trialsrfun Posted March 17, 2018 Report Share Posted March 17, 2018 (edited) Am assisting with the rebuild of a TY 175 which when completed will be ridden in trials including the KIA series. What is the best set up for the frame and forks please, can the skinny leg 175 forks be made to work well, they operate smothly enough but seem very softly sprung with not much damping. The frame is totally standard what changes or improvements could be made to improve steering, handling, footrests etc or is it best left alone? Chain is 428 with 12t gearbox and 51t rear wheel sprockets fitted are these sizes a good choice, needs work before it can be ridden. Edited March 18, 2018 by trialsrfun Quote Link to comment Share on other sites More sharing options...
feetupfun Posted March 17, 2018 Report Share Posted March 17, 2018 Rider weight? Rider size? Motor standard? Rider skill level? Quote Link to comment Share on other sites More sharing options...
turbofurball Posted March 18, 2018 Report Share Posted March 18, 2018 I built my TY for proper competition use, despite being a heavy and unskilled rider. It's a joy to use. Going full Majesty with the frame makes sense if you can afford it, or just tidy it up and make the changes to the original frame (which is what I did - heavier, but behaves the same) - moved the shock mounts, removed the oil tank mounts, added gussets, tidied the steering stops, removed the forward peg mounts, lengthened the swingarm. Bolt-on relocated footpegs are fine, but you need to tweak the brake pedal to match otherwise it's unusable. The skinny front forks can totally work, chuck in Magicals springs and then play with oil weight and the spacers to tune it to the rider (mines pretty much spot on with 10w oil and the stock spacers). A set of decent shocks at the back should balance the front out nicely, their specs will vary depending on where you put the shock mounts. I invested in yokes that steepen the fork angle too, this makes it tiring for trail riding (too twitchy at speed) but super for trials. Also, a stainless downpipe and Wes exhaust saved a LOT of weight. Bone stock my TY was 84Kg, now it's around 80 despite adding material to the frame. I have 12/51 gearing IIRC, and do 95% of my riding in 2nd gear. It works well, but I'm thinking of going to a flat slide carb to go with my new big airbox for more low end torque 2 1 Quote Link to comment Share on other sites More sharing options...
turbofurball Posted March 18, 2018 Report Share Posted March 18, 2018 Oh yeah, the yokes also raised the handlebar mounts 1" and allowed me to use fatbars BTW Quote Link to comment Share on other sites More sharing options...
pschrauber Posted March 18, 2018 Report Share Posted March 18, 2018 These skinny fork tubes works well but are flexible and in a slightly harder crash they simply bent. I had my first crash with them in 82 in to get new stanchions wasn't a problem. Now its much more complicated. What you can do is swap to a TY 250 fork with holes or a TY 250 mono forks, both works fine, I stil thing the mono works even better because of its overrun and I done it to my TY. The rear shocks can be replaced to better. A really good thing is to extend the swing arm 30mm, you need a new brake arm then too. I have made a CAD drawing for that so the longer arm can be cutted by laser and have likewise holes like the originals. Mounting the engine reed cage of the 250cc model is a good fix, too get rid of all internal stuff of the airbox to get better breathe. If you come along a 175 MX clutch case from 74 and 75 that is too an improvement then you got rid of the oil pump and it's casing too. 1 Quote Link to comment Share on other sites More sharing options...
section swept Posted March 18, 2018 Report Share Posted March 18, 2018 4 hours ago, turbofurball said: I built my TY for proper competition use, despite being a heavy and unskilled rider. It's a joy to use. Going full Majesty with the frame makes sense if you can afford it, or just tidy it up and make the changes to the original frame (which is what I did - heavier, but behaves the same) - moved the shock mounts, removed the oil tank mounts, added gussets, tidied the steering stops, removed the forward peg mounts, lengthened the swingarm. Bolt-on relocated footpegs are fine, but you need to tweak the brake pedal to match otherwise it's unusable. The skinny front forks can totally work, chuck in Magicals springs and then play with oil weight and the spacers to tune it to the rider (mines pretty much spot on with 10w oil and the stock spacers). A set of decent shocks at the back should balance the front out nicely, their specs will vary depending on where you put the shock mounts. I invested in yokes that steepen the fork angle too, this makes it tiring for trail riding (too twitchy at speed) but super for trials. Also, a stainless downpipe and Wes exhaust saved a LOT of weight. Bone stock my TY was 84Kg, now it's around 80 despite adding material to the frame. I have 12/51 gearing IIRC, and do 95% of my riding in 2nd gear. It works well, but I'm thinking of going to a flat slide carb to go with my new big airbox for more low end torque Will a flat slide carb give more low down torque. I thought they were better for top end ? Quote Link to comment Share on other sites More sharing options...
turbofurball Posted March 19, 2018 Report Share Posted March 19, 2018 My understanding was they flow better, even from low revs ... happy to be proved wrong though! Quote Link to comment Share on other sites More sharing options...
tony27 Posted March 19, 2018 Report Share Posted March 19, 2018 The flatslides carburate better at low openings due to the slide being smooth on the bottom. Quote Link to comment Share on other sites More sharing options...
pschrauber Posted March 19, 2018 Report Share Posted March 19, 2018 The Mikuni VM is good and works good, you can replace it against something different but be aware that it will be costly to find the right jetting, needle and needle valve. The the flat slide carbs can give a slightly better Performance but these are more picky about the right adjusting and jettingh then old style round slide carbs. Quote Link to comment Share on other sites More sharing options...
trialsrfun Posted March 19, 2018 Author Report Share Posted March 19, 2018 (edited) On 18/03/2018 at 2:30 PM, section swept said: Will a flat slide carb give more low down torque. I thought they were better for top end ? I fitted a 26mm OKO carb to my 250 Bultaco Sherpa model 124 to replace the oiginal 27mm Spanish made Amal concentric which was totally worn out. I carefully followed this tuning guide http://www.mid-atlantictrials.com/Instal.html and the bike now runs very smothly and cleanly all through the rev range, unsure if there is any more bottom end but it runs nicely which makes it easier to ride. As I understand it getting an OKO with the right choke diameter is critical then playing about to find the best pilot jet. There is a lot of OKO info on the weblink above and buy genuine not a copy from an auction site. Edited March 19, 2018 by trialsrfun 2 Quote Link to comment Share on other sites More sharing options...
trialsrfun Posted March 19, 2018 Author Report Share Posted March 19, 2018 (edited) On 17/03/2018 at 9:36 PM, feetupfun said: Rider weight? Rider size? Motor standard? Rider skill level? It is staying a 175, the other questions I will let him come here on tc and give that info himself, should he not then maybe we will make something up eh!!! Edited March 19, 2018 by trialsrfun Quote Link to comment Share on other sites More sharing options...
turbofurball Posted March 19, 2018 Report Share Posted March 19, 2018 I have (the wrong size of) OKO on the Montesa, once teething issues were sorted (many air leaks in the engine, intake pipe, float level wrong etc) it's been working well and wasn't hard to get running right 2 Quote Link to comment Share on other sites More sharing options...
FreeWheel Posted March 26, 2018 Report Share Posted March 26, 2018 Quite a lot of interesting ideas. TrialsRfun is assisting me with the ty175 build. So far I have got ty250 fork to go into it just getting them rechromed. Also on the way is dual stage electronic ignition and and I will be trying on oko flatslide on it. 2 1 Quote Link to comment Share on other sites More sharing options...
turbofurball Posted March 27, 2018 Report Share Posted March 27, 2018 It's probably not worth going to an OKO unless you're changing the air box and exhaust BTW, the original carbs are very good at what they were designed for Quote Link to comment Share on other sites More sharing options...
brewtus Posted March 27, 2018 Report Share Posted March 27, 2018 4 hours ago, turbofurball said: It's probably not worth going to an OKO unless you're changing the air box and exhaust BTW, the original carbs are very good at what they were designed for If the slide isn't completely worn out, that is. Not an uncommon problem out here in the wild, wild west, but YMMV. 1 Quote Link to comment Share on other sites More sharing options...
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