When to re-jet?

I have a '79 KZ1000 st. My modifications are Dyna coils, Dyna wires, Dyna ignition, and 4 into 1 exhaust. Im really into making it look and run nice first. I'd rather have a nice daily driver than breaking the sound barrier in the 1/4 mile. My question involves my carbs. I now know the stock carbs are 28mm's on my bike. My current carbs have a stage 1 jet kit, but are dirty and just arent running quite right, so I purchased another set of 28mm carbs off ebay. They are sonic cleaned and polished. I'm wondering do I need to remove the jets from my original carbs, clean them, and install them in my new carbs, or should I just run my new carbs with stock jetting, or even purchase a differnt re-jet level, or same stage 1 but new jets?

Thanks!

If you are running the stock airbox & filter I would start with the stock jets and new spark plugs. Then run it a couple days to see how it performs, check the color of the plugs, and adjust jetting only if necessary. Ed

650ed wrote: If you are running the stock airbox & filter I would start with the stock jets and new spark plugs. Then run it a couple days to see how it performs, check the color of the plugs, and adjust jetting only if necessary. Ed

+1 Good advice. Give it some time to judge it - especially over some weather change days.

650ed wrote: If you are running the stock airbox & filter I would start with the stock jets and new spark plugs. Then run it a couple days to see how it performs, check the color of the plugs, and adjust jetting only if necessary. Ed

+2... It's unanimous!! Always start stock and work up from there. Need a good foundation to start with, so your not guessing.

Thanks guys!

was the bike running fine, with all of these mods and current carb set up, at one time??

if it was, then it stands to reason that u will need to duplicate this cab profile with the new carbs, providing the new carbs are exactly the same .

as stated above, u can start with the stock jets, but if it doesnt run right , just swap all the jets. keep track of where the air screws are set, on the original carbs. for example, if they are 1 1/2 turns out right now, record that info for latter use.same with the needle clip position. write down every jets #,(for each set of carbs) so u have all the info on hand and then u wont get the 2 carbs jetting , mixed up.

mark1122 wrote: was the bike running fine, with all of these mods and current carb set up, at one time??

if it was, then it stands to reason that u will need to duplicate this cab profile with the new carbs, providing the new carbs are exactly the same .

as stated above, u can start with the stock jets, but if it doesnt run right , just swap all the jets. keep track of where the air screws are set, on the original carbs. for example, if they are 1 1/2 turns out right now, record that info for latter use.same with the needle clip position. write down every jets #,(for each set of carbs) so u have all the info on hand and then u wont get the 2 carbs jetting , mixed up.

+1. Also, only tune one circuit at a time so you know which one to change if it's not right. If you raise the needle and change the main jet it's hard to say which one is making it stumble.

mark1122 wrote: was the bike running fine, with all of these mods and current carb set up, at one time??

if it was, then it stands to reason that u will need to duplicate this cab profile with the new carbs, providing the new carbs are exactly the same .

as stated above, u can start with the stock jets, but if it doesnt run right , just swap all the jets. keep track of where the air screws are set, on the original carbs. for example, if they are 1 1/2 turns out right now, record that info for latter use.same with the needle clip position. write down every jets #,(for each set of carbs) so u have all the info on hand and then u wont get the 2 carbs jetting , mixed up.

Bike ran ok, but in my opinion not great. The original carbs I took apart and cleaned them as well as I could, seafoamed the heck out of them, but I went ahead and bought cleaned andpolished carbs to see if they make a difference. I also noticed I had cracks in my original coils, so today(so excited) I ordered a Dyna 3ohm dual coil, and a dyna S ignition kit, petcock rebuild kit, and accelurator pump rebuild kit. So now, I'm going to wait until all my parts arrive and install them all at once. Also, going to sell my original 28mm carbs with either the stock jets, or the stage 1 jets that I have. All really depends on how the bike runs with all the new stuff installed.

Does your 4-1 have a reasonable baffle in it or closer to straight pipe? If the former, start with stock jettig and adjust,=. If the latter, swap over the old setup for starters and adjust from there.

bountyhunter wrote: Does your 4-1 have a reasonable baffle in it or closer to straight pipe? If the former, start with stock jettig and adjust,=. If the latter, swap over the old setup for starters and adjust from there.

Yep! 4 into 1 has no baffle. I was thinking I should swap over my stage 1 jets and start from there also.