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Performance Problem, Please Help!

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Old 05-28-2006, 06:11 PM
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Performance Problem, Please Help!

Okay, so, I just had my two intake valves replaced, bike ran great before, but they got smashed on a CCT problem. Ths was only the front cylinder aswell. I reinstalled the head, and timed everything correctly, now I have okay power down low, and when I say okay, I mean it will pull the wheel up if I goose it from about 2000 rpm, but it just doesn't seem to be quite as good as it was. Now once I hit about 5500-6000 rpm, if feels as though it is missing on one cylinder, or something like that. The bike idles fine, starts fine, and it will even rev higher then that if I barely touch the throttle, but for some reason it just won't go any higher when I try to give it gas. It seems pretty responsive, and seems to run pretty smooth, it's just when I want to go, it doesn't! Does anyone have any ideas what this might be. I figured that if it was timing, then it wouldn't idle so well. It is so frustrating.. Please help!! Thank so much!

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Old 05-28-2006, 10:50 PM
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Does it seem like it's starving for fuel at higher loads and rpm?

Check your petcock hoses. NOTHING should be hooked up to the bottom nipple - that's the diaphragm vent. The small hose with the wire clip goes on the nipple on the BACK of the petcock. It's hard to see and a lot of folks make the same mistake. If this is it, don't feel bad. You're not alone.
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Old 05-29-2006, 06:06 AM
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Well, I know that this isn't it, or atleast I am pretty sure that I would not be able to ride about 30 km with it running like that. Plus, when I first hooked everything up and fired it for the first time since the head work, I forgot to tighten the drain screws on the bottom of the carbs. They were completely dry when I reinstalled them, and the were pissing gas right after it fired up. So, I know that the carbs are getting fuel. Also, I can completely open the throttle all the way, and it pulls okay, doesn't stumble, or anything till it hits 5500 rpm. Now, I just changed the oil after I finished everything, and I put a tiny bit too much oil in. If the bike is perfectly level, the oil fills the site glass, but if I tip it just a degree or two over, it's there, so it's not much. But could this do it? Does anyone think it could be timing? Or maybe an internal carb problem?? I am going to try and drain some oil out tonight, and take it for another rip, but I have never heard of this as a problem. Thanks for the help!!
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Old 05-29-2006, 07:16 PM
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Well, I was going for the easy answer. Thing about the Superhawk petcock is that it's a piece of ****. It will flow gas if there's nothing hooked up and it will flow gas if it's hooked up wrong. It just won't flow enough gas in those conditions. If it's not the petcock then I think it must be the cam timiing, given all the work you've done to it. I don't think the oil is an issue. If anything, the oil would come out the breather into the airbox and you'd get smoke. That'd be your first sign.
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Old 05-29-2006, 07:26 PM
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Okay, so I drained some oil out, checked the petcock with a short little 5 inch hose and my mouth, and got a face full of gas... I am confident that it is not the petcock. It's the only thing I could find... I cleaned my air filter, and double check all my hoses, and what not. Everything seems to be up to snuff. I attempted to change my spark plugs, but I can't find a socket that will fit either the spark plugs, or inside the head. I just bought a new socket, so I will try that on the next tear apart. As for valve timing, if I didn't touch the rear cylinder, and only had work on the front, if I was off even one tooth, would it not idle rough, or have trouble starting, or something along those lines. The service manual says that if you have poor low speed performance, it could be valves. I am honestly at a loss here. Anyone please help me on this one...
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Old 05-29-2006, 07:41 PM
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If you have a tool kit, it has a plug socket in it.

Sorry about the gas in the face. I would make a comment about sucking on 5 inch...... but I'm not going to go there.

I think it would run with one tooth off, but not well. Depends on which way it's off, IIRC. If there's too much overlap between intake and exhaust it'll run like crap at idle. If there's not enough overlap between intake and exhaust it'll run like crap at higher rpm, or at least lack power. It all has to do with cylinder refilling. Never wanted to do the theory-to-practice on this so I'm just going off what I learned in college and over the years.
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Old 05-30-2006, 08:47 AM
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Well, that is the only tool in the tool kit that is missing. So I just bought another socket to try it with. this is so frustrating. A friend of mine said it may be electronic, something to do with the rectifier. I don't really know how this would affect it. As far as I knew, it would either run, or not if this was faulty. I just wish it was something simple that I could check. I ran it last night with no air box on. and watched the carbs, and the slides were jumping nice and evenly, smooth, good throttle response... I just can't figure it out.
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Old 05-30-2006, 12:34 PM
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Let me know if you figure it out. It sounds alot like the problem I'm having. I don't have the time to jack with it so I sent the bike to a mech. I'll keep you posted on what he tells me.
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Old 05-30-2006, 06:45 PM
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Well, I am just off to try new plugs... check my petcock one more time.. I'll see what the evening permits. Crappy thing is that after all this work, I won't be able to take her for a rip. Got my kids tonight... Can't exactly leave them sleeping in the house alone... Or can I??? Hahah.. Hmmm.. Ride the bike, or be responsible parent.... Always a tough call...


Kidding!!!
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Old 05-30-2006, 07:02 PM
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Depends on there age....lol....If there in a baby seat, you could always duck tape it to the hawk and go....lol....saw that on another site....whack job...
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Old 05-30-2006, 08:28 PM
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Okay, so I finally got the plugs out, both look pretty good. Front Cylinder looks perfect. Nice brownish tinge to the whole thing. The rear looked a little rich, but not too bad at all. I also read through the service manual a bit more. I am 90% positive that it would not be my valves off, everything it says in there basically tells me that it would be hard to start, or idle rough. I know it is not the petcock, Man that thing can dump a lot of fuel out when it's openned. It was saying in there that poor high performance could be clogged carbs... But I don't really know what could be clogged in there to cause it. Anyone have any ideas?
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Old 05-30-2006, 10:56 PM
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Sticky float valve, maybe? How about line routing? Any kinks or sharp bends? If it's not valve timing, and it's not gas, then that only leaves one thing - electric. And I suck at most things electrical so I don't think I can help you out much there. I've heard of bad coils doing similar things, BTW.
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Old 05-31-2006, 08:17 AM
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Well, the thing I don't understand is how after doing some simple head work on the front cylinder, that I can have suck a strange problem, and no one seems to know what the heck it could be. I have asked just about every mechanic I know, and they are all baffled telling me different things to check, which I have. I can't figure how I would all of the sudden get a problem with coils, or anything like that after simply changing the ccts, and a couple of valves... I don't know.. I am going to take her for a good rip tonight and see if I made any progress... I hate mysteries!!
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Old 05-31-2006, 09:39 AM
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You may want to try a compression test if you have a tester around. if the com,pression is close from one cylinder to another you can pretty much eliminate a valve, piston or cylinder wall issue. Recheck your valve timing if you have the time, someone on the list had the procedure on here yesterday.

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