ATV won't start!

[fields_mj]

I've got an 03 Yamaha bigbear 400 that's had the snot beat and ran out of it. It had 13,000 miles on it when I got it in '07. Had the valve exhaust screw back out and fall down into the cyl 2 years ago, so it's got a new pistion, rings, and the head is bored out 0.020" The last 2 years, I've been having more and more problems with it starting. The first few years, the thing would fire right off on the first stroke. Last year I put a new battery and starter on it and that helped. The carb was messed up with the head was rebuilt, so I took it to the shop and had the carb cleaned out, and a rebuild kit put in along with a new plug. Started pretty good this summer, but the last 2 or 3 times I've had it out, I could tell it was starting to have problems again. After getting the carb fixed last time, I started adding Staybil to the fuel because I only go through about one tank a year. Took it out yesterday and it didn't want to stay running at first. Got back to the wood pile with the axe and saw, and did some work. Then it wouldn't start to drive back up to the house. Worked on it for a few hours. Found the plug was not firing at the tip like it should, so I used some sand paper to clean the tips up on it. Still wouldn't start. So I pulled the plug and hit it with some either. Put the plug back in, and tried again. It tried to fire, but didn't even run long enough to burn the either off. Not the battery is dead, and it's still in the back yard. I suspsect that the carb is all gummed up again since I didn't run it hardly at all this summer. Fuel still smells okay though, and like I said, I did put some staybil in it trying to help with this situation. I run 93 octane fuel in it. I find it hard to believe that the carb would be plugged up again. It ran great for over 2 years, and I wasn't running it much then either. Seems hard to believe that now it's lasted less than 6 months.

Any suggestions? I'd really like to get this problem resolved. This plows my drive, and 5 of my elderly neighbors drives, as well as hauling my saws back into the woods when the ground is soft.

Thanks
Mark

 

[tomsteve]

plugs can get weak over time and even though it may look like a good spark, it's not strong enough. try a new plug gapped to specs. i would highly suggest draining the gas, putting in fresh gas and adding some seafoam to the gas. also check the plug wire for cracks or wear. is there a drain on the carb? if so, open it up and let a little gas run through it. there could be a needle gummed stuck and a few raps with a screwdriver handle can pop it open. try it while trying to start it.

 

[mlh29]

I would do as suggested above.
I would also try this..
P B Blaster makes a small engine tune up in a can... I know I laughed when I saw it too.. My wife swears by it..( I am ad mil deployed alot so she gets to play with the lawn mower, rototiller etc..)
This stuff is a solvent/ starting aid in one.. works well..

If the easy stuff doesnt work.. Check the coil/ cdi box etc as they can go bad.. Next I would be looking into the engine cam. cam chain etc as with that kind of miles they are prob toast... if something timing wise went you could crank all day and never start..

Good luck to you

 

[Desmond]

plugs can get weak over time and even though it may look like a good spark, it's not strong enough. try a new plug gapped to specs. i would highly suggest draining the gas, putting in fresh gas and adding some seafoam to the gas. also check the plug wire for cracks or wear. is there a drain on the carb? if so, open it up and let a little gas run through it. there could be a needle gummed stuck and a few raps with a screwdriver handle can pop it open. try it while trying to start it.

That's some excellent advise. I'm not familiar with that engine but look for a fuel filter at the bottom of the tank around the fuel valve if it's not mounted on the carb and clean or replace it. Seafoam is great and as stated, dump the gas and use fresh stuff regardless if you think it should be good.

 

[fubar2]

Motorcycles and ATVs after a while get all the electrical connections oxydized. 03 is just about the age when I would start thinking about it. If nothing else works start at one end and disconnect them and clean them then give them a dab of diaelectric grease till you get to the other end. They ain't got the strongest spark to start with and it sure won't hurt any.

 

[lone wolf]

Before you go any further how much compression does it have?

 

[fields_mj]

Before you go any further how much compression does it have?

Compression is fine. I had to have a new piston, and rings, and the cyl bored out in 2009. The adjustment screw for the exhaust valve had come loose, and fallen off and found it's way down into the cylinder. Before it was hard to use the pull rope to turn it over on a comp stroke. Now it's darn near impossible.

The plug is fine. It was replaced when they put the new carb kit in this summer, and it's only run half a tank or less of fuel since then. Maybe an hour of run time.

Timing and timing chain should be fine also. They were replaced with the piston, wrings, and cyl work in 09. They probably don't have 8 hours of run time on them yet. Not sure about the condition of the cam itself. The shop didn't seem to think there was anything wrong with it at that time.

I do think that something like the coil is starting to go. Is there a way that I can test how strong of a spark it is generating? I've never owned anything that was this contrary to start, and it wasn't always this way. Like I said, it started like a dream the first few years I had it. Then, shortly before the cylinder incident, it started getting harder to start.

I planned on draining the gas tonight. I'll get some seafoam too. I'll pick up some of the stuff from PB blaster too. I think I've seen it at TSC. All I'm going to do to night is pull/push it back to the garage so that I can charge the battery back up and drain the fuel. With new fuel, hopefully it will start. This is a very useful tool for me, and I need to get it back to the point where it's dependable again. Heck, the first 2 years I had it, I only ran MAYBE two tanks of fuel per year through it, and it never missed a beat. I never even had to pull a plug to look at it. Just sit down, turn the key on, and tap the start switch, even in the dead of winter after sitting for 2 months in an old barn. I was hoping that the carb kit this summer would have been the fix, but apparently not. Every time I sit down on it and turn the key on, I wonder whether or not its going to start for me. Not such a big deal if I'm just going to use it to run the X27, a saw, and maybe some bar oil and mix back to the wood pile 100 yds away (more of a chance to let it run than anything else), but when there's 10" of snow on the ground, or when I'm out cutting all day in the bottom of a +50' ravine and it's 42 degrees out and the snow is melting (in other words it's a wet, muddy, misserable mess), it becomes a very big deal.

Thanks,
Mark

 

[lone wolf]

Compression is fine. I had to have a new piston, and rings, and the cyl bored out in 2009. The adjustment screw for the exhaust valve had come loose, and fallen off and found it's way down into the cylinder. Before it was hard to use the pull rope to turn it over on a comp stroke. Now it's darn near impossible.

The plug is fine. It was replaced when they put the new carb kit in this summer, and it's only run half a tank or less of fuel since then. Maybe an hour of run time.

Timing and timing chain should be fine also. They were replaced with the piston, wrings, and cyl work in 09. They probably don't have 8 hours of run time on them yet. Not sure about the condition of the cam itself. The shop didn't seem to think there was anything wrong with it at that time.

I do think that something like the coil is starting to go. Is there a way that I can test how strong of a spark it is generating? I've never owned anything that was this contrary to start, and it wasn't always this way. Like I said, it started like a dream the first few years I had it. Then, shortly before the cylinder incident, it started getting harder to start.

I planned on draining the gas tonight. I'll get some seafoam too. I'll pick up some of the stuff from PB blaster too. I think I've seen it at TSC. All I'm going to do to night is pull/push it back to the garage so that I can charge the battery back up and drain the fuel. With new fuel, hopefully it will start. This is a very useful tool for me, and I need to get it back to the point where it's dependable again. Heck, the first 2 years I had it, I only ran MAYBE two tanks of fuel per year through it, and it never missed a beat. I never even had to pull a plug to look at it. Just sit down, turn the key on, and tap the start switch, even in the dead of winter after sitting for 2 months in an old barn. I was hoping that the carb kit this summer would have been the fix, but apparently not. Every time I sit down on it and turn the key on, I wonder whether or not its going to start for me. Not such a big deal if I'm just going to use it to run the X27, a saw, and maybe some bar oil and mix back to the wood pile 100 yds away (more of a chance to let it run than anything else), but when there's 10" of snow on the ground, or when I'm out cutting all day in the bottom of a +50' ravine and it's 42 degrees out and the snow is melting (in other words it's a wet, muddy, misserable mess), it becomes a very big deal.

Thanks,
Mark

So how many pounds of compression does it have today?

 

[fields_mj]

So how many pounds of compression does it have today?

I don't have a gauge so I don't know. What I do know is that in order to get it to turn over on a compression stroke, I have to have it setting on the exhaust stroke, grab the handle with both hands, put one foot on the left peg, and give it all I've got so that the momentum is enough to cary it over on the compression stroke. That's why I don't think there's a problem with the compression.

 

[OH_Varmntr]

Certified Yamaha Tech here. Not that it means anything.

Try this first. Remove plug wire from spark plug. Take airbox lid off and remove air filter. Place your hand over the intake hole that goes to the carb. Crank the engine for 5 seconds while removing/replacing your hand over the hole a few times. It will have quite a bit of suction. That's good. Doing this may draw whatever may be plugging your pilot circuit out as it forces fuel out of the carb.

If that doesn't help, tear that carb off there and clean it out. If you don't have the means to, take it to a shop and have them do it.

Pilot orifices are extremely small. Pilot circuit is what keeps the engine idling. If the pilot circuit becomes plugged, you'll be lucky if she starts and idles.

If you don't run it much, I suggest shutting the fuel off and running the carb out of fuel when you're finished. You can turn the valve off, then unload the quad while it's idling and it will die in less than a minute.

Fuel evaporates while it sits in the carb bowl, leaving varnish deposits behind which plugs tiny orifices. Stabil is junk, IMO. Seafoam is the stuff.

Good luck.

 

[tomsteve]

just thought of one more thing i've done in this situation. if all else doesnt work, and before puling the carb and if you have a compressor, turn the pressure down to about 20 psi's, pull the fuel line off at the tank and give a blast of air through the fuel line.

 

[aleman]

OH_Varmntr is exactly right. I race motocross and have dealt with bikes my whole life. I know much more about bikes than cutting wood, lol. The gas now days sucks. Its goes stale in just a few months. If your not using the ATV much then the gas sits in the float bowl and turns to varnish. It clogs the pilot jet and your wont get enough fuel to start. It can be a pain to get the jet clean, if you have a dealer close, you could just pick up a new jet and replace it. To keep the problem from re occuring, you can either drain the float bowl or just shut off the fuel supply and run it until it runs out of gas when the ATV is going to sit for a while. Hope this helps..

 

[Iska3]

On small engines Seafoam is your friend. You can't let that ATV sit for weeks on end like that. Like they were saying above. Drain the gas for now and start over. If it sits for a few weeks or a month, add seafoam and run it once every few weeks to keep the gas full in the carb. If you drain the gas and let it sit, the carb gets that white film inside and causes all sorts of troubles. Also the connections get funkey. Clean all of them and add white grease to all the connections so you have good spark. For now I would put some gas in to a spray bottle and spray fresh gas in to the carb and see if it will pop off. If it does keep spraying in more gas until it runs on it's own. If the gas does not help then it is the spark. You might need to touch up the pints a little.

The shop in town uses a spray bottle of gas and try that before they rebuild a carb. 99% of the time it works.

If you leave that thing sit for weeks on end, pick up a cheap battery maintainer and leave it on the battery.

Might want to try and jump the ATV with your car so it has a good strong spark.

 

[lone wolf]

Op did you try a brand new plug yet?:msp_mellow:

 

[OH_Varmntr]

Might want to try and jump the ATV with your car so it has a good strong spark.

IF you jump it with an automobile, turn it off before connecting the jumpers. Automobile charging systems are too high amperage that can fry the regulator/rectifier on your ATV.

 

[woodchop]

I suspect that the ignition trigger coil is getting weak. Rick's Motorsport Electric Coils Ignition Coil

 

[fields_mj]

I worked late. By the time I got home and got the kids fed, I just now got it pushed back up to the garage (up hill, all the way). I did remove the air filter and covering the intake. I got a hand full of gas when I took my hand off. Does that mean the carb should be doing okay, or that it's plugged up?

I will certainly be getting some seafoam, and shutting my fuel supply off from now on. It generally sits for a month or two, not weeks. I use it in spurts, but when I use it, I use it.

If I jump it, I'll jump it off my diesel. No need to start it. If twin 1000 cca batteries can't give me a good spark, then I've really got some problems

The plug is less than 6 months old and has less than 3 hours on it. I did clean it up with some 120 grit, but I'm not going to replace it at this point. The last plug was also only 6 months old. The tech replaced it with the carb kit out of habit. That was okay, but I wish he would have given me the other plug back.

Right now, I think my biggest problem is the spark. Even if the carb needed cleaned, it should have fired on ether, but it didn't. No doubt I need to change my routine with my fuel, and I'll start off now with fresh gas and a charged battery, but in the end I think I'm going to have to put a new ignition module on it.

Thanks,
Mark

 

[superwd6]

My friend & I both had the same problem of the choke plunger corroding in the carb body (2000 & 2001 Kodiak). The choke pulls out but won't return quite all the way. It makes the quad run just rich enough to foul the plug black. You said spark plug is new but not what colour. If it isn't white replace it. Also open drain screw of float bowl & make sure gas is running in at a steady steam. Battery charge has nothing to do with spark output. It isn't a car. Unhook the battery, pull with the rope and it should still spark

 

[fubar2]

I worked late. By the time I got home and got the kids fed, I just now got it pushed back up to the garage (up hill, all the way). I did remove the air filter and covering the intake. I got a hand full of gas when I took my hand off. Does that mean the carb should be doing okay, or that it's plugged up?

I will certainly be getting some seafoam, and shutting my fuel supply off from now on. It generally sits for a month or two, not weeks. I use it in spurts, but when I use it, I use it.

If I jump it, I'll jump it off my diesel. No need to start it. If twin 1000 cca batteries can't give me a good spark, then I've really got some problems

The plug is less than 6 months old and has less than 3 hours on it. I did clean it up with some 120 grit, but I'm not going to replace it at this point. The last plug was also only 6 months old. The tech replaced it with the carb kit out of habit. That was okay, but I wish he would have given me the other plug back.

Right now, I think my biggest problem is the spark. Even if the carb needed cleaned, it should have fired on ether, but it didn't. No doubt I need to change my routine with my fuel, and I'll start off now with fresh gas and a charged battery, but in the end I think I'm going to have to put a new ignition module on it.

Thanks,
Mark

You go shooting 2000 amps in there and your ATV battery is going to light up like a Claymore. If you ever plan on using your battery again I'd reconsider jumping it off the diesel or even a car for that matter. One and a half maybe two amps tops.

 

[joshua mason]

seafoam is some good stuff. used it on my quad and it worked wonders. float was sticking and allowing fuel to run out the overflow, also ran like crap. some seafoam and let it idol for awhile and mine was fixed. as for yours, try a new plug, fresh gas and seafoam. easy and cheap, which is what i like to start checking. bad gas and revving motor with the choke on can foul a plug pretty quick from my experience. if that doesnt work buy a honda. lol. just kidding.