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bbb
MMT 1000 Club
Joined: Wed Sep 02, 2009 2:54 pm Posts: 1554 Location: SW Georgia
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 Mikuni running good, until 2/3 throttle +
I saw a few threads about this, but no final solution.
Runs fine til 2900-3000rpms and then it starts skipping/missing. When it first happened, a few weeks ago, I could feather the throttle and get it up to 4000rpms.
Yesterday with 2 adults and 2 kids, it ran good out of the gate and then started missing after 2 miles.
I have opened up and cleaned out the carb. I've checked valve lash. And I'm just not sure what to do next.
I have noticed the primer bulb is very tight and the filter is full of gas. When I disconnect the fuel line from the carb and turn the motor over, the fuel pump is working fine.
Thinking its in the carb. Not sure I need to buy a rebuild kit after 75-100 hrs, or keep tinkering.
Whatcha say?
_________________ 19x54 Seminole Extreme with a 35hp CDI GDSD. Mikuni. Marsh Mellow. Heads. Cam.
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Sun Jul 01, 2012 10:44 pm |
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Team Camo
MMT Sponsor
Joined: Thu Oct 01, 2009 4:49 pm Posts: 8536 Location: Bridge City, TX
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 Re: Mikuni running good, until 2/3 throttle +
If you have a rev limiter, disconnect the green wire & try it again. Might have a bad rev box
_________________ 1846 GTB & 35 GTR Team Gator-Tail
Killer Kallz & ANGLE PORT dealer (409) 720-8949
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Mon Jul 02, 2012 12:07 am |
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deadbird8
MMT 1000 Club
Joined: Wed Feb 04, 2009 7:50 pm Posts: 3833 Location: Old East Dallas, Texas
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 Re: Mikuni running good, until 2/3 throttle +
IF its a CDI, probably no external limiter on it.
When it starts happening if you pump the primer bulb does it gain RPM?
_________________ Excel 1851F4 w/ MB35HD+R CDI with a little bit of this and little bit of that
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Mon Jul 02, 2012 4:39 am |
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Will
MMT Elite Member
Joined: Fri Jul 08, 2011 1:54 pm Posts: 8133
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 Re: Mikuni running good, until 2/3 throttle +
Will the rpms go up out of the water? If so, not a rev limiter issue. Have you checked the condition of your plug wires? This maybe something other than the carb.
_________________ Before the internet, the majority of the village idiots stayed in their villages.
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Mon Jul 02, 2012 4:44 am |
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bbb
MMT 1000 Club
Joined: Wed Sep 02, 2009 2:54 pm Posts: 1554 Location: SW Georgia
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 Mikuni running good, until 2/3 throttle +
_________________ 19x54 Seminole Extreme with a 35hp CDI GDSD. Mikuni. Marsh Mellow. Heads. Cam.
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Mon Jul 02, 2012 5:54 am |
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dguidry
MMT Super Elite Member
Joined: Tue Jun 29, 2010 1:20 pm Posts: 11166 Location: Cecilia, LA
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 Re: Mikuni running good, until 2/3 throttle +
Check your valve lash now!!! Check your push rods to make sure they are straight.... Pull them out and roll them on a flat surface like you would a pool stick. If this checks out ok your problem will be fuel delivery or water in gas or something else. The more info you can provide the better your diagnostic feedback on this forum will be.
_________________ Formerly:1648 Homemade Cypress Crawfish Skiff GTR23 Performance Cam and Heads; 17x46 Gator Tail with 35GTR and Hoyt's cam;s Currently: 17x48 Gator Tail with XD40 EFI. “Wisdom is not just expertise. It is knowing how much of various areas of expertise you need to know in order to make the decisions that the world needs and that you want to do,” Columbia University President Lee Bollinger.
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Mon Jul 02, 2012 7:45 am |
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Team Camo
MMT Sponsor
Joined: Thu Oct 01, 2009 4:49 pm Posts: 8536 Location: Bridge City, TX
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 Re: Mikuni running good, until 2/3 throttle +
Does it have the external rev limiter that came in the bps kit hooked up?
_________________ 1846 GTB & 35 GTR Team Gator-Tail
Killer Kallz & ANGLE PORT dealer (409) 720-8949
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Mon Jul 02, 2012 8:10 am |
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OwenDickeson
MMT Elite Member
Joined: Wed Mar 11, 2009 12:45 pm Posts: 9869
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 Mikuni running good, until 2/3 throttle +
Mine was doing this with my CDI motor and I had to add a fuel atomizer to the carb.
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Mon Jul 02, 2012 8:55 am |
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bbb
MMT 1000 Club
Joined: Wed Sep 02, 2009 2:54 pm Posts: 1554 Location: SW Georgia
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 Re: Mikuni running good, until 2/3 throttle +
_________________ 19x54 Seminole Extreme with a 35hp CDI GDSD. Mikuni. Marsh Mellow. Heads. Cam.
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Mon Jul 02, 2012 8:58 am |
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dfou
MMT 1000 Club
Joined: Sun Dec 12, 2010 12:38 am Posts: 3986 Location: Pville, La
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 Mikuni running good, until 2/3 throttle +
Had a motor doing pretty much te same thing just last week. Check the diodes and wires from the diode. Where the black wore is zip tied to the intake can get damages and ground out
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Mon Jul 02, 2012 9:07 am |
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OwenDickeson
MMT Elite Member
Joined: Wed Mar 11, 2009 12:45 pm Posts: 9869
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 Mikuni running good, until 2/3 throttle +
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Mon Jul 02, 2012 11:20 am |
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pnazworth
MMT Member
Joined: Tue Mar 13, 2012 12:40 pm Posts: 17
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 Re: Mikuni running good, until 2/3 throttle +
Had this same problem with my stock carb so this may not be relevant. Checked everything and i mean everything! Ended up being ethanol slime in the carb and the main issue was the rod attached to the float in the carb was real rough and would not slide properly. Had to clean the carb and sand down the float rod. It was catching and dumping too much fuel inside the carb, especially under a load. Ran great out of the water like you said
_________________ 4-man Gator Hide w/ MB 5500 BAMF
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Mon Jul 02, 2012 12:27 pm |
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Will
MMT Elite Member
Joined: Fri Jul 08, 2011 1:54 pm Posts: 8133
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 Re: Mikuni running good, until 2/3 throttle +
Plug wire
_________________ Before the internet, the majority of the village idiots stayed in their villages.
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Mon Jul 02, 2012 1:33 pm |
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bbb
MMT 1000 Club
Joined: Wed Sep 02, 2009 2:54 pm Posts: 1554 Location: SW Georgia
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 Re: Mikuni running good, until 2/3 throttle +
Wow, 10 responses and 12 possible solutions. Typical of a Vanguard problem. Could be one of 50 things, and most likely will be the 49th thing you check.
Gonna double check the float pin. Appeared to be in great shape. But a stuck float would make sense as its saying send fuel, but there's no place for it to go, so it makes the fuel bulb tight and fills up the fuel filter. The float bowl had good fuel color and no particles.
Gonna double check the jet. I unscrewed the jet, and it was clear. Not sure what else I can do on that end.
Gonna check the plug and plug wires when I get the cowling off tonight.
I know its something small.
I will say if I launch the boat and take off running, it will run fine for a couple miles. So may be a situation where a wire is heating up and then starts losing a good connection.
Saturday night I cleaned the carb out with some SeaFoam spray and when I ran the boat the next morning, at first, I thought the problem was gone. But low and behold after 5 minutes of run time, it started doing it again.
_________________ 19x54 Seminole Extreme with a 35hp CDI GDSD. Mikuni. Marsh Mellow. Heads. Cam.
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Mon Jul 02, 2012 2:17 pm |
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Team Camo
MMT Sponsor
Joined: Thu Oct 01, 2009 4:49 pm Posts: 8536 Location: Bridge City, TX
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 Re: Re: Mikuni running good, until 2/3 throttle +
_________________ 1846 GTB & 35 GTR Team Gator-Tail
Killer Kallz & ANGLE PORT dealer (409) 720-8949
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Mon Jul 02, 2012 3:14 pm |
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txmudcutter
MMT 1000 Club
Joined: Mon Jan 30, 2012 9:08 am Posts: 2307 Location: Nederland, TX (SETX)
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 Re: Mikuni running good, until 2/3 throttle +
Maybe you have a vent clogged and its getting vapor locked that might be causing your bulb to be so tight
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Mon Jul 02, 2012 3:28 pm |
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txmudcutter
MMT 1000 Club
Joined: Mon Jan 30, 2012 9:08 am Posts: 2307 Location: Nederland, TX (SETX)
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 Re: Mikuni running good, until 2/3 throttle +
Might be the vent on your gas tank
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Mon Jul 02, 2012 3:29 pm |
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Will
MMT Elite Member
Joined: Fri Jul 08, 2011 1:54 pm Posts: 8133
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 Re: Mikuni running good, until 2/3 throttle +
plug wire or cracked ceramic on the spark plug
_________________ Before the internet, the majority of the village idiots stayed in their villages.
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Mon Jul 02, 2012 4:34 pm |
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bbb
MMT 1000 Club
Joined: Wed Sep 02, 2009 2:54 pm Posts: 1554 Location: SW Georgia
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 Mikuni running good, until 2/3 throttle +
Kinda rusty on the sides. Does that matter?
Can you not replace the spark plug cable without replacing the whole coil?
I'm gonna leave it apart, clean everything up, put it back together later thus week, then cross my fingers.
_________________ 19x54 Seminole Extreme with a 35hp CDI GDSD. Mikuni. Marsh Mellow. Heads. Cam.
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Mon Jul 02, 2012 5:51 pm |
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dfou
MMT 1000 Club
Joined: Sun Dec 12, 2010 12:38 am Posts: 3986 Location: Pville, La
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 Mikuni running good, until 2/3 throttle +
I don't believe rust is your problem. Either tape or heat shrink ur plug wires. Did you check your diodes and wires?
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Mon Jul 02, 2012 6:03 pm |
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bbb
MMT 1000 Club
Joined: Wed Sep 02, 2009 2:54 pm Posts: 1554 Location: SW Georgia
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 Mikuni running good, until 2/3 throttle +
What is this? It is split and I can see the metal inside.
_________________ 19x54 Seminole Extreme with a 35hp CDI GDSD. Mikuni. Marsh Mellow. Heads. Cam.
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Tue Jul 03, 2012 6:11 am |
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take'emgator
MMT Super Elite Member
Joined: Mon Oct 19, 2009 6:38 pm Posts: 10201 Location: SETX
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 Re: Mikuni running good, until 2/3 throttle +
That is your mercury switch which allows your motor to start only in level position. could be the problem......
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Tue Jul 03, 2012 6:27 am |
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deadbird8
MMT 1000 Club
Joined: Wed Feb 04, 2009 7:50 pm Posts: 3833 Location: Old East Dallas, Texas
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 Re: Mikuni running good, until 2/3 throttle +
_________________ Excel 1851F4 w/ MB35HD+R CDI with a little bit of this and little bit of that
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Wed Jul 04, 2012 5:52 am |
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BoatDR
MMT Sponsor
Joined: Tue May 24, 2011 6:43 am Posts: 1604
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 Re: Mikuni running good, until 2/3 throttle +
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Wed Jul 04, 2012 7:54 am |
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OwenDickeson
MMT Elite Member
Joined: Wed Mar 11, 2009 12:45 pm Posts: 9869
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 Re: Mikuni running good, until 2/3 throttle +
I HAVE a set of coils boxed up that I can send you. Let me know, I can send them out tomorrow.
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Wed Jul 04, 2012 8:02 am |
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bbb
MMT 1000 Club
Joined: Wed Sep 02, 2009 2:54 pm Posts: 1554 Location: SW Georgia
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 Mikuni running good, until 2/3 throttle +
Thanks guys. Took some guys frog gigging last night so had to put the motor back together before we left.
Seemed to run a little better than last time. But did notice that later into the night, it sounded like the motor would go to one cylinder. When I would throttle up, it would clear up after a few seconds. It did this several times. That's got me thinking carb again.
I think i'll change the plugs, and coils. If that doesn't work I'll dive back into the carb.
Let me know about the coils and how much I need to send you. I have a paypal acct.
Dale Tyre 158 turtle pond rd Bainbridge, ga 39819
_________________ 19x54 Seminole Extreme with a 35hp CDI GDSD. Mikuni. Marsh Mellow. Heads. Cam.
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Wed Jul 04, 2012 8:42 am |
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OwenDickeson
MMT Elite Member
Joined: Wed Mar 11, 2009 12:45 pm Posts: 9869
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 Re: Mikuni running good, until 2/3 throttle +
Me or BoatDr?
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Wed Jul 04, 2012 9:07 am |
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bbb
MMT 1000 Club
Joined: Wed Sep 02, 2009 2:54 pm Posts: 1554 Location: SW Georgia
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 Mikuni running good, until 2/3 throttle +
I'm gonna borrow a buddy's mikuni this weekend and see if that solves my problem. If not, I'll be interested in trying the coils.
Thanks.
_________________ 19x54 Seminole Extreme with a 35hp CDI GDSD. Mikuni. Marsh Mellow. Heads. Cam.
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Wed Jul 04, 2012 1:10 pm |
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Will
MMT Elite Member
Joined: Fri Jul 08, 2011 1:54 pm Posts: 8133
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 Re: Mikuni running good, until 2/3 throttle +
$20 says its not the carb.
_________________ Before the internet, the majority of the village idiots stayed in their villages.
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Wed Jul 04, 2012 7:44 pm |
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duckduckboom
MMT Elite Member
Joined: Tue Nov 23, 2010 6:33 pm Posts: 5603 Location: Corner of Hell an high water, La
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 Re: Mikuni running good, until 2/3 throttle +
i think you friend has to poo. that is the face i make when i have my butt cheeks clinched and i'm running to the shitter
_________________ You have your whole life to be an idiot, take a day off!
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Wed Jul 04, 2012 7:53 pm |
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bbb
MMT 1000 Club
Joined: Wed Sep 02, 2009 2:54 pm Posts: 1554 Location: SW Georgia
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 Mikuni running good, until 2/3 throttle +
_________________ 19x54 Seminole Extreme with a 35hp CDI GDSD. Mikuni. Marsh Mellow. Heads. Cam.
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Wed Jul 04, 2012 8:41 pm |
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Jamie B.
MMT 1000 Club
Joined: Tue May 19, 2009 9:48 am Posts: 2688
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 Re: Mikuni running good, until 2/3 throttle +
I really think that you have an Intake leak of some sort, if it sounds like it runs on one cylinder then when gave a little bit of throttle it goes to running fine.
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Thu Jul 05, 2012 7:46 am |
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Will
MMT Elite Member
Joined: Fri Jul 08, 2011 1:54 pm Posts: 8133
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 Re: Mikuni running good, until 2/3 throttle +
_________________ Before the internet, the majority of the village idiots stayed in their villages.
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Thu Jul 05, 2012 7:53 am |
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bbb
MMT 1000 Club
Joined: Wed Sep 02, 2009 2:54 pm Posts: 1554 Location: SW Georgia
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 Re: Mikuni running good, until 2/3 throttle +
_________________ 19x54 Seminole Extreme with a 35hp CDI GDSD. Mikuni. Marsh Mellow. Heads. Cam.
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Thu Jul 05, 2012 9:10 am |
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cb5331
MMT Super Elite Member
Joined: Fri Dec 18, 2009 8:10 pm Posts: 16915 Location: Rowlett, TX
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 Re: Mikuni running good, until 2/3 throttle +
If oil level is going up, may have a stuck float and be dumping fuel into the case...though it could still be a coil not firing and the gas that isn't getting fire is making its way in the case. Who knows?  Either way, change the oil. Gas does not make a very good lubricant.
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Thu Jul 05, 2012 9:21 am |
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bbb
MMT 1000 Club
Joined: Wed Sep 02, 2009 2:54 pm Posts: 1554 Location: SW Georgia
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 Mikuni running good, until 2/3 throttle +
Well I changed the oil and spark plugs last night. Boat ran perfect. Could a plug have been my issue?
Both plugs were black, but I figured they would be after 4 hours of idling.
_________________ 19x54 Seminole Extreme with a 35hp CDI GDSD. Mikuni. Marsh Mellow. Heads. Cam.
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Sat Jul 07, 2012 8:23 am |
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Will
MMT Elite Member
Joined: Fri Jul 08, 2011 1:54 pm Posts: 8133
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 Re: Mikuni running good, until 2/3 throttle +
The ceramic can get a hairline crack in it and cause issues. Since it was only doing it after you got it warm led me to believe it was a firing issue of some kind....see post from a week ago saying spark plug . I will get the $20 from you on the Seminole run coming up.
_________________ Before the internet, the majority of the village idiots stayed in their villages.
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Sat Jul 07, 2012 12:12 pm |
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coonass381
MMT Pro Member
Joined: Sat Jan 15, 2011 12:47 pm Posts: 269
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 Re: Mikuni running good, until 2/3 throttle +
Mine was doing same thing about a month ago then yesterday was hard to start and was running bad when it would idle and die when I gave it gas messed with everything still was doing it then this morning I disconnected the rev limiter and ran like it was supposed to so might be your rev limiter like it was in my case
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Sat Jul 07, 2012 5:14 pm |
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bbb
MMT 1000 Club
Joined: Wed Sep 02, 2009 2:54 pm Posts: 1554 Location: SW Georgia
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 Mikuni running good, until 2/3 throttle +
I'm gonna run it hard tomorrow and see if I can get it to repeat the symptoms.
Would love if it was just a $4 fix.
That's why I love and hate these motors. Hard to diagnose, unless your the knowledgable Will, but usually an easy and relatively inexpensive fix.
_________________ 19x54 Seminole Extreme with a 35hp CDI GDSD. Mikuni. Marsh Mellow. Heads. Cam.
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Sat Jul 07, 2012 5:59 pm |
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coonass381
MMT Pro Member
Joined: Sat Jan 15, 2011 12:47 pm Posts: 269
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 Re: Re: Mikuni running good, until 2/3 throttle +
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Sat Jul 07, 2012 10:58 pm |
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