Runs great ... sometimes.

J

John S

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All - new to this forum, but not to the bike. 1997 ZL600, 13,000 miles. It's all original, except for the typical maintenance items (plugs, tires, battery, etc.). Very reliable, starts easy, no problems. For years. I'm not a mechanic, so a reliable bike is important to me. Then, had a few rough years that didn't see much time riding, and now I'm paying for it.
So hear goes - fuel tap was leaking (and after reading numerous post hear, I understand so were the carbs) a few years ago. Took the bike to two different shops, both said the fuel tap was fine. I had the carbs cleaned by a shop (yes, in fact it did take them twice, how did you know?), and it was running pretty good. But, occasionally, fuel would leak in the garage, if I left the fuel tap"ON" overnight, but not if left in "RESERVE". That trick only lasted for a year however, and it started leaking bad. I searched for a few years looking for a new fuel tap to no avail, and tried another mechanic, who said the fuel tap was fine, just a bit of varnish in it. He cleaned the tank.... winter came, ... and then the bike sat for a year or two. I finally retrieved the bike, drained the tank, refilled with fresh gas, and it ran great... for about a mile. It's been downhill since.
This year I found this site (thankfully), and thanks to the advice here, rebuilt the fuel tap. So, I've been able to keep gas in the bike without having it fill the garage with fuel over night, and have been riding to work most days, but it just hasn't ran right all summer. Sometimes it's great, and other times I think I won't make it another block. Mostly though, it won't run smooth unless I have a decent load on the engine (accelerating, highway speed, or running up a decent hill). I imagined it's some gum in the carburetors, so I decided to try a fuel treatment called "Mechanic in a bottle" (I know it's probably a gimmick, but, hey, it was only $5). I drained the tank and ran the carb cleaner through it, let it soak over night per directions, and that seemed to help immensely, and every day it got a little better. I refilled with two gallons of fresh gas, and it ran GREAT... for two days. Then (on the same tank of fuel that it ran GREAT on twelve hours earlier), it's running poorly again. I added a little Chevron Techron to the gas, and it cleared it up nicely... for a few days. The next time I decided to fill the tank all the way, it's leaking fuel again. If I keep less than half a tank of fuel, however, it seems to be OK, at least as far as the fuel leak goes. And this goes on for several weeks, thinking that the fuel treatments are helping... or not. Sometimes the bike drips a bit of fuel as I park it in the garage, sometimes I leave a noticeable trail of fuel up the driveway, and other days it leaks no fuel whatsoever.
This week I did some poking around, and discover plugs two and three are covered in muddy green goo - concentrated antifreeze, I presume. Naturally, plugs 1 and 4 (the ones you can see without pulling the tank) are clean and dry like the day it was built. Curiously, when I pulled the tank out (to look at plugs 2 and 3) and disconnected the fuel line and vacuum line from the fuel tap, fuel dribbled out the vacuum port of the fuel tap. The #2 and 3 plugs and spark plug boots were basically fried, so I cleaned out the goo and replaced all four plugs and the two damaged spark plug boots, and one wire (that was a bit short after I trimmed the damaged end back). The next day it ran the best it ever ran that I can remember!... for six miles. Then it started to sound a little rough for the next block or so before I got to work. That night, it ran so-so, but definitely got rougher as it warmed up (only a six mile ride home). Upon inspection, I can see a little dampness on the valve cover gasket.
So, I'm fighting multiple battles that I know aren't related. I figure the leaking valve cover gasket is the culprit for the rough running engine. I guess I need to have the carburetor cleaned or rebuilt - or do I? The dribbling of fuel from the fuel tap has me concerned as it's clearly not right, and I just rebuilt it a few months ago with OEM parts (yeah, I read up the aftermarket rebuild kits here, and heeded your advice). Is it possible a damaged diaphragm in the fuel tap is allowing fuel to be pulled by the engine vacuum and down into the carbs? Not sure what to do on that short of tear the fuel tap apart and rebuild with new parts (again).
I know the right thing to do is to replace the valve cover gasket, but I don't have a reputable shop I can take it to, and I don't know how to do it myself, and don't have much time to learn (and, for the record, I usually break more than I fix). Is there any chance I can buy some time with the coolant weeping at the valve cover gasket with radiator stop-leak, such as BARS leak, or am I just asking for trouble? Does anybody think fuel treatments (like Gumout, Seafoam, or any other) are effective at cleaning carburetors over a period of time (or is pulling the carburetors and sending them out to be cleaned my only practical option)?
Any advice on any (or all) would be most appreciated!
Thanks!
 
I have just seen that you have a petrol tap leak. You need to get that sorted as a priority - the 900 and 1000s have a known issue with the taps. This can go badly wrong if not fixed - it is called a hydro lock and can end up with a bent con rod!

The carbs will almost certainly need taking off and given a good cleaning.
Have you looked inside the petrol tank? Is there signs of rust or debris in there? If so it must be cleaned out properly to avoid the carbs being plugged againg.
 
John S said:
I know the right thing to do is to replace the valve cover gasket, but I don't have a reputable shop I can take it to, and I don't know how to do it myself, and don't have much time to learn (and, for the record, I usually break more than I fix). Is there any chance I can buy some time with the coolant weeping at the valve cover gasket with radiator stop-leak, such as BARS leak, or am I just asking for trouble? Does anybody think fuel treatments (like Gumout, Seafoam, or any other) are effective at cleaning carburetors over a period of time (or is pulling the carburetors and sending them out to be cleaned my only practical option)?
Any advice on any (or all) would be most appreciated!
Thanks!
Click to expand...


Do not put any sealers into the cooling system! You are just asking for more problems in the long run.
Seafoam does wonders but it will not fix all problems like magic. Most people who rebuild carbs dont know about the trick of pollishing the needle seats to get a good seal wich is sometimes the only real problem you get when an otherwise competent mechanic in a shop does your carbs (but seeing you were there twice probably other than competent!)
Antifreeze leak is not the valve cover gasget nor is it the culprit of the ruff running engine. Your tank needs cleaned and the petcock and carbs need going threw by someone who knows this bike.

Post up your location and see if there are any of us zl-oa mechanically inclined close to you who could or might be able to help youi with your problems.,

Otherwise take the petcok and send it to markus56 for a rebuild, send the carbs to wicked zl for a proper rebuild and take your time to find the antifreeze leak and fix it.


Chances are high that if you take your time and are patient with our help here you could fix it without breaking anything and only have to do it once!
 
Thanks Vinny - Fortunately for me, it would appear the fuel runs back into the airbox instead of towards the cylinders. And since I replaced the fuel tap internals, the fuel leak (if any) stops a few seconds after the engine stops. Yes, I checked inside the tank when I was working on the fuel tap a few months ago - it looked clean, no corrosion or debris. I was wondering if I should replace the fuel line from the tank to the carburetors, but I can't see how, without pulling the carburetors. I drained the carburetor bowls last week in case some debris was trapped in one, but didn't think to use a clean glass jar to see if anything washed out. The bike didn't run much different after draining them, however.

Thanks Paulfun - I'm in Southeast Connecticut. Fortunately, I'm patient, but perhaps that's why things are degrading, while I'm patiently waiting for the Seafoam to dissolve the residue that may or may not be there. I admit my ignorance here. I don't see antifreeze coming out the weep holes (it did a few years ago, but had a shop fix it - rather pricey repair for a few O-rings that probably cost less than $1 each). The hoses look solid and dry, as do all the visible connections, hose clamps, etc., but the valve cover is damp. Would the leak be under the cover? Believe me - I'd send the carbs to wicked zl if I thought I could get them out of the bike. And every time I say that's the last straw, and convince myself to tear it apart, the bike straightens out and flies right... for a few days.
 
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:hello: In order to check fuel valve to see if fuel is constantly flowing pull the fuel line & see if fuel flows in all positions. If so something is wrong. If you have fuel dripping an o ring can be pinched. I thing there is a very small o ring on the diaphragm that would cause the vacuum not to function properly. Markus on are forum specializes in rebuilding fuel valves. Also Rick from Old school carbs can redo them. He replaces all the internal parts & ultra sonicly cleans them. When they come back they look better than new. His price range is @ $180 to $200. Or a cheaper option is my Kaw Tech will do them for @ $25 to $50 plus any necessary parts like o rings. He has done many of carbs for myself & friends of mine. I have never had a problem with his work. He has done work for me for the past 28 years. Another option is there is a wright up with photos in the Tech section of our forum that shows & explains in total detail on how to rebuild carbs.
 
As far as coolant leaking onto the motor you my have a loose hose clamp on a hose at the thermostat housing. Some times corrosion gets between a hose & the housing that can cause it to leak under pressure. In that case just remove the hoses & clean them inside & take a small brass wire brush & clean around the thermostat housing. Have you ever flushed the radiator. I am not 100% sure buy I think the drain plug should be down under the motor on the coolant systems coolant pipe just above the header pipes. That is were the one is on the bigger ZLs.
 
I agree with PaulFun. I let my bike sit with gas in the tank and the carbs for years and paid the price. My pilot jets were caked solid and my tank had bunches of crap/rust in it. I think you have crap in your tank and might need the carbs rebuilt. One to two years might be long enough to crap up your carbs and tank. Almost sounds like the carbs aren't too bad and you keep getting crap from the tank once in a while. The fuel system definitely needs to be looked at to determine what your issue is. After I cleaned my tank, I drained my tank a number of times into a gas container to ensure the gas was clean. You might try to run some of your gas from the petcock into a container after your bike sits for a while to see what comes out. What does your tank look like when you peer into it?

The petcock should stop fuel flow but the float needles should also. Polishing float needle seats is a highly recommended step. Listen to PaulFun, he knows what he is speaking about.

As long as the green gunk is on the exterior of the plugs and not in the motor, you are better off. I haven't worked on a 600 but I assume it has a manifold on the back of the engine. The O-rings that seal the manifold to the engine can fail as they age or as RJ mentioned the T-Stat housing or the hose running to the manifold.

Good luck!!

Al
 
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+1 for Paulfun's recommendations.

Your petcock issue could be related to running problems, if it is leaking gas into the vacuum hose then your dumping more gas in thru the carbs. Definitely get that fixed, send to Markus56; you want someone who knows what they're doing on this.

WickedZL900 is the best carb guy on the site [no offense intended to anyone..], he has the equipment, parts and experience to do the job right. Check out his web page at:

http://www.oldskoolcarbs.com/

Agree that leaky valve cover is messy but won't impact performance, if you pull the cover to fix the leak may as well adjust the valves.

Interesting side note, came across a site where the guy claims to be a motorcycle mechanic for 20+ years and he says the biggest mistake people make rebuilding carbs is polishing the seats. Know for a FACT that the only way to clean these up enough to seal is to polish them, kind of scary the "Professional" advice out there.
 
If valve cover is not leaking oil & the coolant is external there is no reason to pull the cover. With only 13K. miles there is no real reason to adjust the valves. He may want to run an external fuel filter. Depending on money situation $25 is a lot less than $200. The Tech I use has a full blown shop in his back yard including a machine shop with lath, mill & 2 boring machines. Yes he knows what he is doing.
 
OK - thanks all. Sounds like I need to look harder. I just got new glasses and can't see up close unless I take them off. But then I can't see more than six inches in front of me. I'll pull the tank and take another look at those hoses and the spark plug wells.

When I pulled the tank a few days ago, the fuel tap did not leak any fuel. I know it will in the prime position, so didn't bother to test that. I didn't flip to reserve while it was off the bike. But I'll try all three next time the tank is off.

No - there was no coolant inside the cylinder, but the spark plug boots for cylinder 2 & 3 were covered with the goo, inside and out. The goo worked it's way up inside the boot and fouled the plug connections. I'm pretty sure that's why the pin on the top of the plug, as well as socket on the inside of plug boot both looked fried. #2 was the worst - the silver plating on the pin on the top of the spark plug was completely gone, and it was down to bare copper, and the plug boot did not feel like it was making solid contact with the plug.

When I rebuilt the fuel tap a few months ago, the tank looked clean and corrosion free, however, no, I did not flush it. The screen on the pet **** looked fine - nothing on it, and no rips or tears either. My fuel tap looks a bit different than the photos I've seen on this website - externally the same, but internally, it has two plastic risers (they look like soda straws), that are etched out to make a screen to filter the fuel. The etchings are at different heights on the risers, and the riser with the lower etching lines up with the reserve position on the fuel tap, So, its immune to a lot of the typical problems others have reported, like the "figure 8" issues and a few other problems that I can't recollect at the moment. Anyway, both risers (one for normal, one for reserve), both looked fine. As recommended on this forum, before I rebuilt it, I soaked the metal parts in carburetor cleaner at my brother-in-laws shop (auto mechanic - he's not familiar with bikes), making sure to keep the plastic parts high and dry, and cleaned them up before I reassembled. I only wiped with a rag - I think someone recommended using steel wool, but I didn't have any at the time. I had a few problems when I put it back on the bike - the tap was leaking around the gasket or diaphragm between the two halves. I snugged the screws up, and eventually it stopped. Mabe I buggered up the new diaphragm when I put it back together? I'm not sure where I screwed up.

Yes, I wanted to add a fuel filter after the fuel tap, but where? There's absolutely no room I can see to squeeze one in. I found a small one that might have fit, but it was for a very small engine - probably wouldn't let enough fuel through to get much past idle. I'm open to suggestions regarding what size filter would be appropriate, and where to locate it.

Oh yeah - one more oddity - a few weeks ago, I went to start it, and had my hand down near the choke lever. When I started the bike, a saw a little squirt of fluid (like you would get from an orange segment when you bight into it), that sprayed down and out onto the coolant hose coming up from the water pump. It evaporated quickly, so I'm guessing it was fuel. But from where? I've been watching to see if it would repeat, but the bike knows it's being watched.... I'm thinking this might somehow be related to the fuel I saw dribble out of the fueltap's vacuum connection perhaps?
 
think maybe the fuel line could be leaking slowly where it connects to the tank? Probably best to invest in some new fuel line anyway as when the original line gets old sometimes it needs a real hose clamp to keep a tight fit. when they get old and brittle the stock squeze clamp becomes useless!
 
:hello: 10 4 on post 11. :thumbsup: I switch to high quality hose clamps with all my motor machines including my lawnmowers.
 
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If your petcock isn't stock, its possible that you rebuilt with the wrong kit. The parts may have kinda fit but.....just sayin!
Putt
 
All - thanks for the info. I went back, and cleaned out the spark plug wells more thoroughly than before, and replaced the spark plug boot on #4 - the only remaining original boot is on plug #1. I checked the thermostat housing and hoses as best I could, and didn't see any evidence of coolant leakage up there. I tightened the clamps on the coolant hoses near the valve covers - but I couldn't get to the ones near the thermostat however. While I had the tank off, I checked the fuel tap - seems to be working fine. (I'm thinking now that when I thought I had fuel in the vacuum line, what I probably actually saw was fuel dribbling out the fuel line, but based on how I was holding the tank, I got the illusion it was leaking from the wrong port.)
It ran better after that, but still a bit rough. It ran pretty well if I had just enough fuel in the tank to keep it off reserve. I ran that way for a month. Then last week, when I was about ready to tear it apart, I decided to give it one more shot of Seafoam in the gas tank, and ran it to work and back, so the Seafoam treated fuel could sit in the carburetor overnight. The next day it ran GREAT! It's ran pretty smooth for the past two weeks now, about 15 miles a day (close to 150 miles total). I filled the tank all the way, and everything is holding now - no more fuel leaks. It's occasionally a little rough at idle, but purrs over 2,000 RPM, and I now have consistently smooth acceleration from a stop all the way up to highway speed. I haven't pulled the tank to see if I still have coolant weeping and collecting around the spark plugs, but so far things look good....

The sad part is, now that I finally got it to the point where it's ride-able, Summer is fading fast and it's almost time to put it away for the year. That said, is there a general consensus about how best to set the bike up for winter so I don't have to repeat this next year? I've typically just filled the tank with stabilized fuel, but would it be better to drain all the fuel from the tank and the carburetors instead? And if so, do most people simply let them run until the engine runs out of fuel, or drain the fuel from each bowl via the bowl drain?

Thanks!
 
:hello: When you store it if you can fill it full with ethanol free fuel with stabilizer. Full is so the tank does not rust. Disconnect the fuel line & put a screw in it with a hose clamp. Run the carbs dry or drain them. Also I thing it is a good idea to put @ 50 psi in each tire so they do not get a flat spot in them. Park the bike on a rug under the tires.
 
Thanks R. J. Unfortunately, no ethanol free gas to be had for about a hundred miles from where I'm at. I wonder if stabilizer with ethanol shield added to it would offset the derogatory effect the ethanol blended fuels pose?
 
:hello: Fuel longevity depends on your climatic location. Here in Florida in we average 90 deg weather with 90% humidity for 8 or 9 months out of the year. In colder dryer climates fuel tends to last longer. I have seen untreated fuel go bad in as little as 2 weeks. I use stabilizers & seen gas go bad in 3 months here in FL. We really ride 365 days a year so I really do not have a problem with fuel going bad in our toys. If fuel sits longer than a few weeks I use it in my mowers. My mowers are also used year round.
 
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