I would welcome some help with the following. I have a 72 Kawasaki H1B 500 (Points model) which has performance problems with mainly what seems to be the middle pot load around 3000 rpm +. The engine has just received a complete overhaul with new conrods, 61mm Wossner pistons & rings, seals, sleeves, crank overhaul, bearings, gaskets, clutch and clutch cable, coils, leads and caps, Gel battery, rectifier, new NOS breaker plate, points and condensers and new K & N air cleaner and new throttle and coke cable and new Doremi exhaust pipes and many other parts etc. Carbs fully refurbished with:
NOS Mikuni Needle jets part number 172 NOS Mikuni Needle jets 5DJ19-4 clip (Also tried 3 clip but no difference) Prepro Decals 100 Main jet (Also tried 95's but no difference) Mikuni pilot 30. Cutaway 2.0 Air screws set at 1 1/2 turns (have tried over range of 1 1/2 to 2 1/2 turns) Float levels 25mm ( Have also tried set to 24mm & 24.5mm) Plugs NKG B8HS set at 0.024" Points set 23 deg BTDC (2.94mm) Kaw air cleaner has additional air intakes for engine no's KAE-61607 up
Bike looks really smart and starts after 1-2 kicks and idles really nice and smooth with each pipe putting out the same amount of smoke, however the bike starts to misfire under load right at 3000 rpm. Have checked for air leaks, checked idle, all electrics, carb sync also tried an NOS H1A air cleaner, swapped carbs and also coils around however no difference. LH & RH plugs look good (light brown), however centre one is black and sooty.
Have taken baffles out - no change with same problem running 95 mains & 30 pilots, however still the same with splutter at 3000 + with sooty black centre plug. Changed mains to 100's and pilots to 25 but still the same.
Checked compression on all cylinders and all 142 psi
Changed float levels to 25mm and also fitted new temp wiring from the coils to the battery and coils to the points to see how this went compared to the old harness. Also fitted new coke cable and used the original factory plungers and set up correctly. Coke action feels much better, however when out on the bike, no change. Starts and idles sweet but still splutters on the centre pot at 3000+ rpm with a sooty plug. I
This is now getting some what frustrating with only 30 miles on the clock since a full rebuild. The only thing I have not tried to do is checking the centre cylinder check valve which I will now do, however if this was faulty, you would assume the centre pipe would be blowing more smoke which it is not.
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