PakerT Posted April 4, 2012 Share Posted April 4, 2012 My bike have a dip in power under about 5-6000rpm. If I give it full throttel the dip feels clearly. But if I accelereate carfully my bike pulls much better and the dip isnt så clear. The same if I rush the engine in neutral. Quote Link to comment Share on other sites More sharing options...
blackhawkxx Posted April 4, 2012 Share Posted April 4, 2012 If it is a 97-98, they do have a flat spot about that RPM but not the kind that you could feel in neutral. What year is it? Quote Link to comment Share on other sites More sharing options...
PakerT Posted April 4, 2012 Author Share Posted April 4, 2012 Its a -98. But I cant imagine that bikes between 97-98 from factory runs better when full throttel isnt used up to about 5-6000rmp?. The diffrens between full end slowley thottel handling is realy clear. Hope you understand my english ( Swedish ) Quote Link to comment Share on other sites More sharing options...
R1000 Posted April 4, 2012 Share Posted April 4, 2012 Its a -98. But I cant imagine that bikes between 97-98 from factory runs better when full throttel isnt used up to about 5-6000rmp?. The diffrens between full end slowley thottel handling is realy clear. Hope you understand my english ( Swedish ) The bike accelerates best with WOT even if you feel the dip more at maximum power than on light throttle (since the power is very low then). I have never seen a carbed BB that not has a huge power dip around 5500 rpm. Quote Link to comment Share on other sites More sharing options...
brianmacza Posted April 4, 2012 Share Posted April 4, 2012 My '97 has stock jets and the flat spot is much less pronounced with my aftermarket slipons than with stock cans. Oh... and I have a K&N filter too. This is at ~1700m above sea level though, so you're probably lower than me. Quote Link to comment Share on other sites More sharing options...
PakerT Posted April 4, 2012 Author Share Posted April 4, 2012 What does WOT meen? The bike accelerates better whit the trottel under max, its a fact, my speedmeter and rpm tells me that. What will happens if I put one more washer on the trottel needles? Quote Link to comment Share on other sites More sharing options...
rockmeupto125 Posted April 4, 2012 Share Posted April 4, 2012 Wide Open Throttle. Its true that the carburated birds have a drop in the power curve at that rpm. The bike doesn't slow, but the rate of acceleration does, giving the impression of a slight power loss. It can be corrected by rejetting, but that will decrease your fuel mileage. If you use full throttle, the dip in the power band is quite noticeable. If you don't use full throttle, the impression is that the dip is not that significant. Be sure your assessment that the bike is slower under full throttle is a timed/measured judgement, not just your seat of the pants impression. If you've timed the bike and it really is faster using less than full throttle, then you've got a problem. You should first check and change the plugs and air filter, then run a fuel system cleaner such as SeaFoam for a couple hundred miles. If it still runs slower at full throttle, it most probably has a lean mixture at full throttle, and the carbs need to be pulled, inspected, and cleaned. That's the most likely cause if the behavior still persists, but be aware there are other conditions that could be involved as well. Quote Link to comment Share on other sites More sharing options...
slowrideCX Posted April 4, 2012 Share Posted April 4, 2012 Wide Open Throttle. Its true that the carburated birds have a drop in the power curve at that rpm. The bike doesn't slow, but the rate of acceleration does, giving the impression of a slight power loss. It can be corrected by rejetting, but that will decrease your fuel mileage. If you use full throttle, the dip in the power band is quite noticeable. If you don't use full throttle, the impression is that the dip is not that significant. Be sure your assessment that the bike is slower under full throttle is a timed/measured judgement, not just your seat of the pants impression. If you've timed the bike and it really is faster using less than full throttle, then you've got a problem. You should first check and change the plugs and air filter, then run a fuel system cleaner such as SeaFoam for a couple hundred miles. If it still runs slower at full throttle, it most probably has a lean mixture at full throttle, and the carbs need to be pulled, inspected, and cleaned. That's the most likely cause if the behavior still persists, but be aware there are other conditions that could be involved as well. This is exactly what I was Going to say. A few minor adjustments / mods can make a huge difference. Quote Link to comment Share on other sites More sharing options...
BearXX Posted April 4, 2012 Share Posted April 4, 2012 Hei! Og velkommen til galehuset I had the same problem with my 97. I put in Dynojet, and after a bit of tuning we got rid of the dip and about 16 hp more on the midrange And it used a bit more fule. Almost 1 L pr MIL. Men sprek som faen Det er ikke mange her inne som leser skandinavisk, så mange vil google oversetting.. hehe Bjørn Quote Link to comment Share on other sites More sharing options...
redxxrdr Posted April 4, 2012 Share Posted April 4, 2012 My XX is FI, not carbed. So I can't speak to the XX directly. But, I recently picked up a carbed SV650 that performed as you described. It had been stored for months with Ethanol based fuel. Seafoam made it better, but not perfect. I researched rebuilding the carbs and took them apart for a good cleaning. I found one jet to be clogged. A through cleaning, with no parts needed and the bike rides great. I spent more time thinking about the job than it took to actually do it. Good luck and post your results. Quote Link to comment Share on other sites More sharing options...
Banshee Posted April 5, 2012 Share Posted April 5, 2012 ... I have never seen a carbed BB that not has a huge power dip around 5500 rpm. I had one! A '98 Candy Apple red. After I had made several mods, I did, anyway... The relevant ones were the: K&N airfilter, '99 headers, Yoshi slip ons, Factory Pro ignition advance (6 degrees, I would have decreased the advance to 4 degrees but couldn't get the crank bolt out again... ), Run on 98RON fuel (or it would ping due to the 6 degree extra advance). I never bothered rejetting as it wasn't too lean. Just a little, so that it popped on overrun when changing down to stop. With that done, the dyno gave a (corrected, I believe) reading of 122kW & 123Nm. The torque curve was 120Nm - 123Nm from 3kRPM to 10kRPM and a really nice smooth curve. Power was a straight line up to max. No dips anywhere. I believe that the '99 headers & Yoshis did most of the work in getting rid of the dip. As engine noise, (down here at least), is measured at 1/2 of the RPM at which max power is developed, it makes sense for Honda to tune the exhaust to suppress excess noise at that point. For the BB, that falls right where the dip is... Quote Link to comment Share on other sites More sharing options...
rockmeupto125 Posted April 5, 2012 Share Posted April 5, 2012 Changing the header would definately improve the power curve....that's exactly why Honda changed the header pairing for the FI models. It bolts up okay but the fittings for the radiator and oil cooler take a little bit of fiddling as they are different from the carb versions. Quote Link to comment Share on other sites More sharing options...
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