Pipe got too hot...

[bondra131]

Put a new New b pipe on my 2014 superjet and originally had changed NS springs to 95 gram but it ran rich on bottom and my pipe barely got warm so I figured the bottom screw (only screw that was open) could use a little tightening. I shut the screw then opened it 1/4 turn at most, maybe less and went for a test ride with the new configuration with stock springs in the carbs. This cleaned up my bottom end and ski felt great but I was running it wide open for a while and felt the motor starting to sieze 3 different times so I pulled onto a beach and found my pipe to be way too hot. Sizzled the water on anywhere water was dropped on the chamber from coupler to stinger nearly burnt the water lol so I take that bottom screw on the head pipe needs to be opened a bit more... Question is, is my brand new motor ok? 3 times a piston swelled enough to make the ski shut off. I suppose time will tell And I shouldnt be surprised if a piston breaks into pieces soon Huh?

 

[Dartman]

1/2 max closed is the norm
should have water injection controller anything under that
if you did have a seizure, piston should be replaced

 

[iangdesign]

Was it just the pipe that sizzled or the engine also? Was water flowing out of the pissers normally? Might have a clog somewhere in the cooling system.

 

[Matt_E]

Well that takes the mind off the water spots.

 

[jetx]

Did you actually rejet or just change the spring? If not than you probably ran it lean.

 

[bondra131]

It's correctly jetted. I had changed to 95 gram springs and my pipe was hardly warm and it ran rich on bottom no matter how lean I got the adjusters so I switched back to stock springs as chris Williams told me to do and it ran great! But pipe was sizzling like crazy it melted a cooling line even... Motor, not very hot. I could hold my hand around the base of cylinders all day long and yes the pissers water output was normal

 

[bondra131]

So the motor wasn't getting hot on the outside but inside sure was. Felt Pistons swell up 3 times enough to start shutting off the motor but all 3 times I just pushed the stop button then started it right back up and it ran fine still. May or may not have weakened Pistons. Oh well

 

[Matt_E]

Are you sure it was getting hot? I'd be closing all three screws and trying again.

 

[bondra131]

Are you sure it was getting hot? I'd be closing all three screws and trying again.

Lmfao

 

[BruceSki]

What main jet are you running?

 

[bondra131]

What main jet are you running?

135's

 

[yamanube]

I have a hard time believing you are soft seizing your motor if it is correctly jetted, no matter how hot your pipe is getting, you should be melting exhaust hoses long before seizing your motor.

 

[bondra131]

Maybe it was running out of fuel supply rather than seizing then but I have felt this before when my old superjet was too lean and after 5 or 6 times of feeling it do this exact same thing, sure enough, the whole skirt of a piston dropped off and wedged in between the crank and case. I may be jetted correctly but maybe my adjusters are in too much so I am lean. Just weird that the motor wasn't very warm at all...

 

[yamanube]

Stock head?

 

[Dartman]

yamaha engine doesn't have to be hot to seize
hot pipe and cold cylinder leads to seizure if not jetted on the rich side
if it's too cold it will surely seize when jetting is on the leaner side

 

[jetx]

Id pm waxhead about your overheating issue...I remember him posting once the 08+ waterbox is too restrictive and causing detonation at high speeds causing pistons to burn up with a pipe..there was a thread where a guy went through 3 sets of pistons, and since u were running wide open for a while if say to look Into that especiAlly since your jettting seems corect

 

[bondra131]

Stock head?

No. Ada girdled with 34cc domes. I run 92 ethanol free

 

[bondra131]

Id pm waxhead about your overheating issue...I remember him posting once the 08+ waterbox is too restrictive and causing pistons to burn up with a pipe..there was a thread where a guy went through 3 sets of pistons

What?! That's whack. I thought the water box was always the same. Looks so. Not inside maybe. Thank you, I will look into that. It's gonna piss me off if I ruined Pistons. Friggin brand new ski. I do have some 82mm Prox pistons new but still, rather not have to go bore it out and rebuild already

 

[Dartman]

you should pull the head and look at the cyl walls
ada makes 31, 33, 35 and 37cc for the 701 heads
did you have custom ones made at 34?
im assuming you have dual cooling?
are you running water restrictors?

 

[Dartman]

i have a set of almost brand new set of OEM pistons/rings/pins if you need a set
81mm less than 5 tanks, went to a 771 big bore w/sleeves