kevin j Posted July 4, 2015 Report Share Posted July 4, 2015 (edited) I have a TY 175 twin shock for Vintage class. Nothing fancy or competitive, and low budget, just for fun. I also have a set of TY250 (believed A model) yokes and forks in the garage. I understand they should fit right on, same wheel, bearings, etc. BACKGROUND DATA I am 64 years old, 200 lbs, and ride simple classic lines. Nothing dramatic or big steps or drops. I ride a GasGas 2000, 200 (160 cc) in modern class and it has enough power for my style usually. And my old tank, the TY350 mono. Engine is basically stock, good running and fresh. Chassis is stock. Sammy Miller peg kits is about it. Rear shocks are toasted. I have stick and mig welding, brazing, and well equipped shop but no machine tools available. QUESTIONS: -Is it worth the effort to put the 250 front end in place? I have heard they are stiffer and more precise in turns and softer in action and move volume of oil. Will I notice any improvement? I don't ride long or hard enough for oil heating or aeration to be an issue with either forks. -I've read in past some modification to the damping orifices on the bottom, or am I confusing with monoshock damper mods? Suggestions? -Original 250 springs seemed pretty good, so prefer not spending money to replace them. What sort of preload spacers should I start with for my weight? PVC pipe ok? -175 I run tubes about even with top of the top yoke. Suggestions on how to set the 250 tubes? -What are some good rear shocks that won't cost more than the bike costs? I will ride as long as I can, but long shock life and rebuildability is not an issue at my age, if they are set up ok form the beginning. Tks for any experience and input. kevin j Mpls MN USA Edited July 4, 2015 by kevin j Quote Link to comment Share on other sites More sharing options...
bestrcpilot Posted July 4, 2015 Report Share Posted July 4, 2015 Yes the ty250 forks and triple trees are a straight swap into a ty175. Do yourself a favor and change out the ball bearings and races with new races and a set of taper bearing. You can use the ty175 triple trees but they will need to be bored out for the ty250 . I run my setup with 1inch of preload and 10W oil at 165 cc The ty250 forks are a great upgrade from the stock forks. Much better in stream beds and over the rock beds. Quote Link to comment Share on other sites More sharing options...
feetupfun Posted July 4, 2015 Report Share Posted July 4, 2015 Kevin, we are about the same weight. I found that my TY175 forks were OK most of the time, but there were a couple of things that they did: When you are loading up the front end under brakes, like when going downhill on dry, grippy rocks, there was noticeable flexing of the front end When you do medium or bigger landings, sometimes they would bottom out I tried quite a few things over the years to improve them including stiffer springs (from a TM125), air caps, heavy oil and while these things improved the bottoming resistance, they made the action of the forks worse in small stuff, and didn't reduce the fork flex Some time in the early 2000s I fitted a TY250A front end and ran it standard to start with and was pleased with the bottoming resistance and reduced flex. A while after that, I saw a video of myself riding a rocky stream bed and realised that I was using less of the fork travel than I wanted. First off I reduced the preload from standard until I got the laden sag to 50%, then later I replaced the preload spacers with short pieces of fork spring (this reduces the spring rate) and again set the laden sag to 50%. I run 10WT oil 125mm from the top, fully compressed, springs out. I'm quite happy now with the spring settings of the forks but may yet do some development on the damping. As far as how high to set TY250 tubes in the clamps, you will find that the TY250 tubes are shorter than TY175 tubes by about 20mm, so your front end will be 20mm lower than your current setup if you set them flush with the top clamp. The TY250 triple clamps have the same geometry as the TY175 triple clamps, they just differ in the size of the tube holes To get the right preload setting for you and your springs, you can measure the laden sag with you aboard with all your weight on the footpegs with the standard preload spacers, then fit shorter and shorter spacers until you get the sag up to around 50%. You will probably end up somewhere around the 1 inch preload as suggested by bestrcpilot. Yes PVC pipe is OK. 1 Quote Link to comment Share on other sites More sharing options...
feetupfun Posted July 4, 2015 Report Share Posted July 4, 2015 I am pretty sure there is no such thing as cheap shocks that have a good action. I have been using Falcons for about 15 years now and can say that they work beautifully straight out of the box and are lots cheaper than Ohlins The most popular trials twin shocks where I live are Betors, which are a bit cheaper here than Falcons, but I find their action is not as agreeable Quote Link to comment Share on other sites More sharing options...
kevin j Posted July 10, 2015 Author Report Share Posted July 10, 2015 Tks all Will get some time next week K Quote Link to comment Share on other sites More sharing options...
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