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Discussion Starter · #1 ·
OK So I figure I'd throw this out there maybe someone can help.

I wrecked my bike about 5 months ago or so, and replaced every piece of the front end off another SV. I've been getting bad gas mileage for quite a long time now (since before the crash), just never really tried to figure it out.

The coils f**ked up about a month or so ago so I put some coils on from another SV, and so it was running fine (still bad gas mileage tho). I also put some new spark plugs in there (I've done this a million times because of the old coils, they were eating plugs). Basically it's like this, my gas light should be coming on around 140-150 miles, but it comes on closer to 115 normally. I've ridden straight through a tank of gas before and got the same mileage so I'm sure it's not a leak on the tank. Anyone have any suggestions? The jetting should be stock as far as I understand it and it has stock exhaust. I'm not the first owner so I'm not sure what might have been done to it before. Anyways, what you guys think??

Here are some pictures my spark plugs I took this morning:

REAR



FRONT

 

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have you done things like sync the carbs or put a new air filter on?
 

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Discussion Starter · #3 ·
No I haven't synced the carbs and the air filter has about 1000 miles on it. It's been getting this same mileage for a long time, since before the air filter swap.
 

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Discussion Starter · #5 ·
I get that kinda mileage no matter what kinda riding I'm doing. If I'm doing 80-85 on the freeway for a whole tank I still get the same mileage pretty much.
 

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That's what my plugs looked like before I had my carbs sync'd. It won't make that much difference in the mileage, but it will feel alot more powerful when it's done. Mine felt like fuel injection after I had it done. I didn't realize how much hesitation I had til it was gone.

As far as mileage, I think it's pretty common for the gas light to come on at 120 miles on forst gens. Mine has always done that. After the sync, it started going to 130.
 

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Discussion Starter · #7 ·
Alright well maybe I'll look into having my carbs sync'ed.

A friend of mine who lives two doors down has a first gen SV with a pipe and a jet kit and he gets close to 150 before the light turns on... and when I told him about the mileage I was getting he said it was horrible (he's about to graduate from MMI).
 

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Does he ever rev above 5k? I have heard of people going that long without the fuel light, but it was always VERY nonaggressive riders. Usually in city commuters.
 

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One of the plugs is rich, the other lean. Synch the carbs, ride for a few days and then look at the plugs again. You might want to go ahead and install a new set of plugs now. The dark one could be carbon tracked.

Also, check your mileage with the odometer and the fuel pump meter. The light may be coming on early (although you said you ran through a tank before). The light is a poor indicator of mileage.
 

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Discussion Starter · #10 ·
I called a local shop and he said that synching the carbs won't fix my problem. He said he would have to clean the carbs and that would solve my problem. He also said that it's 75 bucks PER carb to have them cleaned, I say that's highway robbery! I know you guys have already said maybe sync the carbs but, are you sure? If I need to I can probably pull the carbs and have a friend of mine clean them (I'm too afraid of the carbs to mess with them!). What do you all think?
 

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Spike said:
I called a local shop and he said that synching the carbs won't fix my problem.  He said he would have to clean the carbs and that would solve my problem.  He also said that it's 75 bucks PER carb to have them cleaned, I say that's highway robbery!  I know you guys have already said maybe sync the carbs but, are you sure?  If I need to I can probably pull the carbs and have a friend of mine clean them (I'm too afraid of the carbs to mess with them!).  What do you all think?
I dunno, I ain't a mechanic, but my carbs have only been taken apart and cleaned once, that was at 90,000 miles, I get them sync'd every 7500 miles like it sez on the owners manual
 

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Discussion Starter · #12 ·
Yeah I'm thinking about having him sync my carbs anyways just so I can at least say I ruled that out first since it's cheaper than cleaning the carbs.
 

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I just bought a carb sync tool for ~$35. I used it to sync I4 Kawasaki with carb's and an 01 TL1000S with FI. It's really easy. The hardest part was taking the stuff off to get to the carb's. I haven't looked at the SV, but I doubt it is that difficult. Basically, there is a vacuum spigot off of each of the carb that you have to find. put the carb sync hose on each carb, turn the bike on, and adjust the sync'ing screw. That's basically it. A good shop manual would be really helpful, but not absolutely necessary. I say get the sync tool, sync the carb's and see what if it helps. You then have the ability to sync yoru own carb's and if it still needs work, take it to the mechanic.

Hope that helps.
 

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Discussion Starter · #14 ·
So I would have to find those two vacuum lines and hook the tool up to each carb, then put the airbox back on and start it up? So by turning the knob I'm synching the carbs but how do I know when they're synched???? I don't have a manual does anyknow know where these vacuum spigots are??
 

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Discussion Starter · #17 ·
I'm getting about 30 MPG, no I haven't done anything on the carbs yet because I don't want to mess with them. I don't do carbs.

Thanks for the link about synching my carbs, though I'll probably just let the shop do it now that I've read that page about DIY. It's possible I may not have this SV for very much longer so I just want to get it running right so I can sell it.
 

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carbs out of sync isn't gonna give you bad MPG...

The first thing I'd look for is a leak.

Second would be stuck choke

Third would be float level off

You could pick up a stock set of carbs for ~$50, maybe less... make sure there un-molested and swap them out. I'm pretty sure your problems would go away. Just make sure your choke isn't sticking. To check the choke you might be able to disconnect the 3 way cable joint, removing the part that goes to the control to the cables that go to the carbs.

By any chance is there any change in RPM's when you turn the bars from side to side? Do it slow and keep a close eye on the tach...
 

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Discussion Starter · #19 ·
A leak, how could I find a leak? I'm pretty sure it isn't a leak in the tank... No my RPMs don't change when I turn the handlebars. actually my choke cable has been disconnected at the handlebar for quite a while (but my gas mileage has been this bad way before I took it off). When I hooked it back up a few days ago I guess I had the cable on there strange and when I turned to the right it would make my RPMs jump. I took off the airbox and fiddled with the cable cause it had become stuck.

Since then it's been running exactly how it had run before. Actually down in the lower RPMs sometimes it bogs a tad, the throttle also isn't very responsive, like it takes longer to rev up and takes longer to drop back to idle than it should. When I'm up to speed (say 45 mph) when I hit the gas there's a hesitation that I don't remember being there before, but I could be crazy about that last one. There definitely is a hesitation. It's not always there tho...
 

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it sounds like you're running rich.  I'd check your needle valves and float level.  I'd also remove the chokes and clean them up, one might be stuck.
 
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