Spitfire engine in my Seadoo!

[DavidWang]

Bought a new carb last year, working just fine till the last time, the engine can not go high speed when pushing more gas, the engine spit out flames and make an explosion sound. tried to adjust the low-speed screw no lucky, any idea?

 

[DavidWang]

After go through a lot of posts, I think the only thing I should do is clean the fuel return hose. If you have other ideas, please help!

 

[DavidWang]

Tried changing the hose, tried changing another cab, no lucky at all! Still spitfire make explosion sound and can not go high speed. Help please!!!

 

[Spider4real]

I would like to start this post by saying I am not very experienced with these types of issues. But if it was me I would pull the carb, take it apart and clean. Test the pop off pressure and reassemble. While it is off double check the rotary valve timing and make sure it is turning smoothly when you turn the engine over by hand. Put the carbs back to factory settings (since you were playing with the low speed screw) re-install and see what happens.

If you still have issues after that then hopefully someone with more experience can chime in.

 

[DavidWang]

I would like to start this post by saying I am not very experienced with these types of issues. But if it was me I would pull the carb, take it apart and clean. Test the pop off pressure and reassemble. While it is off double check the rotary valve timing and make sure it is turning smoothly when you turn the engine over by hand. Put the carbs back to factory settings (since you were playing with the low speed screw) re-install and see what happens.

If you still have issues after that then hopefully someone with more experience can chime in.

Thank you for the advice, I checked the carb, the pop off is about 45 psi, since it’s the original setting( new carb) and working fine before so I didn’t touch it and put back as is. Not sure the correct pop off?
Checked the engine seems hard to move by hand, what the possibility could be? I just changed the carton ring, so the problem comes from the engine? So scared to rebuild the engine!

 

[Spider4real]

Let's take a step backwards. Have you checked the condition of the spark plugs? Correct plugs and gap set properly?

 

[DavidWang]

Thank you but unfortunately, I have changed the 2 spark plugs still not lucky the same issue
Can I address the issues to the engine by checking the pressure of the 2 cylinders? or something else?
Just to be sure before disassemble the engine, that’s will be a big task, this season gonna be done early!
Any help is appreciated!!!

 

[Spider4real]

Never hurts to check the engine compression. But if that is fine I think you should check the rotary valve timing.