TOPIC:

Video shows obvious lack of combustion in #4 cylinder.
Could result from an issue with compression, or spark, or mixture.

COMPRESSION --
Even with a perfect carb, inadequate compression may also reduce the suction necessary to pull mixture from the carb.
A compression test alone isn't sufficient.
Where both dry and wet compression tests on the same cylinder are about equal, a leaking valve seat is suspected as being where the compression is being lost during the compression stroke.
Do check the valve clearances in #4, and assure both clearances are within specs.
If either valve is too tight, set it to specs, and repeat the dry compression test and the wet compression test where both valve clearances are known to be within specs.

SPARK --
With the #4 plug removed from the engine head, with cap attached, and plug base held grounded against the engine head,
turn ignition switch ON, and visibly observe the spark while spinning over the engine.
The engine will probably begin running, which is okay.
Should be healthy fat blue sparks.
Then repeat the same test, using a brand new spark plug.
Sometimes a fuel-fouled plug can exhibit good looking spark when observed, but fail to spark when reinstalled.
Would install a brand new spark plug in #4, and test run the engine to see whether #4 begins combusting.

MIXTURE --
Would confirm fuel level is correct via the clear tube test.
And leave carb alone (for now).

Let us know results of dry and wet compression tests, and whether any necessary valve adjustments have been performed, and observed spark quality, and running performance after installing a brand new plug.

And let us know if any help might be needed with regard to compression testing or valve setting.

VALVES --
Measuring (checking) valve clearance is the easy part. Just remove cam cover; point cam away from the valve; and use a thickness (feeler) gauge to determine amount of clearance existing between the cam base and the shim.

If clearance adjustment is needed, shim removal and replacement is the next step, which isn't difficult, but does require a special tool, plus a shim of the necessary thickness.

Good Fortune!

@Patton. Thanks Again.

I got my valve checking tools(Feeler Gauge, Motion Pro Valve Shim Tool)in the mail today.
I will see if I can get to it this weekend sometime. However I do need to find someone to borrow a compression checker.

badrhino wrote: ...got my valve checking tools(Feeler Gauge, Motion Pro Valve Shim Tool)in the mail today...However I do need to find someone to borrow a compression checker.

When using the Motion Pro tool, I ignore the lever and use only the "bat-wing."

When the bat-wing is correctly inserted, the 17mm fake nut (under the points cover) may be used to carefully rotate the crankshaft, whereby the bucket is held down by the bat-wing after the cam point turns away, which removes pressure of the cam against the shim and leaves space to remove the shim.

Some auto parts stores, such as Auto-Zone for example, will have a compression tester that they loan out to customers.

Good Fortune!

Definitely check compression, and your valve clearances. If compression is low you will need to correct that before anything else.
Does the pipe get hot if you run a higher RPM by blipping the throttle?
Was this a problem that just started by itself or came on suddenly?
What does it do if you feed a bit of Propane into the Airhorn of the Carb, any change? If it catches/ increases RPM, its lean. Vacuum leak or plugged Pilot circuit.

Definitely check compression, and your valve clearances. If compression is low you will need to correct that before anything else.
Does the pipe get hot if you run a higher RPM by blipping the throttle?
Was this a problem that just started by itself or came on suddenly?
What does it do if you feed a bit of Propane into the Airhorn of the Carb, any change? If it catches/ increases RPM, its lean. Vacuum leak or plugged Pilot circuit.

The pipe would get fairly hot when I had the bike revving at higher rpm's.
I bought the bike years ago and have just now got it running so I don't know an history about how it ran before. I have sprayed carb cleaner at the back of the carb mouth and it doesn't change anything.

Auto Zone has them for ~ $30....


For rair use, HF Tools (if in your area) has them in various price ranges, @ $13 this will work well enough for diagnosing compression loss, even if off a pound or two in the measurement...

Well I opened up the valve cover and just had enough time to check the #4 intake and exhaust because I have to goto work. Wouldn't you know it. Intake wouldn't take the .04 mm gauge and the exhaust accepted the .10mm gauge.

How does one disengage the cam chain tensioner when I go to put this back together? This sits right in from of the carbs and looks to set sideways from other cam chain tensioners that I have seen.