Member Contributer AvalonRacing Posted June 8, 2009 Member Contributer Share Posted June 8, 2009 Okay, my stock '01 has always pulled nice and strong. The only "mechanical" thing that I've done to the bike was disabling the flapper valve. The tapping was bugging me. So, just for kicks I decided to get an inexpensive slip on just to hear a little more exhaust noise over the gear driven cams. I picked up one from Holeshot Performance. Nice build quality (welds and center stand stop), nice fit, looks good, smaller and much lighter than stock and a nice sound. Here's the question. My bike use to have a very slight but noticeable flat spot at 5K RPM followed by a nice power surge. Now, with the slip on, the power is very smooth and linear. It spins up nice and fast, the power feels like it's all there but it feels like a little less in the seat of the pants just because the flat spot followed by the surge is missing. Could it be that the easier breathing exhaust has improved the tiny flat spot and made the surge feel smaller or could it be that I've lost a little power over 6K due to a lack of back pressure? Thoughts? Opinions? Link to comment Share on other sites More sharing options...
Member Contributer Ryanme17 Posted June 8, 2009 Member Contributer Share Posted June 8, 2009 At that high of RPM's you want 0 backpressure, I would guess that you gained a bit of power at 5K, not lost some at 6K. Link to comment Share on other sites More sharing options...
Member Contributer AvalonRacing Posted June 8, 2009 Author Member Contributer Share Posted June 8, 2009 Sounds good to me. Literally. Link to comment Share on other sites More sharing options...
Member Contributer ccnaylor Posted June 8, 2009 Member Contributer Share Posted June 8, 2009 Sounds good to me. Literally. Wocka-Wocka-Wocka!! He'll be here all week! :biggrin: How does it pull from idle? (literally) Link to comment Share on other sites More sharing options...
Member Contributer AvalonRacing Posted June 8, 2009 Author Member Contributer Share Posted June 8, 2009 How does it pull from idle? (literally) Just fine. It's just a nice, linear pull from 0 on up. Funny though, linear power is great and it is definitely my first choice but there is something about the kick in the pants from hitting a power band that is fun. Link to comment Share on other sites More sharing options...
Member Contributer ccnaylor Posted June 8, 2009 Member Contributer Share Posted June 8, 2009 How does it pull from idle? (literally) Just fine. It's just a nice, linear pull from 0 on up. Funny though, linear power is great and it is definitely my first choice but there is something about the kick in the pants from hitting a power band that is fun. Like it is too predictable/less exciting? I dunno, I get a kick in my pants every time I crack wide open throttle :beer: Of course I gots Vtech though :biggrin: Link to comment Share on other sites More sharing options...
Member Contributer AvalonRacing Posted June 8, 2009 Author Member Contributer Share Posted June 8, 2009 I'll take predicable and I'm not shy about twisting the throttle hard but I once rode a Yamaha RZ350 (two stroke) and wow it was like making the jump to hyperspace when you would hit the power band. Link to comment Share on other sites More sharing options...
Guest Posted June 9, 2009 Share Posted June 9, 2009 I'll take predicable and I'm not shy about twisting the throttle hard but I once rode a Yamaha RZ350 (two stroke) and wow it was like making the jump to hyperspace when you would hit the power band. Usually when one installs an aftermarket exhaust component as you have installed a slip on,the engines fuel mixture will run slightly leaner due to less back pressure or improved exhaust flow. A stock VFR engine with no modifications will usually run very much on the lean side of the fuel mixture. Alot of times when someone makes a change such as you have they tend to inherit flat spots,bogging and sometimes back fireing.You got lucky buy loosing a flat spot. About the only thing that I can think of is your engine, possibly due to incorrect ECM operation, was running slightly rich, in that RPM range, prior to the slip on. Now by improving exhaust flow you have leaned out the entire fuel mixture so when you get to what used to be your flat spot it no longer exhists because the exhaust is flowing more free which tends to lean it out. This is just a quick thought of answer,I may be miles from the truth ,I would like to hear from some other tuners out there just to make sure I havent gone loopy. eddie Link to comment Share on other sites More sharing options...
Member Contributer AvalonRacing Posted June 9, 2009 Author Member Contributer Share Posted June 9, 2009 That seems like an interesting theory. I'm not getting any notable backfiring. I was told that de-snorkeling or disabling the pair valve would fix that. I do get a little bit of exhaust "gurgling" when engine breaking but that doesn't sound so bad. Does anyone think there is a reason to do the the pair valve/snorkel thing? Link to comment Share on other sites More sharing options...
Member Contributer ccnaylor Posted June 9, 2009 Member Contributer Share Posted June 9, 2009 I'll take predicable and I'm not shy about twisting the throttle hard but I once rode a Yamaha RZ350 (two stroke) and wow it was like making the jump to hyperspace when you would hit the power band. I'm green with envy. I drool over 2-strokes! As far as PAIR/snorkel thingy, some people just like to mess with things. I don't always want to mess with things, especially things I don't know much about. Especially when mine runs like a champ with only O2 elims on it (YMMV of course). Link to comment Share on other sites More sharing options...
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