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/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> Mid-range hesitation /cgi-bin/YaBB.pl?num=1298315386 Message started by feelinjunky on 02/21/11 at 11:09:46 |
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Title: Mid-range hesitation Post by feelinjunky on 02/21/11 at 11:09:46 I'm having some issues tuning my carb for best performance. I know, this is a worn out topic, but I couldn't find an answer in the tech section... I have a hard krome exhaust, big k&n intake, 52.5 pilot, 155 main and 1/2 spacer. 2001 6k miles Great performance between 0-1/4 throttle and at low rpms. The main issue I'm having is that at around 3-4krpm, with 3/8-1/2 throttle, the bike hesitates and jerks back and forth. I would put it in 3rd, and give it half gas steady. It accelerates modestly, but at around 3.5k, there is a clear loss of power and jerky hesitation. No popping or other sounds. Does this mean I have too little or too much spacer removed? Also, I have to make sure, the dimple in the plate that goes over the white spacer faces TOWARDS the spacer, making contact with it, correct? http://i811.photobucket.com/albums/zz39/feelinjunky/2011-01-17155857.jpg |
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Title: Re: Mid-range hesitation Post by Serowbot on 02/21/11 at 11:28:17 I think the spacer is right place to look,... don't know if it needs more or less though... Maybe try both, and see which makes an improvement... ... does one notch on the enrichment valve help or hurt?...:-?... |
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Title: Re: Mid-range hesitation Post by verslagen1 on 02/21/11 at 11:33:23 How's the top end? If that's ok, then shave a little more off the spacer. |
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Title: Re: Mid-range hesitation Post by Fuzzy5150 on 02/21/11 at 11:43:30 I just picked up a 2007 with 2,400 miles. After drilling out the brass plug, draining the gas, and setting the idle, I took it for a run. I experienced the very same thing. It will accelerate just fine, but at a steady mid-range rpm, it hunts and stutters. During the evenings this week, I'm going to pull the carb, and reduce the white spacer by 1/2 (down to 2.5MM), and give it another try. I'll update when I'm done and let you know if it solves my problem. I what to get this sorted out before looking at the main jet. Problem right now is the fact that it's 18 degrees here....not man enough for a full out ride with no windshield!!! |
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Title: Re: Mid-range hesitation Post by verslagen1 on 02/21/11 at 11:46:46 You should get the main sorted out before messing with the white spacer. It will affect the results. |
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Title: Re: Mid-range hesitation Post by Fuzzy5150 on 02/21/11 at 13:05:41 It has the stock 145 main jet. I have a stock muffler, but have drilled 4 - 5/8" holes in the end to add some more breath to it. What would you recommend as a starting point on the main? 147.5 or a 150? |
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Title: Re: Mid-range hesitation Post by Routy on 02/21/11 at 13:52:07 By all means, try...... and answer the question at the bottom before hacking any farther,.....making sure you're going in the right direction. If choking improves it, then less spacer may fix it. I can only tell you that I had the same surging problem, only at a much lower RPM range, and the 1/2 spacer mod fixed it perfectly. 1107100D15000D16620 wrote:
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Title: Re: Mid-range hesitation Post by verslagen1 on 02/21/11 at 14:17:48 7D4E4141420E0A0E0B3B0 wrote:
150 |
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Title: Re: Mid-range hesitation Post by Fuzzy5150 on 02/21/11 at 14:38:02 Thanks! I'll let you know how it rolls.....when it gets a shade north of 18 degrees out! 8-) |
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Title: Re: Mid-range hesitation Post by feelinjunky on 02/24/11 at 08:57:49 32213637282523212A75440 wrote:
I did the throttle test for the Main Jet and I have a feeling it's too big. At WOT, it accelerates respectably, BUT as soon as I let off, it stutters a bit maybe 25% of the time. when I'm going uphill, this is more apparent. |
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Title: Re: Mid-range hesitation Post by Serowbot on 02/24/11 at 09:39:21 I just realized,.. it's probably freezing cold where some of you are... :-?... It's generally better to do jetting adjustments on days when the temps and humidity are more average for your location... Jetting in extreme cold or wet is a waste of time, as it will be different when the temps reach normal... Weather makes a big difference. All bikes run less than optimum in unusual weather. You guys might want to hold off for a while.... ;)... There is no such thing as perfect jetting,... just a good average for your location and conditions.... |
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Title: Re: Mid-range hesitation Post by Reelthing on 02/24/11 at 09:47:27 you got the diaphram spring in correct? - pretty easy to get off to one side |
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Title: Re: Mid-range hesitation Post by feelinjunky on 02/24/11 at 10:13:47 16212128302C2D2A23440 wrote:
I made sure that was dead on. And I don't adjust anything if it's below 40 degrees. Also, does the dimple on the metal plate go towards the white spacer, making contact with it, or away from the white spacer, towards the spring? It's the circular-shaped piece that holds the needle in place. |
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Title: Re: Mid-range hesitation Post by Reelthing on 02/24/11 at 10:20:59 yep dimple down was that slide as clean as clean can be? |
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Title: Re: Mid-range hesitation Post by feelinjunky on 02/24/11 at 10:26:12 0136363F273B3A3D34530 wrote:
Soaked in carb cleaner for a few hours and wiped down with microfiber. I guess it could be cleaner, but it wasn't dirty at all. The bowl on the other hand was filthy...then again, the carb was unopened for 10 years... |
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Title: Re: Mid-range hesitation Post by verslagen1 on 02/24/11 at 11:28:03 3B383831343337283336245D0 wrote:
Proper orientation of those parts... http://w3.bikepics.com/pics/2007%5C10%5C24%5Cbikepics-1065897-800.jpg |
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Title: Re: Mid-range hesitation Post by feelinjunky on 02/24/11 at 17:02:51 Yea, I saw that pic, but wanted to be sure. Dimple towards spacer. Got it. So I think I'm going to change from 155 to 152.5 main and if the mid-range symptoms persist, I'll just shave a bit more off the spacer. Thanks for the help, guys. Really appreciate it. Good stuff. |
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Title: Re: Mid-range hesitation Post by feelinjunky on 03/14/11 at 08:53:08 So I changed the Jet to a 152.5 and everything got worse. At around 4k-5k rpm, wot, the bike jerks back and forth really hard. With the 155 main, there was significantly less hesitation. Should I try a 150 main? That seems too small for my pretty much straight pipe exhaust and big k&n intake, so I'm not sure. Any help would be appreciated. Thanks. |
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Title: Re: Mid-range hesitation Post by Routy on 03/14/11 at 16:57:34 1305120F17020F14600 wrote:
Did you ever try this ?? It works very good, trust me ! The alternative,...keep shootin in the dark. |
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Title: Re: Mid-range hesitation Post by feelinjunky on 03/16/11 at 13:32:49 I'm not sure I know which notch you mean. I just ajusted the spacer, main, pilot and idle mixture screws...any more info? |
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Title: Re: Mid-range hesitation Post by bill67 on 03/16/11 at 13:39:13 That notch is on your choke,Pull it out slow and you will feel it. |
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Title: Re: Mid-range hesitation Post by Routy on 03/16/11 at 16:42:02 Sorry,........many here call it an enrichment valve, probably because it doesn't shut off the air like a butterfly choke does. I myself call it a choke so as to not confuse those who don't know there is a difference. But at most any speed....short of WOT, pulling the knob 1 click will tell you real quick whether it needs more fuel or less. |
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Title: Re: Mid-range hesitation Post by ralfyguy on 03/16/11 at 21:42:44 When mine is warmed up, I can't even get it to the first notch without getting major stuttering and chugging and smoking. Going to the first notch then causes the engine to die. On cold start below 60 degrees, it needs it out to the first notch, and that works all the way down to below freezing. I never need to pull it out any further than that, as the motor starts chugging and spitting then. |
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