Yamaha exciter 570 into seadoo

[Stubbs]

The stock exhaust on 80’s 2 stroke Yammies were terrible, any aftermarket pipe will be good for a bunch more power. Those 570 Exciter motors were a little finicky in terms of jetting, had a bad mid range lean spot, so be careful. I’d suggest a set of EGT’s so you can keep an eye on what it doing under load in the midrange.

 

[Anthonynytro]

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[Anthonynytro]

Yamaha exciter 570 PSI performance pipe installed.
First run is gunna be the pipe pointed up just to make sure everything works than I'll make it hook up to the original exhaust.

 

[74Nitro]

The stock exhaust on 80’s 2 stroke Yammies were terrible, any aftermarket pipe will be good for a bunch more power. Those 570 Exciter motors were a little finicky in terms of jetting, had a bad mid range lean spot, so be careful. I’d suggest a set of EGT’s so you can keep an eye on what it doing under load in the midrange.

If I remember correctly, it was the 87 Exciter with butterfly carbs that had the mid range lean condition.
I once owned an 88 with slide carbs and had no issues, although the machine rarely spent much time at 'mid range' throttle opening.

 

[74Nitro]

Yamaha exciter 570 PSI performance pipe installed.
First run is gunna be the pipe pointed up just to make sure everything works than I'll make it hook up to the original exhaust.

That's quite a unit.
Not many people would attempt this, interesting for sure.
The early 570's were about 82 HP
Peak HP rpm with a pipe would be 72-7400
If you don't know how to read piston wash, you should learn it by searching info and pics online.

 

[Yamajon1]

If I remember correctly, it was the 87 Exciter with butterfly carbs that had the mid range lean condition.
I once owned an 88 with slide carbs and had no issues, although the machine rarely spent much time at 'mid range' throttle opening.

PSI made a tapered needle for the slide carb Exciters to correct the mid range lean spot. Burned my 89 up first ride with PSI single pipe back in the day.

 

[Stubbs]

My Dad lost at least one piston even after installing those customs tapered needles. His sled was an ‘89 with the round slide Mikunes.

 

[Anthonynytro]

Well first ride out on the water went terrible...
Couldn't get the engine to go past half throttle.
I had a feeling from all the issues I had last year I hurt the engine abit and when I checked the compression when I got home It read
80psi on PTO side
110psi on MAG side.
Cylinder walls look great and machinist said bore was still within spec so he honed it quick and I'm gunna just slam new rings into it.

 

[Anthonynytro]

That's quite a unit.
Not many people would attempt this, interesting for sure.
The early 570's were about 82 HP
Peak HP rpm with a pipe would be 72-7400
If you don't know how to read piston wash, you should learn it by searching info and pics online.

The stock 657x the boat came with was rated at 80hp so I thought why not?.
Specially when the owner told me the boat was on its 4th or 5th engine.

I really wanted to put a Yamaha Nytro 1049cc engine into it but I couldn't find any that were cheap

 

[Anthonynytro]

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