Hello all,
GS500F 2006 California model.
Carbs cleaned and synced, valve clearances checked, plugs, air filter.
Frame petcock replaced.
Bike starts great, idles well, drives great except after 10 minutes at high speed (5k or higher in 6th). It then "runs out of fuel" and bucks.
I suspect the fuel cap and/or the breather vac line from the carbs.
I've found the thread on how to clean the cap, and I've done it a few years back so I can repeat that (I'll troubleshoot by riding with the cap open I suppose).
However, I can't find a picture of the breather I'm supposed to be looking for.
Any help? Many thanks.
Do you have an in-line fuel filter?
Ditch it. My 97 behaved the same way, clogged/old/fouled filter was the culprit.
It would be fine at around town speeds and in stop and go traffic but a short jog on the interstate would kill it. Was burning fuel faster than it could flow.
Thanks for the response.
No inline fuel filter.
Do you now where the hose I'm looking for is supposed to be? I wonder if it's pinched or missing. Thanks.
The breather on the carbs comes out of the upper "rail" and should be routed to go over the air box and down near the suspension.
The vacuum comes off, IIRC, the left carb on the inside (towards the center) and runs to the frame petcock.
It's POSSIBLE this has a pinhole in it causing an intermittent vacuum leak. This line controls the petcock, and might be shutting off fuel flow at higher RPMs.
It would be easy to diagnose by going for a ride with the petcock on the PRI position.
Could even be a faulty petcock. Was your replacement new?
Thanks.
The problem occurs even on PRI.
So, the fuel cuts off at high sustained speed whether the petcock is on RUN, RES, or even PRI.
(Petcock was used).
Thanks.
Yeah, make sure your breather isn't catching wind. I've got a hose routing diagram somewhere around here...
(http://www.gstwin.com/images/how_to/fuel%20hose/www_gs500_de_HoseRouting.jpg)
Aha!
Wow you've been TREMENDOUS help, THANKS!
So the hose labeled VENT HOSE FROM UPPER T CONNECTION is the one we're talking about? In the diagram I can't tell where it originates.
I'd pull the hoses off that connect the tank/petcock/carbs together and make sure you can blow through them easily if you're going to be pulling stuff apart anyway. I have come across a clutch hose (on a car) that has failed internally. The outside looked fine but the inside had just about swelled shut. Totally different fluids I will admit........but yeah, check for kinks in the routing etc using the diagram Watcher posted.
Quote from: Rallyfan on February 17, 2017, 01:09:50 PM
So the hose labeled VENT HOSE FROM UPPER T CONNECTION is the one we're talking about? In the diagram I can't tell where it originates.
Between the carbs are two rails, an upper and lower rail, each with a T-fitting.
The lower rail is the one you plug the fuel line into. The upper rail is where the vent hose originates.
If you take off the fuel tank you'll be staring right at it.
#6 here.
(http://gstwin.com/images/how_to/fuel%20hose/GRU_HoseRouting2.jpg)
Thanks!
I had a quick look (tank on) and don't see it. I'll have to pull the tank later tonight.
I appreciate this very much! I'll post back with my finding (and frankly I suspect I'll have further questions... sigh...). Thanks!
I 2nd watcher's thoughts on this. The one time this happened to me was when an actual Mechanic worked on my bike. They routed that vent hose up towards the front and the bike would bog down and die after driving at high speeds for a few minutes.
I think it leans out the mixture because my bike also ran really hot when that happened.
I'll post a pic ASAP but I suspect that's my issue. I'm hoping you are all correct. Please keep fingers crossed, I'll post back. Thanks!!!
The round object seems to be a breather. It's T-ed form the top rail of the carbs as described. It faces the side of the bike, outwards, and does not extend backward to the battery. Is this my problem? If so, do I lengthen that hose and route it to the battery box? Will the round thing even fit some where there? (Please pardon my naïveté). Thank you!(https://uploads.tapatalk-cdn.com/20170218/8419d58a79c6f69d6caa6ad3ee8efed3.jpg)(https://uploads.tapatalk-cdn.com/20170218/fe66e67afa0284bfa8eabeb2e75a200c.jpg)
It's hard to see what it is I'm actually looking at. A wider photo would help that.
But I'm not familiar with that round thing.
Typically they have a plug thing on the end to allow liquids to come out but nothing to come back in, but it's fits inside the tube so the diameter is the same if not smaller...
If that's for sure the breather I'd run to an autoparts store and have them cut a length of fuel/vacuum line to replace that.
Sorry, but I don't recall the diameter of the hose you need.
The plot thickens. Please look where I'm pointing. Is THAT the missing hose origin? (https://uploads.tapatalk-cdn.com/20170218/a56cbb9023febc4c48f92aaf25728fa4.jpg)
(https://uploads.tapatalk-cdn.com/20170218/2d841c7e4f454dc8e6b6e29361131104.jpg)
Yessir, that there is your breather with nothing attached to it.
The other thing must be part of the emissions system on the CA model, which would explain why I'm not familiar with it.
Aha! OK I've attached a hose thusly. It's pouring rain so no way to test... I'll post back when it's dry. THANKS!(https://uploads.tapatalk-cdn.com/20170218/92d35ace724b7b930e3aafa85724f26b.jpg)
My issue now is the fuel hoses. Why can't I get both on their barbs?! Reserve leaks...
(https://uploads.tapatalk-cdn.com/20170218/e9b77e05ef097179cdac22f37cd4079b.jpg)
Ohh that is something I've struggled with too... why oh why couldn't there be just a little bit more space there?? Very frustrating!!!
I've seen a lot of different recommendations around the site for what fuel lines to use. I had some success with clear fuel hose from AutoZone or Advance... can't remember which... in the small engine section. It's thin enough to allow room for the clamps. A few years ago I thought it was the hoses and when I changed 'em I realized it was the fuel valve itself in/on the tank that was leaking.
Got it to stop leaking but I M uninspired by the reserve hose. Is this normal, dangerous, or what?!
I should have disconnects the frame peacock instead....
So, now what?
I've actually pulled the brass nipples out of the petcock while trying to pull the hose off, before. You might want to make sure you have them seated nice and tight by tapping them with a mallet.
Or use the plastic handle of a screwdriver as a punch to tap with a hammer.
It's handy that they made the nipples two different lengths, but they are a bit too close together.
You might be able to use a hose one size smaller and really force it on, might even get away with no clamp doing it that way.
You can also sometimes get away with using a zip-tie as a hose clamp by pulling it really tight with a pair of pliers.
Also the screw type hose clamps, while not nearly as handy as those spring ones, do tend to be thinner and may work better in this application.
I can't remember how I did it mine, but on my first GS I did away with the reserve function. Swapped the frame petcock for a simple on/off, and just capped the "on" nipple.
Murphy's law sure favored it, but I DID have to keep a closer eye on my mileage and make sure I zeroed the odometer every fill up.
I've been eyeballing it for an hour and I've also looked online for pictures from other bikes, and I can't for the life of me accept that there's anything different I can do. As far as I can work out, with the stock hardware, this is the best I'm going to get...
If I'm mistaken and am going to have the bike burst into flames underneath me on the freeway, someone please chime in...
I've ordered the stock fuel hoses (perhaps foolishly; in any event, it was before this little fiasco) and they're en route. I'm tempted to simply leave well enough alone at this point. I *think* it's OK (?!...).
THANKS!!!!!!!
(and any further advice ALWAYS welcome and appreciated).
(https://uploads.tapatalk-cdn.com/20170218/758c87a736a62a36ac9eac239a1a5e06.jpg)
So now it's much worse...
I'm stumped.
Here is how I routed the hose. Battery is blue on the right. Hose is between air box and battery box.
Bike cuts out at speed.
Is the hose routed wrong? (https://uploads.tapatalk-cdn.com/20170218/6b09d12f811baa6eba2725f0d55543c0.jpg)
UPDATE:
1. Replaced RES and ON fuel hoses with factory hoses. Also tapped in the brass fitting for the ON hose on the frame petcock (it'd come out in my hand...).
2. Replaced the vent tube with a factory vent tube, routed via a clamp on the lower left bolt screw holding the air cleaner to the space between the battery box and the air cleaner. There is no fitting as far as I can work out; the rubber T off the carbs fits directly into the new tube. To do this I used dielectric grease on the inside of the new tube and a significant amount of pre-lenten profanity. A contortionist would have had an easier time admittedly.
3. Replaced the overflow tube to the tank with a factory tube, routed to the left of the bike clear of the chain and exhaust.
Rain permitting, I'll see how it goes. Meanwhile, am I missing something folks?
Still no joy. Sustained speeds above 75mph make the engine stutter.
Any advice?
Will it rev all the way up to redline at low/no speed?
Test each gear, as safely and legally as possible, to see if it's a speed issue, an RPM issue, or a throttle position issue.
It will rev to redline from idle in neutral, and I've managed to do so in low gears (redline in higher gears isn't feasible on the roads I have).
I believe it is a speed issue, not an RPM issue or throttle position issue, because I can drive around at lower speeds with the engine at 9000 RPM. I believe there is something that happens if/when the bike's speed exceeds, say, roughly 75mph that leads to hickuping and the engine cutting out.
In all the excitement I have not had the clarity of mind to try pulling the choke (so as to enrich the mixture) because (a) the bike is lurching on/off at 75+ mph so I've got other stuff to think about and (b) I don't know if the choke lever has any effect beyond 5K RPM anyway. Would trying the choke enrich the mixture and thus tell me if I am leaning out? The plugs looked fine according to my mechanic, and when I inspected the previous set myself last year they also looked good.
I am tempted to add a "breather element" filter to the end of the carb vent tube but I don't think the stock setup is like that anyway. I am also tempted to start replacing each/every vacuum tube on the bike but that is quite literally a fishing expedition with no rhyme nor reason to do so -- it's a shotgun approach.
Thanks for your help! Any advice appreciated.
get rid of the vacume tap, i had the same issue and solved it by using the fuel tap from a RGT 250 suzuki, it also has dual fuel lines in and a single one out, its a manual tap so you need to blank off the vacume take off on the carbs. since i fitted it i can hang the throttle wide open and she just keps going til the tank runs dry
Thanks for the tip! I've not been able to affect the issue at all regardless of which selection I make on the chassis petcock: ON/RES/PRIME all result in the same issue.
When you had the problem, was it temporarily solvable by selecting PRIME on the stock petcock (thus bypassing the vacuum anyway)?
Thanks!
Say you drop a gear (or raise a gear) when stuttering at 75, what happens?
Also, totally try the choke next time it happens. Never hurts to rule out improper size or clogged main jets.
I'm pretty sure the choke is impartial, and just offers what is essentially another jet right before the cylinder head. It'll dump fuel at idle, at 5k, at 11k...
I've heard of people using them like pseudo cruise control. Great way to foul some plugs, though.
I will try the choke provided the rain stays away. I'll also try raising a gear since I'm uneasy to drop a gear at 75 with no throttle to blip and rev match - if I lock up I may never learn to play the piano.
Quote from: Rallyfan on March 05, 2017, 02:50:38 AM
I will try the choke provided the rain stays away. I'll also try raising a gear since I'm uneasy to drop a gear at 75 with no throttle to blip and rev match - if I lock up I may never learn to play the piano.
You won't "lock up". Just use your clutch like a clutch and you'll be stable. No throttle while downshifting will engine brake fairly aggressively but nothing bad will happen unless you just let go of that clutch lever.
OK so:
1. Choke has no effect. It still cuts out and jerks at high speed.
2. Gear selection has no effect. It'll do it at high speed in 5 or 6 (didn't try 4).
3. Shifting up or down has no effect. Only slowing down salvages the situation and the bike purrs along at under 70 or so.
I believe it is a speed issue, not throttle or RPM.
In that case it means environmental air pressure is getting into the carbs somehow.
If you're sure the hoses are all routed properly, it could be that the airbox boots aren't sealing completely.
Thanks for the patient and helpful responses!
If the airbox boots are not seated properly, wouldn't the idle creep upwards? I'll check the boots nonetheless and report back ASAP.
I love the bike nonetheless! Oh, what I'd do for fuel injection about now though... Sigh... OK! I'll post back when I get a chance to look into it.
Thanks!
Quote from: Rallyfan on March 05, 2017, 12:38:28 AM
Thanks for the tip! I've not been able to affect the issue at all regardless of which selection I make on the chassis petcock: ON/RES/PRIME all result in the same issue.
When you had the problem, was it temporarily solvable by selecting PRIME on the stock petcock (thus bypassing the vacuum anyway)?
Thanks!
nope, it would take slightyly longer to run out of fuel but would ultimatly run out and the bike would go lean, sometimes if you paid attention you could feel it starting and back off the throttle while yanking the choke to keep her alive
I've had this happen at sustained highway riding at about a 100mph.
Tank was half full, so not even close to hitting reserve, but I fueled up at the next gas station to full (bought about half a tank's worth of gas) and the problem went away. I'm thinking not enough hydraulic pressure in the tank with the lower level to account for the increased demand on the other side of the petcock. Sustained riding at those speeds happens so rarely though that I just didn't care after I had arrived so no troubleshooting has been done. I just make sure it's full on the rare occasion...
Quote from: jeZZa on March 05, 2017, 11:45:17 PM
nope, it would take slightyly longer to run out of fuel but would ultimatly run out and the bike would go lean, sometimes if you paid attention you could feel it starting and back off the throttle while yanking the choke to keep her alive
This does sound a lot like what I experience. I too can sometimes feel it starting and roll off the throttle to avoid it for a while. Thanks!
Quote from: Atesz792 on March 06, 2017, 02:35:15 AM
I've had this happen at sustained highway riding at about a 100mph.
Tank was half full, so not even close to hitting reserve, but I fueled up at the next gas station to full (bought about half a tank's worth of gas) and the problem went away. I'm thinking not enough hydraulic pressure in the tank with the lower level to account for the increased demand on the other side of the petcock. Sustained riding at those speeds happens so rarely though that I just didn't care after I had arrived so no troubleshooting has been done. I just make sure it's full on the rare occasion...
I'd trade this situation for mine because of the higher speed involved in what you describe. In my area one has to actually exceed 80mph to sometimes simply follow traffic, making the bike questionable to ride on the freeway as a result. Also, mine does it even with a full tank (and even when the tank is full and the tank cap is open, so I've excluded the cap vent). Thanks!
Do you have an inline fuel filter?
Apologies I haven't read the whole thread, but...
this sounds like a fuel delivery problem. Watcher is right about the inline fuel filter, also whoever said the vacuum petcock may be the culprit is also right to look there. Could also be low float height, stuck (closed) slide, clogged main jet (orifices in carb, not likely the actual jet), severe vacuum leak like a tear in the carb diaphragm(s) or missing o-rings or vacuum port caps, super tight valves, very bad intake boots or intake boot o-rings, carbs loose from intake boots (not seated properly before tightening hose clamp)...
I have had all of these problems happen :)
Basically the symptom is when it needs a certain amount of POWER (which is what it takes to go over 75mph) then it can't deliver, which means it just can't get enough fuel to make that much power. Everything that can cause it to not get enough fuel can be the cause.
You can rule out the petcock by running it on prime. If it works fine on prime then it's the petcock or vacuum supply to the petcock. If it does the same thing on prime, the problem is in the carbs.
My money is on:
1. low floats
2. a kinked/bent fuel hose
3. fuel hose with a crack or air leak somewhere so it sucks in air
4. vacuum leak in the petcock vacuum line so you get double whammy: not enough vacuum to fully open the valve and a vacuum leak that prevents the slide from operating correctly.
Either way the fix is to set the float height and while the carbs are apart replace every single o-ring and all of the hoses (vacuum, fuel), including the intake boot o-rings. That's cheap and easy, way easier than trying to troubleshoot everything. This is a case of: even though it might not be broke, fix it.
Thanks for that. I suspect float level - boots - kinked fuel line too. I've replaced the two lines between the two petcocks; my next step therefore is to replace the main line from the frame petcock to the carbs, the carb boots, and any rings/hoses I can find in there too.
I'll post back once I get a chance to open it up; it may be a while with work but it's on my mind and I want this sorted out.
Thanks!
Update: Main line replaced, all vacuum lines checked (used eyballs and blowtorch off while the bike was running etc.) Carbs removed from bike, cleaned, floats set again.
Fixed!
Likely the floats all along.
BIG THANKS TO EVERYONE!!!!!
@SBW: "Ohh that is something I've struggled with too... why oh why couldn't there be just a little bit more space there?? Very frustrating!!!"
That's another benefit of the OEM fuel lines which remember are different sizes on each end.
True! OEM is the way to go for fuel lines! Bike Bandit to the rescue. May as well pay a little extra and get the clamps; saved me the worry.
I did go ahead and buy them (lines and clamps) a couple weeks ago. Got them in the mail already :D