blackhat250 Posted December 2, 2014 Share Posted December 2, 2014 Yeh " are them cushion rings just to stop chatter,[ noise] . , some triples boys bead blast the steels, for more friction,,, Back up to the reeds, you say you may enlarge the openings on the cage,,,will the reeds still cover, are they plenty big.[overlap]? Link to comment Share on other sites More sharing options...
blackhat250 Posted December 2, 2014 Share Posted December 2, 2014 What tools are you using to file out ports and reed intake ? Link to comment Share on other sites More sharing options...
s900t8v Posted December 3, 2014 Author Share Posted December 3, 2014 this morning I removed the cushion rings, re roughed some used frictions on 800 grit, re packed the clutch pack and added in 2x 10x16mm 1.2 mm thick washers to the underneath of the springs to increase the tension.. THE CLUTCH NO LONGER SLIPS :O wow finally I'm happy yeah the picture shows how the reed cage is restrictive at the base, this will probably only help peak RPM and only if you're peak RPM is higher than stock... (that diagram is from bell saying how to enlarge the YZ80 reed which is bigger than the CT175 reed lol) to open out the reed cage you can use machine files as the reed block is thin, I haven't done it yet as I haven't had time. One thing you can do is to teardrop shape the reed bridge as well as the air eddies behind the reed bridge and thats not ideal... thats nit picking for a high HP motor and not worthwhile on the standard bike. I know plenty of people who do it though on proper builds. you gotta port through from start to finish you can rarely just port one thing and notice an improvement (the exception to this is mild exhaust raising) to open the inlet to fit the DT 175 reed cage i used a 1/4" cone single cut carbide burr in a dremel. remember i only did that to fit the DT175 cage so I could put boyesens in... if you got a DT175 you dont need to do much to the inlet port. I used a combination of a 1/8" double cut carbide burr, an all sorts of files to do my porting work in the cast iron cylinder sleeve. seriously the boyesens sh** all over metal reeds, throttle response and torque is ++++ The easier way (but more expensive) to port is to put a 2-3mm spacer under the cylinder, mill 2-3mm off the top of the cylinder and you have effectively increased the transfer and exhaust duration (and reduced the inlet duration but this doesn't matter in a reed engine as the duration is often 360 with leeway) 1 Link to comment Share on other sites More sharing options...
blackhat250 Posted December 3, 2014 Share Posted December 3, 2014 Thinkn about reeds [boysen] for the DT250, I have 2 spare jugs,[ barrels] may experiment this winter, Link to comment Share on other sites More sharing options...
s900t8v Posted December 4, 2014 Author Share Posted December 4, 2014 Hey the Reed should be a direct fit no modification required. I have a dt 1 hop up article it's for piston port but the mods are the same for Reed. It gives details on how to mod everything together to maximize power Most important thing when porting is to put really good chamfers on the port windows. Even with the stock porting the best thing us a well designed chamber. I'm no sure if the dt 250s has chambers? Link to comment Share on other sites More sharing options...
blackhat250 Posted December 4, 2014 Share Posted December 4, 2014 , I will post a picture of the stock DT250, and a pic of the IT250,,,the ports are massively different,, You have a P.M. .[MESSAGE] Link to comment Share on other sites More sharing options...
s900t8v Posted December 7, 2014 Author Share Posted December 7, 2014 show us these ports blackhat? Link to comment Share on other sites More sharing options...
blackhat250 Posted December 7, 2014 Share Posted December 7, 2014 Stock DT250MX ">http:// IT250, ">http://http://s1110.photobucket.com/user/Blackhat750/media/IT250PORTING.jpg.html'> Link to comment Share on other sites More sharing options...
dose Posted December 14, 2014 Share Posted December 14, 2014 great writeup and thanks for the pictures a yz 80 carb will bolt up and you will have a 28mm for cheap I used a 2001 carb on mine use the yz intake boot and cut off the stuffers flush get the mikuni, not keihn Link to comment Share on other sites More sharing options...
s900t8v Posted December 14, 2014 Author Share Posted December 14, 2014 Yeah but a second hand carb is 60-80-- can buy a new flat slide for double that. Probably going to go 34mm Link to comment Share on other sites More sharing options...
dose Posted December 14, 2014 Share Posted December 14, 2014 in usa they are on ebay for $35 with the boot I guess its different where you live. GREAT job, keep at it!! Link to comment Share on other sites More sharing options...
s900t8v Posted December 14, 2014 Author Share Posted December 14, 2014 So a 2001 fits? Did you notice much improvement with the 4 mm bigger carb? Link to comment Share on other sites More sharing options...
s900t8v Posted December 14, 2014 Author Share Posted December 14, 2014 So a 2001 fits? Did you notice much improvement with the 4 mm bigger carb? Link to comment Share on other sites More sharing options...
dose Posted December 14, 2014 Share Posted December 14, 2014 yes but i did a pipe and boysend reeds at the same time been wanting to put the 24 back on to see the difference of just the carb by itself Link to comment Share on other sites More sharing options...
s900t8v Posted December 14, 2014 Author Share Posted December 14, 2014 Yeah I wanna do that too. Have you got a build thread Those 30 dollar carbs are knock offs right? Did you port the cylinder or? Link to comment Share on other sites More sharing options...
dose Posted December 14, 2014 Share Posted December 14, 2014 its a real mikuni from 2001 yz 80, used i bought a extra cylinder and head to try porting, piston and head mods I guess there is alot of power to be gained http://yamaha-enduros.com/index.php/other-manuals?task=document.viewdoc&id=47 check this out if you havent yet the mx175 stuff should work on our bikes Link to comment Share on other sites More sharing options...
s900t8v Posted December 16, 2014 Author Share Posted December 16, 2014 I don't think the mx has that much going for it. All the porting specs I have show the same porting between endure and mx. Mx just has a smaller combustion chamber aka higher Comp. It's just a fair amount lighter too. I think they used the same carb. The It has the performance porting but even that is a bit rough by today's standards. Square exhaust port etc Link to comment Share on other sites More sharing options...
blackhat250 Posted December 16, 2014 Share Posted December 16, 2014 The It has the performance porting but even that is a bit rough by today's standards. Square exhaust port etc Enlighten us on the Square exhaust port , Link to comment Share on other sites More sharing options...
s900t8v Posted December 16, 2014 Author Share Posted December 16, 2014 I probably shouldn't say square but my understanding is that the very early it 175 series had a really flat exhaust roof. Think this caused them to lose some mid range (I've read descriptions of double power band aka flat spot in mid range) as they lost a lot of charge out the exhaust at mid rpm this is just my understanding I don't Have the it port map or timing .The books suggest a D roof for retaining mid without sacrificing peak power. The advantage of the flat roof is it provides high clearance at high rpm but cos it flattens out the middle you get a Harder power band that isn't suitable for all types of riding or racing 1 Link to comment Share on other sites More sharing options...
dose Posted December 24, 2014 Share Posted December 24, 2014 Interesting, sounds like you or someone you know has some porting experience that racing book was written in the 70s so im sure porting techniques have improved since then any updates on your build? Link to comment Share on other sites More sharing options...
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