Hello all,
I am a new member to this forum, and have been reading up a lot since getting my gs500. About 2 months ago now I purchased a 1990 GS500E with 7200 miles on it for my girlfriend to learn to ride on.
Upon getting it, it suffered from what I read is the common fuel starvation problem. At first the bike would only run decently up to about 55mph (with a slight bog in a roll on), but would pop and spit if attempting to go any faster. I have since
1) Replaced stock fuel petcock with after market valve (couldn't find a rebuild kit for the original, and didn't think it needed it, as it seems to be fine)
2) cleaned filter in tank
3) rebuilt carbs and wired them out, paying particular interest to the pilot circuit
4) attemped to shim the needle jets with 3x1mm o-rings
5) replaced intake pipes on engine side of carbs, which had a massive crack in them
6) Checked and re-gaged plugs
These changes have made an improvement, namely the intake pipe replacement. I can now get the bike up to 70mph, but it still suffers from a minor surge. No back firing this time, but you can feel the bike easing fore and aft. I have also made sure the vent on the tank is performing as it should (no hissing when opening cap).
So my question is, what could I possibly be missing? I have in the mail:
a) a set of #40 pilot jets, as well as a set of #42.5
b) 125 main jets
My hope is that by rejetting a size up I can get the bike to running as good as new. Perhaps this is the solution I need, but I had hoped you guys with more experience than myself on this platform could lend some guidance as to something I may be missing? The one thing fuel/air related that I have no confirmed is valve clearences all around. These were supposedly done by the previous owner within the last 500 miles, but I've yet to confirm for myself
Other than at highway speed the bike runs like a dream, and it will run up through the gears all the way up to redline in 4th with no issue. So I can't figure out why steady-state cruising at highway speeds is an issue.
Thank you all in advance for any guidance you can give.
Brian
After posting this, I have since received and installed my new jets. Upon pulling the carbs apart, I found that the original pilot jet was a 40. So I replaced the mains with 125s, the pilots with 42.5s, and turned the turning screws out 3 turns.
After getting them back on the bike I took it for a cruise and the thing won't run well. The new jets certainly weren't an improvement over the old jets. The bike continues to stumble, no at or around 60 mph. When turning around and heading back on the highway I was able to run the bike up through 5th to ~90mph and it pulled just fine. But when decelerating, it started to surge again.
I pulled the plugs and they are, as to be expected, quite white. The bike appears to me to still be running lean.
At this point I am totally stumped. Could anyone please offer some advise as to what I could be missing? Just to go over it again, my setup is:
Stock Intake
Stock Exhaust
125 mains
42.5 pilots
3 turns
NGK XS-4163 plugs, properly gapped (my only thought is these may need to be replaced? But they appear brand new)
Thanks in advance
have you read the wii re-jet? maybe you have the wrong size jets? i cant say yes or no for sure, but it'a a possibility
I have read and referenced the wiki a number of times. Suggested setup for stock intake/exhaust is 40/125. So if anything I would think with my 42.5/125 I would be a little on the rich side at cruising settings.
My next step that I haven't tried is to shim the needles again. Besides that I plan to evaluate whether there are any leaks I missed by spraying the starting fluid around the carb/intake area.
Thanks iclrag and anyone else for guidance
I will offer up my first thoughts - keep in mind they are first thoughts and may hold no substantial credit :icon_lol:
My hopes for these is that they spark something else for you, or others to help. ;)
After reading your original post, I thought (probably just as you had) that well the carbs aren't getting enough fuel somehow... So I would test via the U-tube method to see how much fuel is actually getting in there to be sure if you haven't already, to get a better idea of where the leaness is coming from.
My next thought was your spark plugs... I'll admit I have limited knowledge of them, so take with a grain of salt... But the XS I thought stood for 'Extreme Sport' .. are they just too hot? For no more they cost, I would eliminate the variable and go with stock if everything else is, other than your jets. Our bikes tend to run lean in stock, so I doubt changing the jets hurt it in any way...
I would probably check for leaks at this point, if carb fuel level checks out, and the spark plugs check out, since you have already done the things I would think of before the carbs like the tank filter and petcock.
My last thought was elevation - but I wouldn't think it would play this much into a problem.
- Bboy
BockinBboy, Thank you for your tips.
I'll have to look for the youtube video you are referencing. I'm assuming it is something alluding to the float height? This is something that I haven't checked whilst on the bike. But i did (at least attempt) to do it while rebuilding the carbs. I'll have to make sure to check that
You are right, with the cost of spark plugs, i'll have to order a set and try them out. If nothing else it would eliminate one variable as you say.
My next plan of attack (upon confirming the float height), is to bypass the aftermarket fuel valve with a t-fitting. That would rule out any possible issues above the carbs, as you would flow fuel from both the main and reserve feed. Also, i'll have to look for leaks using started fluid. At this point, i'd be happy to find anything just so I have something to point the finger at.
Thanks again for your guidance
Brian
Here you go. I should have included a link earlier. Literally, 'U-tube Method' :icon_lol:
http://www.bbburma.net/FloatHeight.htm (http://www.bbburma.net/FloatHeight.htm)
- Bboy
This morning I had a few spare minutes so I checked the float height on my GS. Both sides checked out nenar the head gasket (about 1mm over). So it appears that this is not the culprit.
This again leaves me perplexed. When i get the chance i'll get a new set of spark plugs and try bypassing the after-market petcock. Then i'll be really really stumped.
Thanks again to all those who have weighed in
Brian
Last night I got the chance to test ride the bike with the new, stock, spark plugs. It still refused to run. In fact, it may be getting worse. Now it seems as though there is a lean surge at 50mph, not the 70 like it used to be.
I then bypassed the after-market petcock (a blind stab in the dark), and again nothing. The behavior of the 50mph lean surge persisted.
At this point I am up a size on the mains, and up two sizes on the pilots. I have not shimmed the jets, but considering the fact that the performance has gotten worse as I have gone up in jet sizes, I don't think that is the issue.
Again, i'll take any and all suggestions that people can come up with.
Brian
When you replaced the stock petcock, what did you with the vacuum pipe from the carbs?
You should have blocked it off, if it isnt blocked off, it could be causing your lean condition.
Also, for the surging, check the chain tightness and condition. That can also cause a surge at certain speeds.
I agree with vinny. It sounds like there is an air leak somewhere. Make sure your airbox boots are tight around the outside of the carb mouth, and your carb boots are fully seated and tight on the intake. Also make sure that your carb breather tube is kept out of the wind. It should terminate behind the airbox and be held there by one of those flexible clamps that is screwed un under the bottom left corner of the air filter.
Oh and for sure if you haven't already, you have to cap off the place where the vacuum line attaches to the left carb if you are going to run a non-vacuum petcock. I used one of the same kind of caps that go on top of the carb sync ports.
For a stock setup, 125/40/3 turns should be perfect give or take half a turn on the mixture. You can probably get away with 42.5 pilots, but I would think you would want fewer turns out to avoid being rich at idle.
Thank you both for weighing in. I made sure to block the vacuum line coming out of the carb when installing the non-vacuum pet chicken. I used a short piece of the original tube, blocked with a dowel/pin.
Also, I went all around the carb/airbox area with starter fluid, spraying it in the direction of points where leaks could occur. I noticed no idle change whilst doing this, which would seem to indicate no leaks of air.
As for chain tightness, I have adjusted the chain to factory settings.
I have been advised to check compression, which I will do this evening. I also am going to take it for a ride and see how it performs with the gas cap open. Although I don't think that is the issue, i'm really scratching the bottom of my barrel at this point. Short of that, i'm looking for a set of running carbs that I can replace my carbs with just to see if that is really the culprit.
If there is anyone in the Detroit area that has a functioning GS500e that they wouldn't mind me swapping the carbs off of, just to see if it will run on my bike, that would be awesome. I would be willing to come to wherever would be convenient.
Or, if someone is selling a set of functioning carbs, please PM me
Thank you guys again for the insight. I appreciate it
Brian
I bet you have a 'bad' igniter, or sumptin else ignition related.
Pinched fuel lines?
Is the undertank petcock full open - the slot facing totally vertical?
No other fuel filters in the system?
Michael
Tonight I went through the carbs again. Tomorrow i'll be soaking them in carb cleaner and then i'll reassemble them. I came across one thing of interest. There appears to be a crack in the tube for the enrichment circuit on both carbs. Attached is a picture (assuming I figured out how to attach a picture).
(http://a3.sphotos.ak.fbcdn.net/hphotos-ak-ash4/473509_3523227880442_985408131_o.jpg)
In regards to the recent suggestions: The fuel lines have been straightened, although that was something that I was fearful of initially. The tank chicken is fully open, I figured that one out the hard way by spilling gas all over my drive way. I have a fuel filter on both the main and reserve line. While this definitely could limit the flow, when I connect both main and reserve lines to the carbs via the t-fitting I still have all the same behaviors.
In regards to a bad igniter (coil, plug wires, harness, etc), I would think if that were the case one plug would appear more brown than the other. But, both carbs are equally white. This leaves me perplexed.
Thank you guys for offering your suggestions. I wish that they all were the solution to the problem so I could stop tearing the carbs apart and just start using the bike.
Brian
Quote from: gilkeyb on July 23, 2012, 08:34:36 PM
Tomorrow i'll be soaking them in carb cleaner and then i'll reassemble them.
That is generally frowned upon - too many plastic parts that are not generally supposed to be removed.
Only soak 100% metal parts. Which might be what you meant, but some people have really screwed a carb by forgetting plastic bits they don't see and then melting them in carb cleaner.
What the Haynes manual says:
Caution - the carburetor bodies contain plastic parts that cannot be removed. Do not dip the carburetor bodiesYou have been warned, hopefully in time.
Everything in this thread seems to point to a vacuum leak to me. Have you tried spraying starting fluid around the carburetor?
I would also try to ride the bike around at a lower speed which you haven't experienced problems with, only ride a gear or two lower than you normally would. The higher revs will give you a stronger intake vacuum making any leaks between the carb and engine more apparent.
Also, if you can safely/legally do it, try maintaining full throttle in gear 6 to see if you have the same symptoms (steep hill maybe?). If you can do that without surging it means fuel delivery is not your problem, and again points to a vacuum leak.
(http://sphotos-b.xx.fbcdn.net/hphotos-snc7/c100.0.403.403/p403x403/580997_3524047820940_1035180209_n.jpg)
Upon going through the carbs last night I returned to an issue I noticed when first breaking them down. The gaskets on the bottom end of the guides look pretty shoddy on both carbs, and they weren't included in the rebuild kits. Does this picture look like something that could cause issues? And if so, does anyone know where to get that part, be it just teh o-ring or the whole guide?
Quote from: Badot on July 23, 2012, 09:56:01 PM
Everything in this thread seems to point to a vacuum leak to me. Have you tried spraying starting fluid around the carburetor?
I would also try to ride the bike around at a lower speed which you haven't experienced problems with, only ride a gear or two lower than you normally would. The higher revs will give you a stronger intake vacuum making any leaks between the carb and engine more apparent.
Also, if you can safely/legally do it, try maintaining full throttle in gear 6 to see if you have the same symptoms (steep hill maybe?). If you can do that without surging it means fuel delivery is not your problem, and again points to a vacuum leak.
I couldn't agree with you more. I have tried spraying starter fluid all around the carbs, on both the airbox and engine side. I'll try this again once I put the carbs back together, but it didn't appear to be the issue before.
Before I rejetted the bike, it would pull in 6th at WOT throttle well. But after rejetting it will no longer do this. It pulls decently in 6th up to about 70, but not beyond.
Every time I touch the carbs on this bike, performance changes (sometimes for the better, sometimes for the worse). So that seems to point to the fact that the issue is infact in the carbs. Although, a deeper concern is that there is some type of leak in the engine, which would most likely be catastrophic. I have to contact the auto parts store to see if they loan out compression checkers, as mine doesn't have the right threads.
Brian
You most likely won't find a compression tester with the right threads at the auto parts store. At least I couldn't. I ended up buying one. I'm strongly leaning toward the issue being in the carbs and not the engine anyway.
I don't think that the small crack in the enrichment circuit tube will affect much, but I'm not 100% on that. Maybe it could be fixed with some solder? The o-ring at the bottom of the white slide holder, I've never been able to source that one. Yours doesn't look terrible, I've seen worse (albeit not in a running carb). I would just rub some 2-cycle oil on it and make sure it has integrity. It gets pressed down into the carb and tighted down with the main jet screwing into the emulsion tube anyway.
One thing for you to check would be the diaphragms. You might have a hole in a diaphragm, or they could just be very stiff and preventing the slide from moving as it should. One sign of this would be if you have to do a lot of work to get them back into the groove for reassembly. I replaced my diaphragms that didn't even look that bad, and it helped the bike feel much more smooth and responsive.
I think the best test for you at this point would be a carb swap with something with working carbs.
Quote from: gilkeyb on July 24, 2012, 04:42:27 AM
(http://sphotos-b.xx.fbcdn.net/hphotos-snc7/c100.0.403.403/p403x403/580997_3524047820940_1035180209_n.jpg)
Upon going through the carbs last night I returned to an issue I noticed when first breaking them down. The gaskets on the bottom end of the guides look pretty shoddy on both carbs, and they weren't included in the rebuild kits. Does this picture look like something that could cause issues? And if so, does anyone know where to get that part, be it just teh o-ring or the whole guide?
This thread suggests that that would be 1mm thick 10 mm ID 12mm OD (should be square-section but improvised with round section.)
http://gstwins.com/gsboard/index.php?topic=34265.msg381563#msg381563 (http://gstwins.com/gsboard/index.php?topic=34265.msg381563#msg381563)
Mind, some of the measurements there don't seem to coincide with my measurements, but mine are hampered by the state of my o-rings - and I haven't taken this part apart, nor do I intend to at this time.
This is one of the parts that is not supposedly removable, though you have obviously removed it. The way to get a new one, per any of the parts sellers, is to get a whole new carb body - it's "not supposed to be repairable" and parts are not separately available.
My el cheapo compression tester from Harbor Freight had the proper threads for the GS.
Now, to those who know the GS better than I: Would it harm the bike to run it on one cylinder temporarily? If one cylinder runs fine and the other does not, you would at least narrow down your problem area not to mention give you something to compare (ex. if one cyl. is fine and the other isn't, and both those o-rings look the same, it's probably not those)
Well, i let the carbs soak temporarily in thinned mineral spirits today. Upon taking them out I sprayed them out with carb cleaner and then let them sit for a number of hours. After leaving work I again sprayed out every passage, this time with Jet spray Gum-Out. To fix the hole in the "choke jet" (for lack of a better term), I used a very thin walled piece of brass tubing and some jb weld. The gastket at the bottom appears to possibly be available with the purchase of a new slide guide, at the price of ~70 dollars each. So, I put a very thin layer of RTV on this and clamped it in place. RTV is probably not the best option here, as its not entirely fuel proof. But, I suspect very little, if any, fuel will be in that area.
Lastly, I purchased a compression tester from Advance (o'reillys didn't have one for sale or rent). I only used the 12 mm adapter and my own compression tester, so heres hoping I can return it. The long and short of it is that the compression checks out to 120 psi on both cylinders with the carbs off. From what I have read, this is slightly below recommended (140-190psi), but not bellow minimum (114psi). So although it is marginal, I suspect that compression is acceptable in both cylinders.
I ordered a set of diaphragms today as well. If that fixes the problems, it'll be the best $50 that has been spent on this whole project. If it doesn't, i'll have some new in package diaphragms for anyone interested :embarrassed:
Brian
Well, I got the carbs all back together tonight. Started it and it started idling perfectly. I let it warm up and sprayed starter fluid, looking for leaks: Nothing. No air leaks. Took it for a ride, experienced lean surge at 55mph. Darn it. I shut it off mid-lean-surge and coasted the last 1/2 mile home. Checked the plugs and as to be expected, VERY WHITE. Definitely still lean.
At this point I am:
40 pilots
125 mains
1 shim (3x1mm washer)
3 turns out
No petcock (both main and reserve on tank running straight to carbs)
I'm so beyond lost at this point. The last remaining thing to check, which will have to wait til tomorrow, is running with the tank open. I forgot my spare key tonight otherwise I would have done it then. I talked to a mechanic friend, his advice was "the pilot circuits on those mikunis tend to get clogged up". I would not be surprised at all if that were the case, but i've been through them 3 times with a copper rod and sprayed them out multiple times with gum out. I would have hoped to get all the gunk.
Thanks to all that have weighed in. Hopefully the cause of this can be found eventually...
Brian
Are your exhaust header bolts tight, and do you have exhaust header gaskets in good shape?
Quote from: bombsquad83 on July 25, 2012, 06:39:00 PM
Are your exhaust header bolts tight, and do you have exhaust header gaskets in good shape?
I can honestly say I haven't checked that beyond the visual "Well, its not dangling off, so I think its ok" check. I'll go through tonight and make sure that everything is in order with the exhaust.
I'm really starting to sell myself on the gas cap not flowing (although I had already checked that in some fashion). Then again, i've talked myself into believing my fixes would work a lot of times on this project!
Brian
Quote from: bombsquad83 on July 25, 2012, 06:39:00 PM
Are your exhaust header bolts tight, and do you have exhaust header gaskets in good shape?
+1 on this. Bomb beat me to it ;)
- Bboy
If it's not the exhaust, then it could still be a fuel flow issue. If you run straight up to 55 and keep pushing, does it start sputtering right away, or does it take a while and then start to sputter? After checking the carb breather tube, and the gas tank vent for proper air flow, all that is left in your situation is the needle valves (since you eliminated the petcock). It could be possible that they are adjusted too tight, but they are allowing some fuel flow just due to wear. However, when the bowl empties fast enough, there is not enough flow past the needles to keep up.
Also, I would be very careful running with no petcock...if the needles stick and start allowing gas to flow freely, you will have a flooded mess.
Quote from: bombsquad83 on July 26, 2012, 08:42:05 AM
If it's not the exhaust, then it could still be a fuel flow issue. If you run straight up to 55 and keep pushing, does it start sputtering right away, or does it take a while and then start to sputter? After checking the carb breather tube, and the gas tank vent for proper air flow, all that is left in your situation is the needle valves (since you eliminated the petcock). It could be possible that they are adjusted too tight, but they are allowing some fuel flow just due to wear. However, when the bowl empties fast enough, there is not enough flow past the needles to keep up.
Also, I would be very careful running with no petcock...if the needles stick and start allowing gas to flow freely, you will have a flooded mess.
From a stop it will run up to speed fine and then gradually will surge more and more aggressively, forcing you to slow down.
I considered the needle valve. But, those were replaced when I rebuilt the carbs ~1 month ago. So I would hope that they were ok. But what you describe certainly is possible. I set the float height according to this recommendation
http://cgi.stanford.edu/~sanjayd/gs500/Maintenance/FloatHeight
I definitely agree with you that it feels like the bowls are running out of fuel, and thats when the bike starves. Which is what leads me to believe its above the carbs thats causing the issues. But, everything appears to be clean between the tank and the carbs. I'll have to be sure to go through them one more time...or two.
Thank you for looking out for my lack of petcock. I have been sure to clamp off the line running to the carbs when I let the bike sit. I pull the clamp off only when the bike is running.
All hope isn't lost yet. More things to check and double check at least means I don't have to give up on it. Thanks for your help bombsquad
Brian
I don't trust aftermarket (K&L) needle valves. I had a set that I was never able to get to work properly. I finally replaced them with OEM and haven't missed a beat since. Ronayers.com is a good source for these, or you can try your local dealer.
You could verify the carb bowls are running low. When the surging gets bad, stop quickly and safely. Quickly clamp the gas line, then measure the gas in bowls with the U-tube method. I sure wish they would make carb bowls with a little window in them...
I like vicariously wrenching through others :) :cheers:.
Quote from: bombsquad83 on July 26, 2012, 12:51:08 PM
...I sure wish they would make carb bowls with a little window in them...
I like vicariously wrenching through others :) :cheers:.
I should try to make one, maybe it just wouldn't work because all the fluids moving? but that sounds like a good idea
Quote from: bombsquad83 on July 26, 2012, 12:51:08 PM
I don't trust aftermarket (K&L) needle valves. I had a set that I was never able to get to work properly. I finally replaced them with OEM and haven't missed a beat since. Ronayers.com is a good source for these, or you can try your local dealer.
You could verify the carb bowls are running low. When the surging gets bad, stop quickly and safely. Quickly clamp the gas line, then measure the gas in bowls with the U-tube method. I sure wish they would make carb bowls with a little window in them...
I like vicariously wrenching through others :) :cheers:.
I like this idea a lot. As soon as I can get a chance, and it stops raining, i'm going to give this a try. It sure feels like the bowls are getting drained dry. But I never considered checking mid-surge because it just doesn't make sense for me to be running out of gas...
Thank you for your help, bombsquad. Its nice to at least keep some hope alive on this project. So keep coming up with ideas for me to check!
Brian
The conveluted fuel delivery system on these bikes is nuts.
I ripped it all out, used the on/off petcock from the tank, soldered two copper pipes up into the petcock joining the copper tubes as in a "Y" configuration, soldered that into a nipple for 5/16" fuel line.
I attached the fuel line to the nipple, ran it down beside the carbs, added a motion pro on/off valve.
From the on/off valve I added a few more inches of fuel line and a motion pro quick disconnect, and from the quick dissconnect enough fuel line to get to the carbs.
I leave the original tank petcock ON, shutting the fuel off with the motion pron on/off valve.
Don't want gas in the oil.....
When I want to take the tank off I uncouple the quick disconnect and am good to go.
Works great, no wanting for fuel at any speed.
No reserve, so learn to watch your fuel.
The End
That's way too much work...if you really want to get rid of the vacuum petcock see my build thread. Use a 2007 crf230x petcock. Only takes minor modification and it retains reserve functionality.
Sure, to each their own, if it works it works.
No real work involved, just a little soldering. The petcock already fit, it's stock. And it cost me nothin :)
Nice paint job though !
I'll add some things.
1. Are your plugs on tight? Lately I was having the same issue, and I learned that my plugs were backed out 2 turns. Oops.
2. Carb Vent Tube not routed correctly. If the carb vent tube that runs on top of the airbox is not routed correctly, it causes pressure issues that hurt fuel flowing freely. Make sure the end is routed somewhere out of the wind like behind the battery box.
The rest of the suggestions were my first thoughts as well.
Quote from: jestercinti on July 31, 2012, 07:55:19 AM
I'll add some things.
1. Are your plugs on tight? Lately I was having the same issue, and I learned that my plugs were backed out 2 turns. Oops.
2. Carb Vent Tube not routed correctly. If the carb vent tube that runs on top of the airbox is not routed correctly, it causes pressure issues that hurt fuel flowing freely. Make sure the end is routed somewhere out of the wind like behind the battery box.
The rest of the suggestions were my first thoughts as well.
Based on the fact that the plugs have been in/out/changed/switched and every variation in between, I know its not the plugs. They are in tight.
I do have the vent line from the carb routed to the same location as the vent for the airbox (lower right on trans case). I'll move that and give it a try. Unfortunately I have been out of town and won't get a chance to work on the bike at all until friday most likely. But, thanks to you guys, I have a nice long list of possibles to check out. I also have a new set of diaphragms waiting at the powersports store. I'll pick those up sometime this week, as well as some oil for my Fz6
That was probably one of the worst places you could put the carb vent for wind interference. Hopefully terminating it behind the airbox will help out.
Actually on second thought, the worst place to put the carb vent is connected to the tank overfill drain like another member had from a PO. Sure it works fine...until it rains and puts water straight into your carb bowls.
Quote from: mab32 on July 31, 2012, 07:38:08 AM
Sure, to each their own, if it works it works.
No real work involved, just a little soldering. The petcock already fit, it's stock. And it cost me nothin :)
Nice paint job though !
Thanks for the compliment. Didn't mean to slam your work. Glad it works for you and didn't cost anything. I hope for your sake that you never run out of gas!
The carb vent tube kinks EXTREMELY easily. I had the bike stall and run like hell for 10 minutes before I figured it out. Make sure that there is enough slack, and if necessary go to your local FLAPS and get a hose connector to extend the hose.
By the way, FLAPS = Friendly Local Auto Parts Store
If mounted the wrong way or into the wind just right, it will cause your symptoms. I'm not saying that it's 100% your problem, but it's worth a shot.
More info on "Crosswind Engine Stumble" http://gstwins.com/gsboard/index.php?topic=60976.msg705248#msg705248
Quote from: jestercinti on July 31, 2012, 11:11:21 AM
The carb vent tube kinks EXTREMELY easily. I had the bike stall and run like hell for 10 minutes before I figured it out. Make sure that there is enough slack, and if necessary go to your local FLAPS and get a hose connector to extend the hose.
By the way, FLAPS = Friendly Local Auto Parts Store
If mounted the wrong way or into the wind just right, it will cause your symptoms. I'm not saying that it's 100% your problem, but it's worth a shot.
More info on "Crosswind Engine Stumble" http://gstwins.com/gsboard/index.php?topic=60976.msg705248#msg705248
Well, Jestercinti, you're the winner. If you ever find yourself in the Metro Detroit area, i'll owe you a beer!
I re-routed the carb vent over the airbox and behind the battery (between the battery box and the rear fender). Took the bike for a spin and it runs like a dream. Cruising at 65, 75, 85mph didn't notice even a single hitch in performance. Just smooth sailing the whole time. YEEEEEEEEEEESSSSSSSSSSSSSSSS!!!! (sorry, I had to get that out of my system).
I parked it and it smells the least bit like fuel, so I may be a little rich now. My 3x1mm o-rings are probably closer to 2 shims than one. But its close, and it runs!
Thank you to everyone who weighed in and attempted to help me sort out the issue (bombsquard, jester, Bboy). I knew it was going to be something simple that I missed, and low and behold I was right about one thing! A slap on the wrist to remind me just how little I know about working on powertrains.
Brian
Congrats! Really glad you got it sorted out! Enjoy your bike now bud!
From post #10 in this thread :). Sorry, I had to toot my own horn a bit as they say.
Quote from: bombsquad83 on July 23, 2012, 08:27:58 AMAlso make sure that your carb breather tube is kept out of the wind. It should terminate behind the airbox and be held there by one of those flexible clamps that is screwed un under the bottom left corner of the air filter.
Quote from: bombsquad83 on July 31, 2012, 07:12:35 PM
Congrats! Really glad you got it sorted out! Enjoy your bike now bud!
From post #10 in this thread :). Sorry, I had to toot my own horn a bit as they say.
Quote from: bombsquad83 on July 23, 2012, 08:27:58 AMAlso make sure that your carb breather tube is kept out of the wind. It should terminate behind the airbox and be held there by one of those flexible clamps that is screwed un under the bottom left corner of the air filter.
You are absolutely right. I could have solved this issue much sooner if I had just heeded that advice. I do remember reading it, but for some reason I over looked it in my various trouble shooting steps.
So, I owe you a cold one too. Or a spin around the block on my awesome running 1990 GS500E
This actually couldn't come at a more perfect time. My girlfriend and I have had a trip planned to Ontario to visit family and do some sport touring around the lakes north of Toronto. I'll have to squeeze in some quick shake down cruises on the GS to work out fuel economy and road worthiness. If all checks out, this trip just got a whole lot better since she won't have to ride pillion the 400 miles there
Brian
Glad you got that sorted out... :woohoo:
My wife's uncle lives in Chesterfield, Township (Macomb County) so I may take you up on your officer at some point :cheers:
Definately a BIG congrats. Such a relief for you I'm sure. :cheers:
... Another bright side is: You have the cleanest carbs on a 90 GS500 in this hemisphere! :icon_rolleyes:
- Bboy
Well, since confirming the bike was running last tuesday, i've managed to put almost 350 miles on my GS. Mostly cruising around M-25 which follows the thumb of Michigan. The one thing i didn't like was the bike became quite "chuggy" below 2500 RPMs in 5th or 6th. I pulled the o-ring shim off my needle and that seems to have helped the situation slightly. I'm sure this makes me just slightly on the lean side, but i'll take a slight drop in performance for a more steady low speed and slightly better fuel economy.
The two fill ups i've done netted about 48mpg total, which seems a little on the low side? Most of the riding was just steady cruising at 65mph. Could anyone offer at about which point the bike hits reserve? Is it around the 3 gallon mark? Slightly more perhaps?
Thanks again to everyone for the help. I look forward to taking this touring next week. Its looking like we'll be doing ~1000 miles in 4 days
I think an oring shim is probably a little much. 1 washer is less than 1 oring I'm sure, and I had really good performance with 1 washer and 125/40 jets. You should really probably never be below 2500 rpm in 5th or 6th. That's pretty much bogging the engine and you should just go to a lower gear. At least in my experience.
Quote from: bombsquad83 on August 03, 2012, 08:51:39 AM
I think an oring shim is probably a little much. 1 washer is less than 1 oring I'm sure, and I had really good performance with 1 washer and 125/40 jets. You should really probably never be below 2500 rpm in 5th or 6th. That's pretty much bogging the engine and you should just go to a lower gear. At least in my experience.
Agreed on all counts. 1 washer would probably be perfect. When I get the chance i'll get a couple to put in. As it was I had access to o-rings at work, which are probably more like 1.5 washers, so thats what I tried.
And I definitely prefer to keep the engine up around 3500-4000 rpm. But, it has taken a serious amount of convincing to talk my girlfriend out of lugging the bike down too much. She has gotten rid of the habit for the most part, but I just wanted to make sure the bike wouldn't stumble too badly if it did drop down that low. Shes been well briefed on all the quirks of the little 500
Brian