z650 tuning

have just brought a z650c1 and am pretty happy with the bike, it just could do with a bit more power :laugh:
so with keeping it a 650 what is out there for them?
will prob end up getting a doner motor to rebuild for this as its a daily rider.
spend my life running a classic vw tuning shop so the basics of tuning are the same for any engine. any weak spots i need to pay attention to?
thinking along the lines of a ported head with a increase in c/r poss some bigger carbs or what can be done to the stock ones?
what about cams? whats out there? have used web cams in many vw motors and have seen they do ones for the zeds.
stock rebuilt bottom end? is it strong enough for a mild upgrade?
dont need a drag motor just pep it up a bit and give the bike the power the chassis can take.
cheers rob

any one?
or do i take it that no one tunes the 650 motor?
cheers rob

Does it have to stay a 650? I've got a GPz750 motor for mine, and that will pep it up quite a bit, and bolts in pretty easy. Whereabouts in UK are you? I'm in the Bristol area.

according to kawasaki, the 1980 Z500 has a top speed of 111.8 mph, I would expect a good Z650 to be capable of 115 to 120:)

going to keep the 650 block, its more about tweeking whats in it than just bolting a bigger one in. if i had wanted a big quick sportsbike i would have brought one.
i enjoy the tuning side of the little motors, built a 2 ltr engine for my beetle that has 200bhp.
just want to pepe it up a bit, as i said dont need a drag bike just somthing to have some fun with.
will gear it down a bit when i get it running right, got no need to do more than 120 so getting there is the main idea.

KZ750 (Z750 in the UK) cams are a step up, GPz750 cams are a bigger step.

750 valves are bigger and I think can be installed in the 650 head.

You can also mill the head for more compression.

There is a thread about a 100 hp 650 around here where there are some bolt on parts that can get you 100hp out of your 650 may be a little involved to do it but its worth looking at.

Have you already performed a basic tune-up (point, plugs, timing, etc)? A freshly tuned stock 650 is already fairly peppy, but it isn't going to compete well against new high-tech bikes. If you haven't tuned it up yet, you may be pleasently surprised when you do. Over the past 31 years of owning my '77 KZ650C1 I found that new points make a difference in power. Also, make sure the carbs are clean or the bike won't make the power it should.

Try adding a K&N filter - minor gain, but worth it.

New exhaust ghaskets (copper ones)

Change the sprocket and chain, coil mod maybe?

Just a few basic ideas in addition to the ones previously mentioned.

it has pod filters and a header/race can[not sure whos the system is looks a bit like a kerker but not quite] on it now
has had new wireing loom and coils, full service and set up so im at least starting from a known point.
jetting is not right so thats the first think to sort, booking dyno when i get paid.
going to keep my eyes open for a motor to rebuild for it.
cheers for all the ideas, looks like no week spots to address so makes it all a lot esayer.

1.Consider getting a electronic ignition sytem and matching coils from Dynatek at www.dynaonline.com

2.And doing the "Wired George" relay modifications making your bike more reliable and a easy starter.Many people here have done this to their bikes. The Dyna S is probably what you want.

It bypasses the current dropping wiring in the older looms(wiring harnesses) giving the coils the 12 volts they need with no more sooty black sparkplugs.

His website is www.wgcarbs.com He runs a carb rebuilding business and does wonderful work on the older bike carbs.

been having apoke around the bike today and checking a few things, coils are getting just about full battery voltage less .2volt so happy with that.
not had the carbs of yet to see what, if anything has been changed inside.
repacked the silencer, which has made it a bit better.
checked the points gaps and timing and its all by the book.
think the next step is a dyno run to find out how many of the 60odd ponies have run away over the last 30 years:P
then its time for some upgrades.
1.proper jetting seasion on the dyno
2. electronic ignition sytem and matching coils from Dynatek
3. port and flow a head and poss fit some gpz750 cams, anyone know the valve timing specs of these cams over the stock 650 ones?
4. if thats not enough..................i always have no2:laugh:
cheers rob