[cowtippinzfun]

When I joined this forum, I kept reading about how the fuel tank petcocks cause so many problem. At the time I didn't understand the issue because my 93KQ had a simple manual shut off valve with positions ON OFF and RES. Then I acquired 3 more 93/94 KQ's and the 94 had the valve with positions ON OFF and PRI and a vacuum port to carb. This is the type that causes so many problems. However, on my 94, the vacuum ports were plugged on the valve and carb and was run in PRI with no problems. What's this thing supposed to do? Fortunately I had one available for autopsy:

This is the back side cracked open. Turns out this thing is an automatic fuel shut off valve. A spring loaded poppet valve seats into the selector housing to plug the chamber that leads to the fuel pump feed port. Suck from the carb pulls it open. The reason there is no OFF position on the selector is because when its not running the poppet seats closed and shuts off the fuel, hence automatic OFF...when its working right.

Showing the inner gasket. What if this leaks?

Detail on the back side of the selector housing:

Pulled apart there are 2 gaskets and plastic plate between them:

Spring on the outer gasket side:

The spring is attached to this plate. The suck is put on this plate to open the poppet to let fuel into the fuel pump feed chamber:

Selector side:

These are the ports from the tank:

Back side of the selector note the chamber cut into it. Rotating it directs fuel from the various tank ports. Green is normal ON feed and is not switchable. Yellow is RES feed. It connects the reserve port to the normal port. With RES selected fuel is drawn from both the normal and reserve pickup tube. ON and RES go to the poppet valve. Red is the PRI position which is actually a bypass. It connects from the reserve port direct to the fuel pump feed chamber bypassing the poppet shut off valve. The selector pictured is oriented to the PRI position. You can visualize folding it back on top and see how the selector chamber directs the fuel.

The carburetor connections. Note the petcock vacuum is direct before intake into the engine:

I believe the problems these things cause is when the poppet gaskets leak, the vacuum to operate the valve sucks in fuel. The rouge fuel enters the engine intake after metering and carburetion causing an uncontrollable rich condition. Possibly in some scenarios a siphon or gravity feed with the engine not running causes fuel to flow into the piston area and subsequent crankcase fuel contamination. BS system. I can't imagine a good reason to design this type of tank valve. The on/off type is fine and why drag more vacuum off the engine? Its a solution looking for a problem. Probably a regulatory edict. Does sound like something a government bureaucrat would think is necessary. If you suspect your vacuum operated tank valve causing problems check the vacuum line for fuel contamination. You can run it in PRI with the vacuum ports plugged, disconnecting the rouge feed. Risk here is if your tank is dirty, the lower level position of the reserve tube will pick up the contamination. I intend to use the on/off valves on all my KQ's.

Maybe you can help me as the internet seems to have noone with my problem .I bought a used kfx400 and it DOES have on off res...there is no prime . And any replacement ones I see online say the same ...no prime setting. But the off setting is in the same place as prime is on users posts .could this be an aftermarket peacock and when I turn it to off it is actually just letting gas flow?

 

[McTool]

I doubt it , but pull the fuel hose off the carb and turn the tap to on and res to verify flow . In the off position no fuel should flow . The petcocks with the prime position will flow fuel in prime .....to prime the carb. These petcocks should be left in either on or res as when the engine is running there is manifold vacuum.....which operates a diaphragm and opens fuel cock . When engine is not running there is no vacuum ...tap stays shut ....no fuel flow.
Either type of tap will work you just have to use it correctly.
The thing with these quads ( and a lot of others ) is that fuel will flow under gravity so there has to be some positive way to stop it otherwise the only thing stopping your tank full of fuel pouring into your engine is the float valve . Float valve is designed to control fuel level in the float bowl and is supposed to flow fuel .......so they aint that great at positively stopping fuel flow , hence the petcock and the vacuum petcock turns fuel on and off for you automatically .
Generally they work well but having rubber components they dont last forever and will eventually need to be maintained .

 

[Foot0069]

Here's a replacement petcock if you want to ditch the vacuum style. And a rebuild kit for the fuel pump.

 

[ssmoot]

I just picked up a 99 Suzuki ltf300f king quad and had the cylinder bored out according to my mechanics advice. It runs but not good. It smokes really bad before the bore. Installed everything else, top end kit, new valves, and gaskets all around. It runs on startup with a perfectly clear exhaust but as soon as you hop on tk ride it, it starts smoking again. It has this slight ticking noise, can’t seem to ever read the oil level in the sight glass, (but I know there’s oil in there) it sputters out when you give it gas, it only will hold an idle at like half choke, and I recently just cleaned the entire carb out and all the needles/seats. Please help! I am wondering there’s a crank case vent or breather anywhere? Tube or some other form of ventilation? I also seem to have gas mixing in my oil?

 

[FathertimeNH]

Ok

 

[FathertimeNH]

First thing I would do is check the voltage going into the battery when it is running. My regulator was putting in 18+ and I had similar symptoms. I believe it should be about 14.5. If you unplug the regulator while the bike is running and it runs well you have found the culprit.

 

[ajl719]

Not exactly sure what a voltage regulator has to do with your symptoms, but anyhow. If your having to apply constant half choke to get your 300 to somewhat run ok then it still sounds like there’s a issue with your carb. What method did you use to clean your carb with..? You mentioned you did the needles/seats as well. Like did them in which way, by replacing them..? And your carb will have a vent tube that runs up and under the shift panel.

Now the gas in your oil can be a couple things. Either the float in your carb is stuck in a semi open position or it could be improperly set. The next way gas can mix with your oil is via the fuel petcock. The fuel petcock has a internal diaphragm that over time can develop a small pinhole or just deteriorate altogether. When this happens it can also cause your bike to run poorly. The most common symptoms of a failing or failed fuel petcock are: Poor idling, stalling, power loss, hesitation, bogging, backfiring, and oil contamination. To check to see if the fuel petcock is at fault pull the vacuum line off at fuel petcock. If fuel comes out the vac line or the line is wet, or if fuel comes out of the port where you removed that line, then the fuel petcock is shot and needs to be replaced. So if your fuel petcock is at fault this could also be another reason your bike is running like crap. And the reason your having to apply some choke to get it to run somewhat ok.

For a temporary solution to this, or as I like to call it, a bandaid fix. Plug the vac line at the petcock and plug the vac port on carb and run your bike in the “Pri” (Prime) position. Just make sure to return the fuel petcock back to the “On” position whenever the engine isn’t running as this setting still acts as a fuel shut off. The “Pri” setting is essentially gravity fed. Meaning fuel will flow regardless of if the engine is running or not. So it is imperative that you remember to switch back between “Pri” and “On” whenever the engine isn’t running or that will also lead to oil contamination.

Now when you say smoking, I’m assuming you mean like bluish type smoke like your burning oil..? Or is it more like a whiteish type smoke..? If it’s the later, when you had the cylinder bored did you upgrade the piston and install new rings..? Boring and honing are different. With honing most times you can reuse the old piston and just change the rings depending on the condition of the piston itself.

Bellow is a picture of where the oil level should be within the sight glass:

You’ll note two sets of lines on both sides of the sight glass. A upper set and a lower set of lines. Like on the image the oil level should be in between both sets of lines within the sight glass. If the oil level in the sight glass is over the upper set of lines or the glass is completely full, then you may have overfilled the crankcase. To much oil can also cause you to burn oil, which could be another source of the smoke. The amount of oil your bike should take is around 3.2 quarts without a filter, and around 3.5 quarts with a filter. Note: Whenever checking your oil or performing a oil change make sure whatever surface your bike is parked on is as level as can be. Failure to do so can result in having insufficient oil or too much oil.

 

[Foot0069]

Great tech tips. Checking the clutch unit is a good maintenance tip for that old machine. I haven't looked at my machines yet but I do know the brake fluid resovoir is so cloudy you can't see through it.can the.oil glass do the same?

 

[ajl719]

I haven't looked at my machines yet but I do know the brake fluid resovoir is so cloudy you can't see through it. Can the.oil glass do the same?

The oil sight glass will not discolour over time. It will however get caked on with dirt and mud. Which with a simple wipe of your finger or cloth will clear it up. The oil sight glass is one of my favourite designs of the older KQ’s and QR’s. I wish Suzuki would of stuck with this features on all if it’s atvs throughout the years. It so easy to check your oil level and even better when doing a oil change as you don’t have to repetitively pull the dipstick. It was a simple design but was very practical and functioned great. Quick glance, oil level is fine, hop on and go. So easy you wonder why Suzuki every parted ways with it.

 

[McTool]

The oil sight glass will not discolour over time. It will however get caked on with dirt and mud. Which with a simple wipe of your finger or cloth will clear it up. The oil sight glass is one of my favourite designs of the older KQ’s and QR’s. I wish Suzuki would of stuck with this features on all if it’s atvs throughout the years. It so easy to check your oil level and even better when doing a oil change as you don’t have to repetitively pull the dipstick. It was a simple design but was very practical and functioned great. Quick glance, oil level is fine, hop on and go. So easy you wonder why Suzuki every parted ways with it.

Funny you should say that coz Im thinking its the worst sight glass I seen , hard to see and real sensitive to being perfectly level to get consistent level .
And , just for the record , after a complete drain (clutch cover off ) and filter change mine took almost exactly 4 liters ......filler is worse to get at than the sight glass .

 

[ajl719]

I’m not sure how you think the oil sight glass is the worst. It’s real easy to read and quick to check. And sight glass or not, even with the dipstick method having your bike as level as possible is the best way to ensure a accurate oil reading.

And those oil quantity numbers are per the manual, I’m not making them up. This information is based on a regular oil change with and without a filter. Clutch cover removed, then 4 litres is probable.

 

[McTool]

I’m not sure how you think the oil sight glass is the worst. It’s real easy to read and quick to check. And sight glass or not, even with the dipstick method having your bike as level as possible is the best way to ensure a accurate oil reading.

And those oil quantity numbers are per the manual, I’m not making them up. This information is based on a regular oil change with and without a filter. Clutch cover removed, then 4 litres is probable.

I think it hard to read stuck under the guard where its hard to see and harder to clean . I think also that the length of the cases gives the oil more room to slosh away from the sight glass.
Im comparing ease of reading and fussieness about level with my old LT250ef, sight glass easily visible , stays clean and reads more consistently when a bit off level .
I wasnt suggesting at all that you were just making up figures, dunno why you'd think that . Merely saying , seeing as no one else had ,that if you give it a really good drain 3½l wont cut it , you'll need 4.🙂

 

[ssmoot]

Thank you all so much for the tips and tricks! Our mechanic actually said he bored out the cylinder and installed a new wiseco piston with rings. He also cut new valve seats along with new valves. He also said that it takes 2 hours of run/riding time for the valves to become properly seated. Same with the rings. so my smoking probably is resolved. Now I seem to have a rather decent leek right on the top of the case by the starter dripping down the side with the exhaust. It’s not coming from the starter per say, but it could be? I do not see any residual oil or any fluid that could leak from there anyway. It will not hold an idol either. And my idle adjustment screw is literally either really really stuck, or screwed all the way in and won’t come out. I can not get it to turn even the slightest bit. (At least I think fits the ideal screw, according to reference manuals and whatnot.) I also seem to not be able to see any oil in the sight glass, SOMETIMES. Sometimes I can see it, and sometimes I can not. It’s really weird. But I know the right amount is in there because I have been changing it like crazy trying to get this thing to run right. Other than that, it actually “rides” pretty nice.

 

[ajl719]

The oil sight glass was a good design on my honest opinion. It’s just takes a almost perfectly level surface to get a accurate reading. So if your bike is off level leaning to the left, the oil in the sight glass most likely won’t show up as most of the oil has shifted in the direction of the lean. So it’ll show like there’s no oil at times leaving you scratching your head.

 

[McTool]

The oil sight glass was a good design on my honest opinion. It’s just takes a almost perfectly level surface to get a accurate reading. So if your bike is off level leaning to the left, the oil in the sight glass most likely won’t show up as most of the oil has shifted in the direction of the lean. So it’ll show like there’s no oil at times leaving you scratching your head.

Yeah , I agree that the sight glass is usually the best way of quickly sussin the oil level......just that on this quad it aint so easy to see or clean , and the filler is a pain to get at , but realistically , where else could you put them ?🙂
My Ducati has a different issue in that there is no centre stand and one must hold the bike on its balancing point to see the correct level and that aint easy to do whilst kneeling on the ground let alone cracking ones neck to see the glass.

 

[jatank5316]

Question: What does PRI stand for on 500 F carb. control valve ?

 

[PineLaneRider]

Prime. It provides a constant flow of fuel, bypassing the vacuum portion of the petcock valve.

 

[sutty]

I'm glad this discussion came near to the top, as it reminded me to do some work on my own petcock valve, whilst I have the quad at home for other maintenance. Five years ago, with the aid of some excellent help and advice from various members of the forum, we worked out that my Quadrunner 250 should have had a vacuum operated petcock valve, and someone had changed it to a normal one, blocking off the vacuum. At that time I found an after market cheap equivalent from China, and fitted it. I too had had the issue of fuel in in my oil, because I had been leaving it on, with the issue being unknown to me, at the time. Failing, as the existing one was, a replacement manual one just did not fit the bill for me. Left for weeks, or even months at a time, not near home, the risk of forgetting to select off was too great, so I went for the Chinese clone, for under a tenner, including delivery.

This is what my clone looks like now, after five years.

Pity really, because it still operates as it should, but it's now, all but, illegible, and it's a little stiff to turn. I drained the fuel, removed the plate, and saw that all appears well behind it, with the casting and the seal. The only issue is that plate, so it's a shame they make it out of such low quality steel, or plate it so poorly, such that this is the outcome after 5 years, when the rest of it is fine. £8, delivered from China, I can't really complain, 5 years on, and still working, but I'd have paid an extra £3, or even £5, just to have a more resilient plate. Funny how they cut corners like that, on a part that could make it. One thing I will never do though is pay over £100 for the OEM part, which I suspect will be little better anyway, and at the most worth £20. Daylight robbery.

Anyway, I've manged to rescue it this afternoon, by polishing both sides and then painting the face only. Back was fine, and paint wouldn't last in the petrol environment anyway. I started with zinc paint, but that was an abysmal failure, in that, despite only having given it a very thin coat, my lettering all but disappeared, once surface dry. It was more the colour, than having filled it in, but either way, it was no good. I cleaned that off, with some spirit, it was barely dry anyway, so that was easy, sprayed it black, and then wiped that off immediately, hopefully leaving some black in the impression, and then went over that with clear lacquer. Of course some black paint has gotten into the pitted surface, as a result of the rust, but I think it's going to be good enough, at least for a while.

I'll reassemble it tomorrow, having already de-rusted the screws and painted them with zinc, and having applied some rubber safe lube to the lever.

Whether it will stand the test of time, who can say, but at least for now it has rescued it.

Cheers

Sutty

 

[sutty]

Just as a little addendum, to my above post. It you look closely at the image below, as posted by the original poster, and compare it to either of the pictures I just posted, you will see that the words are shuffled on the cheap Chinese copy. Someone mentioned it earlier in the thread, but perhaps the implications are not so clear, so I thought I would add a note here.

The Chinese ones, all of those I have found online, with good pictures, are laid out like mine. The problem is not so much with them having a different layout, the problem is that you cannot point the active end of the lever, the long end, at reserve, ever. I knew this as soon as I deployed it, but having to use either prime, or reserve, very infrequently, means that I forget which is which. Couple this infrequent use, and minor confusion with, often in poor lighting, and not being the easiest to read, and I don't know which is which, come the time, and the last thing I want to do is accidentally leave it on prime, for the reasons well described in this thread.

For mine, as tested, and most likely with all the other cheapos, long end down is on, long end up is prime, and across is reserve, but for it to be the long end denoting it, as with the other two, the word RES, should be to the left hand side of the plate. So you have to read, long end, short end, long end, which is nonsense. They have the stop blip on the wrong side of the plate, or the word RES, in the wrong place. Probably the word, because if you could get the long end to that side, I don't think the feed slot, on the back, would line up with any of the ports.

As I said above, someone, earlier in the thread, I forget who, mentioned that they had some funky markings, and they were right. Can I live with it for £8 rather than £100, no problem, but still it's irritating. I'm going to laminate my picture, and shove it in the boot, to remind me, for as and when I need it, not just because of that error, but because of, perhaps, having to read it in the dark, when splashed with mud, or maybe even when rusty again.

 

[Foot0069]

Just as a little addendum, to my above post. It you look closely at the image below, as posted by the original poster, and compare it to either of the pictures I just posted, you will see that the words are shuffled on the cheap Chinese copy. Someone mentioned it earlier in the thread, but perhaps the implications are not so clear, so I thought I would add a note here.

The Chinese ones, all of those I have found online, with good pictures, are laid out like mine. The problem is not so much with them having a different layout, the problem is that you cannot point the active end of the lever, the long end, at reserve, ever. I knew this as soon as I deployed it, but having to use either prime, or reserve, very infrequently, means that I forget which is which. Couple this infrequent use, and minor confusion with, often in poor lighting, and not being the easiest to read, and I don't know which is which, come the time, and the last thing I want to do is accidentally leave it on prime, for the reasons well described in this thread.

For mine, as tested, and most likely with all the other cheapos, long end down is on, long end up is prime, and across is reserve, but for it to be the long end denoting it, as with the other two, the word RES, should be to the left hand side of the plate. So you have to read, long end, short end, long end, which is nonsense. They have the stop blip on the wrong side of the plate, or the word RES, in the wrong place. Probably the word, because if you could get the long end to that side, I don't think the feed slot, on the back, would line up with any of the ports.

As I said above, someone, earlier in the thread, I forget who, mentioned that they had some funky markings, and they were right. Can I live with it for £8 rather than £100, no problem, but still it's irritating. I'm going to laminate my picture, and shove it in the boot, to remind me, for as and when I need it, not just because of that error, but because of, perhaps, having to read it in the dark, when splashed with mud, or maybe even when rusty again.

Can you swap just the plate from your old one?