1989 k75s custom build which miss fires under load.

[Adrian]

Hi All,
Can anyone help?

I have built a cafe racer style custom bike from a 1989 k75s which I showed at this years bike shed show(see attached file). The bike is complete frame up rerbuild and has a custom wiring loom.
 It starts on the button, ticks over beautifully but has an issue when put under load. It is as though it is being starved of fuel although the plugs appear wet.
I have taken the bike to Ben at BSK speed works who has changed and swapped out as many parts as he can but between us we have now exhausted options with no improvement in the running.
Can anyone recommend anyone who would have the skill and knowledge to take a look at the bike and finally get the bike on the road.
I love these bikes and think they are massively underrated.
Any suggestions appreciated, I am willing to take the bike anywhere in the uk and spend whatever is needed.
thank you in advance.
Adrian

[Martin]

Test the temperature sender unit and it's connector.
Regards Martin.

[Laitch]

I have built a cafe racer style custom bike from a 1989 k75s which I showed at this years bike shed show(see attached file). The bike is complete frame up rerbuild and has a custom wiring loom.
I have taken the bike to Ben at BSK speed works who has changed and swapped out as many parts as he can but between us we have now exhausted options with no improvement in the running.

Welcome, Adrian.
Your file didn't attach. Try again then Preview your post to verify that it attached. Reduce the file to less than 2MB for a greater chance at success.

List every part that has been replaced by both you and BSK so you don't make responders go over old ground with suggestions that have already been followed and have failed to improve performance.

Your post seems to indicate that cost is not an obstacle so consider making arrangements with BMW for shipment to Germany for diagnosis, or arrange lodging for a factory-trained technician who worked on K-bikes to come to your place. Be sure your place is well-heated; the technician might be elderly.
 :giggles

[The Mighty Gryphon]

Has the engine been modified, specifically the air intake portion?  Did you swap out the mass airflow sensor(MAF)?   Outside of the temperature sensor, the MAF has the largest effect on mixture in the Jetronic ECU system.

Become an expert on electronic fuel injection and the L-Jetronic:

http://www.cardiagnostics.be/-now/Educational_sites_bestanden/BOSCH%20L-Jetronic%20Injection%20Manual.pdf

[billday]

I have taken the bike to Ben at BSK speed works who has changed and swapped out as many parts as he can

Sounds like Ben had a boat payment due.

[The Mighty Gryphon]

And it's probably not a small boat.

[Laitch]

Sounds like Ben had a boat payment due.

And it's probably not a small boat.

Probably a Cigarette.