Hello, so I've been away for awhile, but I finally got another GS500. This one is in much better shape than the previous one I had in that it actually runs, but its still a project. The main issue I'm working on right now is setting up the carbs right. The previous owner had them hooked up all crazy and it made no sense. I've since then put all the hoses back to where they are, cleaned a crap load of crap out of the bottom of the carbs and adjusted everything I can. I should note that the bike does have a yoshi exhaust and a lunchbox air filter. I have no idea if it was ever rejetted so I'm going to do that anyways. The main issue I'm having right now is that it's only running on one cylinder. I ghetto checked compression(thumb on spark plug hole) since my compression tester has become very unreliable and it seems very strong. Spark is also great with some new plugs so I'm assuming that it's not getting fuel. I know the left carb is feeding fuel properly because the bike idles smooth and I've even been able to ride it(before I knew about the one cylinder) although it was very underpowered. Basically I really don't know what all problems I have to deal with yet, but the main one right now seems to be getting fuel to the left cylinder. I'd appreciate any tips or advice on what to look for/do in order to figure out what's the cause and how to fix it. Thank you.
I decided to look into the floats to see if there was an issue there and maybe I'm doing something wrong, but no matter how much I bend the tab up the fuel level is still low. I'm using this guide: http://gstwin.com/float_height_check.htm. The fuel level in the tube is about 1-2cm lower than the top of the float bowl with the tab bent upward as much as possible.
I noticed with carbs, when the float needle gets old, it looses its springyness.. if you replace them, it clears a lot of float weirdness
I actually did try new float needles and it didn't. Help, if anything it actually made it a little worse.
Update: So I just set the floats by measuring 14.6mm. Right now I cant even get it to start without covering an air inlet with my hand. As long as I cover at least one of them the bike will start and then rpms climb up pretty high. I assume that means the bike is running super lean? Could this still be float related? The mixture screw is 3 turns out btw.
Also I said compression seemed good earlier. I have actual results now. I used a loaner gauge from autozone, so the accuracy of the gauge could be questionable, but I got about 100 on left cylinder and 105-110 on right cylinder. This was done completely cold and after adding oil the psi only increased by 5-10 in each cylinder. I'm doubting the accuracy of the autozone gauge, but I guss its possible it needs a valve job. The rings seem fine since it didn't jump up with oil and it actually looks like the cylinders have been off before(gasket sealant is visible around bottom of cylinders) so probably rings have been changed.
So all the valves needed adjustment according to specs, but they are now all in spec. Compression appears to be the same and bike still won't run. One thing I noticed is that the carb pours gas out of the air filter side. When I crank it and put my hand over the right carb's air intake i get gas all over my hand. That doesn't seem right to me, but idk...
Quote from: cmat1120 on February 26, 2015, 02:25:18 PM
So all the valves needed adjustment according to specs, but they are now all in spec. Compression appears to be the same and bike still won't run. One thing I noticed is that the carb pours gas out of the air filter side. When I crank it and put my hand over the right carb's air intake i get gas all over my hand. That doesn't seem right to me, but idk...
somewhere the fuel is being blocked.
under the float needle, the housing it sits in, that comes out... [I haven't figured out a way to take them out without damaging them] so if you remove them, you gonna need to replace them. anyways, there's a little fuel filter/screen thingy under them [unless someones removed them already] sometimes they will clog, and give you the same symptoms as stuck float needle. [fuel being poured back into the air filter]
I'm not sure what you mean... the brass colored thing the float needle is inside of with the o ring? Those just pop in and out on my carbs and theres nothing underneath them...
But also another update. I've swapped a whole other set of carbs from a known running bike and my situation is pretty similar to where I was in the first place. The bike will start and idle on just the left cylinder just fine, when I give it gas quickly it dies, when I give it gas slowly it revs all the way up, spark is great on both sides(visually) and compression in the right cylinder(the non-firing one) is actually higher than the left by about 5-10psi. I'm really not sure where to go at this point. I don't understand where the issue could possibly be if not the carbs, but it seems pretty unlikely that a different set would cause the same issue...
EDIT: I'm not sure if this is a fix or a bandaid, but puytting the pressure of the tank back on fixed it. Before I just had fuel pouring in via a funnel to the carbs and that wasn't working. I put the tank on and everything is perfect...except one very different issue. Fuel pours out when the petcock is on "on" even with the bike off. And doesn't come out at any other setting... I don't think that was happening before, but It might have been. Is this something fixable or should I just get a new/different petcock? I just realized the previous owner had the vaccum from the carb blocked off and it ran on "on", so I guess this probably was a previous issue.
Get an inline fuel filter.
i bought 2 of these, and would recommend them (or greater) if you're not planning on going all out on the bike.
http://www.amazon.com/gp/aw/d/B003CJ95V6
Seeing that your bike is rejetted, and if you want to go all out on it, you might want to look for larger filters.
Yeah, get a fuel filter because he's already got to little gas to the engine :cookoo:
Cmat, I didn't see where you said what your jets are at, but you could give the jetting matrix on the wiki a look if you think it might be your issue.
The bike seems to be running great since I put the different carbs on and the tank. I have a whole new issue now(broke the valve cover threads on my head.. Stupid aluminum lol) but I think carbs are good now.
Awesome, good to hear! Those aluminum bolts are pretty weak, I think the torque specs are sometimes even in inch pounds :technical:
.... thinking.... fuel stations in florida must be crappy! ... selling filthy dirt particle laden fuel at every corner!
... or someone just can't bring themselves to swap to another station?!
:bs:
... there ya go menno! .. I remembered!
:bowdown: :woohoo:
Quote from: mennobike on March 04, 2015, 03:08:24 AM
Yeah, get a fuel filter because he's already got to little gas to the engine :cookoo:
Cmat, I didn't see where you said what your jets are at, but you could give the jetting matrix on the wiki a look if you think it might be your issue.
You mean 'too little gas'?
A good fuel filter doesn't restrict the fuel flow by much.
The ones I posted, actually work quite well on my bike.
Then again, I don't race my bike, and very seldom get above 8K rpm. Actually mostly stay below 6k RPM, unless if I want to accelerate a bit faster.
I think a lot of people have issues with rust in their carb. All the drab in there isn't from gas stations, but from the fuel tank rusting.
I don't have that issue with any of my other bikes.
My GS is from 2004, and it's possible that Suzuki has already addressed the issue in later bikes, but not on my 2004 version, and I believe neither on prior bikes.