pmk

FWIW, you can see how it came to me, the one photo is after blasting (with skidplate also shown), next is sanded, then after polished. Consider the polished photo is after handling and install onto the motor. A couple of minutes touch up and it will be no handling marks from fingers and grease.

I assume, and maybe incorrectly, these are Fox Shox coil spring type units with or without reservoirs. If they are Fox Airshox or Dual Airshox, those uses far different pressures to set up the air springs. Thor Lawson site states 200 psi off road, 100 psi for trials and road.

I will probably need to do the WD trick to the center cases. They came pretty clean but still had a few spots that concerned me enough to avoid painting them until a later time. My center cases are not polished, so for them it will be Scotchbrite and WD.

I did the polishing on my MAR. In the past, I have polished other aluminum items and even plastic aircraft windsheilds. Depending upon how bad the surface is kind of determines the action to take. My OSSA had been stored outdoors for many years. The surfaces of the engine side covers was corroded, and there were scrapes also. Same for the rims, hubs, forks and more. I was able to glass bead all the parts except the rim. Glass beading removed the corrosion for the most part, but leaves a blasted textured finish. Next I used a Dual Action sander, same as for automotive bodywork. I started with 120 grit and finished with 600 grit. For polishing, I secured the item by either clamping or using screws into the wooden makeshift plywood polishing table. I then used an electric polisher, with a large knitted wheel. Foam wheels would work also until the final finish. Using the knitted wheel, I used Mother brand aluminum wheel polish. Going from 600 to near mirror finish is pretty easy. On aircraft parts I have used other polishes. Most work well. Flitz is good. Simichrome is good. Met All. And no doubt others will all give good results. Often it is simply how much time and effort are you willing to endure. It is very dirty work. Once done though, often a simple touchup restores the finish. For those doing the tadk by hand, yes it can be done. To obtain a good result with less effort a low cost polishing pad or wheel in the electric drill can work also. If you do use a knitted or fabric pad, use an old screwdriver and clean the wheel often. Remember, do not use papertowels, they can scratch the finish, I was using old towels, not the best but they do work. Microfibre cloths work well also. Just ensure if you wash the rags, do so outside with soap and water before the washing machine.

Yes, I could have used Rivnuts or one of the variations of that type insert. I have easy access to those also, plus have various install tools for them. ReasonsI opted not to use them. The installation hole is larger than that of a clip nut, unless I used flushhead style, the head thickness is more than the clipnut. Clipnuts utilize all metal high temp locknuts, so there is minimal chance vibration could loosen the plate. Clipnuts also allow greater fastener torque. There are more reasons, but I considered even going with steel pop rivets that could be drilled out next time, but continually returned to the bag of 8/32 clipnuts. Cool video, looks to be some type of aircraft builder training video. Clipnuts are kind of common from places like Aircraft Spruce and Specialty. Ot sure on cost, but should not be too bad.

Got the exhaust mostly done today. Fabricated cover, drilled and verified cover was secure. Washed and applied OSPHO to treat bare steel, then gave it a quick paint job. Packed with silencer packing, if I like the tone, I will remove the cover and seal it, then reinstall the cover and final paint. The cover was made from Stainless tubing, the fasteners are aircraft stuff I had around, we call them clip nuts. The screws are 8/32 or about 4mm and thread into the locknut portion of the clip nut.

Reviving an old post. Recently I had the need to remove three cush drives from 72 and a 73 MAR. Using the proper puller, obtained frim Alex Snoop, the first drive was easily removed. This motor had previously been diassembled. The second motor also had been disassembled previously and this one removed easily also. On my own 73 MAR, which had never had the cush drive removed since it was built in 72, it was a bear to remove. Even with the correct tools the drive spine would not release from the taper. I applied heat from a propane torch while the pullier held tension. After talking with Alex on the phone, he suggested a large hammer striking the actual gear puller end to shock the taper loose. The puller was tensioned via an 18" breaker bar, so there was certainly tension applied to remove the spline cush drive from the crank. Accepting the fact that I may need to cut the drive and hope it split to release, we gave one last effort using the puller. The puller threads got a fresh coat of grease. Tension was applied and still it remained stuck. As before, the amount of tension was very high. While ensuring the clamp was secure that was keeping the puller jaws from slipping outward, the drive released almost exploding off the crankshaft. The cush drive spline was inspected and five cracks were found running along each spline. A replacement was installed after the seal was replaced and the tapers were lapped together. Ensure, when removing these drives to stay off to the side in an effort to prevent injury. It is now reassembled, and hopefully will have no issues. The reason the drive needed to be removed was to replace the crank seal. The seal, while still working, was loose in the case and easily removed.

There is also a respectable area under the clutch that pools oil also.

Photos of modifying KX footpegs to fit the MAR. Note the bolts used are high strength and there are no threads in joint. I did need to install a washer on the front and rear side of the OSSA frame stub to obtain a good side clearance fit. The footpegs are not spring loaded down, and will take a slight effort to drop back if the bolts are set slightly snug. This is good for the left side when starting the engine. I may remove some teeth on the cleat to let the kickstart lever contact the footpeg if it starts easily with the left footpeg down.

I started this topic asking if the right side shift shaft O ring could be replaced without splitting the cases. This week I trimmed the shift shaft. The engine was on the bench, still assembled. The MAR will never be a right side shift, so trimming the shift shaft was not harmful. I knew I needed to remove the clutch cover. So today was the test. At least on my motor, with a close trim of the right side shift shaft, the shaft can be withdrawn exactly enough to allow the O ring to be easily replaced. I think the photos will explain it better than words. I did use a hardened thin washer to act as a guide when trimming. Also, the clutch side cover was installed, holding the shift shaft extended out of the case as far as possible.

Yesterday, I began the repacking of the 1973 OSSA MAR midpipe. The task how I am doing it involved cutting a "window" into the round chamber section, removing the original packing, then making a cover to be fastened with bolts. The cover will be sealed and allow repacking next time to be pretty easy. Inside the the midpipe, the original packing is a crazy but long term packing material. Placed against the perforated baffle tube is a fine steel wire matting. Not steel wool, but rather a non woven almost like a spool wrapped method of placing the fine steel wires around the baffle. Next, the fine wire is held in place by many wraps of a large wire. This offers no true sound deadening, simply secured the fine wire mat onto the baffle tube. Downside of the large wire is removing it. Next, wrapped around the fine wire is a layer of fibreglass packing material. The fibreglass is placed over the fine wires and then rests against the midpipe outer steel wall. Overall, I would say the pipe I have was fine as it was. Unfortunately, there is no easy way to know if the packing is intact, oil soaked, or blown out. I carefully decided where to cut the access window, avoiding any issues when the pipe is mounted. I favored to the right side, to avoid contact of the window cover with frame or left side panel. I plan to repack with all fibreglass packing material, stuffing it into the midpipe. Removal of the oem wire material took quite a while. The forward end of the midpipe where they crimped the midpipe to clear the frame still retains a small amount of oem material. When crimped, the oem sound packing is now wedge between the baffle and midpipe outer shell.

They have been great to deal with.

Wanted to add, I think the guy in NZ is looking for a later OSSA rear wheel setup, suspect he plans to run a rt side brake setup. Also, saw photos of different rear wheels fitted to the OSSA MAR, allowing all RT side brakes.

I have seen photos only, never rode it. In simple terms, a giant "C" shaped brake arm was installed to replace the short cable housing pusher arm. A rod ran from the top of the "C" to the rear wheel.

I did some research into the KX footpegs. I do not beleive that the newer KX pegs will work. The year range seems to be from 98 to 2000, but may be a year later. I threw away my notes, but they were based on what was currently available on EBay at the time. I got model year 2000 KX250 pegs, my riding buddy got 98 KX 125 pegs. At first I thought this was not going to work. The OSSA has 8mm bolts to secure the pegs to the frame. The KX uses 10mm pins. I have not installed mine yet but will as the machine is reassembled. My friend installed his immediately. His comments were the pin hole is a non issue, as the pegs sit proper with no drooping. He did mention the front cleat sets ever so slightly lower than the rear cleat, so front to back is not quite horizontzal. It could be possible to acheive level, then redo the cleats if desired. As for trimming, the KX peg has a flat plate that rests against the KX frame to support the footpeg, the MAR does not support the peg that way. This flat gets trimmed off and allows the KX peg to rest against the oem MAR design to keep the pegs level / flat. The KX pegs also have a limiter to control how far they fold. These my friend ground away. When I accomplish this on my MAR, I will post some photos. In the USA, these pegs are common on EBay for about $20 or less.

Beyond the silliness, the OSSA now runs well. After the flywheel and crank issue, I suggested run it a bit then lets ensure the flywheel remained tight, but also since the case screws were loose, we should check the clutch nut and cush drive. Yesterday, checked flywheel, verified no issues, but did remove nut and retorque with fresh loctite. Countershaft sprocket was loose, tightened it and folded the tab washer. Also rechecked center case screws were tight. All good. Removed clutch cover, no cotter pins on the clutch spring nuts. No issues and not surprised. Removed clutch springs and plates. Clutch inner basket, proper torque 65 / 70 lbft. Not even close. Finger tight plus a little. Maybe 5 lbft to remove the nut. Cush drive, same required torque of 65 / 70, it to was 5 lbft max. Both are supposed to have lock washers and loctite. Lockwasher yes, loctite no. Cleaned all threads and reassmbled to proper torque with loctite. Assembled and ran the bike. Initially clutch worked, then began dragging until the clutch went inop. Dis assembled. Found the cutch inner basket had a depression from the needle bearing inner race. This caused insufficient clearance between the inner and outer baskets when hot. Machined away the worn area. Reassembled again the cush drive and clutch to proper torques with fresh loctite. Again reassembled the clutch and saftied the springs. All back together, fires right up. This time the clutch releases predictably even when hot. So maybe, just maybe, since there are no fasteners between the center cases, this thing can run until it needs bearings or a top end and then we can replace the crank. Also, cush drive removal. We had purchased the cush drive puller from Alex Snoop. Without question, money well spent.

I do, some times. Trust me, I laughed after I Googled it. Yes, a very good chuckle.

Guessing Poofs is some other meaning for non USA English, I can only imagine what I have posted now to create such humor. OK I googled Poofs, yes, no doubt you all had good laugh over that one.

Good tips. This motor was coming apart for a full rebuild, so rust in bearings was no concern. For engines just seeing top end work, upside down to disassemble is good. This engine came out of a recently purchased used bike, no way to know the past history, but it was certainly rusted studs holding the cylinder on.

The bike had been running ok while the new carb was jetted. Prior to this, it was started and idled, with an easy pass up and down the road. The poof and failure to start was an obvious indicator of problems. While troubleshooting, never did I expect the flywheel to have come so loose and move the igniton timing so far off to cause the poofs. The blessing is ultimately that with the flywheel set well on the repaired taper, a replacement key installed, she fired up on two kicks and runs with snap and power. Hoping the makeshift repair to the taper should hold until the engine needs to be torn down for other concerns. At that time the crank and flywheel will be replaced with a rebuilt crank and undamaged flywheel.

Recently, there was a need to remove the cylinder from one of my friends 72 MAR 250s. With the head removed, we expected the cylinder to slide easily off the studs. P, time and water had corroded the studs and cylinder along the cylinders entire height. We soaked the 4 studs for a couple weeks hoping to have the cylinder release. When the cylinder refused to release and be removed, next I attempted to unwind the long studs. While i could see several of the studs twiting as I tried to remove them, each would untwist back to where they originally were positioned. Seeing this I feared the studs would break causing greater problems. Heat was even applied hoping the studs would release and unwind, still the studs and cylinder remained as one. Ultimately, being extremely careful not to damage the cylinder, I resorted to an air hammer on the ends of the studs. Yes this would ruin the studs but drastic measures were needed. With two people, one holding the cylinder and the other operating the air hammer, we spent about 30 minutes with the first 15 minutes just barely getting the cylinder to move away from the base gasket. Once we saw movement, we tried to unscrew the studs. One removed easily, while 3 refused. Continuing, the cylinder moved away further and allowed a second stud to be removed. The last two studs refused to be removed. With care the cylinder was raised until the studs sat just proud of flush. With the cylinder about 1 1/2" above the base gasket surface, the remaining two studs were cut while the cylinder liner was protected from damage by the saw. With the studs cut, the cylinder removed easily. The studs were able ro be removed with no cylinder damage, but did require a well supported cylinder and smart blows from a hammer and punch. With short stubs of the remaining studs, a small bit of heat was applied and the reaning cut studs removed easily. Some may not realize that by design, the 250 OSSA cylinder and head do not have a gasket sealing the studs to prevent water from filling the gap between the stud and cylinder. The water can collect and remain causing corrosion. When shoping for studs Alex Snoop advised using a high quality paint to minimze corrosion by painting the studs. This will be done during reassembly. Currently the entire motor is apart awaiting a crank rebuild, bearing and seals.

Yes, if you ask my friend about the OSSA he would agree it was a shed of a restoration. Regardless he realized the bike had been misrepresented by the previous owner. Now many months and dollars into it, he should get to start riding and enjoying it. Hopefully. Other than splitting the cases, and we are prepared to do that, he has transformed so much that was cobby workmanship into a very nice rider MAR. I did happen upon a second MAR he was able to get reasonably priced. So even though he will be losing a small bit of money in the end, his collection should have a nice fun rider MAR and a well done display MAR that will be very close if not as it came new in 72. Other than a few quirky things, thes old OSSA machines are pretty basic. Not perfect by comparing to a modern machine but still very simple.

Shed of a restoration, not sure of the meaning. I do have a few photos, need to find them, maybe on the phone.

Actually, no, he had no rides on the bike. As for the jet change, the previous owner installed the wrong carb so an OKO was installed. It became pretty obvious, the previous did not smooth anything, in fact his file marks to the key way are obvious and still did not allow the key to seat in the keyway. Basically, the flywheel never seated on the taper. It was also odd to see serious leakage along the center case gasket above the gearbox. A quick check of the case screws made it apparent they were never fully tightened. Best assumption, the flywheel tapers never matched and the flywheel was not torqued to specs.

Not my OSSA MAr, but my friends. The bike he bought a while back, advertised as restored needing nothing has been one hack after another. To late to complain to the guy, and the seller was not honest in how he described and displayed the motorcycle. It was a long distance sale, so between emails, phone calls and videos, the bike was bought and shipped. Suffice to say the seller, that did the work should not handle tools and has no real regard for quality. Along with many issues, the most recent occurred last week. While getting the jetting dialed in, the engine lost power and began rattling. My first comment when told about this on the phone was he seized it. My friend said no, he knew seized and it was not that. He brought the OSSA to my house last week. It had not seized. Fired it up, and lightly rode once around the house. Agreed it was lame in power, but not sure why. I did grab a handful of throttle while in neutral. She wound up then began gurgling and died. A new spark plug and it ran for a moment but died. Would not restart. Checked fuel, ensured carb jet had not fallen out. Disconnected kill switch entirely. Checked for spark, tough to see but there. Nothing appeared wrong. My first thought was the resistor spark plug cap had failed. Not sure why it had one, but swapped on another plug cap. No change. Since my OSSA is apart waiting on parts, we installed my coil. Still the same. Just to verify, we even installed my known good carb. No change. The truly odd thing was it acted like it had seized. While trying to fire it, there was odd poofs out the exhaust, and even poofs out the carb. It got late, I told my friend, unwrap the cobby black electrical tape job the seller did to the wire harness. See if there is a short. Other than that pull the flywheel and install the stator from his other MAR that we have the engine torn down, making it an easy swap. Since the skidplate needs to off to remove the side cover I awoke the next morning, called him, said do not unwrap the wires, pull the flywheel. I suggested the key had sheared. He removed the ignition side cover, then pulled the flywheel. What a mess. The previus owner had issues where the flywheel had come loose. Obvious attempted file repair. Divits in the crank taper and flywheel taper from the previous key either shearing or was knocked out on install. The issue we dealt with was all sections of key were there but sheared. I took a road trip to his house, brought some tools. With care and a steady hand, I blended out the raised points on both tapers. We then lapped the tapers for a good fit. While still damaged, and we know it, evything was cleaned and assembled. The flywheel nut was installed with Loctite and torqued. She fired up in two kicks and ran well. The guy that owns it is finding a crank, flywheel and other bits. For now it is a good temporary repair that will last until we need to open the motor. I did mention, if the guy that built the motor and bike was this much of a hack, we should remove the clutch cover and verify the cush drive and clutch are secure also. What a week. We expect it will easily last the summer, then it can be torn down. So if buying a bike, never be surprised, good or bad. If your MAR gets wonky on how it runs, consider the flywheel. I do give credit to a post I read here a while back where an OSSA did not run correctly, turned out his was flywheel also.