1994 spx rips

[Needle]

I’d like to give a shout out to this form for helping me get my spx running better than new. This thing flat out rips it on the plane in two seconds! I raced newer ones bigger ones none take off like this one goes 0 to 51 mph in 4.1 seconds. I thank that its stock I guess there’s really no way to tell unless you took it apart. compression 165 on both cylinders. i’ve read 150 was good does that mean you have to run 93 fuel?

 

[edchris]

Use what the manual says is required. If it is stock, the manuals recommended fuel is what you use.

 

[etemplet]

I'm curious about the compression being that high but what the hey if it is running good... cool ! Personally I don't know compression numbers that would determine the need for increased octane but it doesn't hurt to run a higher grade fuel.

 

[Needle]

Just put a aftermarket intake grate on top speed is still 51 mph but it does corner better with less cavitation. I would say maybe 20% better my stock on was broken that why I replaced it.

 

[etemplet]

I can say this from my experience with jet skis, I don't have much experience but I know speed and how to get it. These are just my observances thus far. Perhaps with experience I'll fill in the gaps.

What I noticed at these jet skis is they don't care much about weight. I watched my wife and a passenger that was my weight glide right by at the same speed than she does riding alone, about 1.5mph faster than my ski. Same GTX... I was even in the full tuck position which works on motorcycles but not jet skis. LOL They just don't care.

Speed is based on "hull design". So adding power will net very little improvement to overcome design speed..

An extra 20hp (787 to a 951) only gains 5mph top speed difference. That's a 15% increase in performance and you'll play hell getting that much more power without sacrificing reliability.

I wonder if making the hull more slick will make a more significant difference? I have a ski that needs that. It is hella slow for the model which is also a GTX 42mph top speed 6500 RPM Solas Concord Impeller. Hull is funky. I'll clean it up and report back. good luck.

 

[Needle]

I can say this from my experience with jet skis, I don't have much experience but I know speed and how to get it. These are just my observances thus far. Perhaps with experience I'll fill in the gaps.

What I noticed at these jet skis is they don't care much about weight. I watched my wife and a passenger that was my weight glide right by at the same speed than she does riding alone, about 1.5mph faster than my ski. Same GTX... I was even in the full tuck position which works on motorcycles but not jet skis. LOL They just don't care.

Speed is based on "hull design". So adding power will net very little improvement to overcome design speed..

An extra 20hp (787 to a 951) only gains 5mph top speed difference. That's a 15% increase in performance and you'll play hell getting that much more power without sacrificing reliability.

I wonder if making the hull more slick will make a more significant difference? I have a ski that needs that. It is hella slow for the model which is also a GTX 42mph top speed 6500 RPM Solas Concord Impeller. Hull is funky. I'll clean it up and report back. good luck.

I tried waxing the hull and it did make it slick but no difference in speed. Which is fine I mean 51 is fast to me on the water. I’m not sure the rpm but I’d say it’s maxed out when jumping I hear it bounce off the rev limiter. I think the 657 is a great engine for the power to weight ratio of the ski.

 

[etemplet]

51 is pretty dang fast.

 

[Dman142]

I thought wax makes the water stick more to the hull. I’ve also read that dimpling the bottom like a golf ball, times about 2000 will create less drag in the water. So flip over your ski and start drilling. Just don’t go too deep! Lol

 

[Needle]

I thought wax makes the water stick more to the hull. I’ve also read that dimpling the bottom like a golf ball, times about 2000 will create less drag in the water. So flip over your ski and start drilling. Just don’t go too deep! Lol

Who ever said that is retarded

 

[POPPS]

If the compression is that high,,,maybe the gauge is off,,,frequently occurs,,,or possibly,,,someome milled the head,,,you would have to remove it in that case to verify,,,and therefore you should probably use 91 octane.

 

[Needle]

If been putting 93 in it just to be safe.

 

[POPPS]

You can never go too high on octane...