Hello!
New to the GS500, but not new to riding. Currently have a 2013 Ninja 300 (wife's bike) and now a 2008 GS500F as a second bike. I have a couple questions on the carbs, brakes and tires.
Firstly, on the carb troubles. As the ninja is fuel injected, I have been spoiled with flawless starting and running from 0* to 100* :) that being said, I'm not the greatest when it comes to diagnose and correct carb issues. Currently the symptoms are:
1) rich fuel smell
2) very little choking needed on start, a very fine line between a manageable 1500 RPM idle and it revving to 3000 RPM.
3) low RPM hesitation, when trying to modulate the throttle at low RPM, the RPMs are very sluggish to respond and do not like to stay below 3000 and be modulated like I am used to
4) RPMs hang at clutch-in, starting when the RPMs drop to about 3000 and take a couple seconds before they finally fall to idle of 1200.
As the bike is bone stock, my initial thoughts are that something in the carbs is stuck (factory adjustment I believe) or dirty causing an idle/low RPM rich condition. I have seen references to multiple carb types (2 or 3 sets of jets depending on the carb), but not much regarding the idle and low RPM circuits.
Secondly, tires/brakes. The tires on the GS500F are the original Battlax tires that were on the bike new (circa late 2007). I have not found much info on a 140 rear tire for the GS500 and I am not looking at the 140 tire for an aesthetic reason, but for handling and traction. The GS500F has 200cc more displacement, 60lbs heavier and almost 20hp more than the ninja which came with a 110 front and 140 rear. I believe the tire will fit without issue and would be using the Michelin Pilot Street Radial tires, as I have on the ninja (great traction and handling). Has anyone stepped up to a radial 140 tire on this platform?
On the brakes, I haven't found any decent stainless braided brake lines to help firm up the brake feel. These would be coupled with EBC scintered brake pads. Does anyone have info on a good source for said brake lines?
It's not rich,.it's lean. And it has a vacuum leak or multiple vacuum leaks and probably clogged pilot jet and maybe a stuck choke.
You just need basic carb service. Don't spray carb cleaner on it if it.
Hi shadowplane676!
I have Galfer stainless brake lines on my GS and I am happy with them. Here would be for your bike:
http://galferusa.com/product/suzuki-2008-gs-500-f-front-lines-fk003d559-1
http://galferusa.com/product/suzuki-2008-gs-500-f-rear-lines-fk003d559r
I have also read about people liking HEL lines as well. Not sure where you are located but it looks like the HEL site has international distributors:
http://www.helperformance.com/suzuki-gs500-2004-2008
Also there's eBay... where you can order lines custom for decent prices... although I don't know too much about that.
Welcome to the forum! :cheers:
Edit: I've had a 140/80 Michelin Pilot Activ rear tire on my GS for two years now. I'll confess though, I'm not a super aggressive rider so I can't say if it's much better than the stock size for performance.
Was replying on my phone last night. Here's a little more detail.
Quote from: shadowplane676 on September 20, 2017, 06:42:13 PM
1) rich fuel smell
Could be a hundred places seeping fuel on a 9 year old carbureted MC. You should disregard this for now.
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2) very little choking needed on start, a very fine line between a manageable 1500 RPM idle and it revving to 3000 RPM.
When you start it with choke, it will idle at 4-5K rpm. That's how it's supposed to work. It's not supposed to start and idle on choke at 1500 rpm. This "fast warm up" is intended to get it up to temp quicker and also provide enough fuel enrichment to perform a cold start. You should have to use the "choke" (which is really an extra jet) to start it any time the bike's been sitting for an hour or more. No reason not to use full choke to start. Just let it run fast while you get your helmet and gloves on. It may not want to idle without stalling with the choke off until it has been running a few minutes on the road, but it should run through the gears fine and roll with no choke after about 30-60 seconds of warmup. It's not fully warmed up until you've ridden like 15-20 minutes on the road. FYI for future reference, you really should remember this, it will save you a lot of headache in the future :)
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3) low RPM hesitation, when trying to modulate the throttle at low RPM, the RPMs are very sluggish to respond and do not like to stay below 3000 and be modulated like I am used to
Probably because it's lean on pilot. And because you turned the choke off too soon :) and it's not really warmed up. Combination of both. Could also be a vacuum leak. Most likely there are numerous vacuum leaks.
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4) RPMs hang at clutch-in, starting when the RPMs drop to about 3000 and take a couple seconds before they finally fall to idle of 1200.
Classic lean pilot symptom. Actually it's caused by the idle being set too high in effort to compensate for lean idle. Anyway, to fix this you need to up the pilot jet by one size then do an idle mixture/speed adjustment.
1. After you reassemble the carbs/bike, set the pilot needle adjuster ("idle mixture screw") to 2-1/2 turns out.
2. start the bike and
ride on the road for 20 minutes3. set the idle for 1200 rpms
4. back out the pilot needle adjuster ("idle mixture") screw on each carb by 1/4 turn, check the idle speed. If the idle increases, then keep opening this screw (loosening) under each carb by 1/4 turn until the idle speed stops increasing.
5. Reset the idle speed for 1200 rpms. "Blip" the throttle and ensure that it returns to idle promptly, no hanging idle. If it hangs, lower the idle speed.
6. Get good at reaching in and adjusting the idle speed knob while you are on the bike. Over the next few times you ride, once the bike is warmed fully, sometimes 30+ minutes, you may experience idle droop or hanging idle. If the idle speed drops below 1200 and comes back up, then increase the idle speed when you are sitting at a stop sign. If it hangs (doesn't return quickly), lower the idle speed.
Resist the urge to go goofing with the pilot mixture to cure hanging idle. The actual problem is usually idle speed set too high, and often we try to set it way rich to compensate. The bike doesn't want to idle at 1300-1500 rpm. It will idle just fine at 1000 or 1100 rpm. The idle speed is actually set by an orifice in the carb throat and not really throttle plate position. It's not really adjustable. Set the pilot mixture as I said earlier, then tweak the idle speed while riding.
One temptation to set the idle too high is because it may not want to idle or it may stall when it's cold. Just keep it on choke. I think it's really common for these bikes to have the idle set at 1200-1400 rpm when cold, then if the owner ever rides long enough to get it fully warmed up suddenly they find a "hunting" or hanging idle where the bike wants to idle at 2K or 3K rpm. That's because the idle was set with the bike cold. If you get it right, then it will go "blub-blub" and idle at like 500 rpm and almost stall if you take it off choke before riding at least 5 minutes, but after half an hour of riding it'll idle at 1100-1200 per spec. That's normal. You can't work around that or change that behavior without changing the carbs. This is not fuel injection :)
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As the bike is bone stock, my initial thoughts are that something in the carbs is stuck (factory adjustment I believe) or dirty causing an idle/low RPM rich condition. I have seen references to multiple carb types (2 or 3 sets of jets depending on the carb), but not much regarding the idle and low RPM circuits.
Most likely the carbs need a thorough cleaning and checkup. It's easy to do. Take the carbs off and take them apart, there's info in the FAQ on this site. Be sure and remove the rubber diaphragms from the top of the carbs before you come near them with carb cleaner. Clean everything paying special attention to running a tiny wire (0.013" or so... like a guitar string) through the pilot orifice in the carb throat. Replace the pilot jet and maybe the main jet with +1 sized jets. Buddha will have good advice about the right jetting for those 3-circuit carbs, search here and follow it. Replace
ALL O RINGS including the ones on the pilot needles ("idle adjustment screw") which are not frequently included in a "rebuild kit". It's like $12 for all of them for both carbs, do it while the carbs are apart. Also replace the intake boot o-rings and inspect the intake boots for cracks, replace if necessary. Easier to just fix all of this than to try and chase down vacuum leaks.
If you are worried about it at all, you can also replace the float needles while it's apart. Again, cheap insurance and it saves you having to pull the carbs apart again. Set the float height before you mount the carbs.
In this whole job, the hardest part is getting the airbox on and off. I have done this so many times on my own bike I can do this in an hour flat. First timer should be a Saturday morning project if you have all the parts onhand first.
Be patient about idle speed and mixture settings, it may take some time riding and tweaking to get it dead on right but once you get it then you should be golden and the bike will be reliable and work fine. Just remember it's not fuel injection, it's going to be a little bit temperamental and maybe finicky or fussy in certain weather, etc. Plus you have to honor the warm-up procedure and don't fight against the long warm-up time. This is not a water-cooled bike. Just let it be. Start on choke, it idles at 4K or 5K that's fine, keep it on half choke while you ride the first few minutes, turn it all the way off choke after 5 minutes of riding or so and maybe nurse the throttle at stops if it idles low before it's been on the road 20 minutes.
I've run 110/70, 110/80, 120/70 front and 130/70, 130/80, 130/90, 140/70, 140/80, 150/60, 150/70 rear tires on my GSs on the stock 3.0 and 3.5" wheels. All of the tires I've run have been fitments approved by the tires maker except the 150/60 rear. I've run bias, bias belted, and radial tires. No alterations are required to the bike for any of these sizes on stock wheels except the 150/60 and 150/70 which come close to or touch the brake rod and may require bending the rod a bit.
Tires I've run on my 97 and 02 GSs:
https://i.imgur.com/bStVToj.jpg
I think the best all around pair for me were the 150/70 RoadAttack rear with a 110/80 Lasertec front.
Thanks mr72 and showbiz for the info.
Like I mentioned, I have been spoiled with good fuel injection for the last 5 years. Its unusual for me to think of a bike revving to 4 - 5K RPMs dead cold...makes me shudder a bit. It does sound like the carbs need a go-through even though the bike has only 3800 miles on it. Are there any good places to get all the o-rings, gaskets and jets in one spot?
Also, on the RPM hang/low RPM sluggishness, it is not only when cold. It will do it after a 45 minute ride as well. Lends credence to a vacuum leak I think.
Random side question, has anyone converted a GS500 to fuel injection? :)
Quote from: shadowplane676 on September 21, 2017, 12:21:44 PM
Are there any good places to get all the o-rings, gaskets and jets in one spot?
This is where I get them:
http://www.thisoldtractor.com/for_sale_dr350_orings.html
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Also, on the RPM hang/low RPM sluggishness, it is not only when cold. It will do it after a 45 minute ride as well. Lends credence to a vacuum leak I think.
I wasn't talking about only when cold. In fact the "hanging idle" is ordinarily worse when the bike is hot if you have the idle speed too high and pilot mixture lean.
I am sure you probably have a vacuum leak but I don't think it's the main cause of your problem. Lean pilot setting plus trying to correct with idle speed when the bike is cold is much more likely the cause. But you'll sort the vacuum leaks if you order and replace all the o-rings :)
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Random side question, has anyone converted a GS500 to fuel injection? :)
Yeah someone did. It'd be very expensive, super time consuming, and basically a useless project. If you have to ask, then it's probably not for you.
Fix the carbs. They'll work fine.
And before you start asking, suffice to say the real power limitation in the GS500 is the cylinder head. The carbs are up to the task of delivering plenty of fuel and air until the head runs out of breathing room. I suppose with FI you'd get easier cold running and better fuel economy, but even with carbs a GS500 gets like 50-60mpg and I personally have never had a problem with cold running once I got the carbs sorted. You just have to embrace the choke :)
The link you posted shows o-rings for a DR350, not a GS500; do they share the same carb by chance? I think I will pull the carbs and see if they are really in need of a rebuild or just a jet change. Also will do a vacuum leak check then as well. Speaking of jet changes, does anyone have a listing of stock vs more ideal jets? Idle, mid and Main?
Regarding FI/Power: Interest in FI was more for reliability and fuel economy, although understanding that the head is the limiting factor is helpful. Having worked with Megasquirt EFI since 2006, my inquiry was more for seeing what others had done so far.
DR350 has the same carb as a Mk1 GS500E. Many (most) will be the same as your carb.
Quote from: mr72 on September 25, 2017, 01:06:30 PM
DR350 has the same carb as a Mk1 GS500E. Many (most) will be the same as your carb.
So while a DR350 carb is supposedly the same as an early GS500, how does that compare to a 2008 GS500F? I get the sense that there was a carb change for 2004+ GS500F. Unfortunately every parts diagram for the 2004+ carbs do not show any seals or exploded view of the throttle shaft assemblies. Am I missing something with this assessment?
On the subject of tires just because you can doesn't always mean you should.
Basically when you start changing the width of the tire without changing the width of the wheel you change the radius of the tire, and with it, the contact patch with the ground and how much of a side profile you have for cornering.
Contrary to what you'd think, putting a wider tire on the wheel doesn't make for a larger contact area, it makes for a smaller one since the tire is pinched and makes a sharper radius.
For optimum handling for that bike you should stick as close to factory as possible. Theoretically a wider tire will roll better and turn better but may wear out faster and offer less traction due to a narrower contact patch with the ground. A narrower tire will actually be worse, it won't handle as well, has more rolling resistance due to a larger contact patch, and likely won't offer as much grip when sideways.
In the end, though, on a bike like the GS you likely aren't pushing it hard enough to notice that much of a difference.
Shadowplane676,
The carbs are different from 89-00 and then 01-09. I have on 04F and I recently purchased the carb rebuild kit linked below from an eBay seller. They worked fine for me and the price was reasonable. They are not genuine Suzuki but instead are made by K&L who is an aftermarket supplier from Japan. There are multiple eBay sellers offering the same kit at similar prices, but I ordered kits from the one linked below and they shipped fast and when one of my kits was missing an o-ring they sent a new one to me right away. Don't forget to order 2 kits since it only rebuilds one carb per kit.
https://www.ebay.com/itm/New-Carburetor-Rebuild-Kit-Suzuki-99-09-GZ250-04-09-GS500F-Carb-Repair-Set-Q42/361639814254?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649
Ken
I can say that the BT45 stock battlax tires are great, also the ones that you purchase now are not the same as the ones that came with the bike, if that makes any sense. They handle great but then I don't try to slide the bike around corners. As for the brake lines, prolly doesn't matter what brand HEL or otherwise all braided lines are going to be good, but you probably only need to put them on the front anyway. Also the threads on the front calliper banjo and the reservoir banjo are different pitch, I think 1.00 and 1.25.