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Author Topic: help help with a fuel problem or running  (Read 2473 times)

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750FSS

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help help with a fuel problem or running
« on: July 29, 2005, 03:28:54 PM »
hey guys ,
on  my 1976  750f i just bought it from a guy a few days ago it was running fine with no bogging down , idle a little high,(1500 rpm )   but i took it out last night and it was bogging down and dieing out. i pulled the spark plugs and they were fouled and they were champion plugs, so today i put new ngk plugs . it runs ok but it still bogs down but idle good 950 rpm,   now heres the funny thing i do  have fuel in the tank, but   when i put the fuel valve on the on position and rev the engen i get the feeling its being fuel starved ,now when i turn the fuel valve to the reseve position the bike runs better but it has a little hestitation has anybody have any ideas or solutions  ???
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Offline clarkjh

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Re: help help with a fuel problem or running
« Reply #1 on: July 29, 2005, 06:14:42 PM »
how full is the tank, mine will only run on 1-2 when I need to change over to reserve.

James
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750FSS

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Re: help help with a fuel problem or running
« Reply #2 on: July 29, 2005, 06:56:06 PM »
half full. ???
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Offline TwoTired

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Re: help help with a fuel problem or running
« Reply #3 on: July 29, 2005, 06:58:05 PM »
Do you have fuel contamination and/or enough fuel in the tank?
When was the last full and complete tuneup?
Air filter dirty?
Is the bike all stock?
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Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

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eldar

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Re: help help with a fuel problem or running
« Reply #4 on: July 29, 2005, 07:09:38 PM »
Fouled plugs indicate a rich condition usually. You need to tune the carbs. Changing points and condensers, if it has been a while, would be good also.
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750FSS

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Re: help help with a fuel problem or running
« Reply #5 on: July 29, 2005, 08:44:28 PM »
yes the carbs has been rebuild, new plus and point, i called the guy. he think that maybe the seal in the pet cock is bad. because the bike running on on reseve. i sound like the prolben the guy is with reseve  on cb750

http://www.sohc4.us/forums/index.php?topic=2969.0
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eldar

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Re: help help with a fuel problem or running
« Reply #6 on: July 30, 2005, 10:26:03 AM »
Well it is hard to say. Get some small O.D. CLEAR tubing.  shut off your gas and pull the bowl drain screws out. put the tubing in the holes tightly. turn gas back on and see how high your level in the tubes gets. This will then indicate if the fuel level is too high.  The floats my be incorrectly adjusted. or the float valves may not be shutting off flow properly. I had this issue on 1 carb. moved the valve and the float shut off flow correctly.
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Offline DrMark

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Re: help help with a fuel problem or running
« Reply #7 on: July 30, 2005, 10:55:23 AM »
Could it also be clogged jets?   Sounds like they may need a good cleaning...my 1978 CB550 did the same thing....
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eldar

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Re: help help with a fuel problem or running
« Reply #8 on: July 30, 2005, 12:54:56 PM »
If the jets are clogged as to not let in air, then yes it is possible.
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750FSS

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Re: help help with a fuel problem or running
« Reply #9 on: July 31, 2005, 04:50:05 AM »
well today i full the tank up, and the bike is runnig good agian..
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eldar

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Re: help help with a fuel problem or running
« Reply #10 on: July 31, 2005, 08:13:52 AM »
You may have to clean out your tank vents then. If your vents are clogged, as you use fuel, a vacuum is created and that prevents fuel from getting to the carbs. I dont see how this would cause build up on your plugs though. I would say that is a separate issue.
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Offline 78_SaltLick

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Re: help help with a fuel problem or running
« Reply #11 on: July 31, 2005, 08:44:13 AM »
i have a 750K8 with the same problem (bogging) i bought it couple weeks back, and the thing is on "reserve" with just a wee bit of gas in it. i filled it up yesterday, switched it to the "on" position, and it runs great now. I think theres some setiment on the bottom of my tank.
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eldar

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Re: help help with a fuel problem or running
« Reply #12 on: July 31, 2005, 10:25:48 AM »
Could be you petcock needs to be cleaned or some work done on it.
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750FSS

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Re: help help with a fuel problem or running
« Reply #13 on: July 31, 2005, 11:38:36 PM »
 i had the ckoe on which Fouled the plugs  :-[  now eldar your right about the petcock needs to be cleaned, i took it off and it had a lot setiment on the tube, clean it and the tank too .  will see how it go's... ???
« Last Edit: July 31, 2005, 11:40:53 PM by 750FSS »
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