REFERENCE > Known Issues

Exhaust & Exhaust Header Bolts
by Ted Verrill

From the very beginning BMW had problems with the K series exhaust pipes. In the K1100 series this has translated into a particular desire of exhaust header bolts to loosen, and even fall out, and for the pipes to crack just upstream of the collector. Scattered reports of missing and sheared exhaust bolts can be directly attributed to incorrect torquing of these bolts. The cracks may or may not be attributed to loose bolts.

BMW recommends checking the torque of these bolts every Inspection level service (12,000 miles) but it may be prudent to advance that to every 6,000 miles.

The correct settings are <insert data>, and it certainly would not hurt to check that all of the bolts are tight each time the bellypan is removed.

To Check

• Listen - Loose header bolts often result in a knocking noise from the general direction of the headers. When exhaust header bolts are quite loose the sound will be quite pronounced (and when missing your bike will probably sound like a WW1 Biplane!)
• Look - Remove the bellypan and (when the engine has cooled!) try turning the header bolts. Give the header pipes a push - there should be no free play in the headers whatsoever. Take a close look at all junctions, especially where the header/single pipes collect into the exhaust pipe - if it is going to crack this is probably where it will happen.

If you have a loose bolt, tighten it immediately. Failure to do so can result in the bolt falling out (and occasionally destroying the threads on the way out necessitating a Helicoil) or being sheared by the header.

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