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konrad

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Everything posted by konrad
 
 
  1. Talk to your importer. A friend with a '22 thought his shock was bad from Day-1. You may be able to get a good price on a replacement.
  2. Yes, that works to remove the left-hand locker shaft nut.
  3. So does this make you a fixer shaft fixer? 😉 Although getting the old bearing out is somewhat difficult, getting the new bearing back in is even more difficult! Lots about it here: https://www.ossa-efi.com/home/engine/gearbox/locker-shaft
  4. 2024 Vertigo? I thought there was an EU ban on exporting motorcycles priced above €5000 into Russia. Is that no longer in effect?
  5. So the body itself has a damaged thread? This part won't fix it? https://www.splatshop.co.uk/dellorto-float-bowl-nut.html If not, can you run a tap into the body and clean it up? Here's the entire carb with the BS suffix (your jetting may be different) https://www.splatshop.co.uk/dellorto-phbl-trials-carburettor.html
  6. Ask ten guys and you will get at least that many different answers. 😀 You may want to consider your first trials bike as just a learning exercise. Only after gaining some experience will you understand what works for you. If you are actually going to compete on the bike (as opposed to just riding it casually) then repeatedly starting a 250 may become quite taxing if you have physical limitations. Wearing back support is a great idea. Any trials bike can be made more comfortable by fitting bar risers.
  7. The Beta 80 I worked on had 21" / 18" wheels. I think that's what is meant by "big wheel" or senior.
  8. I spent several hours riding a 2006 Beta 80 while attempting to improve it for an early-50s petite female. I still have the notes. On the plus side, the biked weighed 146.5 pounds with a half tank of fuel. The wheelbase was only 49 inches - that's 3 inches shorter than a typical trials bike of that era. Turning was extremely good. It was super-easy to kickstart. On the minus side, the engine was a bored-out 65cc KTM as used in their kid's MX bike. It used a very heavy flywheel and tiny carburetor to try and give it a trials feel. But it still had an expansion chamber type exhaust system. It ran like a detuned MX bike, not a trials bike. I even reshaped the combustion chamber in an effort to improve it. The gearbox ratios were also not well suited to trials. I needed to ride it in 3rd gear to have any reasonable ground speed, but then it lacked rear-wheel torque. It might be a suitable bike if you are very light and don't really have any other off-road experience/expectations. I would suggest you try before buying and also try a 125. A more modern Beta 80 may be completely different.
  9. Also, The Hell Team's notes say 14mm thin wrench. My thin wrenches are Imperial and one was a perfect fit.
  10. It should come apart easily. I would use a thinner 15mm wrench. Buy a cheap tool and grind it thinner. Do you have the same problem with the other side? Gentle heating always helps. Lots of Marzocchi info here: https://www.ossa-efi.com/home/chassis/marzocchi-forks
  11. In John Robinson's 2T tuning book, he classified an oil's load-bearing capability based on the results of Falex and ZN wear tests. In addition to two modern oils (Motul 800 and Silkolene Pro 2) the highest-rated oils were castor based. So for engines having the very highest specific power outputs (e.g. road racing) using a castor-based oil is not completely foolish. But a trials bike does not fall into that category. And castor's drawbacks are, as mentioned, quite a nuisance. At one point in my life I was very interested in the chemistry of combustion. I reasoned that castor oil could also act as a chemical supercharger since it is an oxygen-bearing fuel.
  12. Beautiful restoration work! Same goes for your RTL250F. Will you ride these bikes? Or are they just for show?
  13. That's what I would do. Thinking more about it... I use a synthetic ATF in the gearbox because I like how it makes the clutch feel. But clutch feel would be less important on the Explorer than a trials bike. Might be smarter to use a high-quality gear oil since the gearbox is so fragile.
  14. That shift drum does not look too bad. It does not take long for the neutral detent to wear like that. Your EasyStart is slightly different (and better) than one I disassembled. On yours, the wires are soldered directly to the PCB. On mine, there was an insulation displacement style connector between the wires and the PCB. One of the wires pulled out of that connector.
  15. Excellent! It's much easier to fix these bikes (any bike really) if you have another for comparison.
  16. You can use a degree wheel if you want, but I don't think the "when" is much of an issue. What you need to test is that the Hall switches actuality do switch. Test each Hall switch independently by only powering them one at a time. The top of the pull-up resistor also gets connected to the positive side of your power source. Monitor the voltage between ground and the output of each SS543AT. You want to see the output swing from roughly your power supply voltage to roughly 0.5 volts (or less) as you rotate the flywheel. I would suggest using a battery rather than a battery charger as a power source. Any battery between 5 and 20 volts would be fine.
  17. If you turn down the insert, will the "cover" still fit?
  18. That wiring scheme is completely reasonable. Ground in the center was an assumption on my part. I'll also take this opportunity to mention that you'll need a pullup resistor (say 10k ohms) for the blue wire if you test the Hall sensors as I mentioned previously. Search "Honeywell SS543" if you need a datasheet for the Hall sensor.
  19. Great you were able to get some test values from Chris, he's the best resource in the business! Regarding the early and late timings, that's my nomenclature -- not official Leonelli documentation. I was trying to figure out how the system worked. Pretty sure I used a degree wheel, and supplied the signals marked Vdd via a 5 volt bench power supply and turned the flywheel by hand. Hall-effect sensors can work at zero rpm. The position (timing) of the stator plate will affect the exact high/low transitions. The 3 identical stator coils provide power for the fan and are not related to the ignition. The coil wrapped in white glass-reinforced tape provides the high voltage for the CDI. There is one winding for high-rpm running and another for low-rpm running. One end of each winding is connected together and I think also connects to the chassis. So you should see a very low resistance from one of the charge coil wires (red or green or white) to the aluminum stator plate.
  20. You have my sympathies! That has got to rank as one of the worst ignition systems ever designed! The "pickup" is actually a pair of Hall-effect sensors. You really need specialize knowledge and equipment to diagnose these ignitions, otherwise you just have to throw parts at it. I made some breakout cables to probe the signals and spun the system with my vertical mill.
  21. trialshop.it to the rescue! I'm going to have to learn some Italian. https://trialshop.it/ossa-ricambi-originali/25217-biella-completa-tr280i/ I see it comes with the small-end bearing, just like the GasGas kit. This is unusual, so seems likely it is the GG part. 118mm for conrod center-to-center is probably a good number. I was guessing 120. Thank you. 5 micron (0.0002 inch) runout is perfectly reasonable. I have a dial indicator that has graduations every 0.0001 inch.
  22. The short answer is: I would continued to use that crankshaft. The long answer is: I have not seen crankshaft wear limits for any trials bike. So we are forced to infer service limits from similar 2T engines. A trials crankshaft has an easier life than one in an MX bike or roadracer. The average piston speed is fairly low, but the piston is also relatively heavy. If you feel compelled to rebuild the crank, I probably would not replace just the big end bearing. Typically the rod, big end bearing and pin are all replaced at the same time. Like their gearbox, OSSA did not sell any crankshaft parts separately. As a point of reference, the complete OSSA crankshaft (P/N 3000020211) had an MSRP of $725 USD back in 2013. My best guess for something that would fit is GasGas TXT 250/280/300. They sell a connecting rod set (rod, pin, big end and small end bearings) as part number MT280212100. It has an MSRP of $266 USD today. GasGas also offers the big end bearing alone as MT32050GG-AIZ-1. MSRP of $35 USD. I have been very curious about the OSSA's connecting rod center-to-center length. Could you make that measurement for me?
  23. Your rod side clearance is good. How much runout is 0.5 cents? Is that 0.05mm or 0.005mm? How much small end free play? Rock the rod side to side and measure movement at small end.
  24. I've been working under the assumption that if the clutch slave cylinder is located inside the engine, the system will use mineral oil to mitigate cross-contamination of the seals. If the clutch slave cylinder is located outside the engine, DOT4 will be used to minimize the number of different fluids required for maintenance. Is this a bike that goes counter to my assumption?
  25. trialshop.it is an excellent resource! Their website is the first time I have seen an exploded view of the OSSA gearbox. I must retract that statement. Upon closer inspection, it is for a TRS.
 
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