Coming of age? . . . bike is running more like a harley than a suzuki ????

[bval]

Okay . . . I'm hoping this sounds familiar to someone . . .

I have a 2006 GS500f approaching 23,000km and until about 10 days ago, it was running very consistent - like you would expect a Suzuki GSTwin to run.

One evening on my way home, the bike started feeling like it had a low frequency shudder or vibration. I noticed it mostly on acceleration and even more noticeable in higher gears. Normally, between 5000 and 6000 rpm it smooths out in almost every gear. Now it has a deeper throaty, sound and it vibrates with a low frequency very noticeably when in 5th and 6th gear between 5000 and 6000 rpm. This happens even when cruising on the highway and not really climbing a slope. The throaty sound seems to be getting deeper and the vibration on acceleration more pronounced. It even sounds more throaty when idling now than it did originally.

Here's some things of note:

• I mostly sense it when under power - if I pull in clutch disappears instantly
• It disappears or is not noticeable on deceleration while in gear
• Does not seem to be related to wheel balance, tire pressure/condition, brakes or chain/sprockets
• Does not sputter, surge, stall or anything like that - revs fine

Here's what I've done to date:

• New X-ring chain and front sprocket (back looked fine)
• Full 24,000km service, new plugs, valve adjust (all 2 - 3 thou), etc. Everything looks fine.
• All chassis bolts up to spec torque and no apparent frame problems
• Checked fuel for water and flow

My next guess:

• Carb balance?
• Clutch?

Does any of this sound familiar?

For an almost new bike, this does not seem normal. I'm hoping it's only a carb balance or something like that. But I have to wonder if maybe the bike's just passing another break-in phase or maybe they develop like this when they "come of age". It's my first bike and I've been riding a year now, so I don't have experience with other bikes to draw upon.

Solution:

The problem was likely a combination of things that needed to be dealt with soon anyway, but the primary problem was that the engine mount bolts were not torqued high enough. This was partly due to me misreading the service manual description of these bolts. I had them torqued about 25 ft-lbs too low.   They felt snug for sure, but not enough to prevent some obvious vibration and even some engine movement affecting chain tension, etc. Once I torqued them up to the correct spec, the vibration disappeared instantly, chain slack tightened back up to spec, etc. Yes, I feel foolish  . . . but also glad it wasn't something more costly.

Other things were certainly adding to the mix: a frozen chain link, slightly worn front sprocket, minor front tire cupping, etc. All of those things were needing to be dealt with soon anyway, so I went ahead and replaced them. I also think some of the intermittent electrical problems were due to intermittent poor grounding, because it appears this engine is only grounded through the engine mount bolts. (I can't find a ground strap anywhere) If this is true, then the engine might have been losing it's grounding to the frame momentarily when under torque, etc. Can't be sure of this one.

As far as the exhaust sound goes, I do think this is mostly "coming of age" for the bike. The vibration did accentuate things, but there was no apparent change to the exhaust sound when the engine bolts were torqued up correctly. But without the shake to go along with the deeper throatier sound of the exhaust, it doesn't seem so obvious anymore and the bike is running really well and sounding really well (for a stock muffler)

Anyway, thanks to all who helped out with the troubleshooting. I certainly learned more about my bike during this exercise than I would have otherwise!

Next endeavours . . .

Rejet - Now that I have a K&N filter, time to rejet. Considering aftermarket exhaust, but might hold off on this as the rejet kit has ability to step up later on and the exhaust is in excellent shape. Not really interested in increasing performance at this time, but who knows.

Improve Electrical headroom - LED's have been ordered and are on their way. I'm hoping these will at least match my existing light output while dropping my wattage considerably. I'm not getting cheap ones either - total cost for replacing all filament bulbs (with exception of the headlight) $160 cdn. I'll report on this once the LED's in and I have a chance to compare. I'll start a new post on which ones I bought and how well they work. I'm sure that post will see some activity!

Cheers - Brian

[yamahonkawazuki]

plugs?

[ohgood]

Does it do it while free revving, ie without the bike moving ?

Checked your swing arm, rear axle alignment, chain tension ?

The deeper exhaust note makes me think the carbs need a sync. Maybe you've got a rogue wire that is only effected at that certain RPM ?

Lots of things to check, don't pull your hair out yet

[bval]

Plugs were replaced as part of the 24k service.

Swingarm check, wheel alignment and chain tension were dealt with when the chain was replaced. Nothing seems out of whack there.

It does have a deeper sound with the bike free revving, but the shudder is not really detectable standing still. It only happens when the bikes under heavy load and more pronounced in the higher gear range when the engine has to work harder to accelerate. When it's shuddering heavily in that situation and I pull in the clutch, it instantly disappears. That should rule out wheel inbalance, frame problems, etc., as I would expect to still feel the shudder at speed when the engine is not engaged.

Could be a rogue wire, but that might take me a while to detect as it's hard to check wires while the bikes acting up because it's moving.  If it was more prominent at idle, that might be more easy to diagnose. However, besides the deeper tone, it rev's quite nicely standing still.

Deeper exhaust note is making me also suspect whether it's a carb sync issue. That's probably where I'll go next. There is a guy down the street who's a bit of a suzuki 4 cylinder wizard. I'm going to check with him and if nothing else, he may be able to do the sync for me. But he's one of those guys who has a knack for this type of thing and has often diagnosed problems nobody else could figure out. He's a bit eccentric but well respected in the local scene for his talent.

Funny thing is, I kind of like the throatier sound, but not the shudder in high gears as that would make touring not so fun after a while and I do want to do some touring this year.

Won't be pulling any hair out intentionally . . . that's happening whether I like it or not. No point in rushing that process. 

[ajaxgs]

have you checked the header bolts?, mine have worked loose in the past and gave a throty sound at certain rpm's

[bval]

Yup . . . pulled off the entire exhaust and gave it a scrub down and a coat of high heat paint to help it last longer. Torqued the bolts as per spec with never-cease on them.

Definitely is getting worse though. Rode into work and back today and it's happening mostly when the throttle starts to roll on/off and getting more noticeable now when engine braking and at lower rpms. Going to have to stop riding until I figure this out.

Pulled the plugs as soon as I got home and they look normal. Small amount of greyish coating, but definitely not wet and neither were the cylinders from what I could tell, so it looks like it's firing on both cylinders. No misfire, backfire, hesitation or surging so I'm guessing it's not electrical. However, I'm wondering about advance timing.

I've adjusted the clutch according to spec and tried it both at 1/4 and 1/2 turn out after meeting high resistance. Doesn't seem to have any effect.

Haven't had the chance to sync the carbs, but I'll try and get in touch with the guy down the road tonight and see what he thinks. If he's got the tools, I'll probably get him to check and sync the carbs if they need it.

[gsJack]

I had a vibration that developed in my 97 GS500E after some miles were on it but while it was still fairly new.  Vibrated between 5-6k rpm only while accelerating thru gears.  Mostly centered around 5600-5700 as I recall, it was years ago.  It went away after awhile never to return for the 80k miles I rode that bike.  Never knew what it was but do recall a couple other similar reports here on this forum way back then but not many.

Bought my current 02 GS500 slightly used with about 4500 miles on it and it's never had that same vibration.  It has about 56k miles on it now.  I've never synced the carbs on any bike in the over 360k miles I've put on 6 bikes including the 2 GSs.

[bval]

Interesting, GSJack. A local rider with a DL1000 is regularly having to sync his carbs and is probably the only thing he doesn't like about the bike. I'm seeing TONS of carb related issues with GS500s and I have to say, if I'd read all this before I bought one, I'd probably be riding something else right now. But I have to work through this problem.

An over the phone suggestion was that the clutch sleeve hub nut can come loose and rattle around inside. Seemed to match up with a lot of symptoms, so I pulled the clutch just in case and all looks fine in there, so it's not that. At least I have a clear idea of how the clutch works now. 

Got someone coming over Saturday to lend his ear who's a local legend when it comes to troubleshooting. Hopefully he'll be able to pinpoint the problem.

[ajaxgs]

on your valve adj you said  "valve adjust (all 2 - 3 thou), "  what were you specific mesurments , should be metric .03mm - .08 mm

[galahs]

I am extremely interested in finding out what this is / if anything.


Keep us updated.

[bval]

RE: I am extremely interested in finding out what this is / if anything.

Hey, you and me both!!! No worries, I will update.

Something of note . . . I don't have a carb sync tool yet, but just for fun,  I carefully messed with the carb sync just a little last night, fully knowing I'd have to do it properly in the next couple of days. Prepared to turn around at the first sign of problems, I rode the bike in this morning to see if there was any change, and there was. It seems to run smoother now in the mid range without the constant vibration. Only when just starting to apply throttle and when engine braking at low spped, do I get some vibration and the deep throaty sound. So I'm hoping this is an indication I'm on the right track. My friend Steve is coming over tomorrow, so hopefully his wealth of Suzuki experience will either confirm that carb sync is the problem, or he'll find the true source of the problem. I'll update once I know for sure.

RE: on your valve adj you said  "valve adjust (all 2 - 3 thou), "  what were you specific mesurments , should be metric .03mm - .08 mm

I have a OEM Suzuki shop manual that gives both metric and SAE which says the range is ".001 in - .003 in" in SAE. Unless my math is off (which is very possible given my math marks in school) that's 1 - 3 thousandths of an inch. A friend who has a ton of experience on bikes confirmed this was correct according to the manual. Unfortunately, finding either metric or SAE feeler guages that go that low has been challenging at local auto stores, so I use guages from .002 to .004 to see how much play there is. If I can't get the .002 in there, then I assume it's .001 or less depending on how difficult it is to turn the bucket with my finger. But then I figure if it's .001 or less, I'd rather not have to open the damned thing up again any time soon, so I usually try to change the shim to .002 at minimum. If I can get a .004 in there, which hasn't been the case so far, I'd change it to .003 or .002. My understanding is the valves will typically tighten, not increase in slack (at least while the cam is not worn excessively, which should not be the case with a new bike) This was also confirmed with a Suzuki dealership mechanic. Hopefully this is correct. If I'm wrong, please correct me.

[galahs]

Has anyone explained why carbs get out of sync? 

[bval]

Well . . . my hopes of finding the problem and the solution were not forthcoming today despite my friend Steve's assistance.  However, the journey has not been entirely unrewarding. Some of it even a bit twistedly humerous. 

It seems there were a few things going on in the guise of what I was viewing as a single problem. I guess this happens quite often, but the side benefit is a lot of other things get done that problaby need doing anyway. My philosopy is always to work from the easiest to the hardest, least expensive to the most costly and from the outside to the inside whenever approaching a problem like this. Along the way, if even there is even an outside chance something that needs fixing anyway could be causing the problem, replace or fix it cause you'll be doing down the road regardless.

One thing that bugged me big time was a very loud and obnoxious rumble when accelerating and particularly, decelerating. It sounded like my exhaust system had a huge hole in it, but I knew there was nothing wrong with it. Knowing I might have to pull the tank anyway . . again . . . when my friend was expected today, I drove the bike with the tank mounting bolts only finger tight yesterday. (they couldn't have come out because the seat covers them) It was through this that I discovered where a lot of the sound was coming from. I've had the tank on and off so much during all this, that I never bothered to tie down cables under the tank and in the process also knocked off a rubber mount. When my weight shifted forward on the tank, it howled! That's what clued me in. So much of the noise was coming from the tank acting like a drum and amplifying any vibration of the tank itself or any cables, wires, etc., touching it from underneath. I was shocked at how much the tank amplifies things! Needless to say, everything from that perspective has been taken care of and the bike sounds much more like it did before.

But still, there is the vibration on acceleration and deceleration, however, much less obvious. Steve noticed that the front brake was dragging a fair bit, (which didn't seem to be happening yesterday), but needed to be dealt with nonetheless. He felt that might cause the bike to work harder on acceleration, but that doesn't explain deceleration nor the fact when accelerating, the weight on the front wheel is less, so you'd expect it to be better. It also doesn't explain that when you pull in the clutch, the vibration ceases immediately. He also said the front tire was showing signs of cupping and we saw minor cracking, so I replaced the tire too. Of course those are both good things to do, but unfortunately still doesn't touch the vibration.

Carbs were not far enough out of sync to be the problem according to two people including Steve. The old plugs were a bit on the whitish side, so Steve thinks it may be running a bit lean. Regardless, the manual says if they look white to put colder plugs in, so I did that today. The air filter looks fine and is easy to see light through. At idle, removing the filter does not change the sound of the engine one iota, so I'm not expecting that this is the problem. Regardless, it has 24,000km on it and will have to be replaced at some point, so I've ordered a K&M to replace it that should be in next week.

After that I'll have to get down to some serious stuff like removing and cleaning/checking the carbs and possibly a re-jett, checking the cush drive in the rear wheel, and heaven forbid, transmission problems.

But I'm starting to also wonder about the throttle sensor on the carb. Steve felt the needles might need adjusting, but when I pulled them they looked nothing like the ones in the manual. There were no clips that could be moved to adjust and I can only assume they'd have to be shimmed. He said the needle would affect rpm between 4000 and 6500, which is where I'm experiencing the problem. The needles appear to come into play when the throttle sensor engages a vacuum control valve to the diaphrams on the tops of the carbs. If that is out of adjustment, I'm wondering if the needles are not engaging when they should. Tomorrow, I'm going to carefully mark their current position and try adjusting a bit either way to see if it makes any difference. At least this is easy to try as they are on the outside of the carbs and wouldn't require taking them apart.

Has anyone had to adjust the throttle sensor on their carb? It looks like it's attached by a pivot screw at one end and slotted at the other end to allow for adjustment.

Anyway, it's gonna be like a new bike by the time I'm done! 

[bval]

The bitter taste of defeat . . .

Well, another trusted friend came by and helped me for about 3 hours today to no avail. This mystery is surely going to kill me or cause a divorce if I don't take a break. I didn't get to adjusting the throttle sensor as we didn't think that wouldn't normally change and the setting is the same as it was before the trouble began. I'm going to ponder over the manual for a few days and we all agree that the bike is still ridable, so on go the fairings and I'm going to just ride it for a few days if the weather permits.

On the positive side, I was able to eliminate a lot of things along the way and as Edison said when he was asked how why he never gave up after 1000 attempts to make a light bulb . . ."I found 999 ways not to make a lightbulb" . . . what the f$#% does he know about bikes anyway?? 

There, that felt  better . . .

[bval]

Well, nothing's changed . . . new K&N air filter yesterday didn't even touch the problem at all, so external air draw is the problem. Fuel doesn't seem to be the problem either as it's got lots of flow. Discovered though that this problem occurs mostly when the bike is under load and higher torques. It's noticeably more rough and throatly at idle, but it's clearly obvious whenever gears are shifted and the throttle is rolled on and becomes very prominent in higher gears between 4000 and 6500 rpm. The whole bike is just running like poop. Like someone else in this forum said, I'm tempted to put to the test just how "bullet proof" this engine is.

[ohgood]

Well, nothing's changed . . . new K&N air filter yesterday didn't even touch the problem at all, so external air draw is the problem. Fuel doesn't seem to be the problem either as it's got lots of flow. Discovered though that this problem occurs mostly when the bike is under load and higher torques. It's noticeably more rough and throatly at idle, but it's clearly obvious whenever gears are shifted and the throttle is rolled on and becomes very prominent in higher gears between 4000 and 6500 rpm. The whole bike is just running like poop. Like someone else in this forum said, I'm tempted to put to the test just how "bullet proof" this engine is.

Until your last post ^^ I wondered if you were not revving the bike enough. You know it really doesn't do much pulling until >4000 rpm, and peak is 8,000. If you 'lug' this tiny motor at all, you'll feel all the slack in the chain, cush drive, swingarm, etc all at once. Plus the fact there are only two pistons to smooth things out as opposed to four. Just something to think about.

If you ARE revving it enough to prevent lugging, it could be the carburetors are way out of sync, one jet clogged and the other fine, etc. I'm still betting on a poor electrical connection though.

Mine has had fits with a corroded connection twice now. It started running really crappy, then better, then crappy again. It even seemed to coincide with what rpm I was pushing it at. One day 3500-5000, the next day 4000 -8000. It REALLY seemed like it was a fueling problem though. It turned out to be simply spark for the right cylinder going away intermittently.

Your experienced buddies likely already did the wiggle n shake tests. If they're stumped, maybe it's time to involve a stealership ? I really hate it if you have to. It's expensive, and they may just muck it up in the process.

[galahs]

When I fitted my K&N with stock jetting the bike wouldn't run past 6,000rpm. So could it be as mentioned insufficient jetting or clogged / dirty jets?


Have you ran a bottle of carby cleaner through the tank to clean away some of the intake deposits?


Does your carb breather hose (vents out of the bottom right side of your bike next to your battery breather hose) have any debris in it?


Could it be a bad electrical earth? 


P.S. Where are the GS500's earthing points? 

[Kerry]

Where are the GS500's earthing points? 

You know I can't pass up a chance to post an old photo.  This one's even annotated!  The camera was positioned somewhere between the exhaust pipe and the rear tire.

[galahs]

Thanks Kerry

How often is a bad earth the cause of problems with GS's?

[Kerry]

How often is a bad earth the cause of problems with GS's?

I haven't had a problem with mine yet, so I don't know.... 

Seriously, I wouldn't expect it to be a problem very often.  But if the connection (or the ground wire itself) ever becomes "marginal", I would definitely expect it to cause a problem.