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pmk

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About pmk

  • Rank
    Advanced Member

Previous Fields

  • Bike
    OSSA MAR & SY 250R

Profile Information

  • Location
    Florida, USA
  • Gender
    Male
  1. sprocket bolts

    When are you planning to share photos of this masterpiece?????????
  2. sprocket bolts

    The countersink cutters angle must match the bolt heads angle, otherwise there will be only a small ring of surface contact between the bolts head and countersunk hole in the sprocket. You mentioned using a drill to accomplish countersinking the sprocket. Most drill bits are an angle of 118 degres and some being 135 degrees, but other odd angles may exist. Countersinks come in various angles also, typically 60, 82, 90, 100, 120 degree cutting angles. Pretty certain the proper cutter angle was 90 degrees, but did not run to the toolbox and check.
  3. sprocket bolts

  4. sprocket bolts

    To properly countersink the holes, you must use a countersink in the drill press or milling machine. The countersink angle must match or the sprocket will work as you accellerate or decellerate, ultimatley ruining the hub.
  5. sprocket bolts

    Just dealt with this. No countersunk sprockets in 40t. Only counterbored. Considered swapping from flush head / countersunk style to the counterbored shallow dome stle heads. The Scorpa swingarm to bolthead clearance was pretty tight, and the countebored sprocket and that style bolt was marginal if any clearance. Ultimately, I countersunk the counterbored sprocket and used the original flush head bolts. Catch a look at the recent topic where I installed the Jitsie snails and 40t rear sprocket.
  6. scorpa bash plate

    Assume you are looking for the flat bottom bash plate. Not sure if there is truth to this, but supposedly the flat type can give fits while perched on a log that is not level. The curved type does not force rhe bike to be imbalanced. If you do not find one, consider building one, and in the design, you can add protection for the ignition cover and water pump.
  7. SY250R Heatshield

    Planned to be riveted if this works well. Need to find some #3 monel solid rivets to attach the clamp to the carbon. Putting the silicone sheet between the clamp and pipe should keep it from loosening.
  8. SY250R Heatshield

    Practice helps. If it were something I needed many of, say a production run, it would be more involved as I would make a mold. The mold would allow easier fabrication and a more glossy finish, plus repeatable edge trims. This morning I helped a friend rebuild his leaky MAR fuel tank. Pretty much reskinned the original fibreglass with new materials. More work than the exhaust guard, but worthwhile. Next for the Scorpa SY will be a carbon guard / access cover for the silencer. Going for the carbon appearance, but will not dent, and should allow repacking without welding.
  9. SY250R Heatshield

    Wanted to add, the white line in the carbon is a tracer. Tracers are an option in some carbon fabrics and are an indicator of the fabrics direction in regards to what is known as the warp. In critical repairs, fabric direction is called out. Bummer the tracer is there, but I was not too concerned, just saving the pants from burning.
  10. SY250R Heatshield

    Mark, as an aircraft repair tech with specialized in composites I cheated and was lazy building it, knowing what I could get away with. The headpipe was washed and scrubbed clean with Simple Green soap and Scotchbrite to remove residue from the burnt pants. Next I placed masking tape over the metal surface and drew lines of about the shape and location I wanted. Over the masking tape I placed a layer of high temp very flexible silicone rubber sheet, 1/8” thick. A helper positioned and held the rubber sheet in place while rolling it also around the curves, as this was done, the entire rubber sheet was wrapped in black plastic electrical tape. The tape was wrapped tightly. The silicone sheet provided the uniform air gap between the metal pipe and the carbon guard. I rough cut three sections of carbon cloth approximately to size but adequately oversize. On plastic sheet, I drew the actual cut boundaries for the carbon cloth. Epoxy was mixed, then the three plies were stacked while pouring epoxy between the layers. This epoxy / carbon stack was worked while between two layers of plastic film sheet. Using a Bondo squeegy, the epoxy was worked into the carbon fabric, and all the air was removed. Once ready, the entire stack of wet carbon was cut between the plastic film sheets on the previously drawn template lines. The lower plastic film was peeled away, and the entire stack of carbon was positioned onto the headpipe that was positioned in a vice by clamping the flange, but was over a trash bucket to limit the mesh if drips happened. Once positioned, the upper plastic film was peeled off while carfully draping the wetted carbon. Once positioned, the entire carbon layup was covered in peel ply, then worked by hand to comform to the shape. Then cured. The headpipe was not mold release waxed, I very carfully cut through the cured carbon into the 1/8” silicone sheet with a curting wheel, then the carbon guard came off with black tape stuck on the inside. This tape easily peeled off and the tape on the headpipe removed easily. The edges were final trimmed, then everything was wet sanded with 600. Total time spent, maybe an hour.
  11. SY250R Heatshield

    I was working on building a burnt pants heatshield also. Was not sure the cost of pants was justified so I made this. As for neat and tidy, thanks.
  12. SY250R Heatshield

    When I got this SY, there was evidence of the previous owner burning traces of riding gear onto the exhaust headpipe. During my informal dismantle and reassembly, I scrubbed that headpipe to remove all traces of burnt on gear, oil spooge stains and carbon builup at the headpipe slip joint into the exhaust mid box. After several hours of riding the SY, it was apparent that even I was leaving burnt riding gear traces onto the headpipe. Being frugal, I waited on some leftover high temp epoxy, then rounded up some scraps of carbon cloth. In a short bit of time, I fabricated my copycat heatshield. Mounting is simple, two high temp silicone bands between the carbon and stainless headpipe, everything held secure with two worm clamps. Hope it lasts a while and gets the job done.
  13. 2005 SY250R, USA Version Upgrade

    FWIW, I did take a minute and flipped the master link so the clip is on the tire side of the chain.
  14. 2005 SY250R, USA Version Upgrade

    Do a google search for Jim Snell showing how to install the pump seal on a Gas Gas.
  15. ?:1

    Avgas and Maxima Formula K2 in both the 73 OSSA MAR and the Scorpa SY250R. I take a beating about mixing and running 50:1, but have no spooge with proper jetting, and after talking with Maxima, opted away from anything less oil than 50:1. Yamaha and Scorpa wanted 40:1 in the SY.
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