1996 Wave Venture 700 runaway idle. - PWC Forum: The best hang-out for Personal WaterCraft enthusiasts
 
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post #1 of 6 (permalink) Old 03-16-2019, 02:30 PM Thread Starter
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1996 Wave Venture 700 runaway idle.

Hello everyone. I inherited a blown 700 Wave Venture which I rebuilt bottom up. It starts and idles like a dream UNTIL I goose the throttle and then after release of the throttle the engine starts running away. All gaskets are new, throttle cable is not too tight, butterfly valves are slamming shut, all is torqued to proper spec.

I'm not a two stroke expert as this is my first watercooled 2-stroke rebuild, but I'm pretty mechanically inclined. What on earth would cause something like this? If it was a vacuum leak I would expect the engine to runaway upon start-up. Any help is appreciated. Thanks in advance.
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post #2 of 6 (permalink) Old 03-18-2019, 06:04 AM
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What did you set the pop off and mixture screws to ? Did you do a pressure check on the engine after assembly ?
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post #3 of 6 (permalink) Old 03-18-2019, 10:27 AM Thread Starter
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What did you set the pop off and mixture screws to ? Did you do a pressure check on the engine after assembly ?
Thanks for responding. I left the carbs as I received them since they were okay before the engine was seized (was run through shallow water. I have rebuild kits coming so I will be going through this process for the first time. I'll need to order a popoff gauge.

Pressure test as in compressions test or actually putting then entire engine assembly and intake under air pressure? If so, how does one go about doing that? Thanks again for replying.
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post #4 of 6 (permalink) Old 03-19-2019, 04:49 AM
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You block the exhaust and intake, and pressurize the engine through the pulse port to 6 psi. It should hold it for 15-30 min. The engine should be able to start and idle with the idle screw set at about 1 1/2 turns from just contacting the arm if that much.
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post #5 of 6 (permalink) Old 03-19-2019, 03:37 PM Thread Starter
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You block the exhaust and intake, and pressurize the engine through the pulse port to 6 psi. It should hold it for 15-30 min. The engine should be able to start and idle with the idle screw set at about 1 1/2 turns from just contacting the arm if that much.
Thanks for the tips. I wish I would have known it would have been a good idea to run a leakdown test on the entire system prior to installing. I'll do that when I get time to work on it some more. Can you think of any reason why it would start running away only after cracking the throttle and why it wouldn't also rev high immediately upon start-up? Thanks again for your time.
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post #6 of 6 (permalink) Old 03-20-2019, 04:03 AM
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If the throttle blades are open to far at idle, inlet screen restricted, mixture crews off, pop off bad (doubt that though). You should also be testing it with the flame arrestor on.
Before you go tearing it back apart and having to replace all those gaskets, kit the carbs with true Mikuni kits, and verify pop off (which is prob good). Be sure and find the factory mixture screw settings and compare to what they are now. I would document what they are now (turns out from lightly seated).
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