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  1. #1
    JeepOrvis97's Avatar
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    I just bought a 1991 Waverunner LX 650 and have a couple questions.

    First off, I just want to say hello, I was referred to this forum by one of the guys who had a jet ski I was looking at buying. I ended up buying this waverunner instead because it seemed like a deal I couldn't pass up. Its a 91 and came with a 2002 triton aluminum trailer all for $500. The ski is very clean for 20 years old, still had a great shine but it got even better after I highspeed buffed it out. I just took it out on the lake today and it ran pretty good. I noticed that once it warmed up a bit it didn't like full throttle, it would bog down a bit and would run faster at just before WOT. Also, while going quick and straight on a smooth surface the front would bounce a lot, I'm not sure if this is normal or if there's something I can do about it....I don't mind it that much but I'd just like to check, I know my buddies seadoo goes smooth at full throttle but its also a 2006 3 seater lol So I'm thinking the bouncing is normal and the throttle issue is because the carb may need cleaned out???? Sound right???

    Here's a pic from before I buffed it:


  2. #2
    Old Ski Insanity w/rpm500's Avatar
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    read my threads on the 500's (do a search) its about the same ski,just more motor.. the trottle issue could be bad gas or even a slipping impeller (needs replacement or shimming)..
    you can shim the ride plate down in back with ss washers to stop alot of the bounce..
    there are six bolts, put no washers in front, 3 in the center and 5 to six in back, youll need longer bolts to replace the back two that now wont be long enough... you got a killer deal !!

  3. #3
    JeepOrvis97's Avatar
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    Thanks for the reply. This is the gas from last year so maybe I'll drain it and put some fresh stuff in it. And I'll try the washer thing too.

  4. #4
    JeepOrvis97's Avatar
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    I just went to look at the ride plate, it has adjusters in the back 2 screws on each side so I screwed those up 6 turns in the back and 3 in the middle to see what happens. Before I did anything the ride plate was completely flat, now its a little lower in the back. I also filled the tank up with fresh gas so we'll see what happens, I'm probably going out again today. Whats the best gas to run in these? 87 octane? 89 octane?

  5. #5
    Old Ski Insanity w/rpm500's Avatar
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    sorry, forgot the later 650 version had the adjustsable plate..you did good with the adjustments..

    depending on your ratio of mix, you may still have some stalling issues.. when you run old fuel you can run the risk of seizure, so be easy on the throttle and dont push it till you get a full batch of fresh gas..

    it will prob run best on the 89 right now.. its safer to run in reguards to seizure..(has a slower flame path and a bit cooler running than 87)
    I'll assume that your not knowing of any mods done to the ski yet, its best to run the 89 .. IMO,stock will run the 87 ,Thou I Prefer to run the 89 or higher

  6. #6
    JeepOrvis97's Avatar
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    Ok, thanks, I'll run 89 octane, not like its much more money anyway in the whole scheme of things.

  7. #7
    JeepOrvis97's Avatar
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    Went out on the lake today and after about 45 minutes of riding I couldn't get the ski to plane any more so I pulled over to the dock and realized how low it was sitting in the water.....went and got the trailer right away and took it out of the water and pulled the plug out the back, it started pouring out water and continued to for 15 minutes, by the time I opened the engine compartment there was still water touching the bottom of the motor and that was after draining for about 5 minutes. I let it drain and started the motor real quick and noticed there was an exhaust leak by the exhaust waterbox. Took it out at home and found a huge crack in the fiberglass. I'm assuming this is the main cause for my leak in the ski???

  8. #8
    Old Ski Insanity w/rpm500's Avatar
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    the crack was in the box? if so it prob is/was a northern ski ,wasnt cleared before storage and froze solid breaking the box.. you can find them on ebay and also aftermarkets sell there too
    the box is fiberglass on 5 sides, so you could grind it down and try to reglass that section thats broke..(Alternate: marine tex..).

    You were also running exhaust laden air so once this is fixed it will run even better !!!

    how did she run before it filled?.. bet your bounce was alot less..

  9. #9
    JeepOrvis97's Avatar
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    I live in northeastern ohio and that's where I bought it from. The crack was about 10 inches long on the top of the box, I tried fiberglassing it but I ended up buying a used box off eBay for $25 plus shipping anyway since it doesn't look like the fiberglass will actually hold. I wasn't able to see if the ski had less bounce today since it was the weekend, there were a ton of people at the lake and there was no calm waters. I'm eager to see how it runs too once there exhaust leak is fixed too. I've been very happy with this purchase so far.

  10. #10
    JeepOrvis97's Avatar
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    Finally just got to the lake again yesterday after installing the new water box. Unfortunately there is still a leak around the exhaust manifold. I'm thinking its a rubber tube or something. It did start leaking after I was jumping boat wakes also so I wonder if I just knocked something loose there.

    How do you hook these to the hose at home and run them so I can see better where the leak is coming from?

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