Good RPMs / Bad MPHs

[PETRUS]

I d like to ask advice to find out why i have lost 2mph at same rpm over the last few months

My set-up is 07 RXP (170 hrs), 8.600 ECU reflash, ET140 charger, 50" injs, Riva rrfpr @59psi, 4" front air, XS IC with HKS BOV, Riva open loop kit, Riva grate & 255 plate, 83 ring, 15/20R untouched

Air & water 90F then and now

I used to gps +79mph @8.400 rpms (best 79.5), now i can only get +77mph @8.400 rpms

I tested with 82 ring and it got worse: rpms were down only 50 to 8.350, but speed went down to +75mph

I would understand the speed loss if rpms were down on par but they stay solid...

Carbon seal, wear-ring & pump-shoe were all replaced less than 10hrs ago.
Compression check showed 130 across the 3 cylinders.

What do i do now?
Thanks!

[speedskixp]

I d like to ask advice to find out why i have lost 2mph at same rpm over the last few months

My set-up is 07 RXP (170 hrs), 8.600 ECU reflash, ET140 charger, 50" injs, Riva rrfpr @59psi, 4" front air, XS IC with HKS BOV, Riva open loop kit, Riva grate & 255 plate, 83 ring, 15/20R untouched

Air & water 90F then and now

I used to gps +79mph @8.400 rpms (best 79.5), now i can only get +77mph @8.400 rpms

I tested with 82 ring and it got worse: rpms were down only 50 to 8.350, but speed went down to +75mph

I would understand the speed loss if rpms were down on par but they stay solid...

Carbon seal, wear-ring & pump-shoe were all replaced less than 10hrs ago.
Compression check showed 130 across the 3 cylinders.

What do i do now?
Thanks!

Have you seen good speed since the pump shoe replacement?

[PETRUS]

Have you seen good speed since the pump shoe replacement?

Yes, the speed seemed ok after new pump shoe

[Green Hulk]

Yes, the speed seemed ok after new pump shoe

Tony, it Seemed okay after the pump shoe replacement or ran 79+ mph after the pump shoe replacement?

If the ski hasn't run 79 mph since the pump shoe replacement then I think your problem lies there.

Have you checked the clearance between the wear ring and impeller?

[PETRUS]

Tony, it Seemed okay after the pump shoe replacement or ran 79+ mph after the pump shoe replacement?

If the ski hasn't run 79 mph since the pump shoe replacement then I think your problem lies there.

Have you checked the clearance between the wear ring and impeller?

Hi Jerry, it ran 79+ after pump shoe replacement, problem appeared some time after

Ring/prop clearance seems ok when looking into the pump with a flash-light,
the wear-ring is new...
do you recommend i pull the pump for inspection?

When the dealer changed the shoe, i asked them to align engine too, they wouldn't have bothered checking it if i didnt mention ... i remember they put 2 shims under each rear mount, that seemed a lot...

If it was a boost leak, rpms would be down too, correct?
so we can narrow it down to a pump or alignment problem?
Thanks

[PETRUS]

I did notice something unusual after dealer replaced pump shoe/ wear ring /carbon seal,
after the first ride i found this black carbon line all around the inside of the hull at the level of the seal, see pic attached.
It s everywhere, at the bottom of the hull, on the sides, even on the inside of the seat.
At first it was a very thin fine line like laser-etched, now it s thicker & blurred, i havent cleaned it so i could show it to them next time.
Is this a sign of bad alignment?

[Ocman]

I did notice something unusual after dealer replaced pump shoe/ wear ring /carbon seal,
after the first ride i found this black carbon line all around the inside of the hull at the level of the seal, see pic attached.
It s everywhere, at the bottom of the hull, on the sides, even on the inside of the seat.
At first it was a very thin fine line like laser-etched, now it s thicker & blurred, i havent cleaned it so i could show it to them next time.
Is this a sign of bad alignment?

When I replaced my carbon seal a few months back mine did the same thing inside the hull. I suspect just because its new. Some people have said that means the seal is bad but I have no issues bro.

[troyheb]

I did notice something unusual after dealer replaced pump shoe/ wear ring /carbon seal,
after the first ride i found this black carbon line all around the inside of the hull at the level of the seal, see pic attached.
It s everywhere, at the bottom of the hull, on the sides, even on the inside of the seat.
At first it was a very thin fine line like laser-etched, now it s thicker & blurred, i havent cleaned it so i could show it to them next time.
Is this a sign of bad alignment?

Like Eric said, some do that when they are new.