1980 KZ750 LTD H problems

Hi, Just did a full rebuild on my 1980 KZ750 LTD H including pistons, rings and rejetted the carbs with a 6 sigma carb kit.

The bike starts and idles fine but as soon as its under load, going up a slight hill, it bogs out and dies and then becomes very hard to start again.

Any ideas?

thanks in advance

Is the stock airbox installed w stock type air filter? stock exhaust system?

Yes, stock air box and filter and stock exhaust.

Why did you install a jet kit if the bike is stock? That doesn't make much sense. That said, it seems that your bike is fuel starving. Make sure the fuel cap vent is working as well as your petcock. Try opening the carb float bowl drains after the bike craps out to see if there is any fuel in the float bowls. Just be careful to not dump raw gas on top of the engine when it's hot.

I live at a high elevation so was recommended to rejet the carbs. The float bowls all have fuel when it craps out, the inline fuel filter is free of debris and the petcock is working both in the prime position and in the on position.

Since you live at a high elevation the air is thinner that at ground level, so make sure that the air filter is not dirty as you will also need air to have the proper combustion, too much gas and not enough air and it will bog down and too much air and not enough gas and the same, will happen I HOPE THIS HELPS.

Tell us what did the Six Sigma jet kit include and what jets did you install pls.

Did you check the ignition advance unit? If it's sticky and gets stuck the issues you describe will occur. Remove the right side cover and see if it twists and snaps back easy and clean. If not, try spraying it down with electric parts cleaner and lubing the contacts. It's a common thing. Either that or you have a bad air leak. Are your carb boot manifolds in good shape? When it's idling,spray a liitle carb cleaner around them and see if the idle changes. That's a good test. Do you have the carbs with the nylon plug? Those get bad after a time. Make sure they are in good shape. Or go way up on the main jet. I wanna say a 135?

great ideas thanks i'll give it a try