ty yam fan Posted June 27, 2006 Report Share Posted June 27, 2006 Hi all, does anyone know of any sensible mods to liven up a standard TY175? I'd like to make it respond a little more like modern bikes. Maybe take some meat off the face of the flywheel (how much?) and I know the porting can be altered but don't know the specifics... and I'd hate to end up with a useless barrell! Thanks in anticipation Mark, Perth Australia Quote Link to comment Share on other sites More sharing options...
feetupfun Posted June 27, 2006 Report Share Posted June 27, 2006 (edited) For a standard bore size TY175: Thin head gasket Boyesen reeds Reed case spacer WES two piece exhaust A big bore (205cc) also improves things over standard but if you are going that far with motor mods I wouldn't lighten the flywheel until you are finished. Edited June 27, 2006 by feetupfun Quote Link to comment Share on other sites More sharing options...
mattylad Posted June 27, 2006 Report Share Posted June 27, 2006 (edited) Send the barrel to Nigel Birkett for porting. Ask for the Steve Possy replica that think sure sings!! Sorry didnt see you were in Aus. Birket is Scorpa importer for UK and Yam guru With care you can get a DT reed cage in the same whole by taking about 3mm off the vertical sides. Edited June 27, 2006 by mattylad Quote Link to comment Share on other sites More sharing options...
kuelmuel Posted June 27, 2006 Report Share Posted June 27, 2006 If your going for the 205 barrel, you needn't really bother with this, but one of my friends has had his 175 barrel machined down by 1mm, I don't know whether from the top or the bottom, if you take it off the bottom then it alters the port timings. I'm not sure how much the timing is altered but its more like a mint TY250Mono than any other 175 I've ridden, its really snappy and pulls from realy low revs really cleanly. Whether you take it off the top or the bottom it raises the compression, it may be harder to start but it will be more powerful. You can also get the inlet and exaust ports machined out to make them bigger, and polished up so the gas moves more freely, this, coupled with a thin air filter and bigger jets, allows more gas mixture into the combustion chamber, which then is compressed more if the barrel has been machined down, and can flow out more easily. I would definately recommend lightening the flywheel, it makes the bike much more responsive, I'd try a WES exaust system as well, these really make a difference. I machined 50% off my fly wheel, some people have taken the whole weight off but i wouldn't recommend, they seem to stall a lot... Quote Link to comment Share on other sites More sharing options...
grouchof Posted June 27, 2006 Report Share Posted June 27, 2006 Hi, One my mini Majesty 175cc, the flyweel have 5 mm less in diameter. Do you know how you can go up to 205 cc on a TY175 cylinder ? Witch kind of piston is used ? Regards Quote Link to comment Share on other sites More sharing options...
feetupfun Posted June 28, 2006 Report Share Posted June 28, 2006 (edited) Hi,One my mini Majesty 175cc, the flyweel have 5 mm less in diameter. Do you know how you can go up to 205 cc on a TY175 cylinder ? Witch kind of piston is used ? Regards Mine uses a piston made to increase the capacity of a DT200 or WR200 to 230cc. I've heard but not tried out a big-bore kit piston made by Wiseco for the Yamaha Blaster Quad. It's not listed in the regular Wiseco catalogue but are made for someone selling the kit for the Blaster. I've also heard that a TY250 piston can be used but this must also require a different conrod because the TY250 piston has a larger gudgeon pin than the TY175. KDX220 pistons are the right diameter but I haven't checked ring locating pin locations or pin to crown height on them. There is much more to it than finding a piston. The cylinder has to be resleeved with a larger diameter sleeve, machine the crankcases to suit the sleeve OD, weld the head and remachine to suit the new bore size and weld the cylinder stud holes up and redrill a smaller size. Shape the head to achieve the correct compression ratio. Find longer studs to reach through the head. Use plain nuts. Make a bigger head gasket. Lighten the piston as much as possible. Rebalance the crank, rod and piston to suit the inevitably heavier piston. Edited June 28, 2006 by feetupfun Quote Link to comment Share on other sites More sharing options...
grouchof Posted July 3, 2006 Report Share Posted July 3, 2006 Hi, Thanks for your infos. Here in France, we used to have 203cc kits, using a resleeved cylinder and a special piston. The problem is that this piston (72 mm) is no more available and the sleeve was 1 mm thick, so when you have a problem, you cannot overbore. I will be happy if you can give me reference for you big "230" DT200 or WR200 to check if it works with these of kits. Regards Quote Link to comment Share on other sites More sharing options...
feetupfun Posted July 5, 2006 Report Share Posted July 5, 2006 The sleeve in my bike is made from an early 1980s Suzuki GS1000 sleeve and yes it ends up thin when bored to 72mm but is suitable to be bored to 72.5mm if required. The WR200/DT200 big bore pistons are no longer available here either. I would suggest checking out big-bore kits intended for the Yamaha Blaster Quad if you are serious about making your TY into a 205cc. Quote Link to comment Share on other sites More sharing options...
mikedabike Posted July 12, 2006 Report Share Posted July 12, 2006 I have heard a that a TY 175 can go out to 200 by using a piston from the RD 400. Would the extra work going out to 205 be worth it if this works?....Does it work? Quote Link to comment Share on other sites More sharing options...
feetupfun Posted July 13, 2006 Report Share Posted July 13, 2006 I have heard a that a TY 175 can go out to 200 by using a piston from the RD 400. Would the extra work going out to 205 be worth it if this works?....Does it work? Suggest you go back to whoever told you an RD400 piston will make a TY175 into 200cc and point out that the TY175 (66mm) has a larger bore than an RD400 (64mm) so it would be a small bore TY175 not a big bore. Yes a TY175 made 205cc goes great if done properly but it is not easy or cheap. Quote Link to comment Share on other sites More sharing options...
mikedabike Posted July 13, 2006 Report Share Posted July 13, 2006 (edited) mmmm! might rattle a bit!! OR if you sleeve it DOWN to 200 Thanks for answering the question, ya dunno til ya ask. Saved me doing hours of research I can spend the time in the garage now Edited July 13, 2006 by mikedabike Quote Link to comment Share on other sites More sharing options...
majesty320 Posted July 21, 2006 Report Share Posted July 21, 2006 speak to John Cane at Trail and Trials uk, he does a 200 conversion. A friend of ours fitted one to a whitehawk, the bike also has ty250 front end the engine is awesome and the bike handles like a dream. Quote Link to comment Share on other sites More sharing options...
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