Why is my FX1 so loud?

I put a mod bpipe on my FX1 recently, and just took it out to the lake last weekend. The rest of the motor is stock. It was way, way louder than my RN with limited pipe. Same cooling line routing. I reconfigured the stinger and bypass lines at the tee for more water to the waterbox, but with no change. Problem is, the girlfriend is supposed to be able to ride it half the time, and the superjet half the time. But she rode it 2 min and gave it back because it was too loud.
Any ideas? Has anyone else noticed a huge difference between a Superjet with bpipe and an fx1 with bpipe. What should I try?

Thanks,
 

Mouthfulloflake

ISJWTA member #2
Location
NW Arkansas
I think my wifes FX1 with STOCK exhaust is louder than my super jet with a coffman pipe and a stock water box.

maybe the fx has a much smaller water box or something?
 
I agree with mouth. My buddy has a FX-1 and it is quite a bit louder than a stock ski. I think it has a great growl the way it sounds stock.

I think you should trade my buddy. He is looking for a pipe for his ski. I am pretty sure that he will trade you for his stock setup so that your ski will be quieter. :arms:
 
fx waterbox = square waterbox

I put mine on the water for its maiden voyage today...noticed this as well, although I have a FPP waterbox with Bmod..

maybe its because of the smaller pump??? or the hull material resonating more than a SJ?







has some pretty bad low end cavitation right now with a protec rideplate and protec top loader..

does the ride plate need to be sealed on the fx?
 

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Mouthfulloflake

ISJWTA member #2
Location
NW Arkansas
good call on the hull material, that could likely make a big difference.

I didnt realize the water locks were the same.

My opinion after only riding one a few times is:

If it has more than stock power, it cavitates like MAD
I rode sjaholics a while back, big compression, B pipe, enhancer, and it was a bear to keep the pump hooked up, if you did it was a rocket though.
 
has some pretty bad low end cavitation right now with a protec rideplate and protec top loader..
does the ride plate need to be sealed on the fx?

I have been working on this problem for awhile with Thongbonger. His hit the revlimiter right off of idle and stayed there.

He took the pump out and sealed everything both sides of the pump seal, the rideplate, the pump shoe, intake grate, and it took care of the problem.

I have heard that the pump shoe is pretty delicate and cracks on these if you tighten the intake down too tight. Might want to check that also. Good luck That problem haunted us for a while.
 
Thanks for the input guys. That is why this site is the best for Tech info. Maybe I'll try one of my coffmans resonators with water injection. Any other Ideas on making it quiet like the SJ? I also found an old post on PWCtoday where 11 was saying something about some yamaha noise suppression hardware that was on the SJ but not on the FX1. Not really sure what he was referring to. Is the exhaust tube through the gunwhales just an aluminum tube, or does it have baffles or something on the SJ that isn't there on the FX? Other than that, and the rough water hookup issue, the FX1 is a blast to ride.

Thanks,
 
I have been working on this problem for awhile with Thongbonger. His hit the revlimiter right off of idle and stayed there.

He took the pump out and sealed everything both sides of the pump seal, the rideplate, the pump shoe, intake grate, and it took care of the problem.

I have heard that the pump shoe is pretty delicate and cracks on these if you tighten the intake down too tight. Might want to check that also. Good luck That problem haunted us for a while.


what prop and pipe combo?
 

njfl

X-H2
He took the pump out and sealed everything both sides of the pump seal, the rideplate, the pump shoe, intake grate, and it took care of the problem.

You may also want to replace the pump seal (Yamaha calls this packing) that goes between the pump and shoe. 10+ years of being compressed and possibly repeatedly removed and reinstalled can wear these out (stay compressed to the point where they don't fill the gap adequately).
 
W

wydopen

Guest
mine isnt anylouder than a sj... it has a stock wb and fp fx1 chamber...also t dosnt really cavitiate at all either...it has a protec plate and grate as well
 
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