Carbs for 1015cc or 1075cc Upgrade

PLUMMEN wrote:

larrycavan wrote:

kzz1p wrote:

larrycavan wrote:

DoubleDub wrote:

Larry - I also see on your web site that you say the Webcam 118 needs a new cam chain - do you specifically mean that the cam chain needs to be a different length or just replaced with an OE cam chain?

Sorry for the dealy. I'be been busy and today is my birthday as well:)

Regarding the engine setup in your previous question. YES, it's a perfectly streetable. PM me and I'll put you in touch with a guy that has that exact setup. He just got it together and on the dyno. It went from 74HP - 55Ft/lbs Torque to 104HP - 77 Ft/lbs Torque. It's making like 92HP at 6500RPM.

Out of that 30HP increase, I'd dare say 20 of it came from the cylinderhead porting. That's 5HP per cylinder at 25$ per HP.

I personaly would go with the Web #45 Grind cams. They are not drop in. The 118 grind is a nice street cam, with or without head work.

The 110 & 45 Grind really shine with a flowed head. Or vice-versa...depends on how you look at things I guess.

Here's the story behind the cam chain.

You can take any drop in cam and bolt them in with stock sprockets on 110 lobe centers and they'll work fine. With an old cam chain, there's no way of knowing how muct later than 110 you'd be on the intake cam.

Once you get above that level of cam, they really should be degreed in. These motors are old. Cam chains stretch. A new cam chain is always advisable in a performance type application.

Here are 3 Web streetcams with more than the standard information. That 45 grind will put some ft/lbs where you want them

Master # Lift Dur@.020 Dur@.050 Dur@.100

45 .415 268° 244° 220°
110 .395 284° 256° 228°
118 .365 283° 246° 216°

Larry,
I guess you are an old goat, now! (you know, I love you)
Tell me in simple English. The #45 grind, is it in the 280*(+/-) range @ running clearance?

If so, that would be a dam good, upper mid range, torque cam.

What is your projected RPM range on that cam?

Do you think, it will work, in any size motor?.....John

PS - HAPPY B DAY!

I'm not sure what the dur. is at running lash.

It's relevant to the size of the motor it's going to be used in plus the size of the valve & the carbs chosen.

The thing with motorcycle cams specs is the manufacturers never give you enough information to begin with. Trying to compare two cams based on lift and a single lift point of duration won't tell you much about the cam.

Let's say for example you have a little 1015cc motor with 10.5:1 pistons. It's more cam for that motor than it would be for an 1075 with equal compression.

Let's say you have a typical 1075 street compression motor with 33mm Mikunis and something like a Web #109 grind and a stock or lightly cleaned up KZ head.

That sort of engine combo likes to see 4500+ RPM before it's in the "happy zone". Hit the carbs wide open down low and there's not enough signal on the carb to fuel the motor properly at low RPM because the cam duration is too great.

So you put some 34mm RS carbs on the motor and they help that situation because they have an accelerator pump.

But....if you swapped out the 109 for the 45 grind it would improve the midrange to a greater extent than the carb swap. It would be IMO a better street motor all around.

Now say you have the same 109 Grind in the 1015cc motor with the same 33 Mikunis. It would be a turd below 5000. Put the 34RS carbs on it and it will stil be a turd.... swap the cams for the 45 grind and it will really improve the street behavior...

In short, if you're going to put a carburetor sized for RPM more suited for the top of the tach and still want some respectable lower mid range pull.....pick a cam that will help do that. Compoents must work together. You can, at least to some extent, assist a poor carburetor choice by making a wise cam choice...

IMO and this is just me relating my experiences and preference based on them..... 34mm performance carburetors don't belong on anything less than a 1200cc motor for a streetbike. Guys want them. They buy some used dragbike junk cams off ebay that have way too much duration for a street ride.

They put the bike together and then spend the entire summer trying to make the bike accelerate hard in exactly the RPM range where they actually ride....

Then they're on the Internet trying to find the secret to making bottom end power with top end power components...

Guys want different things out of their old Z powered bikes. Some are willing to accept short comings in the power spread to achieve the thrill from 5500 on up. Some want that "wack it hard and go" at a lower RPM and will trade away the top end thrill for it.

Best advice I can give is this.

Be realistic in how your ride the bike. Pick components that compliment each other for that type of riding...and have a ball running around on your old KZ..

i love this guy! same thing the older guys told me when i was a kid and too smart to listen to them! :laugh:

Larry

Just a couple of things:
I will use myself for an example, as you know, I will be working on my own head because of funds. Can you give me some common pitfalls to avoid? What shouldn't I do to the head, that may affect it's performance? What should my line of thinking be? How can I keep it simple and yet benifit my power output?

Larry

Just a couple of things:
I will use myself for an example, as you know, I will be working on my own head because of funds. Can you give me some common pitfalls to avoid? What shouldn't I do to the head, that may affect it's performance? What should my line of thinking be? How can I keep it simple and yet benifit my power output?

Avoid getting low spots anywhere in the ports when you cut them.

Carefully open up the throats to 88% - 90% of the valve OD.

Use long strips of 80 Grit to work the short side turn. Run the strips right through the port from the valve side through the port runner entrance.

Make or buy a slotted mandrel and use small strips of the paper with it to smooth out the ports. Finish with 60 or 80 Grit.

Here's an 80 Grit finished port

mtkawboy wrote:

I had 33s on my 1105 and traded them even for a set of 29s. Im much happier with the way it runs now, Its a 10.25-1 1105 {sleeved 900 built in 77} Superbike Mike street head & drop in shim on top cam 395 260/260 and Kerker pipe. It may have been a hair stornger wide open but was a pain the butt with the 33s to ride around. Id like to try a set of flat slides but they are too expensive on Social Security. The 29s used are getting almost as expensive as new flat slides though

I dont' get that either Why would a guy buy an ancient rack of carbs for say $600 when he could buy superior Keihin CRS carbs, brand new for a bit more money....

The 29 Mic SB's are a nice carb and they will definitely wake up a Z motor. But how many have you seen with stripped out jet block...wrong floats..worn out needles, scratched to hell slides...etc

Why would a guy buy an ancient rack of carbs for say $600 when he could buy superior Keihin CRS carbs, brand new for a bit more money....

...

Amen to that.... Yup, I paid for brand spanking new, never been used Keihin 29mm CR Specials, $700....

Hell, 30 year old rebuilt carbs these days are what $500... :huh: .... Why would anyone go this route unless needing to keep to OEM looks for re-sale is beyond me...

Oh well, to each their own ...

OMR