I was informed today while getting my new front tire on that my left cylinder isn't functioning properly. I don't know if it's spark or fuel issues or what. What are the ways I can go about trouble shooting this?

replace plugs.

swap coils to opposite side to see if the right side starts acting up.

carb sync.

Plugs are a month old, but I may get new ones just to be sure anyways.

How do I sync the carbs?

And... If the cylinder is missing spark, would that lead to a fouled plug of sorts? If it's missing fuel obviously the plug will be white. So would that be a good starter point to see if it's fuel or spark that's missing?

You need 3 things to make an internal combustion engine run.

Spark
Compression
Correct fuel/air mixture (carbs, injection).

Start with spark.  Is it strong, or weak?  If none, swap coils and plugs and see if the problem follows.
If it's not the spark, coils, or ignition...move to the carbs.  One side may be dirty or not synched.  Baltimore GS has a nice video of synching carbs.
Compression is the last thing...but most likely it's fuel or ignition.

Quote from: jestercinti on January 11, 2013, 01:30:40 PM
You need 3 things to make an internal combustion engine run.

Spark
Compression
Correct fuel/air mixture (carbs, injection).

Start with spark.  Is it strong, or weak?  If none, swap coils and plugs and see if the problem follows.
If it's not the spark, coils, or ignition...move to the carbs.  One side may be dirty or not synched.  Baltimore GS has a nice video of synching carbs.
Compression is the last thing...but most likely it's fuel or ignition.

How do I check the strength of the spark?

You can lay both plugs out on the side of the block still connected to the coils, turn off the fuel off and try to start it and look at the spark on each one and compare. It will give you a good idea and baseline. Doing this in less light works best

How old are the plugs? If you personally don't know, change 'em.

Quote from: jestercinti on January 11, 2013, 01:30:40 PM
If it's not the spark, coils, or ignition...move to the carbs...
Compression is the last thing...but most likely it's fuel or ignition.

Wouldn't compression be easier to test than the carbs?

You can also check the coils with a multimeter.  There are two coils per side.  A primary and a secondary.

The primary can be measured by checking the resistance between +wire and -wire on the coil pack.  It should measure 3-6 ohms or resistance.

The secondary coil can be measured from the +wire to the plug cap and be around 18-30 Kohms.

Alright guys I hit a road block in my work. I got the coils switched around, new plugs. Turns out the old plugs.. The store I bought them from gave 2 completely different ones! But it didn't make a difference the left plug was still pretty fouled after 20 miles, I switched them on the ride to get new ones.

Anyways, I'm at a stand still, as the O-ring in my tank mounted fuel valve has gone past the point of re-use... Gotta order a new one and then continue when I can put the tank on the bike.

Quote from: mustangGT90210 on January 15, 2013, 10:17:31 AM
Alright guys I hit a road block in my work. I got the coils switched around, new plugs. Turns out the old plugs.. The store I bought them from gave 2 completely different ones! But it didn't make a difference the left plug was still pretty fouled after 20 miles, I switched them on the ride to get new ones.

Anyways, I'm at a stand still, as the O-ring in my tank mounted fuel valve has gone past the point of re-use... Gotta order a new one and then continue when I can put the tank on the bike.

That o-ring is super simple to replace. Carefully remove the retaining clip and take out the parts. Be sure you don't lose anything. Pop on a new o-ring and you're good to go. No need for a whole new unit.

That o-ring goes out because the fuel valve is rarely turned off. The o-ring sticks and when you turn it off, it can crack or break just due to lack of use and it got stuck. It should be easy to get that o-ring at an auto parts store. It is nothing unique to motorcycles.

Quote from: adidasguy on January 15, 2013, 12:15:33 PM

Quote from: mustangGT90210 on January 15, 2013, 10:17:31 AM
Alright guys I hit a road block in my work. I got the coils switched around, new plugs. Turns out the old plugs.. The store I bought them from gave 2 completely different ones! But it didn't make a difference the left plug was still pretty fouled after 20 miles, I switched them on the ride to get new ones.

Anyways, I'm at a stand still, as the O-ring in my tank mounted fuel valve has gone past the point of re-use... Gotta order a new one and then continue when I can put the tank on the bike.

That o-ring is super simple to replace. Carefully remove the retaining clip and take out the parts. Be sure you don't lose anything. Pop on a new o-ring and you're good to go. No need for a whole new unit.

That o-ring goes out because the fuel valve is rarely turned off. The o-ring sticks and when you turn it off, it can crack or break just due to lack of use and it got stuck. It should be easy to get that o-ring at an auto parts store. It is nothing unique to motorcycles.

Yup adidas. hit that nail on the head. to the OP, make sure the o-ring is fuel safe. a non fuel safe ring will for lack of a better term, destroy itself in fuel.

Quote from: adidasguy on January 15, 2013, 12:15:33 PM

Quote from: mustangGT90210 on January 15, 2013, 10:17:31 AM
Alright guys I hit a road block in my work. I got the coils switched around, new plugs. Turns out the old plugs.. The store I bought them from gave 2 completely different ones! But it didn't make a difference the left plug was still pretty fouled after 20 miles, I switched them on the ride to get new ones.

Anyways, I'm at a stand still, as the O-ring in my tank mounted fuel valve has gone past the point of re-use... Gotta order a new one and then continue when I can put the tank on the bike.

That o-ring is super simple to replace. Carefully remove the retaining clip and take out the parts. Be sure you don't lose anything. Pop on a new o-ring and you're good to go. No need for a whole new unit.

That o-ring goes out because the fuel valve is rarely turned off. The o-ring sticks and when you turn it off, it can crack or break just due to lack of use and it got stuck. It should be easy to get that o-ring at an auto parts store. It is nothing unique to motorcycles.

I decided to order the OEM Suzuki o-ring. $5 and it gets here on friday. Thanks to you guys last time I had this issue, I learned there even was that ring  I've had to oil the dang thing heavily each of the last 3 times the tank has been off, so I knew it was on it's last legs.

What does a new coil cost anyway? I have yet to chase down that price

Got the new o-ring today... but apparently they mis understood and thought I meant the o-ring between the petcock and tank. Guy took me down into the service area and gave me a few circular o-rings from carbs i'd imagine. Got one that fits and doesn't leak!

Back to the bike, started back up like usual. Runs the same as before switching coils around... I'm letting it cool down right now before the plugs. Took it on about a 7 mile ride. I think it'll be enough to tell me what I need based on how bad the left plug was fouling.

Well, I need to ride it more. Don't have enough information on the spark plugs yet to make a reading

Quote from: mustangGT90210 on January 18, 2013, 05:12:44 PM<snip>Took it on about a 7 mile ride. I think it'll be enough to tell me what I need based on how bad the left plug was fouling.

For what it's worth, I doubt 7 miles is going to tell you anything more than what you already know about what's going on with the left cylinder.  You've not really said anything (unless I missed it) about what *your* observations have been on how the engine is running.

No offense intended, but how are you defining "fouled"? If it is "sooted up", i.e., an accumulation of mostly dry pitch black dust than can be fairly easily removed with a toothbrush (depending on how long it has been running in that condition) chances are that if you have good voltage to the plug and the gap is correct,  and the plug is not somehow defective, the plug is most likely firing. If on the other hand, the accumulation is very heavy, and it's damp, oily and building up to the point that it is starting to close the gap between the center electrode and the outside "bridge" (proper term?) which the spark arcs to, it definitely *will* affect the spark and translate to varying degrees of misfire. I've been maintaining/repairing/rebuilding my own infernal combustion devices for close to 44 years now to include a dozen or so motorcycles (mostly twins) of most all the more common makes (to include my beloved oddball 98 Moto Guzzi 1100EV) along with countless beater cars, pickups, commercial landscaping equipment of 2 and 4 cycle flavors, old and worn out as well as new. I can honestly say I have only had *one* engine where the plug got so fouled over time from sheer neglect that it actually caused the engine to stop running and refuse to start. That was a twin blade 90's vintage Toro mower with a 12HP Kawasaki engine. I thought to myself, "when *was* the last time I checked the plug on this bad boy?" I got to thinking...oops, not once in 4 years of heavy use and I knew it was burning oil. Hey, it happens! Point being, up until that fateful day it *always* started on the second pull, hot or cold, and seemed not to miss a lick! Well, the plug was unbelievably fouled, there was barely *any* gap left!

Electronic ignition produces a nice strong consistent spark, year after year, usually with damn little needed in the way of attention. Unlike the "bad old days" of "points/plugs/condenser" when it came time for a tune-up, and yes I know I am definitely showing my age with that remark!

No sir, most likely the plug is a symptom in your case, and not the problem...just a guess though, I have no way of knowing! You mentioned carb synch. Bad synch will cause "rough" idle and running along with excessive vibration, but does not create a misfire (if anyone agrees or disagrees feel free to comment)

I had no choice but pull the carbs off my GS to address what turned out to be a stubborn bit of trash stuck between the float needle valve and seat resulting in it dumping raw gas into the left cylinder and pouring out the throat of the carb. Usually this can be corrected by pulling the float bowl drain plug, letting some gas run though it, tap lightly on the float bowl, etc. but not this time and no way was I going to let it sit there and fill the cylinder up with gasoline! While I had the carbs off I was able to do a damn fine "static synch" on the carbs using two equal thickness feeler gauges and measuring (by feel) the amount of resistance felt while pulling the feeler gauges through the carb throat while the CV slide was moved up and down by the idle speed screw. Easier done than  described I'm afraid, but it made perfect logical sense to me and it worked!

I don't expect you'll find that procedure listed in the service manual (dunno, don't have one!) but it is nigh on impossible to argue with results!
Mine runs like the proverbial sewing machine, across the board. it starts so easily (once fullly warmed up) it almost seems like the engine has *no* compression! I rode my son's 97 (I think it was) GS500E, with very low miles, recent "professional" tuning, etc. and the difference between his engine and mine in terms of overall smoothness and power delivery, to me, was night and day, with mine hands down the winner. I believe he made a statement to that effect once after he sold the 500E, "no comparison".

I say these things in *no way* to be boastful or anything of the sort. I learned to maintain and repair my own engines as a matter of financial necessity more than anything. That and the issue of not being able to find *competent and ethical* "professional" assistance on the rare occasion when I was forced to avail myself....namely warranty work.

Speaking of which...this dealer comment about the left cylinder. Did that come with an unsolicited invitation to bring the bike in and have it worked on, or did you mention a running issue to the service dept. and/or mechanic? you see where I am going with that, right?

One last thing as I have spent far more time writing this than I had intended and need to be doing other things!

You said the new plugs were "different"? Please clarify if you would.

Thank you for wealth of information there! I don't even know where to start..

Plugs - new ones after 100 miles are looking good, right side is slightly blacker. Both look to be acceptable now. The 2 month old set I had in the bike before were 2 different plugs. NGK DR8xxxx and the other was a DR8Pxxx. One was longer by the length of the electrode.

Carbs - Had them synced today while my tire was getting attended to. That's made a big difference. It doesn't pop while riding anymore, and overall sounds healthier. More steady power delivery, instead of the really peaky delivery from before. Small differences but I can feel it is much improved.

Carbs cont - I was speaking with the mechanic again today about everything I was experiencing. He showed me that my choke seems to be just slightly out of adjustment, so it's always resting on the plunger thing for the left cylinder just a little. I'll tinker with the arm so it has proper clearance and see if that's the cause here. Would also explain the hanging idle, but I think it'll take a little more digging for that to clear up

Mechanic - the shop I go to is a very reputable place. Independently owned so no dealer influence as well. The mechanics are extremely helpful when it comes asking questions. I make sure to let them know I can't afford anything more than what it's there for, and they still help me out in possible things.

I may also have to go in and clean the pilots, would explain my bike not liking to idle lol

And of course, need to adjust the valves I think. I haven't checked them but I think they're due. Just waiting on the proper feeler gauges to ship out here and I'll go from there.

Hey there "Mustang", looks like you're starting to get a handle on things....good on ya!

Quote from: mustangGT90210 on January 20, 2013, 12:24:18 AM

Thank you for wealth of information there! I don't even know where to start..

My pleasure Sir! (chances are good you're male, if not, pardon moi!) You know what they say about assumptions.

Plugs - new ones after 100 miles are looking good, right side is slightly blacker. Both look to be acceptable now. The 2 month old set I had in the bike before were 2 different plugs. NGK DR8xxxx and the other was a DR8Pxxx. One was longer by the length of the electrode.

Well, no reason to stress over it now, water under tbe bridge. But yeah, that should not have been the case. This looks to be a decent "bare bones" FAQ from NGK which covers the basics if you're interested.  It's nothing close to the wealth of product information I have seen from some of the other plug makers in the form of downloadable info/spec  files
http://www.ngksparkplugs.com/tech_support/spark_plugs/faqs/index.asp?mode=nml

Well dog gone, I shouldn't be so quick to dismiss their FAQ....how embarrassing, I *learned* something just now reading one of the Q/A's topics! Not going to tell you what it was though, I can only bear so many crushing blows to my ego in any given 24 hour period!

Oh well, if I'm anywhere close to a shining example of what a "perfect" human being is supposed to be, we're screwed!

Otay, back to biz:

The website says that the standard heat range plug for  a 2004-2009 GS500f is the DPR8EA-9. The "R" just means that it's a resistor plug which reduces radio frequency interference. In your case, one of the plugs was the "projecting insulator" type while the other one is not and they were both one number "hotter" than standard according to this chart:
http://ngksparkplugs.com/docs/tech/design_symbols_plugs.pdf

I don't recall if you stated the year/model and I can't open another window at the moment to find out without a bit of hassle...so I just arbitrarily chose that model range. I have an 07 500F.

The only situation where I  can imagine the "P" designation being an issue would be if our engines *didn't* call for the projected insulator, and the available squish space in the combustion chamber at any given time is so small that the plug could actually hit the top of the piston or one of the valves. Not likely, but I just don't know for sure. (anyone?)

Well actualllllyyyyy, in your case,  these small differences very well *could* make a difference, but again, not likely IMHO.

Carbs - Had them synced today while my tire was getting attended to. That's made a big difference. It doesn't pop while riding anymore, and overall sounds healthier. More steady power delivery, instead of the really peaky delivery from before. Small differences but I can feel it is much improved.


Excellent!!! A good synch job speaks for itself on twins in my experience, money well spent if you can actually tell the difference. A good indication the mechanic knew what the heck they were doing!

Carbs cont - I was speaking with the mechanic again today about everything I was experiencing. He showed me that my choke seems to be just slightly out of adjustment, so it's always resting on the plunger thing for the left cylinder just a little. I'll tinker with the arm so it has proper clearance and see if that's the cause here. Would also explain the hanging idle, but I think it'll take a little more digging for that to clear up


Well, my son had a 97 (I think) GS500E. I believe it was bone stock, no carb mods.

I did the washer "needle lift" mod on mine along with a minor tweak to the idle adjustment screw to richen it up a bit. Both bikes displayed the somewhat annoying "climbing idle rpm" syndrome which apparently is characteristic of these carbs when the "choke" is engaged. No biggie IMO. It's not actually a choke per se, it's a separate low speed circuit that will cause some interesting running issues if you happen to activate the lever slightly while you're out on a ride! Like, OMG! WHAT has happened to this engine! I went through that the first week of ownership. One of those model-specific idiosyncrasies you come to know and may even claim to love depending on what it is. Like say vibration, ya know? These engines DON'T vibrate, they simply emit a complimentary resonant chord which reflects the "oneness", the Zen of Twin, the Ohmmmmmmm, the Chi. Ok, so that's a bunch of bull, they buzz a bit!

Mechanic - the shop I go to is a very reputable place. Independently owned so no dealer influence as well. The mechanics are extremely helpful when it comes asking questions. I make sure to let them know I can't afford anything more than what it's there for, and they still help me out in possible things.


Warms my heart. Truly. Such shops are rare these days, at least around here. (Metro ATL GA area) The KTM dealer down the road a ways is about the closest thing to what you have described anywhere near here. The owner is an old guy like me, an *enthusiast* who obviously is happy with his choice of livelihood. When I had the DL1000, and the Moto Guzzi before that, I would *look* for excuses to stop there now and then and throw a few bucks his way on small merchandise  purchases. It was the best I could do. Hey, someone has to, particularly during the winter months. Unlike up North, snowmobiles aren't real big around here! I assume they play a large part in helping dealers get through the winter months?

So, it's not like I am strictly "anti-dealer" and I don't lump them all together and refer to them as "stealerships". But I have had a couple of *really* bad warranty experiences over the years which I mentioned elsewhere I think, but no need to "go there"!

I may also have to go in and clean the pilots, would explain my bike not liking to idle lol

Well, if you are going to go to all that trouble I would recommend doing it thoroughly or not at all. I would first recommend trying a couple of tanks with a reputable carb/injector cleaner added (following their instructions, not TOO much!). I am partial to Sea Foam, most people have a favorite. There is considerable risk in taking these carbs apart and it should not be approached too casually. You could lose the pins out of the little float valve jet assembly for instance, and you are dead in the water until you find a replacement and some of these parts are not even available according to the microfiche. You ever priced a NEW set of carbs? Absolutely frikking incredible!

Now these are supposedly "discount" prices mind you...
http://www.ronayers.com/Fiche/TypeID/26/Type/Motorcycle/MakeID/2/Make/Suzuki/YearID/48/Year/2007/ModelID/7551/Model/GS500F/GroupID/357784/Group/CARBURETOR_

Aforementioned "float valve assy." (item 21) is $51.12 each. You can lose that little son-of-a-gun by looking at it wrong! And/or bend the teeny tiny retaining clip, or disturb the float height inadvertently, potentially just as much of a pain cuz you won't know that you screwed up until you get everything back together again and it runs like total crap, *much* worse than when you started "fixing" it!

Believe me, getting back into a carburetor engine was a *big* deal for me. My last three  bikes prior to the GS were fuel injected, they each had issues at one time or another, totally different skill set (beyond basic troubleshooting principles, which are always the same) THEN I take possession of this bike from my son and right off the bat the SOB decided to start dumping fuel out of the left carb. I approached it with much trepidation cuz I was dead-ass broke, I'm talking zero funds to fix it, just my time and accumulated knowledge, stuff I hadn't had to use for nearly 20 years! Often times my self=confidence leaves me high and dry when I need it most, but if there is one thing I have learned over the years it is this:
When in doubt, STOP!!! Put down, away, go do something else and come back to it with a clear un-frustrated frame of mind.
Just as important but requires discipline, DON'T fix things that are NOT in need of repair, right? We know this intellectually, but sometimes those prying little fingers seem to take on a mind of their own, eager to futz things up! It happens!

And of course, need to adjust the valves I think. I haven't checked them but I think they're due. Just waiting on the proper feeler gauges to ship out here and I'll go from there.


I enjoyed checking mine. So damn *simple*. I mean *four* valves total? Sheeeeeiiiittt, what's not to like?  I have one valve, the exhaust valve on the left cylinder that is out of spec by about 2 thousandths (inch) to the loose side. you can hear it. I left it be until I get a shim tool, maybe I can borrow one from somebody around here, who knows? I hate to buy one cuz it will be so rarely used. The valves on my DL had the same bucket/shim configuration. Easier on the one hand because the cams are gear driven and you just remove the cams. Ok, it's a trade off because that entails some risk if you are not careful. No question the GS is hands down simpler. I got through the DL, took my time and only had one "OMG" moment, that was when one of the camshaft cap bolts went missing. I liked to never found that sonofagun! It dropped out of the cap and was lodged in a cooling fin right up next to the rear cylinder exhaust header flange. Short of turning the whole bike upside down, I was coming to my wits end for explanations of where it might have gone before the dreaded, "OH NO, tell me it ain't so, it is INSIDE of the engine!!!"

Yep, this stuff should never been taken lightly when you are not able to simply hand your tore up shaZam! to someone else along with a wad of Franklins and say "Fix this please".

Hey, good to hear things are looking up! And yes, I am VERY long winded when it comes to bikes, this one in particular, it has renewed my "spark". Hey, check out my new tail-light/turn signal...I'm very proud! I took the short video before mounting the lamp because I woulda had to move the bike. It was like 4am and I didn;t want to mess with all that!
www.youtube.com/watch?v=o_XgO9ZwqhI

Take care!
Hube

Quote from: mustangGT90210 on January 20, 2013, 12:24:18 AM
Thank you for wealth of information there! I don't even know where to start..

Plugs - new ones after 100 miles are looking good, right side is slightly blacker. Both look to be acceptable now. The 2 month old set I had in the bike before were 2 different plugs. NGK DR8xxxx and the other was a DR8Pxxx. One was longer by the length of the electrode.

Carbs - Had them synced today while my tire was getting attended to. That's made a big difference. It doesn't pop while riding anymore, and overall sounds healthier. More steady power delivery, instead of the really peaky delivery from before. Small differences but I can feel it is much improved.

Carbs cont - I was speaking with the mechanic again today about everything I was experiencing. He showed me that my choke seems to be just slightly out of adjustment, so it's always resting on the plunger thing for the left cylinder just a little. I'll tinker with the arm so it has proper clearance and see if that's the cause here. Would also explain the hanging idle, but I think it'll take a little more digging for that to clear up

Mechanic - the shop I go to is a very reputable place. Independently owned so no dealer influence as well. The mechanics are extremely helpful when it comes asking questions. I make sure to let them know I can't afford anything more than what it's there for, and they still help me out in possible things.

I may also have to go in and clean the pilots, would explain my bike not liking to idle lol

And of course, need to adjust the valves I think. I haven't checked them but I think they're due. Just waiting on the proper feeler gauges to ship out here and I'll go from there.

What feeler guages did you buy? looking to do my shims and cant really settle on some feeler guages. I got some now that go down to .038 but it only fits under two so think I need a smaller set.

After I typed that I started thinking more into which to get and other finances. It may actually come out cheaper to have the shop adjust the valves than me do it. It's gonna cost me $40 to $50 in parts because I need the really small feelers, the shim tool, and new shims, plus the valve cover gasket if it doesn't seal back up right. Shop will charge around $100 for the job, and driving my truck for the week the bike would be in the shop for (only because my hours only mesh up once a week to get there) would cost me around $80.

I'm still trying to figure out everything so I spend the least amount of money at this time. I may crack open the head with the feelers I have knowing full well I can probably just wing it, go down a shim size and it'll come out fine.

So the real question here! Does having the intake valves open at .10mm instead of the specified high end of .08mm make a difference worth worrying about? My smallest gauge is a .05mm, and I believe the shims each go down by .05mm anyway. Am I right in thinking I could just drop one size on the shim and all be alright?

Quote from: mustangGT90210 on January 24, 2013, 11:55:54 PM
So the real question here! Does having the intake valves open at .10mm instead of the specified high end of .08mm make a difference worth worrying about?


Just to be absolutely clear. You mean a measured clearance of .10mm?

A bit loose always better than too tight. My left exhaust valve is out on the high end by the same amount as your intake. I might get around to adjusting it this winter or I might not. Not in the least bit worried about it though. I think in inches, that's roughly two one-thousandths of an inch. If you give two people a feeler gauge I would be surprised if both measured the same clearance within one-thousandth in. unless it was an accurately ground "go, no go" feeler. Sorry, two many words. In my *opinion*, ride it another 10K miles and check it again. I can hear the loose valve on mine when it's cold, it goes away once warmed up. To me that's close enough!

My smallest gauge is a .05mm, and I believe the shims each go down by .05mm anyway. Am I right in thinking I could just drop one size on the shim and all be alright?

I believe they come from the factory with smaller increment shims than you can buy. If they've never been touched, You might luck up pulling them all out and swapping them around and end up with it spot on. Or you could waste a whole bunch of time and gain nothing. $100 for the valve adjustment seems very reasonable to me if it's done right and it really needs it, but if you already know what you have, is that worth it? Your call. My 23 year old F-150 gets 12 mpg,, loaded, unloaded, uphill or down. My GS gets 55-60mpg minimum the way I ride it. I wish I *could* be riding it now, it makes me sick to waste money on gasoline! Good Luck, I'll leave you to it, promise!