1976 KZ900 question / Engine Mods

Interesting stuff guys. What about just blueprinting a straight Z900. Can you lighten the crank or weld it? I hear a lot about that but not a lot of exact information. What mods can you do to with 2006 technology to improve what they put out in the 70's?
I read Oldkaw's info with interest but wiredgeorge and APEjay have to say regarding the porting and engine mods?
Also... does anyone else find Melissa's photo's kinda disturbing?
I'm not definately not gay, just a Dad.

Cheers blokes!

oldkawman's site and choice of photos doesn't enthuse me. I have three daughters and three grand daughters and think that the guy's taste is questionable. The guy's tips are also questionable.

If you blueprint a KZ900, it will make about 70HP stock with NO other mods. If you weld the crank (I can do this in a few minutes), it will make about 70HP. If you take the head to a reputable tuner who has a flow bench, and get the head ported and polished it will make about 70HP. If you punch the engine out and use high compression pistons, put some cams in and know how to degree the cams, use some bigger carburetors and get the head cut for some big valves and such, you will get perhaps a 100hp at the rear wheel tops. The 600cc crotch rockets can make 100-110hp at the rear wheel out the showroom door. OK... you still need some help so you put some beefier pistons in with a shade lower compression and run a juicey bottle... now you will outrun the kids on a $6000 crotch rocket but you have spent a bit more just to fool the kiddies. It can be done.

As far as stoplight to stoplight drag racing, I can typically beat most 600cc bikes off the line and get to the next stop light a bit faster as those things are not intended for drag racing and the kiddies who ride them usually end up smoking the back tire or in a giant wheelie... That is why the GS1100 chassis was valued as a drag racer... it was LONG... the longer swingarm painted black was probably the BEST suggestion for beating the kiddies from stoplight to stoplight as well as knowing how to launch. That is far more important for a couple hundred yard drag race than the engine mods which will only make an inexperienced rider look even more inexperienced with more power on tap... anyway, this is getting pretty far afield from an engine topic and probably more appropriate in chit-chat.

Austin, you will get lots of opinions on block sizes and such but APE Jay is a pro and as a pro he won't tell you something that will cause his shop to look silly. His recommendations will be conservative and if you get with him and he gives you a shopping list of block/piston combos, cams and engine mods, you can bet that this is based on someone else already being the test case. I would give him heed. We have folks that have far exceeded Jay's recommendations as far as how far to take street mods and their bikes live and work on the street but I tend to be more conservative as I get older. Besides, I used to drag race GS1100s and not Kaws so what do I know hehe

wiredgeorge wrote:

oldkawman's site and choice of photos doesn't enthuse me. I have three daughters and three grand daughters and think that the guy's taste is questionable. The guy's tips are also questionable.

If you blueprint a KZ900, it will make about 70HP stock with NO other mods. If you weld the crank (I can do this in a few minutes), it will make about 70HP. If you take the head to a reputable tuner who has a flow bench, and get the head ported and polished it will make about 70HP. If you punch the engine out and use high compression pistons, put some cams in and know how to degree the cams, use some bigger carburetors and get the head cut for some big valves and such, you will get perhaps a 100hp at the rear wheel tops. The 600cc crotch rockets can make 100-110hp at the rear wheel out the showroom door. OK... you still need some help so you put some beefier pistons in with a shade lower compression and run a juicey bottle... now you will outrun the kids on a $6000 crotch rocket but you have spent a bit more just to fool the kiddies. It can be done.

As far as stoplight to stoplight drag racing, I can typically beat most 600cc bikes off the line and get to the next stop light a bit faster as those things are not intended for drag racing and the kiddies who ride them usually end up smoking the back tire or in a giant wheelie... That is why the GS1100 chassis was valued as a drag racer... it was LONG... the longer swingarm painted black was probably the BEST suggestion for beating the kiddies from stoplight to stoplight as well as knowing how to launch. That is far more important for a couple hundred yard drag race than the engine mods which will only make an inexperienced rider look even more inexperienced with more power on tap... anyway, this is getting pretty far afield from an engine topic and probably more appropriate in chit-chat.

Austin, you will get lots of opinions on block sizes and such but APE Jay is a pro and as a pro he won't tell you something that will cause his shop to look silly. His recommendations will be conservative and if you get with him and he gives you a shopping list of block/piston combos, cams and engine mods, you can bet that this is based on someone else already being the test case. I would give him heed. We have folks that have far exceeded Jay's recommendations as far as how far to take street mods and their bikes live and work on the street but I tend to be more conservative as I get older. Besides, I used to drag race GS1100s and not Kaws so what do I know hehe

yeah to say oldkaw guys site is questionable is putting it mildly! from what ive seen of his engine assembly shots i feel like i need a tetnis shot just from looking at all the gunk on his motors he puts together.:sick:

Thanks Wiredgeorge and Wireman.
So, thats 70hp eh...
Got it. I like my Zeds just the way they are really and I find having a properly tuned bike will suprise 95% of crotch rockets anyway. Just look at the basics like their chain tension...
Corners are where its at around here anyway.
Who needs to blast when you look great just parked next to another bike.

My lady is a Pediatric Neuropsychologist (yep, way brainer than my blue collar arse...) and she finds those photos rather disturbing. Borderline stuff.

Kind regards for the info.
Steve

Post edited by: WTF!, at: 2006/08/19 08:54