robmack wrote:Helping a friend with his non-running 87 K75.  I've checked and double checked for all the elements needed to start - air, petrol, spark - but no go.  Usually I'm offering the advice but now I need some.

- brand new battery fully charged 13.17V resting voltage
- starter cranks healthily and engine turns over briskly
- brand new NGK DR7EA plugs, gapped properly.  I confirmed a healthy spark on all plugs
- fuel pump operating with the start switch and 1.5 seconds after release
- air filter clean
- injectors operating as I have used the screwdriver-as-a stethoscope trick to listen for clicks.  Clicks are  present on all three injectors.  
- At times after a cranking session, fuel leaks out of the exhaust between the header and muffler indicating fuel in getting into and out of the cylinders
- all plugs are wet with fuel
- tried the trick to unplug the tank connector and crank the starter.  Engine turns over but still does not catch.


I have had some experience with hard starting K75s.  They tend to flood way too easily.  I'd bet your injectors aren't closing properly and allowing fuel to seep in when sitting since the system is still under pressure.  Have a go with the other injectors.  Then send your injectors to Injector Experts in Rising Sun, Ohio.  $20 each plus shipping.  They have done several sets for me with great results.

What I have not yet done:
- I have not yet gone through each and every connector on the harness with Deoxit but that is my next step.

Interesting Observation:
I had to do some electrical work on the bike because connectors were mashed and McGivered by the previous owner.  Used parts from a doner bike to correct the mess.  During this electrical work, I cranked over the engine once and it caught, and ran for about 15 - 20 seconds.  No fuel tank at the time so this engine operation was with fuel left over in the cylinders and fuel hoses.

I'm hoping someone will point out the obvious (or not so obvious) that I have missed.  Why won't this engine catch and run?

robmack wrote:Helping a friend with his non-running 87 K75.  I've checked and double checked for all the elements needed to start - air, petrol, spark - but no go.  Usually I'm offering the advice but now I need some.

- brand new battery fully charged 13.17V resting voltage
- starter cranks healthily and engine turns over briskly
- brand new NGK DR7EA plugs, gapped properly.  I confirmed a healthy spark on all plugs
- fuel pump operating with the start switch and 1.5 seconds after release
- air filter clean
- injectors operating as I have used the screwdriver-as-a stethoscope trick to listen for clicks.  Clicks are  present on all three injectors.  
- At times after a cranking session, fuel leaks out of the exhaust between the header and muffler indicating fuel in getting into and out of the cylinders
- all plugs are wet with fuel
- tried the trick to unplug the tank connector and crank the starter.  Engine turns over but still does not catch.

What I have not yet done:
- I have not yet gone through each and every connector on the harness with Deoxit but that is my next step.

Interesting Observation:
I had to do some electrical work on the bike because connectors were mashed and McGivered by the previous owner.  Used parts from a doner bike to correct the mess.  During this electrical work, I cranked over the engine once and it caught, and ran for about 15 - 20 seconds.  No fuel tank at the time so this engine operation was with fuel left over in the cylinders and fuel hoses.

I'm hoping someone will point out the obvious (or not so obvious) that I have missed.  Why won't this engine catch and run?

robmack wrote:...
I can run the engine with the tank disconnected and it will run for a good 30 seconds (very smooth and strong sounding) until all fuel is exhausted.

I tried the following.  I got the engine running without the tank then, while running, plugged in the tank.  Within a couple of seconds, the engine began to sputter, then died shortly after that.