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FAQ: Techknuckle Page

Techknuckle Page

SACAQ Written By Bill Silver

What's up with this page?  

What I intend to do here is field a number of significant and commonly asked questions (SACAQs - My invention there!). I will sort through the incoming queries and sort out the ones most relevant to the general maintenance of these bikes and then post them on the web page.

Here are some significant and commonly asked questions (SACAQs):


      Q:    Why does my battery go dead, just sitting in my bike, sometimes just over night?

      A:    Often the selenium rectifiers fail due to old age and damage from being operated without a battery (or with a dead one) in the circuit. They can be tested with an ohmmeter by checking each segment to ground and them
      reversing the test leads. There should be low resistance one way and high resistance the opposite way, if the diode function is working properly. A shorted rectifier will prevent proper charging and will drain the battery through internal shorts.

      Q:    My bike always spits back and misfires just after start-up, until it warms up for a few minutes. What's wrong?

      A:    There is a tendency for all 250-305s to have rough-running operation when cold, even when everything is set perfectly. However, several conditions can aggravate the problem:

      1) Incorrect ignition timing. As the points rubbing blocks wear down the gap closes, retarding the ignition timing to after TDC, instead of 5 degrees before.

      2) Fouled plugs, due to oil fouling (worn rings or valve guides) or fuel fouling (carbs not set to specs, worn parts, choke link out of adjustment, etc.).

      3) Spark plug caps have loose connection or bad internal connection (some have resistors which can fail).

      4) Weak spark, due to dirty points, weak condenser, or weak coils.

      5) Carbs out of synch (on twin-carb versions) when cables are not adjusted to raise both slides together. Also carbs with restricted idle jets, worn slides, and needles in the wrong position (clip should be in the 3rd position except for CB77s, which need them in the 4th position from the top).

      6) Air leaks, at either the carb flanges (warped), insulator blocks (cracked, warped) or damaged O-rings which seal the carbs to the insulators, then seal those to the cylinder heads.

      Q:    How do I order a CB/CL Restoration Guide book or the 250-305 Engine book?

      A:    The books are available for purchase through this web site. Please see the Marketplace section. Price is $24 for CB/CL book and $24 for Engine Book. $45 for both ppd. (in USA).


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