82 750 ltd 4 cylinder running on only 3 cylinders

When i got the bike it would not start (bad starter clutch) but would run and ride great with a push start. I replaced the starter clutch, clutch plates and springs, and put in fresh oil, i also swapped out the gas tank for one in better cosmetic condition. After all that the bike would start but die on idle, turns out the tank i put on had a bad petcock, replaced the petcock and the bike would run but not very good "sputtering and just running like crap" and the #1 exhaust pipe would only get warm, other 3 very hot. Thinking that the newer tank must have been nasty inside i pulled it, drained, replaced it, put fresh gas with a bit of seafoam, i also pulled the carbs and cleaned the jets really good. Now it will start and idle but cylinder 4 exhaust pipe stays cool to the touch all four plugs are getting spark what could cause this?? it refuses to run on all 4 cylinders!

not sure if this post should be in carb, electrical, or engine I'm lost! i just want to ride this damn thing.

thanks for any help this thing is driving me mad

i may have missed some things, i have been messing with this thing for 3 weeks now. at one point the #2 exhaust pipe would not heat, then it moved to the #1, and now the #4 .

also where the heck are the fuel/air screws on the Keihin carbs? i have a colortune coming tomorrow.

You shortcut the carb cleaning process. You can download a copy of the factory manual for free from this link... www.750turbo.com/manuals/
Get the file titled GPz750 Base Manual

Check page 150 for details about the carbs.

Nessism wrote: You shortcut the carb cleaning process. You can download a copy of the factory manual for free from this link... www.750turbo.com/manuals/
Get the file titled GPz750 Base Manual

Check page 150 for details about the carbs.

Thanks for the link! i did all this besides removing the pilot screw. do i need to drill the small plugs on the top of the carbs to get to the screws? what really confuses me is why would the one cylinder that does not work be different every time i mess with it?

The Pilot Screws need to come out in order to clean the pilot circuit. Also, the Bleed Pipes need to come out for cleaning because they have a very small orifice on the end.

Further, in my experience having rebuilt more than a half dozen sets of those carbs the O-rings on the fuel Tee and the fuel transfer tubes will be hard and brittle, which is why unganging the carbs is always best (so the O-rings can be replaced).

Have you replaced the spark plug wires or at least tried cleaning up the spark plug wire connections? I solved an intermittent firing problem by redoing the connections, nipping off the ends of the spark plug wires to freshen the connections. The plug wires unscrew from the coils and the plug caps. I also installed new spark plugs, properly gapped.