RabbitDog Posted July 8, 2011 Share Posted July 8, 2011 Hi I recently bought a yamaha TZR50 2011 model. And i'm having trouble getting the power from the engine, that i would like to have. I did two modifications to it,the restrictors in the exhaust have been taken out, and it was a necessary step since the bike drove 5 KM/T on a very, and i mean very small hill, even in first gear. And the main jet has been replaced with a bigger size. I know it is only a 50cc engine, but i know you can squeeze some max speed out of it. I do get in high revs, but even so there isn't much speed in it. I have tried pushing it a bit to see what max speed i get, but never into the red field though. At 8,000 revs the speed is around 55 and in 9,000 revs it's in around 64. Nobody seems to know what the problem could be, since it should go around 80km/t in 8 to 9000 revs, in 6th gear, ofcourse. Could there be any more restrictors in the bike? Link to comment Share on other sites More sharing options...
Moderator Airhead Posted July 8, 2011 Moderator Share Posted July 8, 2011 is there a sleeve above the carb throttle valve that prevents full throttle opening? Link to comment Share on other sites More sharing options...
RabbitDog Posted July 8, 2011 Author Share Posted July 8, 2011 is there a sleeve above the carb throttle valve that prevents full throttle opening? no, it does go all the way Link to comment Share on other sites More sharing options...
Tuesday Posted July 13, 2011 Share Posted July 13, 2011 Biggest performance boost with the TZR50 is sorting out the exhaust. It could be that all the restrictions have not been sorted. Poster in another thread had to split the standard pipe to remove the restriction and then weld back up again. Have a look in the airbox for any other restrictions. On my TZR50 I have a 110 main jet, needle jet at mid position. Arrow Exhaust. Front cog 11 teeth, back 47 teeth. Spark plug BR9EIX More holes cut in airfilter frame, see pic below. top gear 50 MPH at 9500 RPM and reves passed 12000. Link to comment Share on other sites More sharing options...
RabbitDog Posted July 18, 2011 Author Share Posted July 18, 2011 Biggest performance boost with the TZR50 is sorting out the exhaust. It could be that all the restrictions have not been sorted. Poster in another thread had to split the standard pipe to remove the restriction and then weld back up again. Have a look in the airbox for any other restrictions. On my TZR50 I have a 110 main jet, needle jet at mid position. Arrow Exhaust. Front cog 11 teeth, back 47 teeth. Spark plug BR9EIX More holes cut in airfilter frame, see pic below. top gear 50 MPH at 9500 RPM and reves passed 12000. thanks for the reply ! Link to comment Share on other sites More sharing options...
Killachipmunk Posted July 19, 2011 Share Posted July 19, 2011 Hey, I had one of these bikes until last month. I'd highly reccommend an aftermarket exhaust rather than modifying the standard one. I had a Metrakit RK (They sound amazing). The only other modification done was a carb jet, not done by me. If there's no rev limiter restriction, this should be all you need. I never had any gear ratio changes, I could do medium hills in 5th and I got 65mph in top gear. (Only weigh 8 stone though). The main thing is to remember that on a 2 stroke machine like yours you will get no power in the low revs, basically if you're under 7500 RPM, you're not going anywhere. Hope this helps KC Link to comment Share on other sites More sharing options...
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