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Motorcycle Repair/bike is slow now


QUESTION: hi there I recently replaced a battery for my yamaha r6 2007 but now the bike lags a bit while the engine seems like its hotter then usual while riding it. Additionally I have disconnected the servo motor cables a month ago.....could this be the cause of it being slow now? is the ecu telling it to run slower?

ANSWER: Hello Derek,

First, make sure that charging voltage is at least 13,5v at idle, and 14 to 14,5v at 5000rpm.
Next, check if EXUP butterfly on the exhaust is at fully open position (fully clock-wise, facing it). Hopefully you haven't removed it along with the cables, have you...

Maybe the lack in power is completely irrelevant to the above, though.

Did you, by any chance, changed or added engine oil recently?
If you didn't mention battery and exhaust valve, the first thing I would advice you to do
is, check the oil level.
Number one reason for increased temperature and power loss is, too much oil in the crankcase.

It might seem kindergarten-grade, but I'll specify the correct oil check procedure.
On a level ground, the bike on it's wheels (no paddock stand) and the front wheel perfectly facing straight, bring the bike vertical, at the point where you can hold it by one handlebar with two fingers (perfect balance - perfect perpendicularity).
You should check oil level at this position, which ideally should be a little lower than upper (say 2/3 to 4/5 from lower to upper).

If you find oil level correct, get back to me with the results of the first two checks, and any additional info you can come up with, no matter how irrelevant may seem.

Best Regards,
Lazaros Ampatzidis.      

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QUESTION: Hi thanks for the response.....but now my bike is running bit better but

it usually shuts off on hot days with dash board going blank.  Then when you try to

restart it the battery seems drained. I would run start it back up and then it says

over heating.I would then have to wait till the bike cools down until I

could run start it again which is usually later at night. This has happened a two

times before.

Hi Derek,

This sounds like, lack of battery earth to the engine.
Check the main minus cable, for loose or rusted connection to the crankcase.

If it isn't this, then you have to check all harness grounds to the frame.
As for the overheating, most likely it's fake!!!
Temperature sensor works with ground and if that's insufficient, temp gauge and/or light
goes crazy...

Come back and let me know what you've found.


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Lazaros Ampatzidis


I can help you on EVERY issue involving POST-1980 Japanese Motorcycles plus KTM and Husaberg. My field of expertise includes Engine, Transmission, Fuel system (carburation & EFI),Electrics and Electronics. Maintenance, repair and tuning. Road and off-road suspension tuning. Please don't ask me about non-Japanese Motorcycle, especially American built on which I have low to zero experience.


I'm a rider and hobbyist since childhood. 25 years motorcycle workshop mechanic.15 years motorcycle racing mechanic. In order of experience high to low:Kawasaki,Suzuki,Honda,Yamaha,KTM,Husaberg.

Hellenic (Greek) Technical School.Internal Combustion Engines Engineer. Automotive Electronics.

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