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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: gazman on December 09, 2014, 06:12:59 PM

Title: k11 backfire
Post by: gazman on December 09, 2014, 06:12:59 PM

greetings, Ive found that if riding with lots of throttle and then back off fast she will backfire, doesnt happen if I back off slowly. changed the plugs, no differance,ordered a carbtune so will sink throttle bodies soon. Any ideas?

Title: Re: k11 backfire
Post by: Inge K. on December 09, 2014, 06:28:01 PM

Check for broken weld(s) at the ekshaust collector.

Also check the rubber mountings, especially the one under the gearbox......worn, broken mountings is often
the reason to broken welds at the ekshaust collector.

Title: Re: k11 backfire
Post by: gazman on December 09, 2014, 07:43:40 PM

changed that lower mount about a month ago, old one was broken. just checked for exhaust leaks at collector with hose to the ear and BINGO she,s leaking. I,m thinking take it off and mig weld it, or is there a better method? thanks  :riding:

Title: Re: k11 backfire
Post by: Inge K. on December 09, 2014, 07:57:53 PM

Quote from: gazman on December 09, 2014, 07:43:40 PM

I,m thinking take it off and mig weld it, or is there a better method?

Tig won't crack that easily between the weld and material, and you reach a bit better into those tight Places.

Title: Re: k11 backfire
Post by: gazman on December 09, 2014, 09:31:26 PM

Thanks Inge TIG it is :2thumbup:

Title: Re: k11 backfire
Post by: Grim on December 11, 2014, 10:00:45 PM

Also pull the throttle bodies if that doesnt fix it. The boots (BMW calls them bushing) are proned to failing with age. It's likely yours are due if original.