ddlooping Posted March 16, 2012 Share Posted March 16, 2012 Hi all As the chain on my newly acquired XVS 125 shows quite a bit of rust I am thinking of having it changed. Having read the original " thread I'm leaning towards changing the sprockets as well (maybe using a DID or AFAM kit?). Do you guys have any opinions/recommendations about the modifications made by Markyboy27? @Markyboy27: still happy with the modifications you made? Thanks in advance. ...did the plug-chop test and the electrode was light grey, so running lean. This made me assume the K&N filter was sucking more air so went up again to the 100 jet this morning and took a road trip down my usual test route. Performance was up a tad, mainly visible on the long 2 mile up-hill (as i made 60 almost all the way up). Plug chop was darker so that seemed about right. Came home and upper the front sprocket to 18 teeth (16 being standard, and 17 being what i'd been running) and took it out again... Progress was made ! Gear shifting is now later in each gear, which has benefitted in the respect that it puts the bike in it's 4th gear power-band during up-hills... which before was difficult as it either screamed in 4th or bogged in 5th. Top speed is pushing 77 and long up-hills are still about 60 but the benfit is in the lower gears. I'm about fed up now, so will leave it at that. The modifications list is now as follows: 1). In-line fuel valve removed 2). 18 tooth front sprocket (16 is standard) 3). 100 Jet fitted (90 is standard) 4). EMGO K&N-copy sports airfilter fitted The performance characteristics have changed as follows: 1). Top speed upped from 64 to 74mph (78 with now wind) 2). Legal cruising speed (60) now at half revs instead of high revs 3). Up-hill speed upped from 45 to 60mph. 4). Acceleration improved in all gears up to and including 4th. Total cost of bits? No more than £30 (no labour costs as did them myself). Given what i know know about the 125cc Dragstar i'd say the program is now at and end and i'll either sell it modified, or return it to standard (depending on buyer requirements). Found an '03 Dragstar 250 at a local dealer who says he'll swop with no additional cash so that's where I am ! I've enjoyed the experience and look forward to passing the mint machine onto a lucky learner who will enjoy it as much as I have. Mark. Link to comment Share on other sites More sharing options...
ddlooping Posted March 16, 2012 Author Share Posted March 16, 2012 P.S: I might just go for the simpler 17 teeth front sprocket mod. (still changing the chain and back sprocket). ..just took another run with the 1-tooth bigger sprocket on and am pleased to say the reduction in power is negligible, but the improvement in MPH is just what i was looking for. Before i was changing up into top at 55mph, and screaming at 70. Now I change up to 4th at 55, and into top at 65which means by the time i'm up to 70 it's inthe mid-rev range. I checked again on a long uphill and I still gain, as before on the same hill i was capped at 45/50, whereas now i'm at 55 and creeping up (depending on incline). Link to comment Share on other sites More sharing options...
neversaydie Posted March 16, 2012 Share Posted March 16, 2012 No doubt youll get the usual differing opinions on this, its cropped up here many, many times. In my view, the benefits are neglible. A standard bike should reach 70mph, cruise at 55 to 60. Go down a tooth on the front sprocket, and top speed will increase to perhaps 75mph but engine will be screaming at you to slow down, acceleration will be sharper. Go up a tooth on the front, slightly slower acceleration and top speed 65 mph but at less revs. Anything else aint worth the effort for a couple of mph. If you wanna go faster, then a sportier bike is required Reading marky boys story, hes gained 3 to 4 mph perhaps. Is that significant enough to warrant the work? Link to comment Share on other sites More sharing options...
ddlooping Posted March 16, 2012 Author Share Posted March 16, 2012 Thanks for the feedback, neversaydie. I'm going to stick to just changing the sprockets and chain (swapping the 16 to a 17 at the front). Link to comment Share on other sites More sharing options...
Moderator Cynic Posted March 16, 2012 Moderator Share Posted March 16, 2012 To be honest if there is rust on the chain it will be costing you some of what little horsepower you have. A bad chain can cost you 15% of your available power if its really bad. Poorly lubed they can get hot enough to burn your hand. Link to comment Share on other sites More sharing options...
ddlooping Posted March 16, 2012 Author Share Posted March 16, 2012 Thanks for the feedback, Cynic, especially considering that it confirms what I was thinking. Link to comment Share on other sites More sharing options...
Paulwhite Posted March 17, 2012 Share Posted March 17, 2012 try wemoto.com there good for parts. http://www.wemoto.com/bikes/yamaha/xvs_125_dragstar/00-04/ iv just got my hands on the rear sprocket less 3 teeth so il see how that goes (only took 2 days to get to me) ....to be honest the best thing you could do to get more speed out of the xvs 125 is to take all the plastic off and put it on a diet. its a heavy bike and that will play a big part. .........put it this way the honda cbr 125 (04) engine kicks out the same power as the xvs 125. Link to comment Share on other sites More sharing options...
ddlooping Posted March 17, 2012 Author Share Posted March 17, 2012 Thanks, Paul. To be honest, my main goal is to lower the revs, any increase in speed is a bonus. Link to comment Share on other sites More sharing options...
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