GStwin.com GS500 Message Forum

HI. First post here. I have a 95 gs500e. has about 20,000 mi. I have a few problems with the bike, but i think they may be linked. I cannot get the bike to start. It has a new battery and new spark plugs. It is getting a spark, and is turning over. From the sound of it, it is getting some fuel, because it is hitting. If i try to push start it, sometimes it takes a few tries, and i have to be going pretty fast to get it to crank up. The second prob is it wont idle below 3500 rpm. If i adjust the idle screw it will cut out and die if it gets below about 3000 rpm. I have not messed with the mixture screw yet.  Third, i cannot always get it to idle consistently at 3500. After the loooooooong warm up time (when it starts), sometimes it will still die. I am always playing with the idle screw to keep it running. Could this be a carb problem? If so, if the pilot jet is clogged, will that prevent the bike from starting and also cause the idle problem?  I am completely stumped.  :dunno:

Lean jetting... BTW you have the choke on when you try to start...
Clean carbs, get the float level checked, check for vacuum leaks and if all of that is correct, then take off crabs and rejet, 40 pilots 125 mains, 3 turns on mix screws, and 1 #4 washer under needle.
Cool.
Srinath.

Perhaps one or both of the carburetor pilot jets are partially clogged.  You can remove the carbs, scrub-out the bowls (and clean the needle valve while you're at it), remove the diaphrapm&piston, main jet and piston guide... then use a 1/64" drill bit to clean-out the pilot jet (this will also enlarge it from stock 37.5 to about 39.69, but that should only help).

I do have the choke on when i try to start the bike. Sometimes when the bike is cold i have to manualy push the choke lever back in with my finger as it warms up because the lever doesnt pull it all the way back. I have tried to adjust it, but it does no good.
Thanks for the advice, i will try that. Im not extremely mechanically inclined, but i know my way around good enough (i hope) :thumb:

oh, BTW, what is the best way to check for vacuum leaks? i have heard of the wd-40 test around where the carb joins the head, and have tried it. the bike did not rev or show any change, other than lots of burnt wd-40 smoke. is there another test that i havent heard of?

Could very well be carb related.  

Have you adjusted your valves lately.  As you put more miles on the bike the valves tend to reduce the clearance from the cams.  This can cause the same issues you mentioned.  

Thermal expansion while operating the bike moves the cams away from the valves slightly, sometimes creating normal operation with a warm engine.  You could check your compression with the engine cold.  

It doesn't matter what the carbs are doing if the valves are not operating properly.  Thanks for listening.  

MacDuff

One of these times, when the bike is acting up at low RPMs, pull the plugs and compare them against the Haynes spark plug chart (http://www.bbburma.net/Scans/Haynes_SparkPlugChart.jpg).

Don't freak out because of some of those pictures; I wouldn't expect anything more serious than Carbon fouling, which would mean that you're running rich.  A lean condition probably won't look much different than a Normal condition ... maybe more white than tan.

I already tried the plugs. i changed them about 500 miles ago and it still does the same thing. even the old plugs looked normal. they were tan, but had a little darker hue than the ones in the haynes pic. and i am getting a good blue spark. i dont know what is wrong with this thing. i still assume it is the carb, but will be a couple days b4 i can tear into them.

also, the bike always acts up in low rpms. there hasnt been any change in the way it runs no matter what i have done to it.

Light-colored plugs = good or lean
Acting up at low RPMs only = suspect (a) blocked pilot jet(s)

Given your info so far, I would break down and clean the carbs ... particularly the little metal parts ... especially the pilot jets.  You could go the "carb cleaning fuel additive" route first if you want, but it sounds like the bike is not exactly a joy to ride, so going through a whole tank of "tweaked" fuel may not be a desirable option.

I have cleaned my carbs a couple of times.  The first time was with very little carb knowledge, but with a good manual ("Gentlemen prefer Haynes"  :oops: ), an organized work area, a light touch and no deadline.  It's not difficult - just a little intimidating the first time you create a pile of parts out of a perfectly sound (looking) carburetor.  But if you take your time, do a good job of cleaning, and put everything back together in the reverse order without losing any parts ... I will almost guarantee a marked improvement.

Thanks, I will try cleaning the carbs. BTW, you mentioned carb cleaning fuel additive. After i get them clean, i will probably run some additive through it occaisionally just to keep them clean. Is it ok to run the same stuff as you would put through a car, Or is there a special kind made just for bikes? Do you recommend any specific type?

Quote from: Johnboyi will probably run some additive through it occaisionally just to keep them clean. Is it ok to run the same stuff as you would put through a car, Or is there a special kind made just for bikes?

I don't know of any kind made especially for bikes, but that doesn't mean they don't exist.

Still, the "car stuff" is just fine.  (Carbs are carbs, I guess.)  As far as a recommended brand - take your pick.  STP is pretty ubiquitous, but other brands should work the same.

ok thanks. i was looking at the carbs this afternoon, and the choke slide is binding. the cable works fine, but if i pull the choke, i have to push the slide back in with my finger. im gonna say i need a carb clean. thanks for your help, ill let you know how it goes.

Quote from: Johnboythe choke slide is binding. the cable works fine, but if i pull the choke, i have to push the slide back in with my finger. im gonna say i need a carb clean.

That could also be caused by dirt or lack of lubrication inside your choke cable housing.

The exact same thing happened on my '96.  It was a real drag to have to get off the bike after it was warmed up, so I could locate the choke slide and push it back in.  I replaced that choke cable with a new one, but have since sent the original cable to another board member - who lubricated it and got it to work just fine.

But I still recommend the carb cleanout.  :mrgreen:

:x  :x  :x  ok, i figured out the problem. I went to the local cycle shop just to get another opinion, and after a few hours they checked the compression on the bike. They told me that it was supposed to be running at about 150 psi per cylinder (which i have no idea if that is correct), but that it was actually running at 15 psi on one cylinder and 30 psi on the other. They said i needed pistons, rings, and valves; which equates to about $1000 at the least if i have them do it. Looks like im gonna be broke as piss for a while, cuz im not that skilled of a mechanic. Damn it all to hell.
:guns:  :guns:  :x  :x  :guns:  :x  :x  :guns:  :guns:

Quote from: JohnboyThey told me that it was supposed to be running at about 150 psi per cylinder (which i have no idea if that is correct), but that it was actually running at 15 psi on one cylinder and 30 psi on the other.

Their numbers are close enough.  Here is the scoop from the Haynes manual:


Bummer.  :x

Kerry, i thought about this also: (this is just my opinion, i dont know if i am correct or not) If the rings were bad, it should smoke all the time. The only time is smokes is at or very close to redline, and it is usually very little blue smoke. Also, if the valves were bad, wouldnt the bike backfire, suck air, tick like hell, or not run at all? I wonder if the head gasket could be blown. i dont know if that would make both the cylinders have bad compression, or just one. when i am trying to start it, it blows a lot of air out of the exhaust, i dont know if that is a sign of bad comp. or what. Do you think just the gasket could make it do that?

and also, why didnt it do this before? when i got it about two months ago, it would start and run fine, except for the idle problem, then it started crapping out. i wouldnt think it could happen that quick, but i dunno.

This sounds a little suspicious.  If you really had those compression figures I would expect a lot of oil to leak into the jugs and your plugs show no sign of oil fouling.  I'd be surprised that the bike ran at all with that little compression.  Pick up a compression gauge for $40 or less at your local auto parts store and double check before you let those guys tear your engine apart.

Also...there is NO WAY they could know you would need pistons, rings and valves from a compression test!

I thought I had a compression leak on my old Norton recently until I swapped the carbs.  Couldn't get her to idle under 2k and would sputter on one cylinder.  Different carbs and she settled into perfect idle.

They did a compression test without holding the throtte open. 15 and 30 = wont even run...I believe at ~ 100 it will stop running. Choke is extrerally lubed... wd40 with that thin red plastic spray fitting will work wonders. Lube it, and try it... also check valves.
Cool.
Srinath.

As far as the compression test goes, does the throttle have to be open for it to work? How do you do a correct one? hold throtle open, hit starter? does choke have to be on? i would think that if the compression was that bad, it wouldnt run at all. i can get it to start sometimes, but it takes a while, and it will push start, but i have to be going pretty fast. i dont understand why it was running fine except under 3500 rpm and wouldnt start if all that was bad

seshadri_srinath wrote: Choke is extrerally lubed... wd40 with that thin red plastic spray fitting will work wonders. Lube it, and try it

i tried that already. it worked for about two days, and then gummed up again.

WD40 is mostly a water displacer, with a little bit of oil and a whole lot of solvent as a carrier.  It will temporarily loosen things up, but when the solvent evaporates, it leaves only a small amount of oil (lubricant).  Tri-Flow has more lubricant that will stay-around; Lock-Ease (graphite powder in a solvent carrier) will also leave more lubrication in the cable.

I can't comment on the shop's suggestion, other than it sounds like the mechanic needs to pay for a new patio.  At the very least, I'd get a second opinion.  I agree that their PSI numbers sound unreasonably low.

ok. can you get tri flow at walmart or an auto parts store? ill have to try that

Not sure about Wal-Mart, as their inventory varies quite a bit between stores.  Tri-flow is sold at most bicycle stores, and many hardware stores, usually near the WD40.  It usually looks like this:
(http://www.touringcyclist.com/img/g/7618_1.jpg)

It claims that it's lubricant is Teflon, but I suspect that it is a Teflon/oil mixture.  Anyways, WD40 was not designed to lubricate, whereas Tri-Flow was.

If you want to go on the cheap side, some bicylists use WD40 first to help free-up rust, then follew that with a squirt of motor oil (from an oilcan), to lubricate.  But this is easiest done with the cable sheath empty and off the bike.  If you can figure out a way to get oil in there, then that is probably good enough.

Well, figured out the problem. i had a valve adjustment done on the bike, and it brought the right cyl. from 30 psi to 125 psi. The left cyl. did not change any. Looked further and the exhaust valve is broken. :x  :x  I guess that would explain the all of a sudden breakdown. oh well. could be worse. At least nothing fell into the chamber. id be really pissed if i had to buy a new motor.

ALLRIGHT!! Finally got my bike back from the shop. WOOHOO :mrgreen: Had them replace the valves. Now it runs like a brand new bike. It still hesitates for a second about 3k (still needs carb clean), but now it idles perfectly. One peculiar thing i was told is that when the shop pulled the head off the bike, the innards (pistons, rings etc.) were brand new looking, and the cylinder walls still had the crosshatch in them. The only thing that i can figure is that the valves must have been messed up for a really long time. B/c if the engine has over 20k miles on it, the cylinder walls should be worn, along with all the other parts. Thats cool though, because now i have a "brand new" 95 with over 20k mi. sweet. :thumb: To all who lended advice, thank you much.

Wel, getting screwed by the shop. Got the bike back, runs great, except leaks oil like a M.F. Looks like they are gonna get it back along with a big ass chewing