89 SP running at 43mph...

[FultonD33]

I see everywhere that the top speed on these is 35-38 but I restored one I bought and it is getting 43 mph on gps in good water. No mods as far as I am concerned besides the original owner did away with the round body carb and opted for an SBN38 which I rebuilt (not thinking correctly of course being a newbie) with a kit I used on my Waverunner because it had the same carb. I wonder if it changed the needle valve size and that caused an increase in speed? It is a pretty quick and fun little ski. Does anybody know what the needle valve size is for a 91 VXR 650? I looked everywhere and can't find it, just trying to find out if it found a secret "mod" for these older skis or if it is a common thing. I believe I am also tapping the rev limiter on this thing as recently when I am running WOT it will sometime jerk back but that could just be a piece of trash in the carb.

Here is the kit I used:

Yamaha Wave Runner 650 Genuine Mikuni Carb Rebuild Kit Base Gasket & Needle Seat

 

[Whus02]

You might have a couple parts from later models, an SP with a slightly better carburetor, tuned pipe, and a prop might do about that speed. See if your pipe ends in a cone or a "cap".

Changing the needle valve size only changes the pop-off, which might have some improvements, but nothing that would gain that much top speed.

As far as the rev limiter, it usually won't jerk the ski back, it would just stop the ski from going faster, so junk in the carb is more likely.

 

[AKnarrowback]

Odd question here, but does the seat on your machine flip up on a hinge or pull off the machine like a normal DOO?

 

[Whus02]

Love the 88 SPs, sometimes I wish they stuck with the clamshell design.

The flip up seat looks like this if you have one.

 

[FultonD33]

I will check on the pipe when I get home. But no it is the 89 the seat comes off like a normal sea doo but the colors and body style is just like the one in the picture.

 

[FultonD33]

Love the 88 SPs, sometimes I wish they stuck with the clamshell design.

The flip up seat looks like this if you have one.View attachment 52153

That clamshell design looks great tho! Probably easier for working on it too.

 

[FultonD33]

These are the pics of the ski. No the decals aren’t original obviously

 

[FultonD33]

Here is the inside of the ski. I think the pipe ends in more of a cap in my opinion.

You might have a couple parts from later models, an SP with a slightly better carburetor, tuned pipe, and a prop might do about that speed. See if your pipe ends in a cone or a "cap".

Changing the needle valve size only changes the pop-off, which might have some improvements, but nothing that would gain that much top speed.

As far as the rev limiter, it usually won't jerk the ski back, it would just stop the ski from going faster, so junk in the carb is more likely.

Here is the inside of the ski. I think it’s the “cap” type pipe

 

[mikidymac]

Engine looks all stock with the lower spec pipe.

 

[AKnarrowback]

Love the 88 SPs, sometimes I wish they stuck with the clamshell design.

The flip up seat looks like this if you have one.View attachment 52153

The one 88 I worked on ran more like a 91/92 twin carb XP. It was all stock but had more scoot than the 89s.

 

[FultonD33]

I haven't been in the jet pump but I don't think there's a stainless prop in there. So any other reasons why it would go that fast? I think compression is around 135 even per cylinder. I run 89 mid grade gas nothing special, is that what I should run?

 

[AKnarrowback]

Are you on a lake or river?

 

[FultonD33]

Are you on a lake or river?

I have done both, the river isn't very fast moving so it wouldn't add that much speed.

 

[Seadoo Tuner]

Maybe you have an aftermarket intake grate?

Don't think that would account for that much over stock speed but I have an R & D Racing intake grate on my 96 SPI and it consistently does 46mph with 94 octane gas (stock speed is listed as 42mph for mine).

 

[mikidymac]

A top loader aftermarket intake grate will reduce top speed on smooth water not increase it.