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  1. #1
    96yam701's Avatar
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    96 waveraider 701 rpm issues

    First a little history,
    I purchased the ski a little over 6 months ago after it had sat in a garage for years i think. after riding the ski a few times the first week we put the ski back on trailer to replace a few plastic bits (i broke the throttle trigger on a wake). on "precheck" before putting it back in the water it wouldnt start i used the manual and determined the stator was bad. i didnt feel like breaking the engine down so i let the yamaha shop fix it... yeah 800 dollars and an entirely new electrical system later (new coils, new CDI, and new stator) the ski started IF you hand pumped gas into the carbs. i said i wasnt giving the shop any more money and the kicked the ski out of the shop. i benched the carbs (yep all varnished over) and got everything running again. infact i put 92 octane pump gas and took it out for a run! the best run yet at 50KTS (40ish MPH)

    that is when things went south, the cooling jacket sprung a leak because a bolt on the exhaust riser got striped out (too hot?). which started spraying salt water all over the engine compartment and right into the carbs, which killed the engine streight off (yes i was 3 miles from port) bouncing around on waves i made an emergancy decision to swap the air box to face the rear of the ski and out of the salt spray. made it back to port and diagnosed everything, when once again it wouldnt start! i stripped out the carbs into a gas bath while i troubleshoot the electrics. found that the starter motor was shot and the starting relay went (yes there was water up in the e-box). so after replaceing the starter motor, spark plugs, exhaust manifold, and bypassing the starter relay with a "hidden switch" the ski is back on the water running circles around the rental skis.

    my question
    i cant get 6,000 rpms at full throttle only 5,500 rpms. i dont think it is the carbs (they were benched immediatly). and i want to rule out the CDI and coil because it does do 5500 RPMS. (oh yeah the OHM tests on the electrics are inside factory specs)

    could the faulty starter relay (that is attached but bypassed) be setting things off?
    or
    could a fuel rich condition be keeping the engine from 6,000 RPMS and cause horrible fuel economy? like 10 gals an hour at WOT.


  2. #2
    Carb rich is certainly a possibility. Check you jetting and make sure that you have the needles turned out to manual specs. Try making minor adjustments from there to see if that would do any difference. Also you should be able to read the spark plugs and see more accurately what is the condition from there. Another thing is that the 701 should go to 6600RPM stock and it does approximately 51MPH by GPS. Hope that is helpful.

  3. #3
    96yam701's Avatar
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    thanks,
    i will recheck the carbs, i know the jets are the same ones from the factory when i degunked the carbs last. i will check the mixture screws and recheck the jets (just in case). thanks again!

  4. #4
    Marley Creek, MD
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    I have lots of questions and no answers for ya but...

    Is the ski stock?

    Are you going by the factory tachometer or an aftermarket tach?

    Did the ski get to 6000 before the mishap?

    Are you running on flat/glass water? If not i don't think top speed (52ish) is attainable... but i could be wrong. ( i ask cuz i've never seen glass salt water; but i guess it happens somewhere ) My best in 4"+ chop and 4"+ waves is somewhere around 44mph stock and that was only momentary. (but that is being read from a friends boat matching my speed, not my own gps, i need to get one)

    Are you running wot for a good long while to get to your numbers, or just a few seconds? Mine seems to reach a point on real small chop where it has to be wot for quite a while, and i have to rock the ski back and forth a lot to get it all the way up on plane and get near top speed. (but mine is far from perfect too) On very flat water it's just 1 or 2 rocks and it gets up further, quicker.

    My ski runs pretty good, but some days it runs really great, i think these things have to be tuned really well to get to top numbers in stock trim. Mine seems way underpowered at higher speeds.

    I'd do a compression check.

    92 octane should make no difference, except $3 less per tank to spend on beer; unless the engine is modified.

    Mine goes through 8 gallons in about 1.5 hours if i'm wot most of the time; never been wot for more than 5 minutes straight though.

    And i don't believe the starter relay could be causing a problem, CDI doesn't know it exists. But i hope you still have a functional kill switch/lanyard.

  5. #5
    jdog800's Avatar
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    +1 compression check

  6. #6
    96yam701's Avatar
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    Is the ski stock?

    mostly, it was modified before i purchased it. had an aftermarket CDI and after market exhaust. the CDI was replaced for a factory one.

    Are you going by the factory tachometer or an aftermarket tach?

    factory tach it does still work.

    Did the ski get to 6000 before the mishap?

    yes, it would hit 7500 the first week with the aftermarket CDI. then i GPS'd it after it came from the shop with the factory CDI.

    Are you running on flat/glass water?
    yes and no. yes for the rpm/speed checks. but i live in key west so if i take a right i can go jump waves and have fun if i turn left there is miles upon miles of flat nothing glass water even if the ocean is 2-3 foot inside the reef.

    Are you running wot for a good long while to get to your numbers, or just a few seconds? it only takes a few seconds to get full RPM's but i am running for 10-20 miles on WOT without needing to turn!


    over all i am happy my goal was to be able to beat the rental ski's in the area. but to look down and not see the engine at MAX is frustrating. 92 does make a differance and i have not tried 92 after i stripped the bolt.

    i buggered with the mixture screws today and it was a little rich. havent measured fuel consumption today (i lost the oil cap under the gas tank DUH and i only had 5 gals left over from all this back and forth testing)

    the kill switch works for the most part... IF i start the engine with the lanyard in the dead man's switch, it will kill the engine if it is removed. if i dont put the lanyard in before starting then the only way to stop the engine is via low throttle. yes i set my throttle lower so that it kills the engine if i fall off. but the lanyard does work if i attach it first. the way i bypassed that was to run a new hot wire from the battery to a universal starter switch i got from autozone, then to the hot lead of the motor, the grounding is all still in tack, even the old lead running from the relay is inplace.




    right now i am waiting for an oil cap from riva then i will test 92 octane. i do remember useing 92 for all my speed tests. thanks for the reminder. i will also do compression checks and report back.

  7. #7
    Sorry, I got the impression that the ski was stock. For an aftermarket pipe and/or higher compression head the carb adjustment will differ from the factory manual. If you have a "factory" pipe or a pro-tec wake up kit the ski should do over 57mph GPS just on that and it will rev at about 7200RPM. You may want to find the install manual for your aftermarket pipe from the manufacturer site and it will give you the adjustments for the carbs. Stock compression should be 155 tops. Anything above that will be moded head at the least. I suspect that since 92 does make a difference in this motor, it is probably not stock and you would get higher compression. The bad part is that if you ran on lower octane than 92 you may have caused some damage. Also consider getting rid of the oil injection and running it premix. It can save you a motor at some point.
    Best of luck!

  8. #8
    old school big raider's Avatar
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    Quote Originally Posted by nikolag View Post
    Sorry, I got the impression that the ski was stock. For an aftermarket pipe and/or higher compression head the carb adjustment will differ from the factory manual. If you have a "factory" pipe or a pro-tec wake up kit the ski should do over 57mph GPS just on that and it will rev at about 7200RPM. You may want to find the install manual for your aftermarket pipe from the manufacturer site and it will give you the adjustments for the carbs. Stock compression should be 155 tops. Anything above that will be moded head at the least. I suspect that since 92 does make a difference in this motor, it is probably not stock and you would get higher compression. The bad part is that if you ran on lower octane than 92 you may have caused some damage. Also consider getting rid of the oil injection and running it premix. It can save you a motor at some point.
    Best of luck!
    will not rev to 7200 without an aftermarket cdi or modified stock cdi

  9. #9
    96yam701's Avatar
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    sorry for the confusion,

    yes right now it does have an unmodified stock CDI, but i have an aftermarket available (the shop said it was bad but the ohms are right, i am sure they just wanted to sell me a new one and i let them). i am wanting to wait until i figure out why it is lagging before dropping in the aftermarket just to potially reduce the amount of damage to the engine.

    i am at work right now (12 hr nights hurt) but i will compression test and see if i cant get the RPM's up while at the dock with 92 octane, tomorrow morning.

    although i must admit 57MPH sounds real nice, it does have the factory pipe and water box but stock head/piston to my knowledge.

    if i go premix what could become of that oil pump? i am thinking supercharger since it runs off the fly wheel and should rev up as the engine revs. obviously i dont want to just remove it and leave the engine open so should i just loop the oil lines back onto itself?

  10. #10
    Marley Creek, MD
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    Jul 2008
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    $10 block off plate from any mail order place.
    $3 for vacuum nipple covers from any auto parts store (to block off where the oil lines go into carbs; you'll use the yellow ones prbly)

    Or you could just disconnect it, but that risks overheating/blowing the pump. Or you could run lines into oil tank and just keep circulating oil, but that would be a pain.

    Oh and 1 smoky run on ski to make sure the gas going to the engine is premixed (about 5 minutes of running premix AND oil injection) before switching over. Or you could drain it all, including carbs, premix it and dump it back in; maybe a squirt of oil in each cylinder hole to make sure you're good to go.

    I really wish i still had injection. It was sooo nice just fueling up at any dock and going. Now i have to sit there and premix and ask 3 times if their gallon-o-meter is accurate and check the tank to be sure it seems accurate.... But it is nice not having to wonder if the oil injection is working or not.


    And i agree if 92 makes a difference engine is likely modified.
    But was wondering.... doesn't the aftermarket CDI advance timing, and that might be where the 92 was making a difference???

    (and 12 hour shifts SUCK!)

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