Road King running rough at times?
Thread Starter
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Cruiser
Joined: Mar 2008
Posts: 236
Likes: 1
From: Crestview, Florida
Road King running rough at times?
I have a strange one this time and need ideas. My 98 Road King has developed a vibration from idle up to about 60 mph. It is strange because I can stop and fill the gas tank and it is smooth as silk until I use about 1 or 1 1/2 gallons of fuel,then I get the vibration again. The engine is not missing or sputtering or anything,but it is like the cylinders are not firing right. The engine begins to run rough when I speed up or when I let off the throttle. It is bad enough to vibrate the floorboards and the windshield and rattle my teeth. I can stop,shut it off and not refuel and it does not help,but if I stop and top off the tank it smooths out and only has the Harley shakes and vibes. It has new plugs,wires,Velva Ride front motor mount and I have checked all the exhaust system,swing arm mounts and everything else I can think of. I have not changed the fuel filter yet as my dealer does not have one, but I am thinking of trying that next. I just do not understand why it smooths out as long as the tank is full? Any ideas?
Thread Starter
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Cruiser
Joined: Mar 2008
Posts: 236
Likes: 1
From: Crestview, Florida
I have checked the vent on the cap and it is fine. I have not checked the lines inside the tank yet but that is my next move I think. I am thinking a pinhole in the line that is under the fuel until it drops a little. I am trying to get a filter also so I can change it while I am in there, it has 36,000 on the original filter.
Road Captain
Joined: Sep 2009
Posts: 718
Likes: 1
From: Panama City, FL
Carbed or FI?
ZDo you have the carbed or the old style "Delphi" FI system?
You might want to try KnightRider.com for answers too. They have techs who answer you back within a day or so with very knowledgable folks.
Good luck bro...
Dex
p.s. I picked up my RK at FW Beach Harley Davidson near you!
You might want to try KnightRider.com for answers too. They have techs who answer you back within a day or so with very knowledgable folks.
Good luck bro...
Dex
p.s. I picked up my RK at FW Beach Harley Davidson near you!
Seasoned HDF Member
Joined: Feb 2007
Posts: 6,086
Likes: 1,128
From:
1-smooth with full tank but vibration without full tank?
Just changed front mount?
Is it possible engine is out of alignment after mount was changed?
Description leads me more towards an out of balance situation that becomes balanced with the extra fuel weight on the bike.
I would look at the front mount and also the engine linkage points..
Also check the L bracket for the rear cylinder exhaust..The L bracket is what holds the rear cylinder exhaust to the transmission support..The L breaks...
I do not think it is the internal fuel lines because you have an M and M EFI system..A fuel line pin hole issue would cause bike to have pressure loss and be difficult to ride and inability for pump to maintain pressure..Visible bubbles in tank also..pump would try to repump and repump at pre-start..but i guess i could be wrong.
Just changed front mount?
Is it possible engine is out of alignment after mount was changed?
Description leads me more towards an out of balance situation that becomes balanced with the extra fuel weight on the bike.
I would look at the front mount and also the engine linkage points..
Also check the L bracket for the rear cylinder exhaust..The L bracket is what holds the rear cylinder exhaust to the transmission support..The L breaks...
I do not think it is the internal fuel lines because you have an M and M EFI system..A fuel line pin hole issue would cause bike to have pressure loss and be difficult to ride and inability for pump to maintain pressure..Visible bubbles in tank also..pump would try to repump and repump at pre-start..but i guess i could be wrong.
Tourer
Joined: Dec 2009
Posts: 413
Likes: 3
May be a gas tank mount bolt loose ? May be more noticeable when your fuel load is lighter.I would surely check all the EASY stuff first before tearing things apart.
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Road Captain
Joined: Aug 2008
Posts: 559
Likes: 0
From: Berwick, Pa.
Here is my 2 Cents. You fill your tank, bike runs fine. Weight of gas pressing on fuel filter forceing gas thru system. Tank empties, less pressure, dirty filter clogs causeing poor preformance.
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Thread Starter
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Cruiser
Joined: Mar 2008
Posts: 236
Likes: 1
From: Crestview, Florida
Ok update, I removed the fuel filter and checked it and it is good and clean,checked all lines,tested fuel pump and it holds 60 lbs pressure for 30 minutes with ignition off so I think that rules out the internal fuel tank parts. I have checked the exhaust mount at the transmission and all other mounts. I also loosened the exhaust system to make sure it was not in a bind. The engine mount was changed last year so I don't think it is related but I did pull it loose and che ckecked it and also pulled the adjustment rod off and it sits right down over the bolt hole with no bind. I had no way of checking fuel pressure with the pump connected but I do not have any starting problems. If I squeeze off the return line the idle does increase so I guess it is possible the fuel pressure regulator could be failing? I am just totally out of ideas and this is driving me nuts. I also did check the tank mounting bolts and they are tight. I'm about to pull the engine and put a mazda rotary engine in it.
Just takes the fun out of riding when you have an irritation like this.
Just takes the fun out of riding when you have an irritation like this.