I'm checking the one way valve tomorrow thanks to your videos. My XLT1200 won't rev past 6k, if it does it stalls. If I turn left it briefly revs higher but not for long. I unplugged spark on cyl 3 and at idle it made no difference. I can hear pressure releasing when I open the fuel cap. I'm hoping its the one way valve or possibly cyl 3 fuel pump.. maybe the reeds? Who knows but I'm determined to fix it!
Yes always check your fuel pressure on any two-stroke engine that you are building because it will create a lean condition and it will fry your back piston so you always want to pressure up the fuel system and check your tank Valves and make sure everything is holding but also you want to get rid of that paper thin lanyard that you are using and get a good Yamaha one I have been building 2-stroke jet skis for over 20 years
I set popoff pressure on each carb and pressure test the tank and fuel system. I just learned the hard way on a Kawasaki not to trust old engine seals on a ski that has been sitting for years even if it has great compression. There was water and rust on the crank bearings and bye bye front piston. I just picked up a gp1300R and will be doing videos on that soon.
Hello Shadetree, I bought a Yamaha XLT1200 few months ago and got the same problem when I pull up the full throttle more than 5/6 seconds. Suddenly the engine stops or goes down. I’ll try your idea. Hope it’ll work. Thanks for your videos (on reverse cable, I’ll change mine in a few days, waiting for the cable delivery). Great videos ! Thanks Norman (From France :))
You are welcome. Pressure test your fuel system with very low air no more than 3 psi and soapy water. Spray that soapy water around the fuel cap and fuel pickups as well as your fittings. Bubbles will indicate air leaks. You could also have a bad check valve in the vent line. The biggest issue is the carb and using genuine mikuni kits and getting it adjusted properly.
I have 3 good jugs for a 1200 but no case or any other parts. Put tygon oil lines on with oeitiker clamps for your oil system or run a blockoff plate with premix. If you have the 1200 with a catalytic converter you need to run a D plate and jump the o2 sensor wire. Make sure you have the improved powervalve plunger holders or put waveeater clips on the old style. Those things will keep you on the water much longer.
I have a Yamaha Suv 1200. I have owned it for 8 years. I know that after a long period of inactivity, when I roll it out onto the water, I add a little gasoline to the carburetors through the plugs to help it start. He's so very easy to start. But over time I had another problem. During active driving, after a pause of 10-30-60 minutes, I find it difficult to start it again, the starter turns for about 10 seconds. Then a problem occurs, it doesn’t want to go, and if you press the gas it immediately stalls. I have to drive in circles for another 40-60 seconds at idle and pressing the gas a little, the engine seems to twitch and doesn’t want to go. After these 60 seconds, he begins to accelerate and drive as he should. If you turn it off and start it right away, everything will be ok. But if I come to the shore again and stand for 5-10-30 minutes, then the problem repeats. How can I fix this, what to check and where to look
@zhenyaBMW Sounds like you are loosing pressure in the fuel system. Could be a cracked gasket under the fuelcap, could be a bad one way valve, could be a bad fuel selector valve. You pressurize the fuel system with 2psi of air through the return line and spray every place with soapy water and look for bubbles.
So I did the Mikuni carburetor rebuild kit and the WSM carburetor rebuilt it without needle and seat. Test drove both of them they both feel like they feel great. Did not set the pop off pressure just reuse the same old spring
@@FireTruckTech22 yes those stock settings have NEVER worked for me. 1/2 turn out on high 1 3/4 to 1 7/8 on lows at 76 psi popoff. I am amazed they seem to work for others.
@@ShadetreeJetski my gas cap is definitely cracked and repaired that. Check valve is OK all hoses. No gas leaks around the rim of a gas can gasket either. Just for safety measures while I’m all elbow deep in this tear out the carburetor and give a good spray out. It just started doing what you’re describing last year and won’t get up to full speed this year. I completely did a new engine rehome with a complete rebuild kit and gaskets and everything on. It ran perfect as soon as I rebuilt it.
My jet sky has a similar issue to what yours was doing. I recently replaced the seal on the fuel cap with a new one so that should be good. What else could cause it?
A bad check valve. It is the small white piece right above the fuel sending unit on the center of the fuel tank. It is connected to the vent tubing. Air should only pass through it in one direction
@@ShadetreeJetski thanks for replying, not many people out there to offer knowledge on 2 stroke skis. I will try and have a look at that now. I will also take the inline fuel filter out and run it without a filter to see if that helps. It has a brand new carb in it so that wasn't the issue
@@ShadetreeJetski hello again upon inspection, the fuel cap seal was not on right so i sorted that and got fuel system air tight. one way check valve is all good also. i have managed to get it to rev up better but still at wide open throttle i get this surging happen. i havent tried changing the fuel filter yet could that cause this issue??
Dude I love your channel
I'm checking the one way valve tomorrow thanks to your videos. My XLT1200 won't rev past 6k, if it does it stalls. If I turn left it briefly revs higher but not for long. I unplugged spark on cyl 3 and at idle it made no difference. I can hear pressure releasing when I open the fuel cap. I'm hoping its the one way valve or possibly cyl 3 fuel pump.. maybe the reeds? Who knows but I'm determined to fix it!
Sounda like a fuel delivery problem for sure. Look up Oside Bill fuel mods for that ski and do them.
Yes always check your fuel pressure on any two-stroke engine that you are building because it will create a lean condition and it will fry your back piston so you always want to pressure up the fuel system and check your tank Valves and make sure everything is holding but also you want to get rid of that paper thin lanyard that you are using and get a good Yamaha one I have been building 2-stroke jet skis for over 20 years
I set popoff pressure on each carb and pressure test the tank and fuel system. I just learned the hard way on a Kawasaki not to trust old engine seals on a ski that has been sitting for years even if it has great compression. There was water and rust on the crank bearings and bye bye front piston. I just picked up a gp1300R and will be doing videos on that soon.
Hello Shadetree,
I bought a Yamaha XLT1200 few months ago and got the same problem when I pull up the full throttle more than 5/6 seconds.
Suddenly the engine stops or goes down.
I’ll try your idea.
Hope it’ll work.
Thanks for your videos (on reverse cable, I’ll change mine in a few days, waiting for the cable delivery).
Great videos !
Thanks
Norman (From France :))
You are welcome. Pressure test your fuel system with very low air no more than 3 psi and soapy water. Spray that soapy water around the fuel cap and fuel pickups as well as your fittings. Bubbles will indicate air leaks. You could also have a bad check valve in the vent line. The biggest issue is the carb and using genuine mikuni kits and getting it adjusted properly.
I’ll check that thank you !
EXACT same issue with my EXACT same jetski
I have a yamaha waverider 700 Ra with same problem
I knew you would figure it out just didn't know you fixed in your sleep. Lol
I woke up at 4a.m. and knew what the problem was.
Good job mate, I have xl1200pv in bits slowly getting their..
I have 3 good jugs for a 1200 but no case or any other parts. Put tygon oil lines on with oeitiker clamps for your oil system or run a blockoff plate with premix. If you have the 1200 with a catalytic converter you need to run a D plate and jump the o2 sensor wire. Make sure you have the improved powervalve plunger holders or put waveeater clips on the old style.
Those things will keep you on the water much longer.
I have a Yamaha Suv 1200. I have owned it for 8 years. I know that after a long period of inactivity, when I roll it out onto the water, I add a little gasoline to the carburetors through the plugs to help it start. He's so very easy to start. But over time I had another problem. During active driving, after a pause of 10-30-60 minutes, I find it difficult to start it again, the starter turns for about 10 seconds. Then a problem occurs, it doesn’t want to go, and if you press the gas it immediately stalls. I have to drive in circles for another 40-60 seconds at idle and pressing the gas a little, the engine seems to twitch and doesn’t want to go. After these 60 seconds, he begins to accelerate and drive as he should. If you turn it off and start it right away, everything will be ok. But if I come to the shore again and stand for 5-10-30 minutes, then the problem repeats. How can I fix this, what to check and where to look
@zhenyaBMW Sounds like you are loosing pressure in the fuel system. Could be a cracked gasket under the fuelcap, could be a bad one way valve, could be a bad fuel selector valve. You pressurize the fuel system with 2psi of air through the return line and spray every place with soapy water and look for bubbles.
So I did the Mikuni carburetor rebuild kit and the WSM carburetor rebuilt it without needle and seat. Test drove both of them they both feel like they feel great. Did not set the pop off pressure just reuse the same old spring
You came out better than I did. I built 2 carbs and neither runs right.
@@atypicalhiker did you follow the back off procedures for the high and low jet?
@@FireTruckTech22 yes those stock settings have NEVER worked for me. 1/2 turn out on high 1 3/4 to 1 7/8 on lows at 76 psi popoff. I am amazed they seem to work for others.
@@atypicalhiker What’s your problem with drivability
@@FireTruckTech22 8mph on water wont take throttle. Switched seats to 1.5 instead of 1.2 factory .popoff set to 55. Seems to be running too rich.
My JetSki just started doing that. 2000 XL800. Hope this fixes it.
You can buy just the rubber seal. A new cap DOES NOT come with the gasket anymore.
@@ShadetreeJetski my gas cap is definitely cracked and repaired that. Check valve is OK all hoses. No gas leaks around the rim of a gas can gasket either. Just for safety measures while I’m all elbow deep in this tear out the carburetor and give a good spray out. It just started doing what you’re describing last year and won’t get up to full speed this year. I completely did a new engine rehome with a complete rebuild kit and gaskets and everything on. It ran perfect as soon as I rebuilt it.
My jet sky has a similar issue to what yours was doing. I recently replaced the seal on the fuel cap with a new one so that should be good. What else could cause it?
A bad check valve. It is the small white piece right above the fuel sending unit on the center of the fuel tank. It is connected to the vent tubing. Air should only pass through it in one direction
@@ShadetreeJetski thanks for replying, not many people out there to offer knowledge on 2 stroke skis. I will try and have a look at that now. I will also take the inline fuel filter out and run it without a filter to see if that helps. It has a brand new carb in it so that wasn't the issue
@@ShadetreeJetski hello again upon inspection, the fuel cap seal was not on right so i sorted that and got fuel system air tight. one way check valve is all good also. i have managed to get it to rev up better but still at wide open throttle i get this surging happen. i havent tried changing the fuel filter yet could that cause this issue??
@@jordandoesmx9862 I am making another video showing what it could be. Look for it today.
@@ShadetreeJetski do I have to take the fuel sending unit out to see if it is damaged in the same way as your new video?