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About pmk

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    Advanced Member

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  • Bike
    OSSA MAR & SY250R

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  • Location
    Florida, USA
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  1. pmk

    Compression Release

    I have remained a bit intrigued by the photo of a compression release on the TYZ in the link provided by faussy. Finally, sorted it out. There was one TYZ model that did come with a handlebar compression release from new by Yamaha. That model was a Japan version, the specifics are the 1995 TY250ZS Scottish. https://www.megazip.net/zapchasti-dlya-motocyklov/yamaha/ty250-3456/ty250-9696/4ml1-768572 This model also seems to be the 4ML series, which if you notice, most TYZ parts are 4GG. The cylinder on the 1996 TYZ for all countries is the 4ML type with the hex head plug above the reed cage. All the compression release parts are also 4ML prefix. The Scorpa SY250R uses this same style cylinder, with the hex head plug, same as the other TYZ models for other countries and the non S model for Japan. At a guess, the TY250ZS is a Japan only street version of the TYZ. The TY250ZS, has as original, also was oil injected, had a battery, and coolant tank. All these parts associated with the street version are also 4ML prefix.
  2. pmk

    Ossa MAR ..restoration advice please!

    Appears you painted the fork lower tubes. Pretty certain if you are restoring, I thought all the MARs had polished aluminum lower fork legs.
  3. pmk

    bosi off road website

    I had mentioned wanting to get a Bosi rear fender to my riding buddy. Buying one from Italy and shipping to the USA was simply too expensive. Not sure who the dealer was, but there is someone in UK selling Bosi fenders at least.
  4. pmk

    2 stroke oil facts & myths

    Yes, whenever possible, metal fuel storage cans are best.
  5. pmk

    2 stroke oil facts & myths

    Agreed. I learned my lesson about this. Being lazy, I wanted to run one premix in all the motorcycles. After some spooge issues, I did my homework. The oil I know and love had a high flashpoint, causing the spooge issue. Lubrication was certainly not a concern. Most times it is recommended to run ratios with less oil than a manufacturer of the engine suggests. I called the oil company and had a nice chat with them, actually learned quite a bit. I opted to run the oil ratio suggested for the oil. Slightly less oil than my engine manufacturer, but morethan what other riders suggest. Between the low flashpoint, quality oil at a good ratio everything seems good.
  6. pmk

    Show Me Your Twin Shocker!

    Wow, that trailer setup looks like a mobil footpeg test rig
  7. pmk

    smokey mar

    Pardon my dumb question, what is SMF?
  8. pmk

    smokey mar

    Agree. As I posted, after switching oils and getting tne pipe pretty hot, just sitting there not running smoke was coming out the pipe. Plug was fun. After it did its thing, smoke subsided.
  9. pmk

    smokey mar

    Agree with what B40 said. For comparison, my MAR, I had switched oils and all is good. However at a recent event, between the hill sections and immediate connector sections, my pipe was smoking pretty good. Laughing about it, we questioned if the bike was going to burn to the ground, which it did not. Merely residue built up from slower running. But do not rule out the oil seal, or retightening the case screws, though that should not be a concern with a fresh rebuild.
  10. pmk

    Footpeg Location

    Progress. Footpeg relocating also entailed relocating the kickstand. Been busy getting a lot done on this OSSA. Still getting messages that I can not post photos, otherwise I would.
  11. pmk

    OZO Rear Shock Question

    Sorry, a few posts touched upon what they are on. Bike is an 72 OSSA MAR. Overall though, removing the spherical bearings and replacing with vinyl tubing got them mounted with no concerns regarding installation. However, open to hear what other ideas you might have that could be better.
  12. Emulsion shocks run body up...Yes, you should be ok. My own MAR runs period correct Curnutt shock, bodies up, shafts down and are emulsion type. I would say, but have not tested these shocks as emulsion shocks. I suspect that what I have seen with these shocks, if you ran them as emulsion type, you could also not gas them since the sealhead is clamped between the clip and the end cap. No doubt gas pressurized performs better, but no pressure makes seals last longer and less likely to leak.
  13. I modified the IFP with a bleed hole that is sealed with a sealing washer and screw after the shock is bled and IFP position set. I serviced the fluid from the top since I removed the upper eyelet from the shock body. If you do not modify the the IFP, you could position the IFP to the proper depth, then do not insert the seal into the counterbore. The excess fluid will leak past the DU bushing until the sealhead seats on the circlip. Insert the combined oil / dust seal and install the end cap. As for softening the damping, I installed a bleed shim between the single main shim and piston face, plus altered the far side clamp diameter by adding a small shim above the machined aluminum seat. Used Motorex 2 1/2 wt fluid. Yes I know it says fork on it but it is also a very good rear shock oil. Also, while apart, everything was deburred, and the shafts were polished. I went a touch lower than typical gas pressure at 125 psi, but was higher than the 60 psi in one and 80 psi in the other shock from the factory. These shocks now will extend freely, and so far, when installed, the bike feels good and returns to static height. As I mentioned before, not bad shocks for the money, the price point seems OK for two shocks with springs. The real question will be are parts available?
  14. pmk

    Footpeg Location

    Unladen. Even my stock footpeg location MAR, when riding the footpegs are below axle centers.
  15. Ironically, expecting an internal bladder, I was super cautious on disassembling the first shock. Once I saw the internals, the second was apart in minutes. No bladder lessened any likelihood of damage while working on them.