Hi all I just got a CB400 project big 1, and 3 times now its killed the spark plug in the same cylnder, take the plug out test it nothing nada zip not a flicker. Relplace it with another one and its fine (well until it kills that plug) I'm kinda at loss as to what to try and not very sure on where to buy or what spares will fit.

Any help much appreciated

Odd. Maybe leaky a float valve on the carb flooding the cylinder while its standing?

What do the knackered plugs look like?

Thanks for the reply , the plug itself is ok just wont spark not even on another HTlead. i'm guessing its a coil problem but having trouble finding a replacment coil. Are they specific to the bike or will another model fit.

thanks .

does the ceramic look burnt? could be side vtracking on the cap try a little electrical terminal grease (the stuff you spray on battery terminals).

Its been a while since i was here so a be-lated thanks for the replies ....and a quick update the problem was reemed out pilot jet on #3 carb for some reason some tool had rammed a file down it ..... replaced all the jets to be on the safe side, sorted that problem ,then had the mid range misfire sorted that thanks to this forum, wife complained about the reach of the clucth(lever was bent) replaced that... testing clutch , Throttle cable snapped , push cable was fraid too , replaced them took bike out last sunday got 20 miles down the rd and fuel pipe split ...

Sorted fuel pipe bike runs sweet as a nut now. despite all the little niggles i love this little 400 bought it for the wife but i will no doubt us it more than her ...

Appoligies for rambling in what is proberbly the wrong forum...

Oh P.S if any of you have the R-204C color code bike i would like some pics if possible , want to put mine back to that color