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Various CB400 problems :(

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by cb rookie, Jul 3, 2011.

  1. Hey all,

    I've been reading up on what information I can find pertaining to my CB400 woes, though I thought I'd post anyway to hopefully get some specific advice. (I'm a noobie, it's my first bike)

    I just bought a CB400 (1995), and the guy who had it before me replaced both the fuel tank and fuel tap (not sure why the tap) before I bought it.

    Today, I noticed that fuel is leaking on the engine only when it's turned on, and it appears to be limited to the left hand side (from the fuel tap). I suspect it's either the joint to the tank or the tap itself. Should I replace it or may it just simply be a case of tightening something?

    In addition, the choke appears to be inoperable (the lever only moves halfway down the corresponding white arrow marked on the handle), and whenever put in position other than off, will cause the engine to stall/not start. When it does start, it sounds strained (low revs), and warming it up can only really be down through opening the throttle slightly to raise the revs to about 2,000. Alternatively, if I leave it, it idles at just above the 0, so maybe 500 if that.
    I find that no matter whether the engine i warmed up, I need to open the throttle just after hitting the start button in order to get the bike going. So any information/suggestions here would be much appreciated!

    On a slightly side note (not the biggest concern at the moment), the bike seems to be underpowered. That is in comparison to videos I've seen of others riding this same model. For example, in first, they get the bike to 60km/h, though I can barely get it to 30. The stop speed is usually 180 or so in 6th gear, but my bike is nearly at it's limit doing 145-150. My concern is that something may be wrong with it, though I hope nothing major. I read somewhere a suggestion of maybe some cylinders not firing (ie spark plugs).

    The guy I bought it off told me he cleaned the carbs, and made a passing comment about altering the revs, or making them low or some such. Anyway, I'm going to see him tomorrow, and try and get my mechanic to have a look.

    I was just hoping to get some thoughts/theories/suggestions so I can get an idea of the issues.
    (I wonder if for example the spark plugs could be the cause of lacking power and low idles).