Suzuki DT 65 1995 model, stalling when in gear/under load. Fuel problem?

After searching this forum extensively I have gotten a lot of help, but failed to find a solution to my problem. Hopefully someone will give me an input to help me crack this one.

I just bought a 1995 Suzuki DT 65. It starts fine, and revs fine while in neutral, but when I set it in gear it will bog down and die very quickly. I don´t have a working tach, so no idea what rpm, but I can basically not go abouv . If i pump the bulb I can keep it going a bit longer, and this leads me to think it might be a fuel problem. In reverse I can keep it going for a long time, but in forward it quickly dies.

I have tried the following:

• Different tank, fuel hose and connectors
• Checked timing with timing light
• Change Throttle valve sensor (expensive!)
• Changed fuel pump (a bit expensive)
• Check all fuel lines
• Changed spark plugs
• Cleaned carbs
• Checked cylinder compression (by running the electric starter)

Still the same problem. I disconnected the fuel line going from the pump, and ran the engine on the electric starter, and the pump hardly delivered any fuel. Not sure if this is an adequate test of the pump, but I am thinking it could be a problem with the crankcase compression/vacume? My next idea is to try installing an electric fuel pump on the fuel line from the tank to see if this help, but would like some input. My plan is to bypass the fuel pump, but I am worried that I risk rupturing the diaphragm by so? Am I on the right track?

Before I bought the engine, it supposedly ran fine. The only thing that has been done to since then, is a carb clean (by a professional, using ultrasound cleaning). Could the carbs still be a problem?

Appreciate any input here, as I feel kinda lost.

I'm currently working on a similar issue with a 65, early 90's. We've gone through most of what you've done, the next thing we have in mind the next sunny day is to pull the flywheel and check the Magneto. Our plugs have spark, but seem pretty weak, narrow & dance all over the place.

I have been thinking it might be a faulty oil level sensor? I have not had a chance to test it yet tough

Does it bog down as soon as it goes into gear or once you start to open the throttle? Does your timing light showing that it loses spark when it dies? Presumably the oil level sensor cuts the ignition if it is doing what you suspect.

Stuart

We found the issue to our dt65. It was the magnetos and the main flywheel magnets. At some point fresh water got under the flywheel and rusted away at one of the grounds, causing a weak spark. Also, the main magnets were heavily corroded. We cleaned up the connections and the magnets and reassembled. The motor came right to life, cold start no choke. This thing runs like new now. Hopefully this helps.
Our flywheel had a keyed shaft and you cannot get an outer flywheel puller connected. We had to purchase a LARGE flywheel puller that bolts to the flywheel itself. It took some patience of tightening and pounding and waiting and repeat.
I hope this helps!