Weird surging on the highway....?? - TwoWheelForum: Motorcycle and Sportbike forums
 
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post #1 of 14 (permalink) Old 02-25-2006, 04:17 PM Thread Starter
 
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Weird surging on the highway....??

Hey guys, i have a 2002 Suzuki sv650s with 2500 miles on it. I bought it used about a month ago. When i bought it, it seemed to ride around town jsut fine but when i got it on the highway i'd occasionally run in to problems. I had issues with getting it up to speed - plus it would start surging in 5th and 6th gear around 5-6k rpm. Pretty violent surging too. I took it to a shop where they determined that it was running VERY lean. I had the carbs re-jetted and i noticed that it put out a lot more power than it had before. The highway is still a bit of a hard part - occasionally it would run OK and i could get up to around 90mph in 6th (it would still surge every now and then) but other times i could be holding it at 100% full throttle and 6th couldn't break 80mph and 5.5k rpm. has anyone had an issue like this before? Any idea on what it could be that would cause surging at high speeds like that?
-Anton
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post #2 of 14 (permalink) Old 02-25-2006, 05:16 PM
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When it was jetted... did they sync the carbs as well?




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post #3 of 14 (permalink) Old 02-25-2006, 09:19 PM
 
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For high-rpm problems, it's usually weak spark or incorrect fuel mixture. You could check for any sparks coming off the ignition wires. But I would check the ignition timing using a standard timing light first.

The main jet hardly ever clogs up, but the needle pulling out of the main jet could be slow getting out of the main jet. A sticky needle/piston would cause this. It is actually very common with constant-velocity carbs. If you can reach the intake of your carbs, you can test them. With the engine off, raise the diaphram piston with your finger. It should go up smoothly and drop smoothly. Any stickyness and they have to be cleaned. Just don't drop anything into the carbs.
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post #4 of 14 (permalink) Old 02-25-2006, 10:32 PM
 
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hmm something sounds really wrong here with the air/fuel mixture ratio. I don't think it's a spark issue. I never had this problem on my 2000 SV which is the same engine and bike for that matter.
1. Check your air filter / box.
2. Check your fuel lines.
3. Get the carbs checked/sync'd.
4. Check the jets.

I'll try to think of other possibilites in the mean time.
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post #5 of 14 (permalink) Old 02-26-2006, 09:15 AM Thread Starter
 
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Hmm - i'll ask the maintenance guy if he synched the carbs or not - he should have done that after jetting anyway, right?? I'll ask..

The problem seems to get better with a little bit of choke on the highway - more power and it accelerates more linearly with little bogginess. Could it just be the cold weather? I'll see how much the shop will charge to get the carbs synched - labor on sports bikes is damn expensive, unfortunately...

If you guys come up with more ideas don't hesitate to post 'em! I'm heading out on a little road trip on the bike for spring break and i need it running right
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post #6 of 14 (permalink) Old 02-26-2006, 10:11 AM
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I would have them sync'ed or re-done... and cleaned. That's a good maintance thing to do anyway and would rule that out.

To check for spark leak. Start your bike in a dark garage and look for flashing light...




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post #7 of 14 (permalink) Old 02-26-2006, 10:38 AM
 
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The choke circuit can also be a problem on the carburetted SV's.
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post #8 of 14 (permalink) Old 02-26-2006, 10:45 AM Thread Starter
 
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Thanks for the advice gasman!

mojo - How could the choke circuit be an issue?
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post #9 of 14 (permalink) Old 02-26-2006, 08:03 PM
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No worries mate. That's why




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post #10 of 14 (permalink) Old 02-28-2006, 10:10 AM Thread Starter
 
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thanks guys - i'm taking it into the shop tonight. I'll let you know what turns out to be the issue.... assuming they find it.

oh.. my turn signal is being awkward too. The frequency of the flashing changes each time i use it.... sometimes even if i go over a bump, it'll wither slow down or speed up in frequency. I don't even know where to start with this one...
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post #11 of 14 (permalink) Old 02-28-2006, 10:36 AM
 
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Quote:
Originally Posted by kolomian
thanks guys - i'm taking it into the shop tonight. I'll let you know what turns out to be the issue.... assuming they find it.

oh.. my turn signal is being awkward too. The frequency of the flashing changes each time i use it.... sometimes even if i go over a bump, it'll wither slow down or speed up in frequency. I don't even know where to start with this one...

Pinched wire somewhere in the harness?



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post #12 of 14 (permalink) Old 02-28-2006, 10:48 AM
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Does it have a pip and or aftermarket filter? This could bring it back to improper jetting. Check that all plug wires are attached properly and not cracked or broken. (Spark leak as GasMan suggested) I also agree with Mojo that the choke circuit may be an issue since you can improve performance by adjusting it.

The signals
Do you have aftermarket lights? LED bulbs will blink faster then standard bulbs. It could be just a bad bulb that hasn't given up all the way yet or a bad connection or pinched wire.

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post #13 of 14 (permalink) Old 02-28-2006, 11:28 AM
 
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Quote:
Originally Posted by kolomian
Thanks for the advice gasman!

mojo - How could the choke circuit be an issue?
They mount into the carbs with plastic guides that can break during r&r, also, they're on a cable that can get stuck in the out position during reinstallation. The thing to check is that there isn't any tension on the choke circuit cable at the carb. There's an adjuster in the cable also.
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post #14 of 14 (permalink) Old 02-28-2006, 11:48 AM
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Blinkers... pinched wire... or a loose bulb or connection. Or even a bad or loose flasher unit. Should be a wasy fix... not a complicated system.




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