Stalling issue with my 82 750

I just got an 82 KZ750 LTD (I don't know what letter goes after the model name).

It seems to not want to take off in first gear under 3k RPMs or so. I brought it home Saturday and Sunday I got it off my truck and took it up the street. I had to give it extra throttle and slip the clutch a bit until I got it going. Then it seemed fine. My neighbor said the same thing when I let him run it.

Then yesterday (Monday) I started it up (with choke) and took it around the block. I switched the choke off once I got down the street. With the choke off, it was idling at about 1100rpm. Once it got warmed up, the idle dropped to about 900 or so. Even in 2nd gear while riding, it seemed like it wanted to stall under 3 or 4K.

I haven't gotten a service manual yet, so I am a little in the dark. I have had other Japanese 4cyl, but none have ever had any carb problems, so I am quite inexperienced in that area.

It came with 3/4 tank of gas, but I don't know if it's fresh or not. My first thought was to drain the gas into my lawnmower can and fill it up with some 93 octane and a little seafoam. If that doesn't work, I'll have to pull the carb rack and see if I can spray clean them.

Stock airbox, stock exhaust.

Am I headed in the right direction?

Sounds like plugged up carbs. I would drain the tank and rinse it. Run cleaner down through the carbs and out the drains. Change fuel filters. New gas and seafoam and see if it runs better.

Concur with Bountyhunter. Sounds like your pilot circuit is plugged/restricted. You might luck out running the new gas/sea foam. Make sure you get a fuel filter on that system.

One other thing to look at is the vacuum hose on your petcock. The hose has to take a sharp bend off the petcock to get to the #2 carb port and sometimes there's a kink in it (that's how I got my 750 for $600!) If your idle is running low after you warm up you can adjust it with the idle screw (lower back middle of the carbs should be a knob. Normal idle sits around 1250.

If you have to pull the carbs, you'll get to find out how much fun old carb hoses can be!

Thanks. I pulled the carbs off of my 79 GS1000 plenty of times after I let them sit all winter with gas in them. So I assume it's similar.

I'll pull the tank and drain out whats in there. What cleaner are you referring to? Is there a stock spot for a fuel filter, or do I just get a universal and cut the hose to add it in?

Even when it idled ok it was just about 1k, so I guess that needs adjusted no matter what. Althogh I guess it's possible that the idle will change after they are cleaned, so maybe I shouldn't touch it yet.

I missread. I though you said to run cleaner through the tank and down through the carbs. I realize now that you just meant carb cleaner.

Here's a link to a full manual for the 750. Pictures are a little dark, but it works until you can get a copy off of e-bay. Make sure you also reference the back chapters that are specific to the different year models. Especially important with the clutch adjustment

kz.mbsween.com/media/GPz750-full.pdf

Still having this low RPM issue. Fresh gas, seafoam, and a healthy dose of carb while the carbs are still on the bike. No change.

I want to get it inspected this week, so I guess I'll run it as is until I do.

I take it the carbs have to come off before the airbox can be removed?

Also, there are no hoses coming off of the bottom of the carbs, I assume they are supposed to be there?

Yep, have to remove the carbs to get the airbox out. Between the 1981 and 1982 versions of the kz750-4, Ma Kaw eliminated the carb overflow tubes. You get to provide that for yourself.