Superjet bogs down after 30 minutes

[parisp22]

Hello, my 2014 superjet will run perfectly fine for about 30 minutes. It will start up no problem however after 30 minutes of ride time it will rev up and then start to bog out. It still moves and will get up there in speed but there’s a definite power lose when you go wide open. I replaced the spark plugs, fuel filter, and check valve already. I tried switching to reserve and it still does it. I don’t think there’s an exhaust leak because it does it with the hood off. From what I’ve read everyone who’s had a similar issue rebuilt the carbs and it still did it. How should I go about this?

 

[Pro-pulsion]

If you know how to use a multimeter or know anyone that does, the easiest test to start with is the secondary winding on the coil. To test this, put one test probe in each spark plug boot and put the meter on resistance to k-ohms. The range should be from 3.5 - 4.7 k-ohms. If it's higher than 4.7 then likely what is happening is, the coil is breaking down under load. Yamaha coils have a habit of failing around the 10 years mark. I've personally had a couple fail at just a few years old. This would be my first test because nothing has to be dismantled to do it and it's a really easy test

 

[Myself]

I'll add another easy test. When it starts bogging down try pulling a bit of choke while throttling and see what it does. If it immediately bogs worse and tries to die, that's normal. If it increases RPM and runs better, then you have a fuel supply issue.

 

[OCD Solutions]

If and when you source a new coil, look for one out of a Kawasaki twin. Industry insiders have claimed for years that the Kawi coils are wound with a larger wire gauge and are less prone to breaking down and heat saturation. Jetmaniac assembles them and offers them for sale under the name "Yamasaki" coil. The external wires can still fail but the internals are more robust...allegedly.

Is this a new symptom or something it's always done, or at least as long as you've owned it? I'd love to see if a new Yamaha coil does the same thing and if it does, swap in a Kawi coil to see if the above claims are actually based on some truth.

 

[parisp22]

If and when you source a new coil, look for one out of a Kawasaki twin. Industry insiders have claimed for years that the Kawi coils are wound with a larger wire gauge and are less prone to breaking down and heat saturation. Jetmaniac assembles them and offers them for sale under the name "Yamasaki" coil. The external wires can still fail but the internals are more robust...allegedly.

Is this a new symptom or something it's always done, or at least as long as you've owned it? I'd love to see if a new Yamaha coil does the same thing and if it does, swap in a Kawi coil to see if the above claims are actually based on some truth.

It is new, never did it before.