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C

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Discussion Starter #1
My 03 SV650S has been running rough since the end of last season and I
am seeking some guidance. After sitting over the winter, the problem
became more than just an annoyance.

A little background:

The bike would start ok, but it had no throttle response and would
occasionally buck during constant acceleration to a point that it was
becoming dangerous in the turns. I could rev the bike, and the engine
would sound like it was running ok, but the bike would not go
anywhere. It would simply creep along. Then, it would catch sudden and
fly down the road. When I shifted, the problem repeated itself in the
next gear. After running the bike for several days straight like this,
It calmed down a bit. But if it would sit for over 24 hours, I would
be back to square 1.

I took it to a local shop to have it serviced, and they claimed to
have fixed it. When I asked what the did, they said the adjusted the
fuel injector and tightened the exhaust. They told me the computer
they hoked it up to said nothing was wrong. But, as I have heard from
a mechanic at another shop that no computer exists to diagnose that
bike, and he also told me the bike runs on two carbs and is not fuel injected, I thought I
was getting the shaft. I also had them change the plugs to the highest
grade they had and the oil to synthetic as I was over 3500 miles.

Recently, it seemed to start running a little better. But, yesterday
after riding in a very light rain for 5 minutes at most, it bogged
down completely. I suppose I was then running on 1 cylinder. It did
not buck, it simply had no power. Felt like I was on a 50CC moped   ???

So, now money is tight as I just moved out of state (from PA to NC)
but I need to have my bike up and running again.

Does anyone have any idea of what the problem may be and how to fix
it??? I do not know a lot about working on bikes, but I am a
biomedical engineer and am mechanically inclined so I figure I can
give working on it myself a shot.

Sorry for the long post and the earlier miconception about the carbs. I never gave carbs vs injetors much thought while the bike was running smoothly and havnt had this specific bike for very long.
 

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The Well-Leathered Mod
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4,614 Posts
Re: Bike acting strange - maybe the carbs?

Um, dude, you have an 03.

Your bike DOES have Fuel Injection.  It does NOT have carbs!


Pull your plugs and see what they look like.  Sounds like you're running on 1 cyl.

Check your coil connections, and plug wire connections.
 

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Premium Member
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11,333 Posts
Re: Bike acting strange - maybe the carbs?

03s don't have carbs, doh!
 

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Hall Monitor
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Re: Bike acting strange - maybe the carbs?

You didn't run the bike on the old gas that was left in it over the winter, did you?

If you haven't already drained all the old gas out (even if it only had, say a gallon of old fuel and you topped off with fresh gas), drain the tank completely. Start with fresh fuel and a healthy dose of a toluene-based carburetor/injector cleaner. Ride 100 miles and see if it doesn't clear up.

It kind of sounds like two issues- clogged or dirty injectors, and a dead front cylinder when it rains. The latter can be addressed by something as simple as making sure the plug lead is snugly in place. There's also a drain hole that leads from the front cylinder's spark plug well- these have been known to clog up, leading to a dead front cylinder. Some people also seal up the front plug lead using silicone-based grease.

HTH

Bill
 
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Discussion Starter #5
The bike sat drained of most of the gas ( ie I ran it until it started to sputter) and was given fresh fuel when I started it again in the spring. I did not run it on much old gas if any, but I also did not add any winterizer to the tank either. Over all, it only sat a little over a month as I still rode it most of the winter. I have also tried two different fuel injection cleaners thus far to no avail (Penzoil and Seafoam). As far as the problem in the rain, this was the first time that happened. I figured it was a clogged plug drainage hole, or plug full of water, from what I have read up on, but it never had that problem when it was running smoothly. That should be an easy fix, but the other issue still has me concerned as the fuel injection cleaners did not work.
 

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Could it be something electrical?
Had the same problem last year, where the bike would sometimes catch & then not & then all of a sudden again. She was running of and on, on 1 cyclinder, then both - not fun at all.
Checked the plugs but they were clean & changing them didn't solve the problem so I took her to the shop and they found a wire that was partly burned, replaced that and it was fixed.
 
N

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Discussion Starter #7
"...would occasionally buck during constant acceleration to a point that it was becoming dangerous in the turns...."
What does "buck" mean in this context? Sudden acceleration, deceleration, backfire, loss of power etc?

"...I could rev the bike, and the engine would sound like it was running ok, but the bike would not go anywhere. It would simply creep along..."
It would rev but not go anywhere? With the clutch out, RPMs would increase without a corresponding increase in road speed?

"...They told me the computer they hoked it up to said nothing was wrong. But, as I have heard from a mechanic at another shop that no computer exists to diagnose that bike..."
The 2nd generation bikes (-03 & up) have some limited onboard diagnostics that you can get to fairly easily. I don't have the specifics but a search for "dealer mode" or "debug" etc would probably get you going in the right direction.

"...Does anyone have any idea of what the problem may be and how to fix it??? I do not know a lot about working on bikes, but I am a biomedical engineer and am mechanically inclined so I figure I can give working on it myself a shot."
Personally, I would probably start by inspecting the connections to the ECU/ computer/ igniter box (whatever you may choose to call it!) to ensure that they were properly connected and free of corrosion, contamination etc. I would also look into accessing the dealer mode to see what info it can provide. A service manual might also be a good investment (the OEM manual is downloadable free from a couple of different places). You might consider asking around for a good local shop, too.

BTW, where in NC are you?

:)
 
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Discussion Starter #8
Buck would refer to a balls out sudden acceleration. The clutch would be out, and the RPMs up, but the bike would lazily make its way down the road at a slow pace (ie in 6xth gear I cant go above 65) - then it would catch and would rapidly accelerate to catch up to the speed where it should be based on the RPMs and gear. It really sucks when it happens in a turn.

I will tear the bike apart this weekend and look over all the plugs and wires that I can get to. I am not familiar with how to use the on board computer at all, but can look into it. I have also looked around for a local shop, but they are few and far between. I live in the middle of no where and love it - Bennet, NC. It is between Siler City and Sanford, about 20 miles from Pittsboro and 40 miles west of Raleigh. Only one shop has come recommended but at a high price.

Where are you located???
 

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You are describing some interesting symptoms, which is bad news.

"RPMs are up, but the bike...lazily down the road...then it would catch". What you are describing here is a slipping clutch or one that is hanging up. Check the actuator under the front sprocket cover. Make sure it's all properly adusted and working smoothly. There's no reason why sitting a bike up for a couple of months would cause the clutch to slip. If it rusted then it could be hanging up, but that's very unlikely.

Leaving a bike with an empty tank is a very bad idea. You stand a good chance of condensing water in the tank, which would make the bike act like your initial descriptions. Some injectors can be damaged if they pass water, but that's a constant problem once it happens, not intermittent.

Holeshot sells a product called the Fenda Extenda. It keeps water off the plug and keeps the front of the engine cleaner. Consider it.

I would try some water absorber added to a fresh tank of gas.
 
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Discussion Starter #10
So RPM is out of sync with road speed. As andyauger said, that would indicate a clutch problem (slipping). The "bucking" thing and the sudden acceleration makes it sound like the clutch cable may be hanging up or binding somewhere. Does the clutch seem normal, (i.e. moves smoothly when you pull the lever) and is there excessive freeplay at the lever when it's doing the bucking thing?

Johnston Co. is one county south of Raleigh, famous for...well, nothing much!


:)
 
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