1977 kz1000 A1

Hello, I just recently bought this bike for my dad and I would like some help from people who know these bikes inside and out, so thank you in advance.

It is a stock 1977 kz1000, no modifications to engine, carbs, suspension, chassis, airbox etc as far as we know. The seat/fork emblem and grabrail are cosmetic, we're keeping the originals along with the factory exhaust. The kerker header with no baffle is the only way he will ride his bike however. He is too addicted to the sound, and I agree with him.

The current setup is with the factory airbox and open kerker as seen in the pics attached.

welcome.

leon

Welcome...how does it run with stock jetting and airbox?

Runs well, idles good and pulls hard with no stumbling. Keeping an eye out for blue-ing on the headers but it isnt being ridden due to old cracked tires which are next on the list. Once he gets some miles on it I'll have a look at the plugs, I would say its going to run lean. I can convince him to smack the cap back in but he wants no baffle at all, just like they did it in the day.

Im searching the technical forums to see what jetting would allow the open header with the stock airbox in place.

DAYNE wrote: Runs well, idles good and pulls hard with no stumbling. Keeping an eye out for blue-ing on the headers but it isnt being ridden due to old cracked tires which are next on the list. Once he gets some miles on it I'll have a look at the plugs, I would say its going to run lean. I can convince him to smack the cap back in but he wants no baffle at all, just like they did it in the day.

Im searching the technical forums to see what jetting would allow the open header with the stock airbox in place.

Hello, DAYNE, and WELCOME to KZr!

The stock headers are probably double-walled, which helps avoid bluing even when running overly lean.

Steady idle with strong pull-away indicates proper pilot jet size.

Plug reading for main jet sizing should be done immediately after a high speed throttle chop with simultaneous ignition kill.

The existing main jet size may already be okay.

Would also bear in mind that any testing related to fuel mixture depends on fuel levels being within specs as determined by the clear tube test.

Good Fortune!

DAYNE wrote: Runs well, idles good and pulls hard with no stumbling. Keeping an eye out for blue-ing on the headers but it isnt being ridden due to old cracked tires which are next on the list. Once he gets some miles on it I'll have a look at the plugs, I would say its going to run lean. I can convince him to smack the cap back in but he wants no baffle at all, just like they did it in the day.

Im searching the technical forums to see what jetting would allow the open header with the stock airbox in place.

The changes that folks generally do when throwing on a set of headers many times involve ditching the stock airbox and using pods. As it turns out, with some brands of headers, if you leave the stock airbox intact, rejetting may not be necessary. I'd suggest that you check the plugs in a while and if not running spot-on, run a baffle or at least a baffle cap, recheck the plugs and you may not have to do any rejetting.

Plug reading after high speed throttle chop is often done at roadside while the engine is still hot.

Remember to carry along a short section of rubber tubing that will fit snugly onto a loosened plug and allow lifting it for inspection without burning fingers. Also helpful when reinstalling to assure the threads mesh properly.

Good Fortune!

Appreciate all the good ideas, especially the rubber tubing haha...not interested in getting burnt fingers. We will do the high speed chops and inspect the plugs once the new rubber is on.

Reading up on the clear tube test now. Much thanks...
--Dayne