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About pmk

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    Advanced Member

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  • Bike
    OSSA MAR & SY250R

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    Florida, USA
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  1. You will need to drain the coolant. Remove the kickstart lever. Remove the clutch cover. Remove the small bolts and clutch springs securing the clutch pressure plate. Remove the pressure plate. In the center of the clutch is a pusher, remove that. Next there is a steel ball, remove that, then withdraw the clutch pushrod. With the pushrod removed, the arm should lift out. Accomplish the reverse to reassemble. You may need a new gasket on reassembly. The link below is from a TYZ parts manual and visually explains what I just wrote, sort of. https://us.fowlersparts.co.uk/parts/4120715/ty250z-250-trials-4gg3-1994-999-a/clutch The link posted by Feetupfun is the service manual. That shows a similar sketch, but is handy as it is a workshop manual explaining the clutch disassembly.
  2. Have not had my Scorpa engine apart, but typically you remove the clutch pressure plate, slide the pushrod in, then remove the actuator arm assembly.
  3. Please share photos of how you get tne cable setup to work. I had considered similar and studied the TYZ setup, knowing it would plug and play. Downside was tne clearance from the Scorpas exhaust.
  4. The actuator arm, there is a spring inside the slave cylinder that assures no freeplay between the slave piston and the adjuster pin / arm. Installing the jamb nut to the inside allows the adjuster to be into the slave slightly further, but do not overdo this adjustment as you may find the adjuster pin will scrape the snap ring. Worse still is fully extending the slave piston into the snap ring under hydraulic pressure. Realize too, the slave cylinder is secured via one bolt. This allows during assembly to obtain the best alignment of the actuator arm pin into the slave pistons cup. It all sounds complicated, but is not bad if you take your time getting a good bleed and best alignment when setting it up.
  5. Before taking the time, effort, and money to redesign it, I must ask, is the clutch system properly bled. This system is a closed dead end with no bleeder. To get it bled, you must ensure the adjuster on the lever is not depressing the piston where the fill hole is covered / blocked. When I bled mine from having no fluid, I followed Ryan Young's tip and moved the slave / arm adjuster jamb nut to the inside of the actuating arm. Doing this made it less likely to bottom the slave piston against the snap ring causing damage or no clutch release. Ultimately, The adjuster is proud of flush about 1/2 turn of a thread. As for bleeding, it takes patience and time. You must push the actuator arm to compress the slave piston into the bore. Then slowly pump the lever as you slowly release the slave piston. It take a bit, but the system will fill, and you can see air being expelled into the reservoir. Once you begin to get clutch action, continue a bit more bleeds. Once confident in the bleed, make the adjustment on the lever, but ensure the plunger on the lever has a couple mm freeplay before depressing the piston in the master cylinder. I considered converting to cable also, but stuck with hydraulic. Actually the action is pretty good and the clutch is controlled and predictable.
  6. Fire up the engine, most times the rattle is more difficult to hear then. If it really is a bother, add a slight bit of front brake as you ride, Yes, my 2005 rattles a bit. Could be wrong, but thought I saw in a parts book, O rings are used to lessen the noise.
  7. After accomplishing repairs for leaks and soft spots on my friends MAR tank, it was block sanded to remove any sharp edges, not sanded perfectly true. Leak checked again, pressurized with a bicycle hand pump and submerged. As a person that repairs composite aircraft parts, using that knowledge and experience, we had the paint shop apply these coats. Epoxy primer onto the bare fibreglass surface. A fill primer was applied next. This is a two part high build spray on product that sands easily. Once the final sanding and fill prime layers were accomplished, top coat layers of paint then stripes were applied. The paint shop stepped up and then applied clear over the entire tank outer surfaces. The frame side panels were done the same way. As for not painting myself, couple reasons, one, I do not like to and two is I am not a great painter. Sometimes, claiming to have restored or built a bike, you are allowed some poetic license for specialty services such as welding, powdercoating, paint, crank rebuilds and maybe a few more. Kind of falls under the know your limits rule.
  8. pmk

    Ossa Mar paint codes

    FWIW, it is for sale,
  9. pmk

    Ossa Mar paint codes

    Very doubtful the seat is MK2, but willing to listen to why it could be. That seat came off my own MAR that is built in October 1972. Could the original owner have replaced his original seat, possibly. I got my MAR from the original owner and a longtime friend. He made no mention of changing it.
  10. pmk

    Ossa Mar paint codes

    The MAR in the photo is very original, took a bit of effort to get to what it is.
  11. pmk

    Ossa Mar paint codes

    Alex Snoop asnoop13@optonline.net He is in the USA and a great source of OSSA parts and services, plus info, like paint codes. I would ask my buddy that owns the MAR in the photo, but he is a bit too busy currently.
  12. pmk

    Ossa Mar paint codes

    Alex Snoop recently gave the color codes to my riding buddy when we were having his fuel tank and side panels sprayed. Might contact him for the info. As a caution, the fuel tank work was a serious pain. As many have posted, over time the fuel, especially ethanol added fuel will attack the resin system used to build the fuel tank. Hopefully you have the aluminum tank. If not, expect a bunch of work to remove the soft area and leaks on the fibreglass tank. For my buddies MAR, essentially, the tank was pressurized with a bicycle tire pump while submerged. All the weeps and leak areas were noted. For his, due to soft areas from knee impacts, the entire outer exterior was abraded, then repaired with Vinylester resin and fibreglass. Noted leaks on the underside were repaired also. The tank was block sanded to a reasonably close profile of original, then leak checked again. Once all leaks were addressed, and the tank was structurally sound, I had a friend accomplish the finish work. This included a first layer of epoxy primer over the entire tank and side panel surface to help seal the finish top coats from the fibreglass and possible issues that lift many paints. Next, they used a skim layer of body filler to obtain the correct shape and profile smoothness. Final work involved a correct fill primer for the paint used. The fill primer was utilized to remove any pinholes in the body filler. The the final top coats were applied. Certainly was a lot of work.
  13. pmk

    Mar engine weight

    I do not know the weight, but do know they are heavy...
  14. Yes sir, mine will stick at the beginning of the next ride. I find it best to roll the bike, engine running, in neutral, as it is rolling, pop it i to gear. Then ride a bit until it releases. Normally pretty quick. On a side note, my buddies MAR, I just rebuilt his motor and gearbox. He installed new plates and trials clutch springs, plus polished the clutch release shaft. He already had a MSR lever. Have not ridden it yet, but suffice to say his clutch pull effort is as light, maybe even lighter than his 17 Sherco.
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