Low Idle

Hey guys, new to the site and the bike. Got an '85 GPZ 750 cheap that had a slew of problems I've worked out except the low idle. To my understanding I have Mikuni BS 34's running pod filters. My jetting is 115 main, 3.75 pilot. The PO had obviously mucked with the carbs and I am missing the pilot jet plug covers. My mix screws were out 3 turns, I went to 5 and it helped only slightly. My question is do I need bigger pilot jets or will having the plugs magically fix my problem? Doesn't make sense bc the plugs should restrict fuel flow. :dry:

Just thought of something, I did install a mechanical timing chain tensioner bc the old one had way too much slack. Maybe the chain is a bit too tight preventing idle engine speed?

I didn't see pilot jet plugs in the diagrams at Partilla for the 85 ZX750.
Do you mean the pilot air screws at the top/front of the carburetor body?
If so, I don't think the anti-tamper plugs over those are necessary. I could be wrong, though.

The parts diagram doesn't show the plug, but the fishe shows the part number. The carbs are BS34's and those carbs use the plugs so pretty sure they are required.

Any time you are running pods it's a crapshot as to what jetting is needed. A Dynojet kit is a short cut to the jetting process plus, they provide better needles.

Between #2 and #3 carbs you will find a knob that increases idle, turn it to the right and it will increase your idle, 5 turns on air/gas mixture jet seems too much, 2/ 1/2 to 3 turns should be enough, If not, carbs and internal jets and passages are dirty and need to be cleaned. Look at the spark plugs and tell us what condition they are in, or better yet post a picture of your plugs,

Thank you Mopguy. I feel pretty dumb that was an obvious fix. I was thinking that nob was to set the rev limiter. Got my idle set perfect now I have fuel leaking from the bowls bc the gaskets are shot. New ones are on the way. If it's not one thing it's another......

9/10 it's not the bowl gaskets that are causing the leaking. It's usually either the fuel transfer tube O-rings or the float needles are letting in to much fuel. At any rate, a full tear down is in order if you want to fix the problem properly the first time.