Waverunner won't run at high rpms, need help asap - PWC Forum: The best hang-out for Personal WaterCraft enthusiasts
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post #1 of 40 (permalink) Old 07-28-2016, 03:47 PM Thread Starter
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Waverunner won't run at high rpms, need help asap

Have an old 95 Yamaha Wave Venture WV700t, has run perfectly for two years since I bought it but while running the other day wide open and it just bogged down from full speed and was only able to limp back in. I checked for anything clogging intake and it was fine. Changed spark plugs and fuel filter. I always run stabil gas and use sea foam regularly too. It runs fine out of water but when we tried it under load in the water the same thing happened. I checked the rectifier because battery wasn't holding charge but it read 13-14 v while running and it ended up that was just a bad battery which I replaced. I then rebuilt the carbs though hadn't done it before and felt like I did it correctly. I did not change any of the idle or jet settings. The only concern I had was the spring in the carb, the kit had 4 and I'm not sure I used the right one (all looked the same and got the original mixed up with them). Could an incorrect "pop off pressure" from the wrong spring cause the issue I'm still having? It is improved after the rebuild and was able to slowly get on plane but would bog down almost immediately. It does seem to be running more roughly since the problem started and makes me wonder if this is a result of insufficent fuel causing the roughness or could it all be the result of a bad bearing in the drive shaft? Could it also be an impeller clearance issue? That seems to be very tight after removing the grate and just looking around the impeller. Please help with any suggestions! My son and my addictions to getting away to the lake are jonesing badly now and summer is dwindling away!! Taking to a mechanic is not option as we need to try to fix it ourselves at a reasonable cost.
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post #2 of 40 (permalink) Old 07-28-2016, 03:48 PM Thread Starter
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PS

Checked compression and both good at around 150-155.
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post #3 of 40 (permalink) Old 07-29-2016, 05:40 AM
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If you can see light around the impeller, chances are it's not scrubing, but need to check with a feeler gauge to be sure. Pop off is very important. You need a pop gauge to set it correctly. Sounds like you used a generic kit. Mikuni kits (that I have seen) only come with one spring. It's actually pretty important that the mixture screws be removed so the passages can be cleaned. All you need to do is document how many turns from lightly seated each one is for each carb. You also should have gotten a new inlet screen that should have been replaced. Also check and make sure the oil injection lines have not come off or leaking, and that water is coming out of the pisser.
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post #4 of 40 (permalink) Old 07-29-2016, 08:27 PM Thread Starter
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Found original springs and put them back in, had two different ones in previously. Also removed and cleaned mixture screws and set back to original settings. Already replaced inlet screens, oil connections good, pisser pissing. Checked entire fuel supply system from tank inlet to carbs and all good and clear. Tried again today and no surging as before but still not able to get high end power. I'm thinking surging was a result of wrong pop off pressure from two different and wrong weight springs. I added a grommet to a high end mixture screw that showed in the schematic but was not there when I cleaned it. I'm wondering if it was running too rich due to the added spacing of the grommet and this is why is had no high end power. Trying again in the morning with no grommet which I'm guessing was equal to possibly two turns of the adjustment screw. That seems to be a big deal sing the original setting was 1 1/4 turns. Not addressing impeller issue yet. Don't see any light around it but do when I shine a bright light from other side. It looks to be about 1/8 to 1/16 of an inch. Wouldn't that be a gradual decline in performance, not the sudden bog down that occurred originally? Will post results of high end jet adjustment after testing in the morning.
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post #5 of 40 (permalink) Old 07-29-2016, 08:38 PM Thread Starter
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re carb springs

Appears springs' weight are determined by color:

Gold 115
Dull Silver 95 (Wound counter clockwise)
Black 80
Shiny silver 65

After further close inspection, it was easy to see the differences. The kit had zero instructions, would have been extremely helpful to know this sooner. Hope it helps someone. I just put back in my originals which were the 65's. Mistakenly thought they were softer because they were old and had become weak.
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post #6 of 40 (permalink) Old 07-30-2016, 06:38 AM
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A o-ring or seal on the screw should not affect it's adjustment as that is set from a internal seat. 1/16" is to much. It will cavitate and be very slow as the pump cannot build the required pressure. Looks like it should be .001-.002 with a limit of .024.
This is a 96 manual, but should still apply. If I find the 95 I will post it.
http://www.mdmotors.ru/netcat_files/...00_wvt1100.pdf
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post #7 of 40 (permalink) Old 07-30-2016, 06:42 PM Thread Starter
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Put o-ring back in and set jet screws to factory at:
front carb high and low 5/8
rear carb 1 1/4 high, 5/8 low

same issue though no surging, just can't hit high end rpms.

Played around with settings on water, thought it was running rich (choking didn't improve, drowned it out). could only adjust rear high and front low. Closing both down some got a burst of good high end before it bogged down so don't think it's an impeller clearance issue. Played around further with no improvement, gave up trying to tune it.

Any suggestions would be greatly appreciated. Should I set all jets back to factory and focus on electrical now? Where should I start? Clip ends of plug wires? Not sure where to go from here or if it may simply be a tuning issue. Please let me know of any ideas.
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post #8 of 40 (permalink) Old 07-30-2016, 07:03 PM
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Low speed screws should be set for highest smooth idle + 1/8 turn out. Adjust idle speed as ness. to get proper idle speed.
You should get a pop off gauge if you don't have one and check the pop off. That will affect off idle and up to 1/4 throttle. Set the high speed screws at 7/8 turn out and see what happens.
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post #9 of 40 (permalink) Old 07-31-2016, 10:55 AM Thread Starter
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No improvement. I assume you meant both high end jets. May be a stupid question, but how do you adjust rear low and front high (inside edges of both carbs when put together) other then removing the carbs (or even carb cover) to get to those screws? None of the carb tuning how to articles address how to do two connected. That has me confused because factory setting are not the same for both. When the mention adjusting, do you have to take both carbs off to get to those screws to make the adjustments? If I have to buy a pop off guage I'm thinking I may as well pay to have it tuned up. At least I'd have it for future tune ups I guess, but if each adjustment requires taking carbs off, may be best to pay the professionals I'm thinking. I hate to give in to the defeat of not figuring it out myself, not to mention the costs. Thoughts?
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post #10 of 40 (permalink) Old 07-31-2016, 04:34 PM
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