What is Surging?

**XR Max 600** · #1 17 Jan 2004

You guys keep writing about this mysterious thing called surging... Can someone please let me in on what that is?
Thanks and apologies for my ignorance!

**G. Kennedy** · #2 20 Jan 2004

Surging is a is an anomoly associated with fuel injected BMW twins. Some have it worse than others. I am sure some one will come along with a more professional description, but in laymans terms: It is a surge or pulse of the engine. It is mostly felt at lower rpm. Often when putting through a town. I think it has to do with the throttle bodies being connected via cable. They are very sensitive and the cable is not. My '95 seemed almost cured, then I got a new throttle cable and it seems to be back. I think as the cable stretches and then settles in, it can then be adjusted to lessen surge. Sorry I can't explain it better.

**Grant Johnson** · #3 20 Jan 2004

To perhaps explain it a little further:

What it FEELS like is some moron child has his hand on the throttle - and instead of holding dead smooth and steady as you cruise through town at 30mph, is just slightly twitching it up and down - off on off on off on. Nastiness is extremely variable.

If you've ever ridden a two-stoke at a low steady speed you know all about it.

As noted the BMW fuel injection models have a problem with it. Most are fine, some aren't. Long technical dissertation follows... not.

Extremely precise setup usually cures it. Sometimes a trick or two is needed. There's tons of info on the web about it.

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Grant Johnson

Seek, and ye shall find.
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One world, Two wheels.
www.HorizonsUnlimited.com