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Discussion Starter #1
OK so now I have rebuilt the carb and well the same results. Here the problem. I bought form my brother. He says it most likely has 1500 hrs or more on the engine. It runs, it starts it looks great. No leaks , very clean. I have put new plugs, all new carb parts as recommended to begin with and she starts up great but as soon as she hits the water. No Power, No Pickup, Just struggles to get up to speed. I am thinking it needs a new top end done on it and I am not so sure if I can do that big a job. Any ideas and also anyone know about what it should cost to do the top end.
 

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Yep, 1500 hrs., bogs under load, most likely worn out engine. A compression check will probably confirm the diagnosis. Top end kit from SBT is around $210. You may want to consider a new engine. Pretty easy to work on these 2 strokes if you have any mechanical ability.
 

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Discussion Starter #3
Thanks

You mentioned SBT is that a online parts house? Also If I did decide to replace the engine, what should I expect to pay for one. Also the top end price you mentioned, what does that include. I do have some mechincal skills not so deep that I would replace the crank, but I think I could do the pistons and rings if that all I would be replacing. Would I need just a stock set or do I need to have the cyl. bored out?
 

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Here is the SBT site: SBT Jetski Engines, Parts & Accessories They are probably the #1 in sales of rebuilt ski motors and parts. Plug in your model and year and they will list all the parts they have available for your ski. They also have installation guides to show you how to pull and install a new engine for example: http://www.shopsbt.com/pdfs/y650701x.pdf

You can contact them directly, and they will tell you exactly what you need for your ski. They are not the only site that you can find ski parts from, but in my experience they are probably the easiest to deal with.
 

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Discussion Starter #5
Re-built Carb Still No Power

I have replaced all the carb parts recommended by the dealer and she still is having the same problem. Starting the think its a money pit. Wanted to check the compression but don't know what it should be. Anyone know what the compression for a 94 Waverunner III should be?
 

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For a 2 cylinder yamaha engine around 150 psi is ideal spec for new engines. For an older engine you would like to see 140 psi and both cylinders within 10% of each other.
 

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Discussion Starter #7
OK... So I have rebuilt the carb and put a completely new top end. Cylinders and pistons and rings. I went with the .050 bore and have got it all back together. I took it out today and tried to test the unit and I am still having the same problem I had before I replaced the top-end. It has no power and it seems to be starving for fuel. Should I have changed out the main jets to larger jet since I went to a oversize piston? Please and advise that might help me identify the problem would be greatly appreciated.
 

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Discussion Starter #8
Still Having a Problem

OK... So I have rebuilt the carb and put a completely new top end. Cylinders and pistons and rings. I went with the .050 bore and have got it all back together. I took it out today and tried to test the unit and I am still having the same problem I had before I replaced the top-end. It has no power and it seems to be starving for fuel. Should I have changed out the main jets to larger jet since I went to a oversize piston? Please and advise that might help me identify the problem would be greatly appreciated.
 

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Discussion Starter #9
Wet Box Failure

Whats happens when your wet box fails. I had someone say it sounded like it was not getting enough air flow. I did notice that there is some exhaust smoke under the hood when I open it. And when I start it up out of the water it smokes I have sealed all the hoses and claps but I saw were someone said the wet box fail and wouldn't allow for a clear exhaust flow. I am going to take it back to the river today and play with the pilot screw and see if maybe it the mix.
 

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what did you find

I have the same issue under almost excatly the same circumstances. I was given 2 waverunner III ('92), wne trough the carbs, but from about half throttle up it just bogs down, but they idle great.
 

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Discussion Starter #11
Found the problem..

Well after spending a small fortune I finally found the problem. These engines are very temperamental if they aren't getting enough clean air they will choke themselves out and bog down. The way I found out was I had noticed that there was some smoke coming from the wet box and I took it out and found an exhaust leak. Well really there was a crack in the case. If you have any exhaust fumes being trapped in the engine compartment it will bog down the engine when you start putting a load on the exhaust. When its in the water there is a bit of back pressure that you don't have when its just idling. Try unlocking the engine hood and see if it will running ok with clean air getting under the hood. let me know. I have become somewhat of an expert at what these models have for issues.
 

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94 waverunner 3 gp

Well after spending a small fortune I finally found the problem. These engines are very temperamental if they aren't getting enough clean air they will choke themselves out and bog down. The way I found out was I had noticed that there was some smoke coming from the wet box and I took it out and found an exhaust leak. Well really there was a crack in the case. If you have any exhaust fumes being trapped in the engine compartment it will bog down the engine when you start putting a load on the exhaust. When its in the water there is a bit of back pressure that you don't have when its just idling. Try unlocking the engine hood and see if it will running ok with clean air getting under the hood. let me know. I have become somewhat of an expert at what these models have for issues.
Hey tmosley i dont know if you still visit this site but im having kind of the same issue. my ski only wants about half throttle after that she wants to bog down. it still goes 33 at half throttle though.
 
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