TOPIC:

Dear Fellow KZers,

Been a viewer and member for a while. Gotten lots of great info and I've finally decided to post something that could be of some value to all the HP heads out there.

I've owned a low mile (10,000) 79 KZ1000ST (shaft) for about 10 years. Since I've owned this bike I've taken a couple steps to get more power out of it. The graph tells the numbers. (there should be a graph w/dyno results at the top of this post) The mods are as follows:

stock - the stock numbers come from the August 1980 issue of Cycle Guide Magazine

KZ1000ST
74 hp @ 8000
51 lb*ft @ 6500


mod 1 - mild port work on heads (done myself), 4-1 exhaust (don't know the mfg. came with the bike), Dyno Jet Stage 3, K&N filters.

conditions - temp 85 deg, bar press 30.0
82 hp @ 8500
53 lb*ft @ 7500
This shop and Dyno were a little suspect though I think the numbers are fairly accurate. The test was performed about 8 years ago and the bike went into storage shortly after that.


mod 2 - 34mm RS flat slides (120 main jet), heads port matched to carbs (done myself), web 118 cam (properly degreed with slotted sprokets), V&H Street megaphone with baffle removed.

conditions - temp 72 deg, bar press 28.7
90 hp @ 9000
59 lb*ft @ 7500

This shop and dyno were more pro than the first and the test included exhaust gas analization. It was perfomed last weekend. Currently, my RS carbs are running a little lean on the top end. A/F is 14:1 and should be closer to 13:1. Will switch to a 125 main jet. If anyone is interested, I can test after rejetting and post the numbers. Don't expect much...maybe 1 or 2 ponies.


These are random notes/observations/thoughts:

Bike has stock bottom end and pistions w/175psi across all, Accel coils, stock electronic igintion advanced 10 deg (I slotted the advancer plate
mounting holes. this gave me alot more throttle respons in the midrange)

I live in NYC. Both Dyno test were performed in NJ within 30 miles of the city - Effectively sea level. I realize the importance of testing on the same Dyno but...this is what I've got.

Someone once told me that a shaft will waste about 5 HP more than a chain. Fact or fiction? I don't know.

I switched to the RS carbs because I could never get my stock 28mm carbs to run consistently well (after removing the stock airbox and exhaust). They seemed to be very sensitive to alttitued. They would run good in the city (sea level) then I would take the bike upstate to the catskills (2000-3000 ft above SL) and they'ed run much too lean (running with choke would smooth things out). Once I got back to the city they would run fine again. Ditched 'em for the 34mm flat slides. Love em!

Old Kaw Man told me "when running RS carbs and a V&H pipe, you have to pull the baffle out of the megaphone to get the carbs to perform. I played with
tuning for a couple weeks before pulling the baffle...then finally pulled the baffle...He was right. Night and day difference! I would rather it not be so loud but it runs SO much better - even in the midrange.

I also own a bone stock 82 GS1100E in excellent condition. That engine will pull STRONG from 2K to redline. Would love to get that kind of midrange into the KZ. Probably calls for more comperssion i.e. 1075 kit.

I'm certainly not the first to say it but; peak HP and Torque number don't mean much for a street bike. That's why I included the graph.

When this bike is really hot it will use some oil sending a thin steam of blue smoke from the pipe. Compression is good on all cyliniders.? Engine
will also ping between 3 and 4K under load when really hot. I purchased an oil cooler from OKM and will install for next season.

This bike is alot of fun! And the mods have payed off in a big way thanks in-part to the Forum. If the engine had a bit more midrange I'd probably stop
messing with it...probably.

Thanks to everyone for this great resource! Hope my ramblings are of some value. Yours certainly have been...

Dave

cool;) welcome to z-jungle

davel wrote:

...

Interesting reading - thanks for putting it up.

Someone once told me that a shaft will waste about 5 HP more than a chain. Fact or fiction? I don't know.

Fact, more or less.

Drive shaft vs. chain/belt drive power losses are usually expressed in percentages rather than any specific horsepower value.

Power transfer effciency for a shaft is given at about %92 give or take, depending on details of design, while a chain drive in top shape can be as high as %98 efficient.

A driveshaft consumes more power for two basic reasons: inertial and frictional.

A driveshaft is guaranteed to be heavier - it has to take the sheer and torque loads reliably, and in order to transfer power it has to be spun up and kept spinning. That's inertia.

Most motorcycle shaft drives change the orientation of spin between the output shaft of the tranny and the rear wheel via a series of bevel gears. The interface of each bevel is a frictional loss to some percentage, and they add up. Also, most motorcycle shafts run inside a housing, and that imposes an additional frictional loss.

So, the increase in smoothness and mechanical reliability comes at about a %5 cost in power transfer efficiency, all things being equal in a perfect world.

The facts are that a scrap chain with scrap sprockets, out of tension and unlubed, grinding itself to powder drops efficiency as much as %20...

Nice post Dave...

Put a 1075 kit with that combo and you'll be a very happy camper. If you can find one, or get him to make you one....give a Murray pipe a whirl..

Larry C:)

I wouldn't a thunk that 90 hp was possible out of a stock bike with cams and carb/pipe mods. That is great! I might have to search around for some cams hehe... To get almost 20hp without opening up the engine and not much cost is a real horsepower gain for very little.

FWIW: Most stock Z1/KZ900/KZ1000s will make less than 70 HP at the rear wheel on a dyno has been my observation. Horsepower will range from low to high 60s generally.

wiredgeorge wrote:

FWIW: Most stock Z1/KZ900/KZ1000s will make less than 70 HP at the rear wheel on a dyno has been my observation. Horsepower will range from low to high 60s generally.

Low to high 60's from a kz1000? That doesn't seem very impressive. Aren't the stock specs of my kz550 just about 50hp? It is certainly not one of the faster bikes I've ridden. If I could get it up to 60hp it might keep me from upgrading so soon.

Post edited by: Grebnaws Inc., at: 2006/10/29 21:02

Grebnaws Inc. wrote:

wiredgeorge wrote:

FWIW: Most stock Z1/KZ900/KZ1000s will make less than 70 HP at the rear wheel on a dyno has been my observation. Horsepower will range from low to high 60s generally.

Low to high 60's from a kz1000? That doesn't seem very impressive. Aren't the stock specs of my kz550 just about 50hp? It is certainly not one of the faster bikes I've ridden. If I could get it up to 60hp it might keep me from upgrading so soon.<br><br>Post edited by: Grebnaws Inc., at: 2006/10/29 21:02

your 50hp rating should be at crank which is probably closer to 35 at rer wheel

Grebnaws Inc. wrote:

Low to high 60's from a kz1000? That doesn't seem very impressive.

But it's real-world true.

1. Published specs are exactly that - the most optimistic perspective possible put out by a manufacturer that has every interest in everyone thinking the best of their product.

2. Magazine tests - especially way back when - were often performed on factory-selected machines that had the benefit of extra TLC.

3. Motors get tired. A fresh motor will put out absolute peak power for a very brief portion of its potential lifetime.

4. Rear wheel horsepower ain't output shaft horsepower. There's a couple of items like the various parts of the drivetrain that eat power along the way.

Thanks for the replies guys! A couple more notes, thoughts:

I don't want to make it sound too easy to get 90hp at the rear wheel because it hasn't been. Lots of tweeking and tuning and testing and researching (the forum). Also hasn't been exactly cheap. RS carbs $600, Cams $320, Pipe $300, Dyna coils $120 misc (K&N filters, slotted cam sprokets, engine gaskets) $200, oil cooler kit $200. We're getting close to $2000 and if someone else were payed to do the head porting and installation work, the cost would be astonimical...But then it's not about all this...There's a part of me that's just a gear head, I enjoy it...

In my experience, no single piece is responsible for major HP gains. Bolt a set of $600 RS carbs to a stock engine and it will perform no better at best and probably worse.

Thought the dyno results were useful because I felt - after years of tinkering, this is finally a combination that works! Also, if one piece of the puzzle is wrong, it won't work. For instance, there was no way to get this combo to work with the baffle installed on the V&H Pipe. I tried for weeks...

When you end up with a combination that works you can hear it...you can FEEL it...

I realize this is purely academic but might be of interst. The numbers I posted for the recent Dyno test were "Uncorrected" A dyno correction factor can be calculated and applied if we know:
1 ambient air temperature
2 barametric pressure
3 water vapor pressure
I used these two online calculators
www.csgnetwork.com/vaporpressurecalc.html
wahiduddin.net/calc/calc_cf.htm
and came up with a dyno correction factor of 1.04. The HP and Torque numbers are then mulitplied by the correction factor. It put my peak numbers at 93HP and 61LB*FT. This is the "Corrected" RWHP

Wired, you're right about the stock numbers. The same issue of Cycle Guide (Aug 1980) Dyno tested the chain drive KZ1000 and it posted a peak of 68HP. Don't know why the ST came in at 73HP. Maybe a little more cam from the factory? Maybe a factory ringer?

larrycavan, Do you have contact info for the Murray pipe? Thanks!

Swapped out the 120 mains for 125s. Will try to have it dynod this week. Let you know what comes of it.

Phone number should be on the website www.murrayexhaust.com.

Back in the days of my 900 Ninja, his pipe was the only one that worked well with 33CRS carbs. We tried them all in 85, Kerker 4/2, Cobra, Supertrap Slip-ons and the Murray 4/1.

Supertraps made good power too but the Murray provided the absolute best throttle response. We ran his pipes on KZs of various sizes and states of tune. Everyone had positive things to say about his pipes.

Thanks for the info.I have a 1980 cycle mag.with hp#'s and stage 1 & 2 kits for a ELR.If i get a scaner i will copy it.

In my experience, no single piece is responsible for major HP gains.

That's something that everyone needs to have engraved in their memory, it's the total package that does it, not a set of pipes/carbs/cams/big bore kit/etc, it's all about the combo and the tune.