jenzi Posted February 7, 2009 Share Posted February 7, 2009 Hey I read on the forum that there was a Highway Hawk exhaust system for the 125 xvs fragstar that would increase the HP by 3 or 4. Has any of you guys tried it and can you confirm that it works? And if you have it how does it sound? Would also like to know where its possbile to buy it. PS: Im from Norway so my English isn't the best Link to comment Share on other sites More sharing options...
pigkiller Posted June 1, 2009 Share Posted June 1, 2009 Hey I read on the forum that there was a Highway Hawk exhaust system for the 125 xvs fragstar that would increase the HP by 3 or 4. Has any of you guys tried it and can you confirm that it works? And if you have it how does it sound? Would also like to know where its possbile to buy it. PS: Im from Norway so my English isn't the best yeah put highway hawk drag pipes on my 125 the man at the shop who re-jetted the carb and dinoed the bike said they do nothing for the bike there is no back pressure if anything its better with the old ones on but the sound is great and you get the pop pop on tick over had mine off ebay Link to comment Share on other sites More sharing options...
El Muerte Posted June 2, 2009 Share Posted June 2, 2009 Everywhere I see this 'back pressure' myth.If that was true than no one would instal straight pipes on racing cars. I think that people forgett that Dragstar is four stroke engine, and not two-stroke where back pressure is very important. People think that straight pipes damages valves, but that is not true. I spoken to my brother who is mechanic, and he explained it very simple: When engine disposes of hot fumes and exhaust valve closes, fumes now travel through exhaust pipe and get away from bike..... Once exhaust valve is closed there is no influece from so called back pressure becouse it can't get back into the engine.Only thing wich can open exhaust valve again is cranckchaft. Problem in this 'myth' is that people often swap danger of having no pipes and having straight pipes on their bikes. Problem of having no pipes is becouse it damages valves due to extreme temperature differences form inner to outter side of valve. Once hot valve opens, the cold fresh air from outside bonds to it wich couses extreme damage. As for the rest of it......it is perfectly safe to have straight pipes. But once you place straight pipes, you must re-jet your carb.If your mixture is too lean it will also damage valves. This is where most of people got everything wrong, and think it is lack of back pressure that coused all damage. Link to comment Share on other sites More sharing options...
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