Bike stall after auto-choke phase

[chung]

I replaced the tensioner replaced last week at Yamaha's agent in Singapore.

After the replacement, the rpm of the bike dipped below 1,000 after the auto-choke phase.

It has even stalled a few times in the past 6 days.

The rpm will stable at 1,000 after 5 mins of riding.

Never happen before in tropical Singapore before I replaced the tensioner.

The idling cable is already turned to the max.

Went back to the agent but they could not identify the problem cos there is no fault code.

They suggest that i try fiddling with the CO levels.

Anyone encounter similar problem before?

 

[chung]

BTW, the TPS is 15/100.

Also did the throttle body synchronisation last week.

It didn't solve the problem

 

[chung]

Condition seems to improve after i lower the CO level to -30.

Will monitor fuel consumption for the next two week.

BTW, what does the CO level do?

Does it mean that lower CO level will emit less carbon-monoxide?

Does it affect fuel combustion/consumption & perfromance?

 

[Ignacio]

I'll make the point that most of the members on this board are in North America and our bike doesn't have the ability to change CO in stock form. There might be a few who have that option.

And, frankly I have no idea what you're talking about with "auto choke". Nothing in my manual talks about it.

 

[chung]

And, frankly I have no idea what you're talking about with "auto choke". Nothing in my manual talks about it.

When u cold start the bike. The rpm is higher at about 1,500. When the bike is warmed, the rpm drop to normal idle speed aroung 1,000 rpm. This is the "auto-choke" phase.

In older bikes, there is a choke cable/switch which can be turn on for start-up and switch off when the bike warmed up. With auto-choke, there is no control except to turn the throttle.

Regarding CO level, i didn't relase the limitation of North America's bike.

Although i did read about it.

It must hv slipped my mind.

CO adjustment link

 

[Geezer]

I'm with you on the auto-choke and CO adjustment, but what is the 'tensioner'?

 

[chung]

I'm with you on the auto-choke and CO adjustment, but what is the 'tensioner'?

Tensioner is one of the parts.

Replace it due to wear & tear.

I'm not really good in the technical aspect.

 

[ionbeam]

When Chung is referring to 'tensioner' I believe he is referring to the 'high tension cable' which would be the high voltage cables from the coil (spark plug wires). It may also be the cam chain tensioner but he makes reference to the tropical weather in Singapore which leads me to believe it is the ignition cables. I'm old enough to remember when the coil wire between the coil and distribuitor was called the 'high tension' cable.

Not being able to adjust idle speed is not correct. If there are no other problems such as vacuum leaks the inability to adjust idle speed is typically related to a throttle body synch problem. If the idle speed is not adjusted while the throttle body sync is performed it is not uncommon to no longer have full idle speed adjustability. After the last synch did the 4 rubber caps get placed back on the sync ports?

The CO levels are set at Yamaha and the values are stored in the ECU (computer). This level shouldn't need to be changed for drivability issues, it is for emissions. Some USA owners have made small adjustments to smooth surging at light engine loads. This should not be part of your idle problems. The CO level is Carbon Monoxide content in the exhaust gasses at idle. Changing the CO level should not effect your idle problem. If you do choose to make changes be sure to write down the starting values so you can set them back to factory levels if it does not improve your problems. Most people who make adjustments do not adjust more than + or - 7 for each cylinder.

The first problem you need to address is the idle speed. You must have 1,000 to 1,200 RPM or stalling is likely. In this Forum Warchild has a procedure on how to re-set the Throttle Body Sync adjuster screws and start again. I believe this will cure your idle speed adjustment problem which will then in turn cure your stalling problem. Try to make only one change at a time so you know what cause and effect.

Best of luck!

Edited to add:

It was RADMAN and Warchild that offered TBS help. Click here for the post.