Cold Cylinder #2, '81 KZ750 LTD

Injected wrote:

You need a minimum of around 100 PSI for combustion to occur. I would also check valve lash while your running thru all the rest of a basic checks.

I've already done the valve clearance checks and re-shimmed. The valve clearances are in spec.

Have you tried setting the petcock to "prime" and blanking the vacum port on #2 carb ?

Wookie58 wrote:

Have you tried setting the petcock to "prime" and blanking the vacum port on #2 carb ?

Thought I had done that when my test/secondary fuel tank was connected. I usually hook that up to the fuel line in and then block the vacuum connection on cylinder #2. When doing that got the same result.

Wookie58 wrote:

Have you tried setting the petcock to "prime" and blanking the vacum port on #2 carb ?

I was mistaken. With the test tank connected and the vacuum connection blocked on cylinder 2 it fires up and cylinder #2 exhaust pipe is hot as expected. Though I am now also getting a runaway RPM issue. Blip the throttle and the RPMs climb to about 4k and just stay there. 

Progress then, looks like a vacum leak through the petcock. Sounds like you also have other air leaks given the "hanging revs"

Wookie58 wrote:

Progress then, looks like a vacum leak through the petcock. Sounds like you also have other air leaks given the "hanging revs"

I already have new carb intake boots as well as new airbox boots. Do I need to start spraying WD-40 or starter fluid in places? 

SnyperX wrote:

Wookie58 wrote:

Progress then, looks like a vacum leak through the petcock. Sounds like you also have other air leaks given the "hanging revs"

I already have new carb intake boots as well as new airbox boots. Do I need to start spraying WD-40 or starter fluid in places? 

You can try WD40 but it tends to be inconclusive unless the leak is huge. Have you tried slackening the throttle cables then operate the throttle linage by hand (this will rule out a mechanical or cable adjustment issue)