Reply With QuoteMy step father who is a long time mechanic says, broadly something wrong with the Carbs. Choke might be on, double check oil level to see if it is overfilled, damaged carburator diaphram maybe. Very experienced mechanic. Good luck.
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Suzuki GS500F High-RPM Hesitation
Hey all, I just purchased an '08 GS500F, with 8k miles and good maintenance records. The bike idles wonderfully (about 1,200 rpm), and accelerates pretty smoothly.. But when start getting to about 5,000 rpm, the engine sounds like it's struggling to gain anymore. It has a shortly spaced (about every half second or so) moment of 'normal' power feel, but then it seems to hold back on the power.. Even if I'm applying full throttle, I can only get to about 80 mph, or just a touch over 7,000 rpm. If I am still trying to roll on the power anywhere between 5-7,000 rpm (I wouldn't know if this ceases at any higher rpm because It will not climb much higher), it just feels very twitchy, a "shutter" feeling really. This happens when in any gear. Any ideas as to what might be the cause? Any help you guys could offer would be greatly appreciated. Thanks!
My step father who is a long time mechanic says, broadly something wrong with the Carbs. Choke might be on, double check oil level to see if it is overfilled, damaged carburator diaphram maybe. Very experienced mechanic. Good luck.
1996 Kawasaki KLR 250
2005 Suzuki DRZ400SM
The bike definitely shouldn't feel like that. It loves to rev at 8-9k, thats where it actually has power.
I can only offer speculation but it sounds like a fuel delivery problem. Fuel line could be obstructed, or the vacuum diaphragm in the fuel petcock could have a small leak, preventing it from fully opening. You can diagnose the latter by setting the fuel petcock to PRI, but remember to turn it back to ON when you're done.
I just finished riding again, same problem.. Whether it's set to PRI, ON, or RES. Not sure what or how to check fuel delivery. I'm sure I could check the fuel filter if I knew where it was located. I'll see about looking at that this morning. Any other ideas? Thanks guys for the help!
seafoam? might help with the carbs
What is that and where can I get that? (sounds interesting lol)
Okay so you can eliminate a faulty petcock as the problem. By fuel delivery, I simply meant a problem with getting enough gas into the engine. Seems like some is getting through, but not enough for a high load. The next step is to check the carbs. If the bike was stored without stabilizer, some old deteriorating gas could have gummed up the carbs. The best way is to take the carbs out of the bike and take them apart to clean them. An easier solution already mentioned, is to put seafoam in your gas tank and ride through the tank, but it may not clean stubborn deposits.Originally Posted by icebox
Here is a thread on cleaning carbs: http://www.gtamotorcycle.com/vbforum...-Sol-Degreaser
Alternatively, the GS500 is an easy bike to work on, so you may be able to get a mechanic to take out your carbs, inspect them and then sync them for an hour or two labour.
I had a similar problem with my old virago. I had run out of gas and managed to burn out the spark plugs. New plugs fixed the issue. Given how easy and cheap they are to replace, I would start there.
Taking out your spark plugs and inspecting them cant hurt. Check the condition they are in and the color of the tip. Dark black means you're running too rich (unlikely) and light grey / white means you're running too lean (more likely). Post a picture if you're unsure
Do u have an after market exhaust on the bike?
Maybe fuel pump? fuel filter?
Resident Loudmouth
Hey all, here's a pic of the plugs.. I went ahead and replaced them, no change in performance. These plugs are almost porcelain white.. Not much brown in them at all. Any thoughts? Also, no changes or modifications to the bike, I believe it's 100% stock. Thanks again guys!
Last edited by icebox; 12-14-2010 at 04:52 PM.
Those plugs look normal to me.
Maybe a side pic would have been more helpful. But they look OK
Resident Loudmouth
Here's another shot, from the side:
they look pretty mint, maybe your jets in your carb are clogged happened to my old dirt bike
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Sorry, u are right, they do a look a little white. But a lot of bikes are tuned on the lean side when they leave the factory, just for better emissions. If u said the bike is completely stock, I guess it could be any of the above mentioned. It would have to be fixed by trial and error I suppose
Resident Loudmouth
Well, after about 25 miles of riding with some Seafoam and a fresh set of plugs, no change. Guess it's time to look into the carbs (and maybe the coils?) a little deeper. Any suggestions on the easiest way to get the carbs out for cleaning/examining? Thanks guys for the help so far!
A few things, since the tank has to come off anyway:
--Check the fuel shutoff valve. Unless the gs500 has changed, you unbolt the tank (one on either side of the frame, under the seat front), pull it away from the frame/steering head and prop up the right side. Not too much though, about an inch. You can't lift the tank much due to the short fuel lines to the petcock.
The brass shutoff (with main and reserve fuel lines) protrudes from the tank bottom on the left side, but the valve fitting faces right. The fitting has a slotted head. It should be facing up/down. A good 12" screwdriver is needed to turn it clockwise to horizontal, which closes the valve. Anything else means it's partially opened.
It's a goofy design and a pain to deal with (especially the hose clips), so it's possible that the PO or mechanic failed to reopen it properly when reinstalling the tank.
--If that looks good, carefully remove the clips/fuel lines to the shutoff (some gas will spill). Set aside the tank in a safe location and take a peek at the throttle cable. Is is moving freely? Or is it damaged? Too much slack? It may need some lubrication. The throttle return spring (on a shaft between the carbs) may be damaged in some way.
Log into GSTwins.com. Always a good resource. Earlier GS500s don't feature a fuel filter, but some folks spliced them in. This often led to fuel starvation at higher RPMs, depending on the type, probably due to the lack of fuel pump (it's old school gravity feed).
Double checked. No filter, except the screens inside the tank inlets. Your bike is pretty new, so I doubt rust would be a problem yet.
Last edited by Flywheel; 12-14-2010 at 11:01 PM.
Awesome, thanks for the resource. I did everything you mentioned, the valve was full-on. Throttle cable feels like new, no binding, strong return spring. Is there a way to check/clean the tank fuel screens?
I think the inlets/shutoff are held on by two bolts. Here's the BB microfiche for that part:
http://www.bikebandit.com/2008-suzuk...4444#sch554388
Those gaskets are probably tricky to reinstall. Try to look inside with a small inspection mirror first. If there's an issue, crud is bound to be everywhere. Should you decide to drain the tank, exercise caution. The vapours trapped inside will be extremely volatile!
Your bike is pretty new though, right? Rust clogged inlets doesn't sound very plausible. The carbs, maybe, but my GS500 had 5 previous owners, no maintenance, a gutted muffler (so it was super-lean) and it STILL started up. Ran fine on the highway. How's the air filter and airbox? Insects or Mice can build nests or cache seeds in the strangest places.
Last edited by Flywheel; 12-17-2010 at 09:40 PM.
Has the bike ever had a valve job done? At 8kms I doubt it but it'll be due based on my experience with the bike, the valves are likely tight.
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