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About rpt50

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  1. oxy acetylene. Why would you heat the core until the metal glows? You only need to get the carbon hot to have it come right off.
  2. Real easy, but you can cause damage if you don't do it right. The torch you need is what I call a "plumber's torch", which is just a propane torch, You don't want other kinds as they can get too hot and there is a lot less room for error. All you need to do is heat the perforated core until THE CARBON glows red (not the metal). There will be a lot of smoke as the oil burns off--that's fine. Allow it to cool, and then wire brush it. It will very easily come off with virtually no "elbow grease". If the core was that gummed up, you probably also want to look at the head pipe while your at it, as it probably has a ton of carbon too. Remove the rubber O rings so they don't melt, and then heat up the head pipe until the carbon is glowing. I usually point the flame right in the opening of the pipe, but you will also need to heat from the outside. This part of the pipe will take a lot more heat than the silencer core. After you get it glowing, let it cool, and scrape it out with an old screwdriver or something similar.
  3. rpt50

    YZ125 Trail Bike Conversion

    Modifying the engine would be way down on the list of things I would do on a YZ 125 for off-road use. It already has the most user friendly powerband of the 125s. My 03 and 06 are essentially stock engine wise (see woods products post above), and they do very well even racing. Suspension is where you need to spend some money. A lot of guys think their MX suspension is fine in the woods, until they swing a leg over a bike with a woods set up. Back in my CR250 days, I spent money on my first revalve of an MX bike. There was a woods loop near my house that I could run in about 7.5 minutes. After the revalve, not only did it feel so much better, I was consistently about 25 seconds faster. That's a huge difference.
  4. rpt50

    Crank Seals are shot, have a few questions

    There should zero up-and-down play in the flywheel. If you feel anything at all, time for new bearings. Same for the rod (no up and down play) when you pull the top-end. Oil in the left side would probably not be from the crank seal. Remember that on a two stroke the crank is lubricated by premix, and the oil for the transmission is separate. Not sure with the YZ 250 exactly what the set up is, but some bikes have a seal around the clutch mechanism concealed behind the left side case. That is where the oil is likely coming from. Edit: Sorry, but I did not fully read the post just above mine. Yes, part #26 is likely the problem.
  5. rpt50

    how fast will a yz 125 go?

    ha ha yes but 9.8 meters per second per second (meters per second squared).
  6. rpt50

    2017 YZ-125 pipe

    Don't expect big differences by adding a pipe. I'm a woods guy so I don't see much difference at all besides some over-rev. My advice would be to wait until you smash the stocker before replacing it. If you are looking to improve lap times, there are a number of things that are more effective (and cost effective) than adding a pipe and silencer. Tires, suspension, playing with the gearing to better match the track, etc. are all much more likely to lower your lap times than adding a pipe/silencer. If you are outside the target weight range for a YZ125, I would start with springs for your weight.
  7. rpt50

    YZ125 Trail Bike Conversion

    Forget the rekluse for a 125. Call your suspension tuner now. Here you go...
  8. rpt50

    yz250x opinions?

    Two strokes don't "flame out" if you are using the term like what happens with 4 strokes at low rpm--hard to describe--not really a stall, but they just sort of inexplicably die when you try to give them some gas. You won't have to worry about that with any smoker you buy. You can however stall a two stroke. I would probably think about a rekluse if you are doing a lot of slow rocky stuff where stalling is likely. The Euro bikes have a real advantage with the extra low end of a 300, and push button start. I rarely ride those conditions myself, but when I do it's obvious how much of an advantage electric start, or a rekluse, is. I get left behind with my kick start YZ or pre e-start KTM, as I invariably wind up in a position where I can't get a clean kick.
  9. rpt50

    WR450F rim work with YZ250X hub?

    Not sure if you have considered it, but I recently bought a Tusk (Rockymountainmc.com) rim and spoke it for my YZ to convert to an 18" wheel. Seems like high quality stuff and it all went together well. I went with silver, but I think they have a bunch of color options.
  10. I've run as little oil as 40:1, but normally I run 32:1 in everything. Japanese bikes come jetted for 32:1 (30:1 actually) so they are usually need very little jetting. A late model KTM will likely need a little jetting to run on 32:1, but mine have all run very well on 32:1 once sorted. A recently acquired 04 200 has been giving me trouble, but turns out the crank seal was bad. Below is a pic of one of my 125 pistons with 95 (yes, 95) hours of woods riding (hare scrambles and lots of race-pace riding) run at 32:1 (yamalube 2r). I am also always surprised by folks who seem to be happy with a crank life of 250-300 hours. That seems really short to me. Maybe a little more oil would help. I am also skeptical about high-price oils. I am currently running an experiment with a yz 125 and cheap outboard oil. At 40 hours everything looked fantastic, although currently I have been unable to rack up more hours on that bike as the aforementioned ktm 200 has had me side tracked. When I get over 90 hours I will report with pics.
  11. rpt50

    Suspension re-valving advice

    Until recently, I have always sent mine to a tuner. Earlier this year I did a race tech gold valve kit on a YZ shock, and it worked out really well. I would not call it an easy job, but it was really not that difficult. The next time I get a bike that needs a fork revalve, I will try a race tech kit. One thing to consider however, is the condition of the stuff you are starting with. The shock I did needed parts, and by the time I bought the oil, race tech kit, and rebuild kit for the shock, it was about the same price as what my tuner would have charged to rebuild and revalve.
  12. rpt50

    yz125 good trail/enduro bike?

    Here is a thread that will give you some information:
  13. rpt50

    Swap jets without removing carb?

    Yes, if you have the stock tank, you should be able to access the needle and main/pilot jets simply by tilting the carb. Just make sure that you don't damage the throttle cable or pull the vent lines off. It might be a good idea to pull the tank before you head out to the track and make sure that your throttle cable and vent lines are routed properly and they can slide enough for the carb to tilt. Also, make sure that 17mm nut on the bottom of the carb has not been gorilla tightened by a previous owner. Finally, I can't remember if the screws that hold the cap on the carb are "captured" or not on your bike, but those little screws, and the tiny little clip on the needle are easy to drop in the dirt and lose. Having spares is a good idea. Oh yea, if you are an old fart like me, bring along a magnifying glass to read jets, or someone young enough to see the numbers.
  14. Yea, not even sure what is being asked. To me, the difference between hydraulic and cable clutches is not even something I notice, even though I regularly use both (my current bikes are a ktm 200 and a couple of YZ 125s). I would never spend money to replace a cable clutch with a hydraulic clutch--there are lots of better things to use that money on. I can think of maybe a couple of races over the years with conditions where the self-adjusting nature of a hydraulic clutch would have been nice, but it does not occur often enough to justify the price and hassle. I have noticed a big difference in the quality of clutch components over the years. I don't recall ever having to mess with any of the components of a KTM clutch, but I regularly have to replace plates, baskets, perches, and levers on Japanese brands.
  15. If the bikes are keepers and you want to invest a bit of money, your best bet is to buy forged pistons and send them off with the cylinders so the pistons can be matched with the new plating by a reputable plating company. When you have the bike back together, jet it properly to run with a 32:1 ratio. Then you need to identify a ring and piston replacement interval. I am a single track eastern woods guy with two YZ125s. I inspect everything and replace the ring at 45 hours, and then replace the top-end at 90-95 hours. I would never run these kind of intervals with a cast piston, and I often take a look up the exhaust port for anything amiss, and carefully monitor how the bikes run and sound (and it's easy to tell if something changes since I have two). Normally I have no problem going 45 on the ring and 90+ on the piston, but sometimes things do happen. One of the bikes ingested some sand recently. I replaced what needed to be replaced, and I've been pulling the jug for inspections about every 20 hours. So far, so good. MX riding is considerably more demanding on the top-end than tight woods riding/racing, so you will need a shorter interval for sure. I would think a good place to start would be an inspection/re-ring at 20-25 hours, and top end around 45. Depending on your speed and skill, and how you ride, you may want to adjust this up or down a bit. BTW, I would not use compression as a diagnostic. I know many guys do, but I find that too many variables can affect readings. I think you are better off actually taking measurements. I only use compression gauges to measure consistency across cylinders (like in a PWC triple or outboard). Also, remember that if you are using forged pistons, clearances will be different than what your manual states. Go with the measurements provided by the piston manufacturer.