Surging

[Rick Ward]

I have read if not here then some other forum that surging can be fixed thru proper valve adjustment (R1100RT). Is that true or is it necessary to modify the fuel management system?

 

[Michaelr11]

Yes. Careful valve adjustment, clean and equally flowing injectors and a good throttle body sync should give you a smooth running Oilhead. Fuel system modification is recommended by a bunch of guys here but it isn't necessary, not on the R1100RT.

[Jim Moore]

Occasionally you can get everything right and the surge will disappear for awhile. It's almost impossible to do on a regular basis though. There are too many variables and the system is too delicate. Imo your best bet is to simply remove the cat code plug (CCP). That takes the O2 sensor out of the loop and has fixed surging on every oilhead I've ever owned.

[dirtrider]

I have read if not here then some other forum that surging can be fixed thru proper valve adjustment (R1100RT). Is that true or is it necessary to modify the fuel management system?

 

Morning Rick

 

They ALL (BMW 1100/1150) surge to some extent or the other regardless of the valve setting & TB balance. Some riders (like myself) are very critical to the surge & others hardly notice it, or don't notice it at all. It also depends a little on how a rider rides the bike.

 

Some BMW 1100/1150 bikes stack up to be very bad surgers & others stack up as just moderate surgers.

 

To have much effect on engine surge the valve adjustment would have to be W-A-Y off as the take-up ramps on the cam lobes pretty well set the (effective) valve lift point even if the valve lash is off a little bit.

 

Even a perfect TB balance can make the surging worse as it is mostly even fueling not even air flow that effects the surging the most.

 

If the TB balance is off in a way that helps, or evens out, asymmetrical combustion due to uneven fueling then setting a perfect TB balance can increase the surging.

 

No real easy answer unless the fueling is richened up enough in the surging range to cover up the uneven fueling-- If the combustion is basically run on the rich side in the surging operating range then uneven fueling has way less effect on the surging.

 

In the later BMW 1150 engines BMW tried to somewhat even out the lean (o2 controlled) combustion by going to two spark plugs per cylinder-- That helped & still allowed the engine to operate lean enough to maintain emission compliance.

 

The real answer on the BMW 1100 or 1150 bikes is to just bite the bullet & add an aftermarket fuel controller to richen the overall fueling in the surging operating range. With richer overall fueling that pretty well eliminates the surging concerns enough that it then doesn't bother even the picky riders.

 

On the BMW 1100 bikes there is a way to sort of richen the lower RPM surging by removing the CCP from the fuse box-- That forces the fueling control to look for an idle trim pot (was used on non o2 sensor equipped 1100 bikes)- Running an 1100 bike with no CCP & no idle trim pot severely richens the idle & that carries up just enough into the lower surging range to help eliminate some of the light throttle surging.

[roger 04 rt]

I have read if not here then some other forum that surging can be fixed thru proper valve adjustment (R1100RT). Is that true or is it necessary to modify the fuel management system?

 

Morning Rick

 

They ALL (BMW 1100/1150) surge to some extent or the other regardless of the valve setting & TB balance. Some riders (like myself) are very critical to the surge & others hardly notice it, or don't notice it at all. It also depends a little on how a rider rides the bike.

 

Some BMW 1100/1150 bikes stack up to be very bad surgers & others stack up as just moderate surgers.

 

To have much effect on engine surge the valve adjustment would have to be W-A-Y off as the take-up ramps on the cam lobes pretty well set the (effective) valve lift point even if the valve lash is off a little bit.

 

Even a perfect TB balance can make the surging worse as it is mostly even fueling not even air flow that effects the surging the most.

 

If the TB balance is off in a way that helps, or evens out, asymmetrical combustion due to uneven fueling then setting a perfect TB balance can increase the surging.

 

No real easy answer unless the fueling is richened up enough in the surging range to cover up the uneven fueling-- If the combustion is basically run on the rich side in the surging operating range then uneven fueling has way less effect on the surging.

 

In the later BMW 1150 engines BMW tried to somewhat even out the lean (o2 controlled) combustion by going to two spark plugs per cylinder-- That helped & still allowed the engine to operate lean enough to maintain emission compliance.

 

The real answer on the BMW 1100 or 1150 bikes is to just bite the bullet & add an aftermarket fuel controller to richen the overall fueling in the surging operating range. With richer overall fueling that pretty well eliminates the surging concerns enough that it then doesn't bother even the picky riders.

 

On the BMW 1100 bikes there is a way to sort of richen the lower RPM surging by removing the CCP from the fuse box-- That forces the fueling control to look for an idle trim pot (was used on non o2 sensor equipped 1100 bikes)- Running an 1100 bike with no CCP & no idle trim pot severely richens the idle & that carries up just enough into the lower surging range to help eliminate some of the light throttle surging.

 

+1 to DR.

 

One thing to keep in mind though is that removal of the Coding Plug (CCP) and installation of a CO Pot is a lot more effective if you run gas without ethanol. In that case, the basic fuel map is such that you get about a 5% richer mixture for the first few degrees of throttle operation. But that basic factory map was designed for non-ethanol fuel. E10 is 4% leaner than pure gas so you end up 5% richer minus 4% leaner, in other words back where you started. And, you loose the Motronic's ability to adapt to other fueling related issues when you remove the CCP.

 

The enrichening effect of CCP removal has been measured with a Wideband O2 and so has the lean-off effect of E10. If anyone's interested I'll add a link to the charts.

 

Edit: One thing that could be done if E10 is your fuel, pull the CCP and add a boosterplug ($150) but if you're going to spend that much money an AF-XIED is a much better deal for the long run.

 

 

 

 

Edited April 18, 2017 by roger 04 rt

[Tri750]

Also, a no cost, no negative on gas mileage is to simply upshift when you get to the surge-ey rpm band.

If you are new to the bike, ride it a few thousand before you change anything is my advice.

Many folks get a bike and read too much on the internet about a problem "everyone has " but in your world, in real life, it ain't so bad.

 

Having a competent tech who has a lot of experience cleaning, adjusting and synching your model of bike can make a big difference too.

Many independent shops are out there with lots of bmw experience of your era so

I'm not saying "DEALER" for the dealer haters.

 

[tallman]

Also, a no cost, no negative on gas mileage is to simply upshift when you get to the surge-ey rpm band.

If you are new to the bike, ride it a few thousand before you change anything is my advice.

Many folks get a bike and read too much on the internet about a problem "everyone has " but in your world, in real life, it ain't so bad.

 

Having a competent tech who has a lot of experience cleaning, adjusting and synching your model of bike can make a big difference too.

Many independent shops are out there with lots of bmw experience of your era so

I'm not saying "DEALER" for the dealer haters.

 

 

"Doc, it hurts when I do this", "don't do that."

If you're riding a surger, ot will be in a certain range, don't linger.