the fibreglass...

Finally, pretty much finished except the lights operating. 1973 MAR 250.

In early November I started this topic. I posted two photos of what I started with, a 1973 MAR. Picked up from the original owner, ridden but not destroyed. Months later, and I never planned to restore it to original, this is how it finished up. Many of the original parts that were needed for my riding buddies MAR he is restoring to original were given to him. Mine is pretty much done, except for lighting simply so I can get from trail to trail without too much hassle. I have posted the photos on FB also, sorry if you have seen them before. The before and after photos. As it was when it was rolled out of the truck when it got to the house and how it sits today. As a kid that grew up around Japanese machines in the 70's, the OSSA had a bit of a learning curve. I truly appreciate thank you all for the help and input from everyone, especially Woody on this site, and Alex Snoop here in the USA. The internet and keyboard does not always convey gratitude, but rest assured it is genuine.

If it helps, the thicker steel plate that goes into the clutch first is 2mm thick. The remainder of the steel plates are 1 1/2mm thick. Visually, other than thickness, they are indentical as best I could tell. Simple to correct, and now proper.

Yes, was not aware and did not suspect one oddball clutch plate that retained the good looks of the others. Correct it is the first plate in the entire basket and supports the rest of them. Not a big deal to check, and won't happen to me again. So many little quirky things to learn, certainly have been spoiled by Japanese stuff.

Lotus54, thank you for getting me to look that info up. I learned one more of the quirky things about OSSA motors. Apparently, they use three different clutch plates. All the fibers are the same. However, while the steel driven plates appear the same, one plate is thicker according to the manual. I did not notice or remember reading that, so, I'll pull the clutch plates out and see. I expect the manual is correct. Not difficult, just one more thing.

OSSA stuff is new to me. Japanese and KTMs, even Maicos I have worked on before. When I got this MAR of mine, I started researching and reading. What I did notice was that the guy that wrote the manual almost seemed to have been or was an aircraft technician. Many of the words and phrases had me thinking I was at work repairing an aircraft. Oddly, I agree, non of the three OSSA MAR motors I have disassembled had locwire. Two had cotter keys and one had nothing. The manual though, did say to use either cotter keys or safety wire. I have rolls of lockwire, less expensive, easier to do, and few bits to accidentally drop into the gearbox. That was the reason I chose that route. From a safety standpoint, not that we as moto riders ever concern ourselves with safety, fewer sharp pointy edges to remove fingerprints.

Should I redo it?

The photo shows how the locwire was used to single strand the 5 safeties. The studs are welded into the inner clutch basket, so while not normally positioned in the way I did the wire, even though the wire appears to pull to loosen, the studs will not rotate. The wire is simply ensuring the slotted nuts do not unwind. The wire laid down best as shown for my clutch. Depending upon how the stud holes are in a different basket, it may lay better in a pull towards CW direction. Ensure you do not pull the wire fully tight, the cups the springs are inserted into will raise and fall as the clutch is used. If the wire is drawn tight, it could break.

I locwired single strand through all holes. I can post a photo later when I am on the laptop.

Having fully rebuilt Fox MTB rear shocks, moto stuff, especially vintage stuff is super easy. No micro parts, just simple old school shocks. Even my Curnutts, while a bit more intricate, are super easy. Check Thors site to see if the parts are special or standard.

Yes, correct, the only adjustment made while running is idle rpm. As for other adjustments, upon initially running the engine, the carb was a bit rich. So, I shut it down, held the throttle wide open, and turned the adjuster screw. Took all of about 30 seconds max. Refired the engine and checked. No jets to swap at all. Plus the carb, once set is supposedly able to self compensate for altitude changes. Agree, there is no pilot air screw to turn while the engine is idling. The bike does need a good run to verify the correct needle is installed, though Corey at Smartcarb was pretty confident it would be correct as he shipped it. If nothing else, being made from billet aluminum, it does look good.

Correction, I posted it as an APT, when actually it is the newer company called Technolgy Elevated Smartcarb. I am still getting the OSSA MAR fully completed. My experience with the Smartcarb is minimal, but so far very good. I should get a real ride in hopefully in a couple of weeks. Finishing a few items, mainly rebuilding the Curnutt rear shocks. Maybe a new topic should be started, but overall, I beleive the topic of polishing parts has been well covered here already. https://technologyelevatedco.com/ This carb style and size, 28mm, has been fitted to modern trials bikes with excellent results according to Technology Elevated.

Technology Elevated Smartcarb. My friend needed an original carb for the MAR he is restoring. Knowing I did not want a restored bike, but rather a rider with minimal concerns with things like the fibreglass tank or metal fenders, many of the original parts from my bike were went into the parts bin for the restored bike.

150 PSI is a pretty standard pressure we use when building modern shocks. Correctly it is 10 atmosphere or 147 PSI. The 100 PSI is fine for slower shafts speeds that are not sustained and will provide a bit more compliance on the initial bump. You did not mention where the leak is at. Those should be an easy rebuild and parts should be reasonably priced. If those are the red, white, blue FoxShox, they always had a great appearance to them also.