KZ Turbo Buildup Help!

I just bought a turbo kit for my 1976 KZ900 on EBay. I have been working on the motor for this bike most of the winter. I work in a engine machine shop so all of the tools are pretty readily available. I have ported/polished the head, Installed new bronze guides, 1mm oversize stainless steel swirl polished undercut valves on both intake and exhaust, backcut the valves, bought APE .410 lift cams and the appropriate valve springs, and also bought a Wiseco K1015 10.25 compression ratio piston set. The turbo was not a planned addition but I really wanted to go that route but had my doubts about doing it. Anyways now I have it and I would like to use it. I need all of the help I can get on what I need to change to make this bike fairly streetable and to get it running right. If anyone can provide some knowledge on the subject or know anyone who can please let me know! I live in the Madison, WI area. Thanks!!

Welcome to KZR, there a few turbo guys here that are glad to help. We like pics, enjoy the site
Mark

I will try to get pics...its not much to look at right now just a plain bike. I have a 2004 r6 swingarm and hopefully a 2005 r6 set of inverted forks in the works for it. Right now though I just need to get on top of this turbo deal so I can get out and ride this summer! This is my first major motorcycle rebuild and definitely my first turbo motor so I will be happy if it doesn't grenade itself on startup!

You could put the turbo on the motor with the parts you have listed but you couldn't run much boost with it. Best is to run lower compression ratio...like 8 to 1. Many alcohol fueled bikes run 10.5 to 1 ratio's but not on gas. Always told two ways to make a turbo motor...low compression/high boost and higher compression/low boost. On gas, most go with the low compression. Turbo motors like cams with lift but not duration. That's why stock cams work really good. If you have a MK11 crank in the motor, you can run stock GPZ cams, which are very popular. Need the MK11 cams so you can use APE conversion cam sprockets to mate GPZ 2-bolt cams to KZ motor. Web-cams make a couple sets of special turbo cams....340 and I think around .410 lift but they are special because they have low duration on them. Too much duration and the boodt blows the charge through the motor and doesn't stay in the cylinder so you lose compression. Porting is not as big a s concern on a turbo motor, although it does help. If you are planning on using the turbo HP much, a good idea would be to o-ring the cylinders and use a copper head gasket. Be sure to retard the timing also. I've heard anywhere between stock and retarded to 22 degrees on boost. Mine starts at 36 degrees with stock advancer and retarded 6 degrees. I have been told to retard timing 1 degree for every 2 pounds of boost. More advance at lower rpm will make it easier to run around town, etc. but retard the timing when boost starts to increase at whatever rate you need to. Remember to run gas that's good enough for the boost you will be running at peak boost.

The cams and pistons are wrong for that application. You'd be best either putting the turbo to the side, or the pistons and cams (or build two bikes).

On my turbo, I'm running 8:1 pistons with stock cams and slotted cam sprockets. The oil pump / pan was modified with the pickup being moved to the bottom of a deep rear sump, and the pump optimized by lapping the case side to get the tolerances tight inside the pump. The crank is welded. I run heavy-duty clutch springs with a barnett clutch.

what kind of turbo do you have?the exhuast side is where you need the oversize valves and port work on a turbo motor,the turbo is going to force fuel/air in so you need a better way to get it out.definately go with the smaller cams that will also make it more drivable when you are off boost and will be easier on valvetrain.if you can swing it id get another block and a set of 8:1 pistons save the other stuff for a differant motor or sell it.dont forget a good ignition,and a welded crank a mkII is not really neded unless youre gonna run a really big sticky tire or a major amount of boost .make sure you you bullet proof the rest of the bike to handle the motor and most importantly,HANG ON TIGHT!youre in for a big suprise the first time she hooks up hard under boost!!!!!!!!! :evil: goodluck,happy wrenching!

Post edited by: wireman, at: 2006/03/26 11:19

Thanks for the help....Keep the advice coming as I can use all that I can get. I will definitely be switching the pistons to a lower compression ratio. I will also probably end up switching the cams to a web cam turbo grind with .340 lift. As far as piston size goes I was just going to try to find a set of 1000 jugs and bore them to 1075. Would this be a good size or will it not have enough power off boost? I was also thinking about a Dyna2000 with the appropriate coils, however, I was also thinking about the msd MC-3 set up and coils as I have had their car products in the past. Any recommendations?

1075 will be plenty to keep you entertained especially when it starts to come under boost.ive got a dyna 2000 that im gonna use on my 1327 bike when i get that far along to go with that little equalizer im thinking about hiding under the seat:whistle: if it works out ill get one for z1 project.goodluck,happy wrenching!

i will trade you a very restorable z1 for that engine, and throw in another engine from a 76 900 if you want to build a different engine for boost

I'm running the .340 turbo-grind Web-cams in my motor. The head has a very mild, clean-up port work done to it. Also, a rear deep-sump system like what Jeff is talking about. A welded Z1 crank with crank plate in the bottom end. Have been told that some like the MK11 crank to put a load on the turbo. It doesn't rev as fast as a lighter Z1 or KZ, but once moving, there isn't much difference. Also, the heavier crank is better with bigger tires...so it's actually a matter of circumstance and parts combination. You don't need a big motor with a turbo to make insane speed but bigger is better, as some live by. It's the combination, how deep is your pocket...speed costs-how fast do you want to go?

I'm also running light springs with a lock-up and stock clutch plates. Very easy pull and with the lock-up I have no problems although for the street, I'd run stock clutch springs.

Pay real close attention to oil supply for turbo. Turbos need a very good supply of good clean oil. Don't skimp on the oiling system.