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  1. #81
    Sage18's Avatar
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    Quote Originally Posted by hyoctane23 View Post
    Your clearance sounds about right. If the cylinders looked like that before you got into it, the engine probably wasn't warmed up enough before dropping the hammer or was ridden in very cold water. You can use a Scotch-Brite pad to remove the shiny glazing on the cylinder walls. I've also used a Flex-Hone to remove heavy glazing but don't overdo it. The plating looks okay in the pictures...as long as it isn't peeling anywhere. You'll be able to easily see that if it was happening.
    Great. Do you know the stock bore opening size? The guy before me didnít know much about the boat and how to run it. Or even what pistons were in it. No peeling in the plating. It feels very smooth. What grit hone would be good to just go over it slightly. I have a medium grit, think itís 220. Get rings directly from Wiseco?

  2. #82

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    Quote Originally Posted by Sage18 View Post
    Great. Do you know the stock bore opening size? The guy before me didn’t know much about the boat and how to run it. Or even what pistons were in it. No peeling in the plating. It feels very smooth. What grit hone would be good to just go over it slightly. I have a medium grit, think it’s 220. Get rings directly from Wiseco?
    Those look like wiseco pistons, so yes. But you should be 100% careful with warming that thing up, those marks are because someone wasn't doing a very good job warming it up. You should always use the same brand rings with the same brand pistons. Stock pro 785 wiseco pistons should have
    722M06970 stamped on top of them, which is the part number. You can supposedly use the 750 pistons (I never have), those part numbers start with 633M. The last five digits of a Wiseco piston part number are the size, so 06970 is 069.70mm.

    You want to hone it. The hone will keep it round. If you start manually sanding you will make high and low points and compression will leak, causing blow-by. And 220 is way, way too much. If you want to clean it up you should use something much higher, like 500+ and sand a lot. If this were some stupid 750 couch or something I would say go ahead but it's not ideal. But for a Pro you want to do it right. Diamond hones are not that expensive, you should have one. They aren't that difficult to use and the service manual even explains it.

    https://www.lasleeve.com/tech/catalogs

  3. #83
    Sage18's Avatar
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    Quote Originally Posted by sdlvx View Post
    Those look like wiseco pistons, so yes. But you should be 100% careful with warming that thing up, those marks are because someone wasn't doing a very good job warming it up. You should always use the same brand rings with the same brand pistons. Stock pro 785 wiseco pistons should have
    722M06970 stamped on top of them, which is the part number. You can supposedly use the 750 pistons (I never have), those part numbers start with 633M. The last five digits of a Wiseco piston part number are the size, so 06970 is 069.70mm.

    You want to hone it. The hone will keep it round. If you start manually sanding you will make high and low points and compression will leak, causing blow-by. And 220 is way, way too much. If you want to clean it up you should use something much higher, like 500+ and sand a lot. If this were some stupid 750 couch or something I would say go ahead but it's not ideal. But for a Pro you want to do it right. Diamond hones are not that expensive, you should have one. They aren't that difficult to use and the service manual even explains it.
    Thanks for the info. So how long do you need to warm the thing up would you say? Idle it for 5-10 min. Or what RPM? I heard till the pissers get warm? Also what grit diamond hone? Like I said itís smooth but can see lines. Iíll look in the manual tomorrow as well.

    Can you or anyone on here point me in the direction of a good sl750 stock piston with rings? Iím putting one back together for the kids to play with and donít want to put a lot of money into it. Boat is in great shape just had a ring break and stick in the top of the piston.

  4. #84

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    Quote Originally Posted by Sage18 View Post
    Thanks for the info. So how long do you need to warm the thing up would you say? Idle it for 5-10 min. Or what RPM? I heard till the pissers get warm? Also what grit diamond hone? Like I said it’s smooth but can see lines. I’ll look in the manual tomorrow as well.

    Can you or anyone on here point me in the direction of a good sl750 stock piston with rings? I’m putting one back together for the kids to play with and don’t want to put a lot of money into it. Boat is in great shape just had a ring break and stick in the top of the piston.
    Well, I never use mine if the water temp is below 55, and even then I wait a while, at least until the pissers are warm. If you give it throttle and it does a little bog type thing, it's still cold. I am lucky because I have 1300 foot slow now wake zone to go through. Some people can just hit it right after they get off their dock or launch. If you don't like putting new pistons in it, I would suggest over 60 only with wiseco. I can't guarantee that, so don't hate me if it still seizes. But that's my recommendation.

    I run through the slow no wake zone at that speed, and then after that I go about a mile with just barely getting on the pipes, but still on plane (about 4000 rpm). My lake is usually around 65 to 75 degrees. I've never cold seized a pro with wiseco in these conditions. The only time I've done it was when I was in colder water. If you're on a deep lake, remember that it gets warmer from the outside in spring and cooler from the outside in fall. Just because it's April and the water is 55 at the launch, it could easily be in the lower 40s in the middle of the lake.

    I think I mentioned this before, but if your lake is cold, I would replace the WiseCo pistons with cast ones. I know xlint has problems with wiseco, and he rides in Lake Erie. Even in June Erie is barely in the 60s on average. That's something you need to consider. If you are riding on Lake Ontario I would get rid of them. Looking at average lake Ontario temps, the only time I would feel safe riding a pro with wiseco is between june and september. Lots of missed season. And a new set of cast pro 785 pistons are going to cost A LOT LESS than having to fix a cylinder with a gouge in the wall and get new pistons.

    As for the 750, from what I've seen people run the WSM pistons, and they are the cheapest. SBT makes some too. I had an SL 750 before my pro and the thing was nearly invincible. They are industrial water pump engines and they are sort of detuned with the lower rev limiter.

  5. #85
    Sage18's Avatar
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    Quote Originally Posted by sdlvx View Post
    Well, I never use mine if the water temp is below 55, and even then I wait a while, at least until the pissers are warm. If you give it throttle and it does a little bog type thing, it's still cold. I am lucky because I have 1300 foot slow now wake zone to go through. Some people can just hit it right after they get off their dock or launch. If you don't like putting new pistons in it, I would suggest over 60 only with wiseco. I can't guarantee that, so don't hate me if it still seizes. But that's my recommendation.

    I run through the slow no wake zone at that speed, and then after that I go about a mile with just barely getting on the pipes, but still on plane (about 4000 rpm). My lake is usually around 65 to 75 degrees. I've never cold seized a pro with wiseco in these conditions. The only time I've done it was when I was in colder water. If you're on a deep lake, remember that it gets warmer from the outside in spring and cooler from the outside in fall. Just because it's April and the water is 55 at the launch, it could easily be in the lower 40s in the middle of the lake.

    I think I mentioned this before, but if your lake is cold, I would replace the WiseCo pistons with cast ones. I know xlint has problems with wiseco, and he rides in Lake Erie. Even in June Erie is barely in the 60s on average. That's something you need to consider. If you are riding on Lake Ontario I would get rid of them. Looking at average lake Ontario temps, the only time I would feel safe riding a pro with wiseco is between june and september. Lots of missed season. And a new set of cast pro 785 pistons are going to cost A LOT LESS than having to fix a cylinder with a gouge in the wall and get new pistons.

    As for the 750, from what I've seen people run the WSM pistons, and they are the cheapest. SBT makes some too. I had an SL 750 before my pro and the thing was nearly invincible. They are industrial water pump engines and they are sort of detuned with the lower rev limiter.
    Well thought out. I ride a few bays around here that are warmer but also Lake Ontario so it sounds like cast pistons are the way to go. Suggestions on what cast pistons to buy?

  6. #86
    I'D RATHER SWEAT THAN SHIVER hyoctane23's Avatar
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    Quote Originally Posted by Sage18 View Post
    Well thought out. I ride a few bays around here that are warmer but also Lake Ontario so it sounds like cast pistons are the way to go. Suggestions on what cast pistons to buy?
    Have you read the whole thread lol. Already a couple of suggestions

  7. #87
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    Quote Originally Posted by hyoctane23 View Post
    Have you read the whole thread lol. Already a couple of suggestions
    :-/ youíre right time to go back through and re-read the whole thread.


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