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/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> I've got a feeling... /cgi-bin/YaBB.pl?num=1349682389 Message started by HondaLavis on 10/08/12 at 00:46:28 |
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Title: I've got a feeling... Post by HondaLavis on 10/08/12 at 00:46:28 When I'm riding, I've got this feeling in the seat of my pants... I don't know how to describe it. NO, this isn't related to the joy and freedom of being on a motorcycle. :P It happens when I hold a steady throttle speed anywhere between 30-38mph in 3rd, 38-45mph in 4th. The best way I can describe it is similar to the uneven pulling you get when you're starting to run out of gas. A couple of pertinent things I've done recently: lifted the rear of the gas tank approx. 3/4", installed a raptor, installed a fuel filter with all new 5/16" fuel line, and I modded my stock rubber intake tract to fit my K&N cone filter on the end. Also, I STILL have an exhaust leak between the muffler and header... >:( More grinding and another go with the MIG in a couple of weeks, and that will all be taken care of... Any ideas? It DEFINITELY feels like a front-to-back motion, not like it's just weird bumps in the road. While I'm here: I LOVE my tank lift! I have a sportster seat that already had the front tab lifted about a half an inch. I used a thick rubber stopper from Ace HDWR to lift up the tank. It was enough that I can now remove my spark plug using oem tools without removing ANYTHING else, and it also made my seat immensely more comfortable! 8-) |
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Title: Re: I've got a feeling... Post by Wake51 on 10/08/12 at 01:36:37 Well schucks... that Sportster Seat/Tank lift mod sounds pretty cool. Getting to the plug that easy peasy would be a dream. I also own a Sportster and can attest to how much more comfortable the more firm seat is. Unfortunately I'm not quite sure what the issue is. It "pulsing" like that would sound like a petcock issue off of top of the head forum go to knowledge. But clearly you've replaced that and that's typically not under load. Is your clutch slipping perhaps? Granted that's typically pretty noticeable. I can't imagine the exhaust leak causing it. I have a Dyna as well.. I can't get the exahust leak to go away despite everything but applying a sealer and welding. (I hear the sealer causes a nasty mess, the slight puff and occasional backfire don't bother me enough to mess with the goo) I ever tried the crush can method. Guess I'm not precise enough. Is your battery putting out good voltage? I'm just stabbing here, as I'm not really sure. |
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Title: Re: I've got a feeling... Post by ToesNose on 10/08/12 at 04:12:42 HLavis what type of fuel filter did you install? Is it possible that you put it in backwards, I've heard of this type of symptom occuring from that. |
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Title: Re: I've got a feeling... Post by Dave on 10/08/12 at 04:45:52 Is the "pulsing" worse when the engine is cold? Does it go away if you accelerate.....and feel worse when holding a steady cruising speed? If so......You may be slightly lean at the 1/8 - 1/4 throttle setting. Mine did that until I raised the needle slightly, and it richened up the mixture over the entire range. I ended up dropping a main jet size after doing so. |
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Title: Re: I've got a feeling... Post by lrutt on 10/08/12 at 05:51:31 4A717C6B7A766D6B7078756A190 wrote:
I'd agree with this, need a slight rasing of the needle likely to take care of this. Assuming you have adjusted your low speed screw properly at idle. |
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Title: Re: I've got a feeling... Post by Gyrobob on 10/08/12 at 06:37:37 One way to get some actual data on your situation, rather than just guessing about symptoms is to use a vacuum guage. Use the port on the carb that used to be for the line to the old petcock, temporarily hook up a vacuum gauge, and go for a ride. See what the needle is doing when you feel the unevenness. If it moves exactly with the unevenness, then you most likely have something happening with mixture and/or intake leaks, etc. It won't tell you exactly what is wrong, but at least you'll eliminate a few things or narrow it down, anyway. You'll need to put a restriction of some sort in the line between the carb and the gauge so the the vacuum seen by the gauge is not the thump thump thump of our big 650 single, but more of a slow leak. The size of the hole should be large enough to allow the needle to react quickly, but not so large as to have it moving with each thump once you get past about 2000 rpm. |
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Title: Re: I've got a feeling... Post by justin_o_guy2 on 10/08/12 at 08:11:19 That was informative.. I never woulda thot to restrict/meter the gauge line. |
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Title: Re: I've got a feeling... Post by HondaLavis on 10/08/12 at 13:08:10 Wake: I wouldn't suspect the clutch since I only have <4,500 miles. Also, it isn't noticeable under acceleration. The battery is a brand new mini AGM that I installed about a month ago. No issues with it so far; just adapting to having a lot less AH. I mentioned the exhaust leak because I understood it makes tuning difficult to impossible. I was under the impression that it causes a lean condition, which I thought might have an affect on this feeling. As for my fuel filter: it's just a generic cheap-o paper element filter from Autozone. The arrow (which you can't see in the pic) points in the direction of fuel flow, so I'm fairly certain it's installed right. http://i230.photobucket.com/albums/ee291/Lavis325CL/20121008_131028_zpsc7cb81e4.jpg Here's a pic of my robber stopper tank lift. I just drilled a hole in the middle and installed longer bolts. http://i230.photobucket.com/albums/ee291/Lavis325CL/20121008_131442_zps55dd82b0.jpg Before I go out and buy a vacuum gauge, I'm going to test for intake leaks. If I have a leak, I suspect it would be where my cone goes into the rubber tract. http://i230.photobucket.com/albums/ee291/Lavis325CL/20121008_131504_zps687c351a.jpg I shaved down the inner lip of the stock throat so that the cone could fit all the way in. I then cut the clamp portion off of a large hose clamp and used the remaining ring of steel as a spring. I inserted my new spring inside the rubber boot of the cone filter to give it support. I then placed the whole boot inside the stock throat and used the stock clamp to hold the thing together. It seems to work fairly well so far. It'll come off if you tug on it hard, but I expected as much with now kind of locking lip or ridge. I'll check for intake leaks later today. Gently spray some carb cleaner around the edges, look for surging, right? P.S. I just realized that my description of my intake mod might be confusing. Pics to come later this afternoon. |
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Title: Re: I've got a feeling... Post by Johnny57 on 10/08/12 at 13:51:53 I'm guessing it has something to do with your Tank lift and the flow of gas into the petcock. Because these bikes are usually filled with gas while they are on the stand, they do not have as much in them as you think. The petcock is near the rear of the tank. Has the "angle of the dangle" and gas "sloshing" in the tank changed such as to cause this condition? Also, that fuel filter could be a little too restrictive. Experiment with different filters and with none at all. I have had the same problem with a lawn tractor that I own. |
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Title: Re: I've got a feeling... Post by HondaLavis on 10/08/12 at 16:25:44 I initially thought that the fuel filter might be too restrictive, but it's the same style that has been posted in the tech section for proper installation of a filter. I did a flow test, and fuel seems to flow just as regularly with the filter as without. However, I didn't take any official measurements. I added the fuel filter, welded the exhaust, and modded the intake about 2 weeks ago. I only added the raptor and tank lift yesterday. I started noticing the problem about 10 days ago. I've been busy all afternoon, so I'll go test my intake now. Might ride without the filter just for gits and shiggles. :D Also, I meant to ask: I noticed that if I snap the throttle and let go, RPM dips below idle speed before returning to normal. This is less noticeable with a properly set idle, much easier to tell with a low idle. Is this because we don't have an accelerator pump, or is this a symptom of something else? |
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Title: Re: I've got a feeling... Post by CalisOsin on 10/08/12 at 16:34:40 You made a few changes pretty close together, so I think I'd eliminate them as options. Can you remove the filter and lower the tank back down? I Would start there are see how it rides. If that doesn't make any difference, at least you can eliminate them. To me it sounds like the surging/bucking you get with a lean condition. I'd try going up a size in the main jet or maybe the half spacer mod. |
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Title: Re: I've got a feeling... Post by HondaLavis on 10/08/12 at 17:25:26 Well, my intake is a lot better than I thought it was. Definitely no leaks. However, the "spring" that's in the cone seems to have burnt edges... :-? Not sure how that is even possible. Valve gap and timing are all good and set, just checked it last month. FWIW, I'm currently at 2 turns on the mix screw, 55 pilot, 152.5 main, and white spacer is shaved to 0.64. SE Dyna muff and K&N cone on the stock throat, as mentioned earlier. Lean condition in the needle jet circuit certainly sounds plausible. I'll wait until I get that exhaust leak fixed so that no more of my tuning is in vain, and I'll probably still go get a vac gauge just to plug it in and see. Thanks for the input guys. |
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Title: Re: I've got a feeling... Post by tomw on 10/08/12 at 19:54:59 I think may be air restrictions from bottom of air filter and combinations of dirty filter and restriction of air when rideing bike from your legs doze it matter what the weather is ??? |
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Title: Re: I've got a feeling... Post by Digger on 10/08/12 at 20:12:33 4F717A676A676A080 wrote:
Before getting a vacuum gauge, check that the vacuum port on the carb (mentioned by Gyro, above) is plugged up good and solid. Here's how I did that when I installed my Raptor petcock several years ago: http://i235.photobucket.com/albums/ee201/Digger109/CarbVacuumPortPlugE.jpg I squirted some RTV into the tube before folding it. The tube was the OEM vacuum tube. If you get an air leak here, it could cause the symptoms you are experiencing. |
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Title: Re: I've got a feeling... Post by Cavi Mike on 10/08/12 at 20:58:44 A lot of the endmills and special tools we get come in tubes with rubber caps on the ends - perfect for capping off that vacuum port. We just throw them away but I'll gladly save them if you guys are interested. They work great for replacing the lost caps for bleed-screws on brakes as well. |
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Title: Re: I've got a feeling... Post by HondaLavis on 10/08/12 at 21:17:02 http://i230.photobucket.com/albums/ee291/Lavis325CL/20121008_132004_zpscf5d4478.jpg I'm not sure if you can make it out, but I put a 3/16" vacuum cap on there and used a spring clip to hold it in place. I'm fairly certain I don't have a leak from the vacuum port. As for the filter, it was cleaned and serviced just last month. Those spots are from where I used to have it attached directly to the carb, and the top used to hit the seat/tank mount bracket. The only thing even touching it now is where the wiring harness goes over top of it. It has LOTS of available air flowing to it. You should be able to see int he picture, it's pretty free up. The seat gives it another couple of inches of room up top, too. Had an evening ride out to dinner with the wife, and I got to hit my reserve! According to my mileage calculations, reserve was hit right around 2.28-2.3 gal. traveled about another 10 miles til my fill up, resulting in 2.478 gallons to proper full. While the remaining fuel did have slightly less of an aft decline, it was still there. I had no issues travelling at highway speeds up and down hills on my reserve. For the next few days I'll ride without the fuel filter (which I didn't have time to remove tonight) and look for any change. Ran into another WEIRD issue that kinda freaked US out. Different enough that I'm starting a new thread. |
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