bad to drive slow speeds

savorau

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Last week was left of RTW, 83.000km behing. Total 111.000km. Bike wont run smoothly in low rpm. No prblems when speeding / high rpm:s. . Today I changed new spark plugs and air filter, but no affect. Balance of fuel injection could cause this?
 

EricV

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Possibly, but probably not. The Trottle body balance is about air, not fuel. Try balancing the throttle bodies and looking for blockages in the air flow at the radiator inlet.

Fuel

Spark

Air

These are the three things required for the engine to run. Typically fuel issue would be worse at higher rpm where demand is greater.

Spark - could be shorting at the coils. You changed the spark plugs. Did you notice any corrosion on the coils or tubes running down into the spark plug wells? A bad coil or shorting could cause this. Spark issues can sometimes improve at higher rpm and be poor at low rpm. The opposite is also true, runs ok at low rpm, but under strong demand misses and runs poorly.

Fuel - Dirty fuel filter sock in the tank could be causing issues, but again I suspect this would only be worse at higher rpms.

Air - Vacuum leak/crimped lines? Unbalanced throttle bodies, partially blocked air flow to the intake or radiator.

I hope this gives you some ideas and places to look. Good luck and let us know when you find the problem and how you fixed it.
 

2daMax

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Possible carbon deposits growing on your intake valves and injectors. Add in some good intake valve carbon cleaner such as the Yamalube Ring free.

When the deposits are too thick, it would prevent the injected fuel mist from properly dispensing, some are absorbed into the carbon deposits causing insufficient fuel to reach the combustion chamber. lean mixtures is one cause of poor driveability.

Before doing the TB sync, it is advisable to clean up the TB from gum and varnishes on the throttle plates, and also both the barbs near the air screws. Any carbon stuck in those passages is going to cause the air flow issues. Check that RHS rubber plug. It often cracks and causes air leaks into the TB - leaning out the Right TB and get an imbalance power output from each cylinders.
 

Checkswrecks

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+1 to what has been said, especially by Eric.


Cleaning the injectors is cheap, never hurts, and sounds like it might be a help for you. I do it roughly like Noah in this KTM video, with one difference. I fill the injector with MAF (mass airflow sensor) cleaner, hang it upside down to keep the fluid in the injector, and let it soak for at least 15-20 minutes before hitting the starter button. Do it a couple of more times and it always does the trick. https://www.youtube.com/watch?v=PU8dVC4t5vU
 

OldRider

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I had a similar problem and it was fixed with a new battery. Even though my old battery was starting the machine, I think it wasn't letting the ecu get a handle on what was going on. Anyway, a new battery fixed it.
 

EricV

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OldRider said:
I had a similar problem and it was fixed with a new battery. Even though my old battery was starting the machine, I think it wasn't letting the ecu get a handle on what was going on. Anyway, a new battery fixed it.
And if you get to this, update to a YTZ14S instead of the stock YTZ12S. The 14S is the same physical size and terminal orientation, but more CCAs and an over all heavier batter with better starting capabilities for our big parallel twin machine.
 

OldRider

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EricV said:
And if you get to this, update to a YTZ14S instead of the stock YTZ12S. The 14S is the same physical size and terminal orientation, but more CCAs and an over all heavier batter with better starting capabilities for our big parallel twin machine.y.
I shot right past the 14Z and went with a 360cca WPS lithium battery. It doesn't turn over any faster, but it starts right on cue every time and the system is happy.
 
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