Hi!

I decided to have a go at fixing my 1984 K100 today.

Tank and fairing removed.
Air filter housing and airflow meter removed.
FI Relay checked (heard it click) so am figuring it must be good.
Fuel Pump connected to 12v battery and it ran. I am assuming it is in working order and delivering the correct pressure for the moment.
Starter motor turning

As I inspected the pressure regulator I found that the bottom hose was off the union!! This must have blown off as I didn't remove it. Could this explain why the bike wouldn't start?

The short hose from the air intake box that goes into the engine case by the alternator had a split that may have been right through!

I replaced this hose and the pressure regulator pipe that had come off with parts from my donor bike which has only done 12500 miles.

The pressure regulator itself looked good - no dents, splits or visible damage. All other hoses looked good and tight.

Next on the agenda is:
refit battery and tank, fill her up and test.

Other jobs to do are:
Steering head upper bearing replacement
Bevel box to change as a little play in rear wheel bearing
And probably a good few more...

Has anyone encountered a problem with this pressure regulator hose blowing or coming off the union by itself?

Regards, Neal

No mate, but I had a split hose and the bike wouldn't start until I replaced it
so it's an important piece of the chain of events. Good luck.
RT

For the fun, when the bike is idling, open the oil plug on the crankcase cover (the plastic plug where you fill up the oil).
You will notice right away the effect of an air intake leak.
You engine will die or run really bad.

Cheers for the replies.
I will let you know what happens when I try to fire her up.

The donor bike is a great thing! I can't help thinking that I should use the older one to get the newer one on the road. But that day may still come.