I have an 81 kz750H (18000km) and am having some runability issues. When cold with the choke on the bike fires up with a quick touch of the starter button. After warming up a little I can ride without choke but the idle is quite low and wants to stall out at traffic lights. However, once fully warmed up, the idle is much higher (almost 2k rpm). I have removed and cleaned the carbs, set the idle mixture screws at 2 turns out, vacuum synced (within 1/2” mercury), replaces plugs (NGK B8ES), fresh oil, oil filter and air filter. I haven’t however checked the ignition timing or advancer as I haven’t found anything online pertaining to my model.
As far as I know there are no modifications to the bike as I got it from the original owner. I am getting a little popping in the exhaust once the bike is fully warmed up so I’m thinking I’ll have to check my valve clearances. What I have been searching for all over is a list of symptoms of intake valve adjustment out of spec and the same for the exhaust valves. My main issue is hot starting. After riding for a while,(full operating temperature) and I stop for gas or whatever, the bike if it doesn’t fire up right away (feathering the throttle) it takes some serious cranking to start it. Once running it seems fine again.
I’m thinking the exhaust valves my be a little tight and once fully warmed up are not fully closed when they should be. Could it possibly be ignition advancer or more likely valve adjustment? I love the bike but I don’t want to have to worry about it stalling and not possibly starting again. What do you fine folks think??