650 going to a 700

If I bore the cylinders to run the 700cc pistons do I need to do any work to the head

Using the Wiseco 700 kit
Thanks in advance

While the head is off it would be wise to pull the valves, clean and inspect, fix anything wrong, and then install new valve stem seals.

Did you purchase the piston kit already? What about the camshafts? I would assume you'd want them from a KZ700 , 750 or maybe a ZN700. I don't know that much about it, but when installing 750 cylinder block & pistons onto a 650, it's best to get 750 camshafts. So I assume the 700 cam performance curve would be a better match for the 700 kit than the 650 cams. But again, I don't know that much about it.

edit: The KZ700 has the same camshafts as a number of 750-4 models, especially the intake cams, so there's a wider range to choose from.
....

Under the knife

Spoke to megacyclecams about sending my cams out for hard hardfacing and a new set of springs and the head is also going out for some work. I emailed the guy asking if it would be recommended that I enlarge the valves since I have bored the cylinders, does anyone have an answer to that? Not sure on the size difference between the 650 and 700 valves.

The KZ750/4 heads have bigger valves and ports compared to the KZ650.
Just swapping the whole head would be less expensive. Some have used the
750 valves on the 650 head. It all depends on what you want to accomplish.


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I was going to do the swap but figured I would be in the same boat getting the head cleaned up. i had the guy make some stainless valves (slightly larger) and port the head, should be back within a couple weeks and at that point I will be able to start reassembling the engine!

I regret not having the head ported mildly (and maybe 1mm bigger intakes) but things were adding up and I decided not to. Am looking forward to seeing how your runs..... should be a beast.

I hear you on that, nothing about this is really cheap but knowing that it's done right will pay off entirely in the end. When I hurt the motor I knew I was going to be spending some money and because I had already bored the cylinders for the 700 kit and after talking to the guy doing the head work he said theres no point in keeping it stock if theres room for more compression, so i said if the beast is hungry let's feed it lol

So got some parts piling up but the list never seems to end lol
Got the cams back also a new set of valve springs
Cams went to megacyclecams, went with the stage 2 option
The head went out and got new stainless valves, seats cut, ported, and new guides
I'll get some more pictures of the parts later on but everything is packed up right now
I definitely have a few questions for the gurus with some carburetor questions and ignition so all the help is appreciated.
I'm going to hold the questions until later on today so I can show the specs.

Started getting my engine back together but I'm at a stand still with some questions, hopefully some of you can help.

I was told that after going with larger intake valves and the upgraded cams (specs in picture) I would have to mill the cam sprockets to adjust the timing, if so how do I come up with the measurements for the machining and then what do I go off of to set the engine in time






I am also wondering if I can jet the factory carbs enough to allow the engine to run to its potential with the new upgrades

Thanks for any help

...I'm saving the electrical questions until I get the engine fully back together just to stay focused on one thing here,

yes you should do adj cam sprockets, also if this far in I would replace valve with stainless and O/S if porting head & yes you can use stock carbs you will give up a few ponies but you can upgrade carbs later, back in the day I ran KZ650 with 720 kit O/S intake & exhaust valves , cams , 29mm smoothbores 900 & 1000s could not touch me light to light and it took a built one to beat me in 1/4 mile ! not just one with pipe and pods on.