Bucking bike

[Fluffy_Dog]

1996 R1100R. 7K Miles. I bought the bike this year with 2K miles on it.

OK I did two things to my bike this week and am having a sudden bucking when I accelerate.

What I did...

1. Installed quick disconnects from Small Parts on both fuel lines. Other members have posted recommendations on these and while I doubt they are the problem I mention it because I did it.

2. Managed to run out of gas the very next day. Had a hell of a time getting the bike started but after several attempts it finally turned over, ran crappy for a minute and then ran fine.

Following these two events I traveled 1500 miles on the bike this weekend. First half of the trip was uneventful. On the way home the bike began to buck when ever I accelerated. The bucking seems to happen only when I accelerate at highway speeds. It never happens while my speed is constant, nor does it happen as I pull away from a dead stop and run thru the gears e.g. entering the highway from a rest stop.

The bucking feels just like snapping the throttle forward for a split second, and is a little terrifying when it happens as you overtake another vehicle! I don't want to conclude it is a fuel delivery issue but it sure feels like it. I went thru several tanks of gas from various vendors... so unlikely the fuel itself is the issue.

At highway speeds I can recreate the problem at will. I have watched the tach and it does not fluctuate at all when the bike bucks (so drive train issues ruled out?).

Thinking back I kind of remember this happening from time to time but NEVER to the extent it is happening now. I just chalked it up to having an old bike.

What do you think? Fuel pump, Fuel filter, something else?

 

[jduke]

Sounds to me something electrical. Pull the tank and see if you might have pinched a wire. Also with the tank off it might be a good time to check the spark plug wires and look at the coil.
A couple of other possibilities are the side stand switch and the HES.
You can do a search on both.
It might be an O2 sensor going back but I don't think the effect would be as drastic as what you describe.
Good luck, problems like this can be a major PIA.

 

[m0rbid45]

Mine has started doing that about a month ago and this is on a 04 1150GS. Thought it was the fuel that I got but like you said I too have been through several tanks of gas. Thought that there might be some water in the tank so put in some 91% rubbing alcohol. Changed out the fuel filter too. Plugs are new. Trying some fuel injection cleaner now and it has seemed to help a bit.

So in the end.. Confused like you too.

Mack

 

[manicmechanic]

You might consider checking the fuel pump. They are cooled by the fuel flowing through them and have been known to stop/seize after running out of fuel.

 

[krpreston]

Rubbing alcohol???

. Thought that there might be some water in the tank so put in some 91% rubbing alcohol.

Why would you put 91% rubbing alcohol in the tank? Since the other 9% is water now you truly have water in your gas! Use gasline antifreeze, water eliminator or something actually designed to be put in a gas tank. Living in Texas chances are you probably already have ethanol in your gasoline!

 

[kgadley01]

Why would you put 91% rubbing alcohol in the tank? Since the other 9% is water now you truly have water in your gas! Use gasline antifreeze, water eliminator or something actually designed to be put in a gas tank. Living in Texas chances are you probably already have ethanol in you gasoline!

My thoughts exactly. Rubbing Alcohol???? I must have missed something in Motorhead school...

 

[Fluffy_Dog]

Hi all and thanks for the feedback so far.

I'd like to get this narrowed down as best I can before I get dirty.

If it were an electrical problem (short, coil, plug wire, etc.) do you think the problem would be so easy to replicate? To restate the problem... If I am riding the bike rock steady at 70mph (engine at 4300 rpm roughly) all I have to do is twist the throttle a few degrees and the bike will buck a couple of times until acceleration is complete then all is well once again. I know electrical issues can be illusive but are they so predictable?

I am asking myself if it is a fuel issue and if it is related to me running out of gas then why would it take several hundred miles to show up.

I am thinking, bring everything back to the beginning. First take the quick connects out, test the bike. Then replace the fuel filter, then test the bike, and so on. Does this make sense. Are there some easy electrical tests I can run as well i.e. to see if the coil or wires might be to blame?

Thanks.

 

[patiodadio]

Sounds like my R1100RSL , long story made short..... fuel filter . When I changed the fuel filter out , I found a crack in the old one. Ever since replacing it, the bike has ran great.

 

[PGlaves]

You have a fuel delivery problem. Maybe a clogged fuel filter. Maybe water in the fuel. Maybe both - sloshed up when you ran out of gas.

I would use 1/2 bottle of Isoheet in the red bottle first. If that doesn't clear the problem then change the filter.

Finally, you may need to pull the injectors and have them back flushed and tested.

 

[mrhall]

There you go, solved!
I agree.

 

[pauls1150]

Heet in the red bottle works better than the Heet in the yellow bottle, at least in my car with Kalifawnia gas...
There's a new gas additive out called StarTron - the advertising looks great; does anybody know if it actually works?

 

[m0rbid45]

Well now.. Never thought of that. I never did claim to be the sharpest tack in the bunch. Looks like I will take the advice that was a few posts below and go and get some heat.

Thanks to all for being kind and not running me out of here.

Why would you put 91% rubbing alcohol in the tank? Since the other 9% is water now you truly have water in your gas! Use gasline antifreeze, water eliminator or something actually designed to be put in a gas tank. Living in Texas chances are you probably already have ethanol in you gasoline!

 

[Fluffy_Dog]

Bucking eliminated!

Thanks to all for your suggestions. Paul got it right... 1/2 bottle of Isoheet (Red) did the trick. All is well for $1.25 (still have 1/2 bottle)... I love this bike. Plan on putting a new fuel filter on as part of my winter maintenance.