TOPIC:

I built this bike prob 6 years ago, but ive had it for about 11. She's been bulletproof and I've never had to do anything serious to it, but she's been leaking for awhile and I'm tired of the mess. I scored an nos gasket kit off eBay and I'm looking to do them. Probably going to have it water hone cleaned while its apart also. I'm not really a motor guy moreso I am a metal guy,...
you guys have any insight as to what I'm going to get into? Problems that may arise? What upgrades should i look into? Torgue spec info on bolts? Thanks a ton guys.

I dig that exhaust, i remember seeing your build somewhere online years ago. It always depends on how deep you want to go. Whats your budget? at the very least I would get the late model OEM headgasket (green/brown one) over that Versah one, these engines are prone to head gasket leaks and that is the best available. The factory service manual is actually very easy to follow for a full engine rebuild. You can slap it together with what you have already, but if you want to freshen it up I would measure everything you want to reuse. Start with the cylinder bores/pistons and see if they are spec, you might be able to get away with new rings and a hone. Rebuild the head with new valve seals, lap the valves, or possibly a 3 angle valve job. New cam chain and cam sprockets are nice. heavy duty APE studs will let you torque the head down tighter. I wouldn't mess with the balancer or transmission at all unless its been giving you issues. just clean and inspect everything.

If you want more power its pretty easy to get some gains out of this engine for not too much money. you can swap a exhaust cam for the intake for more lift and duration, deck the head to raise compression, and get some mikuni VM carbs, with a free flowing muffler.

I did a mid/high level engine build with the stock bore, port and polish, decked the head, custom cams, flatslide carbs, balanced the crank, optical ignition, and saw 62HP at the rear wheel. I'm currently working on an all-out street motor with 86mm big bore kit to push displacement to 906cc. hoping to see 75-80HP at the wheel

Yea...I dunno about all that machine work you're suggesting. Definitely out of my league there. I'd have to have someone do that....and I can't imagine what all that work would cost. Any suggestion on who does that kind of machine work and what I may cost?....and where does one score a factory service manual for a kz750b?

Where is it leaking?

mothradeath wrote: ........................and where does one score a factory service manual for a kz750b?

You should be able to find one on eBay, but until you do there's an electronic version right here on KZRider at:

www.kzrider.com/modules/ServiceManuals/K...l%20KZ750%20Twin.pdf

Ed

martin_csr wrote: Where is it leaking?

It looks like a little from the valve cover right above the left exhaust port, at the cylinder head below the right exhaust, possibly where the starter mounts.

If you just want to fix the leak I don't think you really need to do a full tear down based on your pictures. For sure the valve cover and starter engine are leaking and those are easy fixes. it also looks like the head gasket is leaking. if it has the OEM gasket still they were extremely prone to leaks up until 1980. you could fix that without tearing the engine down.

if your engine was running fine before there should be no need to replace parts but since you're in there it can make sense to do some preventative work, by taking advantage of the fact you're in there.

Any competent machine shop can rebuild your head. Ive used APE a few times and they do good work. decking a head is about $50-80. I'm not sure what they would charge to rebuild a kz750 twin head, but a 4 cylinder is $125 not including parts. you will probably have to provide seals. new valve springs are nice but they can be pricey as your only option is ebay for NOS. If you want/need new pistons options are limited, there is Cruzin image which i personally have not had great sucess with. or there NOS parts on ebay.

Aa far as degreeing an exhaust cam in on the intake its pretty simple. The exhaust cam has quite a bit more lift and duration than the intake so by getting and extra one and putting it on the intake side you can get some power gains. To do this you cut the worm gear off and oval the holes on the cam sprocket with a file. This lets you degree the cam in properly. You can watch one of the numerous cam degreeing videos out there.

The biggest problem these bikes faced was the overly complicated carbs. There are a couple outfits that sell aftermarket carbs if you're interested, but if you're inexperienced with tuning it can be a whole can of worms.