Gpz900 engine temp struggle...

Hi hall, i have a big headache .. the bike is a gpz 900r, good engine conditions.
Valve clearance done
New coils
New coils wires
Compression all 4 cylinders around 150psi
New plugs
New carb boots from tourmax.
Carburetors was totally rebuild with orings, gaskets and well cleaned in a ulstrasonic machine.
The bike runs really GREAT ABOVE 3000 RPM. Its just a Monster plenty of Power.
Start everytime cold or hot in just a second.
Idle is a bit "sluggish" ..and continuosly variations between
900rpm
1000rpm
850rpm
1100rpm...etc etc..

The Real problem is i think the two right cilynders are running lean.
When i stop the bike and i use my infrared thermometer on the headers i read the two left cylinders are 180°C and the two right are hotter, 230°

I think this is the reason the bike is so INCONSISTENT , SLUGGISH under 3000 rpm. When cruising at Little gas aperture i Can feel its tipycally LEAN. a bit SLOWLY to return to idle and the idle sounds Like a v8 muscle car " TOTOTOTOTO.."
I was NOT ABLE to find any vacuum leak using flammable sprays , gas, wd40 .. anything.
And i was able to synch the carb ONLY with the Morgan carbtune upside down. If i hook the gauge in the normal position there is no sufficient amount of vacuum to pull the sticks. Its Like is not producing vacuum.

Please, help. I want so bad to reach that SHARP, CRISPY ,gas response..

shamal wrote:
And i was able to synch the carb ONLY with the Morgan carbtune upside down. If i hook the gauge in the normal position there is no sufficient amount of vacuum to pull the sticks. Its Like is not producing vacuum.

I would try the classic sync clocks, works in every position.



You have to check/calibrate the clocks before on one vacuum port if they showing equal values.

Im absolutely sure the gauge its ok since i used It before and After the gpz problem on many other bike and It works great. .. i have not the Classic needle gauges . Anyway with the carbtune upside down i was able to Sync Them . I recall 14/16 cmhg on the gauge.
What Can be the problem? I forgor to say the mix screws are 3 turns out , but in any case is inconsistent. No response from the engine. They work the same 1 turn or 3 or 4 damn turns out ...

I would say check your pilot screws!!!

Thank you, but i wrote the carb was rebuilted totally , even in the mix screws oring. Im stumped how is possibile for this engine be at idle but at the same time no vacuum in the gauge? Anyway.. what about the temperature differemce? Can be spark plugs caps problem?

Have you set the correct float high?

Yes, Yes..maintenance as per manual. Can be a vacuum leak on the Butterfly shaft in the right side of the carb? But if there is a leak, why i cant find It ?

No more ideas?

Hook up your timing light and look for a miss on those cylinders.
Steve

Something is wrong if you can't pull enough vacuum to do a proper sync job. Do the sync tool vacuum lines have the proper restrictor valves installed?

Are you running the stock airbox or pods? Any mods?

Thank you.bike is stock. New rubbers both side of carbs. No modificazione, the only thing im missing is the center compenser in the exhasut. The previous owner removed It and then he welded two caps on.im still wondering why.
This strange lack of vacuum is my concern. Can be something in the head? Valve clearance is fine, timing is ok, the bike idles..

shamal wrote:
And i was able to synch the carb ONLY with the Morgan carbtune upside down. If i hook the gauge in the normal position there is no sufficient amount of vacuum to pull the sticks. Its Like is not producing vacuum.

I doubt you get a correct crab sync with your Morgan carbtune hook up upside down.
Something is wrong with your vacuum ports.