Broken DASA Power Valve

Location
USA
I need some help. I am running a DASA 950 with power valves, this weekend in between rides I found that my front power valve broke. This is the second time in 1 year this has happened to me.
After the first power valve broke I had the engine rebuilt with 2 new power valves that were cut to match the cylinders, the engine has approximately 25 hours on it since the rebuild.
Has anyone else experienced this?


Power Valve.jpg
 
Reminds me of Polaris Liberty motors lol those things will come apart and sometimes make their way out of the exhaust and still run!

Are these pv's stainless?
 
Location
USA
We have nosed in several back flip attempts that has caused the ski to sub. Do you feel water entering the engine could break a power valve? I never considered that.

I believe the power valves are aluminum.

Thank you for your responses, I am totally lost and frustrated.
 

Christian_83

Xscream
Location
Denmark
Water entering the engine and water lock it, and that will cause your engine to be in pieces.
Did you speak to your engine builder or DASA? This seems really strange.
Did have this engien from new?
 
Location
USA
I did not have the engine from new. I spoke to DASA when the first Power Valve broke, we assumed it broke because the screw that connects the power valve to the top fell out several times and figured that the tightening of the screw numerous times fatigued the shaft causing it to break. The screw has not came out of the power valve that broke yesterday. I have spoke to the engine builder but have yet to bring him the engine for further analysis.
 

DAG

Yes, my balls tickled from that landing
Location
Charlotte, NC
Did they both break at the same spot?

Both breaks on same cylinder?

When you bought new, did you buy just the valve or the complete assembly with the mounting base?

When you assembled did you confirm the valve clearanced the rings by cycling the piston up and down the bore?
 
Location
USA
Yes both valves broke in the same spot.
Same cylinder front.
Just bought the valves.
We did check the power valve to piston clearance during the machining process. There are currently no signs on the the power valve that it contacted the piston, I have not yet removed the head. I have my fingers crossed that the cylinder/piston are not damaged.
The ski was running great just came back into add more fuel before going back out. I did not really notice a loss in power at the the time but before completing the ride I was struggling to make it all the way around on a back flip. I assume it was due to the power loss caused by the broken power valve. Or maybe I was just getting worn out. LOL.
 

Jr.

Standing Tall
Staff member
Site Supporter
Location
Hot-Lanta
Have you checked the dimensional clearance of the giotine body to the cyl slide?
Excessive clearance will cause the giotine to rock in the slide, putting side pressure on the stem.
DASA will need to give you the clearance specs per their design.
 
don't believe he is.
Since when? He was still there like a month ago...

Can you take a picture of the face of the fracture? We may be able to tell you the failure mode. Seems like it propagated from the stress riser where the small diameter stem meets the larger diameter...but why? May have started from over tightening the pv screw?

They are aluminum btw
 
Location
USA
Thank You Kaylee. I will get a few more pictures posted later this evening.
I have only used a allen wrench to ever tighten these screws, do you feel enough torque could be generated to damage the valve using just and allen wrench?
 
Thank You Kaylee. I will get a few more pictures posted later this evening.
I have only used a allen wrench to ever tighten these screws, do you feel enough torque could be generated to damage the valve using just and allen wrench?
Being aluminum... I'm pretty confident one could do some damage with just an allen wrench.
 
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