K75c

[justintime]

Hi all for my sins the good lord made me get a k75c this devil has issues. I have done the usual stuff changed plugs ht leads airflow meter.
Yet the dam thing still runs lumpy as hell at low revs. With the choke on its fine.Also when i tweak the throttle with the choke on the revs lift and stay high. But when its warm and the choke is off it hunts like hell dropping below 1000 and back up the throttle response lags, There is defo a miss fire. HELP PLEASE ANYONE its driving me mad           

[Motorhobo]

When you say ht leads do you mean the spark plug wires? Is that what you replaced? If not, that'd be a good idea.

I guess you know the choke isn't really a choke and all it does is add throttle. Maybe your idle is just set low? Does it run smooth at or above 1000rpms?

[subforry]

Hunting usually means its running to lean, which more likely means there is an air leak somewhere.

Maybe try the starter fluid trick.  No, DO NOT spay that stuff into an engine to get it running.  Instead spray it around the air box, intake boots, injectors, etc.  The butane vapor (starting fluid) will be pulled into any air leaks thus enriching the mixture and the engine will run better.  If that happens the there is a leak in the area where you sprayed the starting fluid.

[Scott_]

Not uncommon to have bad vac lines(crankcase breather hose) on the backside of the throttle bodies.

[justintime]

Thanks all will try and let you know regards

[koapono]

as others have said: check for intake air and vacuum leaks. i recently removed airbox (94 K1100) to find source of oil mist/crud on engine. I found: 2 cracked and leaking rubber intake bushings, cracked and leaking hose on timing chain cover vent, the hose  from crankcase vent to air box was cracked and the vacuum manifold hose at rear of throttle bodies (connects three or four vacuum ports to air box) was also in need of replacement. Some of the hoses can be readily fabricated from auto parts store generic hose of proper diameter other hoses are bent, shaped and formed to fit so i bought from BMW parts source (pricey!). after replacement of hoses and throttle body synch scoot purrs like a K-itty! also found source of oil misting, crankcase and timing cover vents.
g'luck

[justintime]

Thanks to all give me some good tips can not wait till Sat to have a look, watch this space will let you all know if any of your tips work out regards