My son has a 1992 Zodiac Projet which is a 14' inflatable built around a fiberglass hull. It uses the running gear from a Waverunner 3. It weighs 660 lbs without passengers and tops out in the high 20 mph range. It leaps out of the water with its current 50 hp 650 engine/jet configuration but with 4 passengers its kinda slow.
My son has been scouring the internet looking for performance upgrades but nothing seems to be promising based on the 650 platform.
See this video to learn what boat this is
I just bought a donor ski. It's a like new 2000 gp760 with only 56 hours. It is completely stock and perfect in everyway. Compression checks out and I will do a case leakdown test before installing it in my sons boat.
Anyway's I have a few questions.
#1. Will I benefit by milling .010 or more from the stock cylinder head. I recall the 760 cylinders are port timed towards best high rpm power. Will a small compression bump give me a little more low end grunt? I will be running leaded 93 octane fuel from the marina. If it is a worthy mod what type of difference would it make? In other words will It be noticeable or worth the trouble?
#2. I haven't yet removed the 144mm pump assembly from the Zodiac so I do not know what pitch prop is in there. I will need to speak with someone with excellent knowledge on prop sizing. Will the 144mm GP760 jet pump fit where a WR3 jet pump goes? Which prop should I start out with? The GP760 is 160 lbs lighter so the prop may be to tall a ratio. However the prop in the Zodiac allows the 650 engine to reach at least 6500 rpm and tops out under 30mph. My goal is to get 35 mph with a 1000 lbs total weight. Better acceleration is what I seek the most.
Should I try to fit a 155mm pump? Has that ever been done on a WR3?
#3. While the 760 engine is out are there any worthwhile mods to do? How about those reed stuffers? Worth the $65.00?
#4. I am not sure if the stock 760 pipe will fit in the Zodiac engine bay. Will the 650 pipe fit? Will performance suffer greatly?
Here are a few pictures
My son has been scouring the internet looking for performance upgrades but nothing seems to be promising based on the 650 platform.
See this video to learn what boat this is
Anyway's I have a few questions.
#1. Will I benefit by milling .010 or more from the stock cylinder head. I recall the 760 cylinders are port timed towards best high rpm power. Will a small compression bump give me a little more low end grunt? I will be running leaded 93 octane fuel from the marina. If it is a worthy mod what type of difference would it make? In other words will It be noticeable or worth the trouble?
#2. I haven't yet removed the 144mm pump assembly from the Zodiac so I do not know what pitch prop is in there. I will need to speak with someone with excellent knowledge on prop sizing. Will the 144mm GP760 jet pump fit where a WR3 jet pump goes? Which prop should I start out with? The GP760 is 160 lbs lighter so the prop may be to tall a ratio. However the prop in the Zodiac allows the 650 engine to reach at least 6500 rpm and tops out under 30mph. My goal is to get 35 mph with a 1000 lbs total weight. Better acceleration is what I seek the most.
Should I try to fit a 155mm pump? Has that ever been done on a WR3?
#3. While the 760 engine is out are there any worthwhile mods to do? How about those reed stuffers? Worth the $65.00?
#4. I am not sure if the stock 760 pipe will fit in the Zodiac engine bay. Will the 650 pipe fit? Will performance suffer greatly?
Here are a few pictures
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