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Discussion Starter #1 (Edited)
Hi, my name is Sean and I just recently got a motorcycle (June last year) to commute to and from campus for school. It's a 2004 SV650 with 21.4k miles on it (34.4k km). Over winter break I didn't ride my bike very much and it sat in the garage for probably 2 or 3 weeks. I turned it on every couple of days to make sure the battery stayed juiced up and to make sure everything was running properly. However, after my first week of classes I began to have an issue where the bike would die if I didn't stay on the throttle even with the bike fully warmed up (above ~140F or 60C). After a few days the issue got worse and now the bike will not stay alive at all unless I am on the throttle and so I haven't been able to ride it for the past few weeks because I haven't had a ton of time to work on it, nor have I figured out exactly what the issue is. Let me preface with the information that the bike isn't tuned super well because the previous owner straight-piped the bike and so I would usually have to stay on the throttle until about 70F (21C) before it would keep itself alive properly. I've been fine with this because I didn't want to spend a lot of money tuning the bike when I'm probably going to move to another one in the near-ish future. But, with this new issue the bike dies even after doing my normal "warm-up" routine and it doesn't matter how warm the bike is, whether it's at a fully warmed up operating temperature or the bare minimum of it keeping itself alive as normal. The best example I can give of what happens is as follows: I turn on the bike and hold on the throttle to warm it up so it will stay alive, but as I hold the throttle (at a constant position) the RPM would fluctuate/surge between 1100 or so to about 2500 - 3500 depending on where I keep my hand on the throttle (it can go higher, but I didn't want to give it a ton of gas while warming it up). The RPM needle also seems to wander a little bit, but I'm not completely sure what I should be looking to fix at this point and was looking for some advice from more experienced people as to what the issue could be.

I do know that my battery was pretty old and causing some issues with low voltage, so I just replaced that today (Feb. 14, 2020), but that hasn't fixed the issue at all (thought that poor voltage could be causing a lack of fuel to be getting to the engine since the bike is fuel injected). I have read that the TPS (throttle position sensor) could potentially be the issue, or bad fuel injectors, but I wanted to make a post to a forum to as people myself and see what they think. I have a video that I'll post that shows the bike warmed up here:
and it dies when I let off of the throttle. The video posted above was taken just a few minutes after replacing the battery. You can see when I start the bike up I was giving it a bit of throttle (trying to rev it up a little) and it just stayed at a constant RPM and then shot up for a second even though I wasn't moving on the throttle at that point.

I would prefer to not have to take the bike into a mechanic to fix the issue if it's something relatively easy that I can do myself, but if it ends up being a more complicated issue I can take it into a mechanic. Just wanted to ask people with more experience what they think the issue could be. She's a rough bike, but it's a starter bike for me and I just need her to run well so I can go to and from places and eventually pass her off to someone else to ride when I move up to a larger bike eventually. I'm not looking for the bike to run flawlessly, but well enough that it is getting the power it's supposed to be making and isn't going to just randomly die on me at a stoplight or anything. If you have any other questions or if there's information I left out that I should put in this post or even a request for more videos of the bike and the issues then let me know and I'll respond as soon as I can.

Edit: Adding a video of the bike starting from cold and warming up. You don't need to watch the whole video to get the gist of things, but I thought I would post it in whole so people can see what it sounds like, the small wandering that the rpm has and the fact that I have to stay on the throttle to keep it alive. Here's the video:

I assume that the bike dying like it does when it's cold is due to it being poorly tuned, which is fine, because it usually would idle fine after warming up a little. But, the fact that it eventually dies (and quite suddenly) even after warming up is what the issue is. You can see throughout the video I'll adjust where I'm holding the throttle at and the bike will drop down to 1 - 1.5k rpm, even though I haven't let off the throttle very much at all (should probably only drop 500 rpm instead of 1000 - 1500). Another thing to note, the throttle seems like it's delayed between when I give it some throttle and when it's reflected in the rpm going up. Also, you can see near the end of the video when I give the bike throttle it will sometimes struggle to get the rpm up and then suddenly shoot up to where it should have gone to begin with when initially giving it throttle.
 

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Try see if both cylinders are firing.

Begin with the engine cold, as it warms up squirt water on the front and rear header pipes to see if they heat evenly.
 

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Discussion Starter #3
Try see if both cylinders are firing.

Begin with the engine cold, as it warms up squirt water on the front and rear header pipes to see if they heat evenly.
I'll give this a try and see what I can find out.
 

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Discussion Starter #4
Try see if both cylinders are firing.

Begin with the engine cold, as it warms up squirt water on the front and rear header pipes to see if they heat evenly.
Both cylinders are firing fine, so I don't believe that is the issue.
 

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Next likely cause would be the fuel pump. It is a common problem on older bikes especially if they have been sitting.

Fuel volume should be 6oz in 10 seconds. Instead of jumping the fuel pump directly to 12v, easier and safer to just turn the key on/off three times. Each key on/off will run the pump for 3 seconds. Expect at least 5.5oz in 9 seconds.
52401


Fuel pressure should be 43psi.
52402
 

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Discussion Starter #6
Next likely cause would be the fuel pump. It is a common problem on older bikes especially if they have been sitting.

Fuel volume should be 6oz in 10 seconds. Instead of jumping the fuel pump directly to 12v, easier and safer to just turn the key on/off three times. Each key on/off will run the pump for 3 seconds. Expect at least 5.5oz in 9 seconds.
View attachment 52401

Fuel pressure should be 43psi.
View attachment 52402
Okay I'll check the fuel pump and see if that's the issue. I've seen people mention on other forums that it could be the TPS, but I wanted to see if others actually thought about it as well.
 

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It might be worth adding some SeaFoam to the fuel and running it for a few minutes. If you haven't heard of it, it's a fuel additive that does a pretty good job of cleaning fuel systems. Every auto parts store has it. If dirty injectors or water in the fuel is causing any grief, it might help.


PS Hello, TeeRiver. Hope all is well with you
 

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Discussion Starter #8
It might be worth adding some SeaFoam to the fuel and running it for a few minutes. If you haven't heard of it, it's a fuel additive that does a pretty good job of cleaning fuel systems. Every auto parts store has it. If dirty injectors or water in the fuel is causing any grief, it might help.


PS Hello, TeeRiver. Hope all is well with you
I'll check that out as well and see if it helps. I'm thinking that there is an electrical issue either with the fuel pump or the fuel injectors because there is a consistent buzzing noise when fuel is being injected into the engine, but the tone of it drops when the bike begins to die/stall out. I assume either the fuel pump isn't putting out as much fuel as it should be, or the injectors are failing.
 

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Might sound basic but I didn't see anywhere that you opened the choke first. That would 100% cause this issue.
 

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Discussion Starter #10
Might sound basic but I didn't see anywhere that you opened the choke first. That would 100% cause this issue.
The bike is fuel injected, not carbureted, so I don't have a choke to open. 2004 was the first year that this bike became fuel injected. I'd definitely be able to fix this issue a lot more easily if the bike were carbureted, but the fuel injection makes it a bit more difficult since all of the gasoline is fed based off of electronic settings, not mechanical.
 

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Discussion Starter #12
fresh gas?
Yeah, I put fresh gas in the tank a few days before it began to really get bad. I'm doubtful the gas itself is causing the issue though since the symptoms were prevalent before getting the gas, only becoming much worse a few days after putting it in. I presume I'd have immediately seen something wrong right after putting the gas in if that were the issue.
 

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Your kickstand safety switch is intermittently shutting the bike down. Put a stronger spring on it to hold it up tighter and closer to the frame. I am currently painting an SV 650 THAT I JUST PICKED UP, IT HAD THE SAME PROBLEM.

Hi, my name is Sean and I just recently got a motorcycle (June last year) to commute to and from campus for school. It's a 2004 SV650 with 21.4k miles on it (34.4k km). Over winter break I didn't ride my bike very much and it sat in the garage for probably 2 or 3 weeks. I turned it on every couple of days to make sure the battery stayed juiced up and to make sure everything was running properly. However, after my first week of classes I began to have an issue where the bike would die if I didn't stay on the throttle even with the bike fully warmed up (above ~140F or 60C). After a few days the issue got worse and now the bike will not stay alive at all unless I am on the throttle and so I haven't been able to ride it for the past few weeks because I haven't had a ton of time to work on it, nor have I figured out exactly what the issue is. Let me preface with the information that the bike isn't tuned super well because the previous owner straight-piped the bike and so I would usually have to stay on the throttle until about 70F (21C) before it would keep itself alive properly. I've been fine with this because I didn't want to spend a lot of money tuning the bike when I'm probably going to move to another one in the near-ish future. But, with this new issue the bike dies even after doing my normal "warm-up" routine and it doesn't matter how warm the bike is, whether it's at a fully warmed up operating temperature or the bare minimum of it keeping itself alive as normal. The best example I can give of what happens is as follows: I turn on the bike and hold on the throttle to warm it up so it will stay alive, but as I hold the throttle (at a constant position) the RPM would fluctuate/surge between 1100 or so to about 2500 - 3500 depending on where I keep my hand on the throttle (it can go higher, but I didn't want to give it a ton of gas while warming it up). The RPM needle also seems to wander a little bit, but I'm not completely sure what I should be looking to fix at this point and was looking for some advice from more experienced people as to what the issue could be.

I do know that my battery was pretty old and causing some issues with low voltage, so I just replaced that today (Feb. 14, 2020), but that hasn't fixed the issue at all (thought that poor voltage could be causing a lack of fuel to be getting to the engine since the bike is fuel injected). I have read that the TPS (throttle position sensor) could potentially be the issue, or bad fuel injectors, but I wanted to make a post to a forum to as people myself and see what they think. I have a video that I'll post that shows the bike warmed up here:
and it dies when I let off of the throttle. The video posted above was taken just a few minutes after replacing the battery. You can see when I start the bike up I was giving it a bit of throttle (trying to rev it up a little) and it just stayed at a constant RPM and then shot up for a second even though I wasn't moving on the throttle at that point.

I would prefer to not have to take the bike into a mechanic to fix the issue if it's something relatively easy that I can do myself, but if it ends up being a more complicated issue I can take it into a mechanic. Just wanted to ask people with more experience what they think the issue could be. She's a rough bike, but it's a starter bike for me and I just need her to run well so I can go to and from places and eventually pass her off to someone else to ride when I move up to a larger bike eventually. I'm not looking for the bike to run flawlessly, but well enough that it is getting the power it's supposed to be making and isn't going to just randomly die on me at a stoplight or anything. If you have any other questions or if there's information I left out that I should put in this post or even a request for more videos of the bike and the issues then let me know and I'll respond as soon as I can.

Edit: Adding a video of the bike starting from cold and warming up. You don't need to watch the whole video to get the gist of things, but I thought I would post it in whole so people can see what it sounds like, the small wandering that the rpm has and the fact that I have to stay on the throttle to keep it alive. Here's the video:

I assume that the bike dying like it does when it's cold is due to it being poorly tuned, which is fine, because it usually would idle fine after warming up a little. But, the fact that it eventually dies (and quite suddenly) even after warming up is what the issue is. You can see throughout the video I'll adjust where I'm holding the throttle at and the bike will drop down to 1 - 1.5k rpm, even though I haven't let off the throttle very much at all (should probably only drop 500 rpm instead of 1000 - 1500). Another thing to note, the throttle seems like it's delayed between when I give it some throttle and when it's reflected in the rpm going up. Also, you can see near the end of the video when I give the bike throttle it will sometimes struggle to get the rpm up and then suddenly shoot up to where it should have gone to begin with when initially giving it throttle.
 

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Discussion Starter #14
Update on the bike for anyone who might have similar issues to what I was having. I've had time during my spring break to open up the bike and look at it and after opening up the bike to replace the spark plugs I saw that it seems the previous owner hack-sawed off the top of the air box (only God knows why).
52693
52694

I discovered the primary issue for the bike not running was cheap spark plugs that were placed into the bike, so I replaced those and it fires up and runs pretty well now (despite having the top of the air box cut off. These plugs were easily the worst I've seen plugs in a while. I assume that they got gunked up pretty quickly because the bike is straight-piped and runs rich (previous owner straight piped it and I've just left it).
(Picture of old spark plugs)
52695
52696

I replaced them with NGK CR8E plugs and the bike runs a lot better now and I'm also running some sea-foam through it with some fresh gas to hopefully clear the system up a bit more. I've ordered a new air box to replace the top on this one and the filter, so I can provide an update after I get the new air-box in to see if that helps clear up the wandering.

Moral of the story, my primary issue of the bike not starting up and being able to idle was due to bad spark plugs (primarily), so I'd definitely advise checking those first if you have issues with the bike idling or starting up. The front plug is a bit of a pain to get to because of the radiator, but if you have a friend who can hold it forward, or you can place a block of wood between it and the engine case to keep it pushed out, then it's not too bad to take out. I'll be sure to keep this thread updated with any other issues related to this that I end up fixing.
 

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Discussion Starter #17
What a butcher's job.
Yeah, I quite literally set my gas tank back down over the air box in disbelief and thinking I was imagining it until I picked it back up and saw that it was actually completely butchered across the top.
 

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Discussion Starter #20
Final update for the bike from me.

I replaced the top of the air box along with the air filter and the bike runs much smoother now, even more so than when I replaced the spark plugs. The idle wanders much less and the bike is able to warm up from completely cold without dying now. I do suspect that it needs tuned still because it doesn't run completely perfectly, but it still runs very well now. So, just to recap for anyone who might have similar issues:

  1. I replaced the spark plugs with NGK CR8E plugs ($8 or so at auto-zone).
  2. I ran sea-foam through the bike and noticed white smoke for a bit while running it through the system, so some gunk was cleaned out.
  3. Finally, I replaced the severed air box and dirty air filter.
All of this seemed to fix most of my issues, while any remaining issues I have are likely due to the bike being straight piped and not tuned for the straight pipe. Thanks for the suggestions and help to everyone that commented, I appreciate it. Hopefully this can help anyone else out that might have similar issues and isn't certain what to start with.
 
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