jetting question

currently i have a 1977 kz650C. Im thinking of ordering a V&H 4-1 exhaust system, but want to order new jets at the same time.. this is assuming they are needed corrrect? Anyways i was wondering if anyone else had this same setup on their bike. If so what size jets do you have? I am just looking to save some time tinkering with different sizes. thanks!

If all you are changing is the exhaust, and you are using a street legal baffle (not a straight pipe), my silly wild ass guess would be that you could probably run the stock pilot jets or MAYBE go one size up and go one or two sizes up on the mains. That's my best guess.

What exhaust system is on it now? BTW, if it's a stock system in good condition it's worth $$$. Pics would be nice. Ed

No matter what modifications I have ever done to my bikes I have never had to change the Pilot jets. Only the main jets and needles or needle positions, and do some pilot screw adjustments. If you are changing to a pipe and say putting on pod filters, than you can go up by two or as much as four main jet sizes, richen up the pilot screws by one-half turn and raise the needle positions by 2 notches. This should put you in a good running position.

In this case you will likely not have to change pilots.

With a V&H exhaust, I would increase the mains by 1 step, but thats it. Most stuff comes jetted fairly rich from the factory, even though they kept leaning shit out for emitions.

Put the exhaust and mains on there and properly tune the pilot circuit, then ride and enjoy.

Properly tuning the pilot circuits involves using a very accurate tachometer/vacuum guages to find the absolute highest power for each cylinder. There will be no exact number of turns out, they will all differ slightly at max power.

Your carbs will also need to be vac synced afterwards.

Good luck!

If you run it lean it'll have torque through the roof. They are so lean already, I,d say jet it up just to keep it running cool for hot weather, (and some extra grunt at higher r's.

yea the stock exhaust is in great shape. I'm still not sure if i want to buy the V&H just yet. I want to make sure i know exactly what I am doing so i can just install in a day, rather than tinkering around for a week while i could be riding. As for pictures i don't have any yet but i will definately post when i get my hands on one of those fancy digital ones. Any additional information would be a great help.
Thanks a lot guys