SOHC.co.uk Forums > CB350/400
Really bad cold starting. Ign or fuel?
Scottish Badger:
Hi folks. My CB400F2 is giving me grief. When I bought it last year, it was a poor starter but I figured a good service and some new plugs etc would sort it out, how wrong was I!
So far, I've checked the valve clearances, ignition timing, removed the carbs and given them a full overhaul, fitted NGK Iridium plugs, new air filter, oil change and new battery. The carbs were bench-synchronised so can't be that far out.
Once the engine is running and warmed up, it's really smooth and quiet and after tweaking the idle mixture screws (max adjustment about 1/4 turn from factory on one carb, 1/8 on another two) it idles beautifully. When switched off, hot, it will re-start on the button instantly.
My problem is cold starting. No amount of throttle or choke seems to have any effect, after what seems like ages cranking it, it'll fire randomly with the choke almost fully off, repeated attempts will get it to go a bit longer each time until eventually it'll pick up and run. I've tried more and less fast-idle on the adjuster, altering the idle speed screw, and every combination of throttle and choke imaginable! I get nothing at all trying to kickstart it. The carbs have been back off and re-checked, the plugs have a lovely fat spark whilst cranking and are clean....
Help, it's doing my head in!!
McCabe-Thiele (Ted):
Will it start easily after standing for an hour?
Nurse Julie:
Ditching the Iridium plugs would be a good start. Fit NGK D8EA.
Scottish Badger:
Ted, it re-starts just fine until the next day. Fuel flow to the carbs is good, confirmed by checking each one in turn with drain screw undone.
Julie, the Iridiums were fitted to see if they made any difference - they didn't. It was exactly the same with the D8EA's previously fitted. I've used Iridiums in all my bikes to good effect, my XL500 fires up first kick from cold since fitting one - ok, different ignition system type, but the plug made a big difference.
K2-K6:
Try misting some e-z-start into the airbox intake before you crank it first time to see if it changes at all.
Have you got any compression figures for it ?
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