itsdgm
Jetboaters Admiral
- Messages
- 3,658
- Reaction score
- 3,154
- Points
- 417
- Location
- Rancho Santa Margarita, California
- Boat Make
- Yamaha
- Year
- 2007
- Boat Model
- AR
- Boat Length
- 21
So a little history. Boat is running great, rpm’s are normal. But over the past few seasons I’ve noticed that I’ve lost a few mph on the top end and that the boat takes a bit more time getting out of the hole. I’d guess that I’ve lost maybe 5-10% of thrust max.
I figured that this winter I’d tear down the propulsion system, rebuild the pumps, check impellers, wear rings and silicone on the intake end of things. This is the first time in the 13 years that I’ve owned the boat that I’ve looked at the thrust system. All I can say is wow. The pumps unbolted and slid out of the boat with ease. Things look and feel way better than I expected. The pump bearings are smooth as silk, no play at all. The impellers leading edges look clean as a whistle too. The intake looks pretty good, possibly a tiny bit of silicone that could be touched up here and there. The wear rings look evenly worn, with no real obvious signs of damage. But I’m not really sure what the impeller/wear ring gap should be. So I haven’t measured that out yet.
So what I’d like to know from you guys who have been down this road before. Where do you think my 5% loss of thrust could be? It has to be somewhere in the thrust system.
I’m planning on re-siliconing any missing gaps on the intake before putting it all back together. But my real dilemma is whether or not to replace the wear rings. They look pretty good to me. But I’ve never measured the gap on one or know what a normal gap should look like. I don’t mind buying new ones, but would hate to spend the $ (they aren’t cheap) if it didn’t help my issue.
Heres a few pics of the Port pump (both are in exact same condition). I appreciate any recommendations that come from real life experience.
Thanks in advance.
PS. If you do recommend wear rings. Would you go OEM or aftermarket? If aftermarket, which ones?
![004AE1D7-73BD-4576-B39F-02F554E10568.jpeg 004AE1D7-73BD-4576-B39F-02F554E10568.jpeg](https://jetboaters.nyc3.digitaloceanspaces.com/data/attachments/170/170330-50b0a31ca6d5ba1d6bc8fd0625850e6e.jpg?hash=ULCjHKbVuh)
![F344F61C-48B6-496D-94DA-7630DC5CF456.jpeg F344F61C-48B6-496D-94DA-7630DC5CF456.jpeg](https://jetboaters.nyc3.digitaloceanspaces.com/data/attachments/170/170331-f7ac6b5fe205f2e58ef92aaac5d5fc3c.jpg?hash=96xrX-IF8u)
![ADAA29D2-2F65-46B9-915C-45DD1BB3B78E.jpeg ADAA29D2-2F65-46B9-915C-45DD1BB3B78E.jpeg](https://jetboaters.nyc3.digitaloceanspaces.com/data/attachments/170/170332-3f13fa65f0cdac57934d943ebb553989.jpg?hash=PxP6ZfDNrF)
![433540B6-2282-4810-841C-F6BAB6AEB367.jpeg 433540B6-2282-4810-841C-F6BAB6AEB367.jpeg](https://jetboaters.nyc3.digitaloceanspaces.com/data/attachments/170/170333-4d604761a3181846d3931eb2be4380c8.jpg?hash=TWBHYaMYGE)
@swatski @Julian @CrankyGypsy @Bruce @Cobra Jet Steering LLC
I figured that this winter I’d tear down the propulsion system, rebuild the pumps, check impellers, wear rings and silicone on the intake end of things. This is the first time in the 13 years that I’ve owned the boat that I’ve looked at the thrust system. All I can say is wow. The pumps unbolted and slid out of the boat with ease. Things look and feel way better than I expected. The pump bearings are smooth as silk, no play at all. The impellers leading edges look clean as a whistle too. The intake looks pretty good, possibly a tiny bit of silicone that could be touched up here and there. The wear rings look evenly worn, with no real obvious signs of damage. But I’m not really sure what the impeller/wear ring gap should be. So I haven’t measured that out yet.
So what I’d like to know from you guys who have been down this road before. Where do you think my 5% loss of thrust could be? It has to be somewhere in the thrust system.
I’m planning on re-siliconing any missing gaps on the intake before putting it all back together. But my real dilemma is whether or not to replace the wear rings. They look pretty good to me. But I’ve never measured the gap on one or know what a normal gap should look like. I don’t mind buying new ones, but would hate to spend the $ (they aren’t cheap) if it didn’t help my issue.
Heres a few pics of the Port pump (both are in exact same condition). I appreciate any recommendations that come from real life experience.
Thanks in advance.
PS. If you do recommend wear rings. Would you go OEM or aftermarket? If aftermarket, which ones?
![004AE1D7-73BD-4576-B39F-02F554E10568.jpeg 004AE1D7-73BD-4576-B39F-02F554E10568.jpeg](https://jetboaters.nyc3.digitaloceanspaces.com/data/attachments/170/170330-50b0a31ca6d5ba1d6bc8fd0625850e6e.jpg?hash=ULCjHKbVuh)
![F344F61C-48B6-496D-94DA-7630DC5CF456.jpeg F344F61C-48B6-496D-94DA-7630DC5CF456.jpeg](https://jetboaters.nyc3.digitaloceanspaces.com/data/attachments/170/170331-f7ac6b5fe205f2e58ef92aaac5d5fc3c.jpg?hash=96xrX-IF8u)
![ADAA29D2-2F65-46B9-915C-45DD1BB3B78E.jpeg ADAA29D2-2F65-46B9-915C-45DD1BB3B78E.jpeg](https://jetboaters.nyc3.digitaloceanspaces.com/data/attachments/170/170332-3f13fa65f0cdac57934d943ebb553989.jpg?hash=PxP6ZfDNrF)
![433540B6-2282-4810-841C-F6BAB6AEB367.jpeg 433540B6-2282-4810-841C-F6BAB6AEB367.jpeg](https://jetboaters.nyc3.digitaloceanspaces.com/data/attachments/170/170333-4d604761a3181846d3931eb2be4380c8.jpg?hash=TWBHYaMYGE)
@swatski @Julian @CrankyGypsy @Bruce @Cobra Jet Steering LLC
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