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kzz1p wrote:

Mark Please check my line of thinking (yes it did hurt)
I need to know if I'm on the right track or not.
If you advance the intake cam to solve the reversion problem the valve overlap goes up and takes away your bottom end/mid range torque.Advancing the intake will increase bottom end torque not? I don't want to split hairs over the power differance. We are not talking about tearing the pockets off the back of your pants here. I will assume you want the intake and exhaust to have the same lobe center. I'm not the smartest guy here but this is how I see it.

112* L/C has a timing of 18*-62* / 62*-18* (36* overlap)
(this is int. retarted 4*/exh. advanced 4*)

110* L/C has a timing of 20*-60* / 60*-20* (40* overlap)
(this is int. retarted 2*/exh. advanced 2*)

108* L/C has a timing of 22*-58* / 58*-22* (44* overlap)
(this is stock RC timing)

106* L/C has a timing of 24*-56* / 56*-24* (48* overlap)
(this is int. advanced 2*/exh.retarded 2*)

104* L/C has a timing of 26*-54* / 54*-26* (52* overlap)
(this is int. advanced 4*/exh. retared 4*)

It looks to me that the lower the lobe center #, the more overlap you get. As you close the intake valve sooner, the power curve is moved upward. You might be able to find a different timing choice OR live with what you have OR Use cams that have a sooner closing point(stock without advancing or retarding)
Well my friend thats the best I know. I wish I could help you more.........KZZ1p

nads.com wrote:

kzz1p wrote:

Mark Please check my line of thinking (yes it did hurt)
I need to know if I'm on the right track or not.
If you advance the intake cam to solve the reversion problem the valve overlap goes up and takes away your bottom end/mid range torque.Advancing the intake will increase bottom end torque not? I don't want to split hairs over the power differance. We are not talking about tearing the pockets off the back of your pants here. I will assume you want the intake and exhaust to have the same lobe center. I'm not the smartest guy here but this is how I see it.

112* L/C has a timing of 18*-62* / 62*-18* (36* overlap)
(this is int. retarted 4*/exh. advanced 4*)

110* L/C has a timing of 20*-60* / 60*-20* (40* overlap)
(this is int. retarted 2*/exh. advanced 2*)

108* L/C has a timing of 22*-58* / 58*-22* (44* overlap)
(this is stock RC timing)

106* L/C has a timing of 24*-56* / 56*-24* (48* overlap)
(this is int. advanced 2*/exh.retarded 2*)

104* L/C has a timing of 26*-54* / 54*-26* (52* overlap)
(this is int. advanced 4*/exh. retared 4*)

It looks to me that the lower the lobe center #, the more overlap you get. As you close the intake valve sooner, the power curve is moved upward.Closing the intake sooner will move the power curve down not? You might be able to find a different timing choice OR live with what you have OR Use cams that have a sooner closing point(stock without advancing or retarding)
Well my friend thats the best I know. I wish I could help you more.........KZZ1p

I have a friend who built an early z1 years ago just out of the army. I did'nt know him then. Never asked him what size cam and motor he used in the bike. He said he bought a big bore kit and it had big carbs and cam. He told me about how it would spit fuel out of the carbs at idle and the power band would run off the tach. He mentioned 12-1 for compression but it kept blowing head gaskets so he went down to 11. Said he could let the clutch out at idle, hold the front brake lever and the back wheel would chirp on the pavement, said he used to do figure eights with it in parking lots, that it would cruise at 150. Said the only thing that beat him was a yamaha triple, and that's when the compression was lowered. I think your lobe centers were way out and that's why it reverted. Your intakes were closing way late and that's what happens-that's a pretty big cam. Your plagued man, PLAGUED! I did take a sattelite pic over head of your garage at midnite one night and lo! GREMLINS MAN! Crawling all over your bike all drinking beers, one was smoking a joint, I turned up the audio and all heard was EHEEHEEE.. HEE.. HEEHEEHEEE. Ever wonder why your tools are not always where you left them? And why the dog's getting so fat?

OK Then. Now It's obvious what the problem is.
So how do I get rid of Gremlins ?:laugh:

kzz1p wrote:

mark1122 wrote:

WFO! YEE HAA!.That is where i useualy end up.Lets face it if u want to accelorate where does your wrist go? WFO.
I realy enjoy getting deep into subjects like this and learning all i can about what makes these thing tick.
Do u have any coments on why the intake runners may have accumulated differant amounts of reversion?
I'm thinking exht tube length diferances?
Can it be cause on the intake side from improper carb sync?

I have no clue, every cylinder is different, the same as every motor is different. If we could only get them to run the same (100%) boy would we have some power. Once the ports are clean try it again, I think the timing change will clean it up or reduce it. It's like Smokey Yunick said "One test is worth a thousand expert opinions" He believed in keeping it simple. I like to keep a couple of different old beatup exhaust pipes laying around. I try each one to see witch one works the best for performance. Most of the time it's the one I least expect, works the best. You can do the math until the cows come home, it doesn't mean it will work best. I don't think carb sync has anything to do with it at all...

That is probably one of the best posts I have ever seen on any motorcycle forum....

kzz1p wrote:

After thinking about this some more, more and some more. I will give it one last shot.

Davel has some good points. I know that you spent good money on this head and want to use it. If it were Me, myself and I, this is what I would do:

Advance both cams - This will increase your torque in the bottom end and mid range, while closing the intake valve 6* sooner and not increasing the overlap or raising the power curve.


104* L/C intake cam
112* L/c exhaust cam
108* lobe speration angle
26*-54*/62*-18* valve timing
44* overlap (same as RC recommended at 108* L/C)

This is 4* advance for both the intake and exhaust cams........Now I will shut up!

Why would you shut up? You're right on the money. I read this thread all the way through. Advance them both to put bottom in the motor. I'm leaning toward 106 / 111 for Marks 1200.

Had arrived here flowing 82CFM with 37.5mm intakes and the bike was not performing up to expectations.

It left here flowing 92CFM and was sectioned for a 1327cc motor. Now the cubes are falling again back to 1200cc

If you want to run with your buddies, keep that epoxy away from your ports. If you want to run like stocker with 26mm carbs...then by all means...fill 'er up. You'll have that stock carb, stock airbox affect you're searching for.

The cams in that motor are not midrange cams.

34mm carbs are way overkill on a 1075cc street motor. I don't care what the Mikuni charts says.

People piss around with 34mm CV carbs because they are broke. Run a real carb on your motor, you'll never go back to those things again.

The cams and carbs you choose will decide where the power comes in. Timing can be tweaked to some extent to assist that but duration is the key factor.

People amaze me. They want a 30 year old 2valve motor to go run with the new sport bikes....then they want the same throttle response down at 3000 it had with stock cams, carbs and airbox.

Crisp throttle also comes from compression. Cool....crank it up and buy race fuel every day....

You got to give something to get something. This is the real world.

nads.com wrote:

I have a friend who built an early z1 years ago just out of the army. I did'nt know him then. Never asked him what size cam and motor he used in the bike. He said he bought a big bore kit and it had big carbs and cam. He told me about how it would spit fuel out of the carbs at idle and the power band would run off the tach. He mentioned 12-1 for compression but it kept blowing head gaskets so he went down to 11. Said he could let the clutch out at idle, hold the front brake lever and the back wheel would chirp on the pavement, said he used to do figure eights with it in parking lots, that it would cruise at 150. Said the only thing that beat him was a yamaha triple, and that's when the compression was lowered. I think your lobe centers were way out and that's why it reverted. Your intakes were closing way late and that's what happens-that's a pretty big cam. Your plagued man, PLAGUED! I did take a sattelite pic over head of your garage at midnite one night and lo! GREMLINS MAN! Crawling all over your bike all drinking beers, one was smoking a joint, I turned up the audio and all heard was EHEEHEEE.. HEE.. HEEHEEHEEE. Ever wonder why your tools are not always where you left them? And why the dog's getting so fat?

Now that's some funny stuff...:silly:

larrycavan wrote:

If you want to run with your buddies, keep that epoxy away from your ports. If you want to run like stocker with 26mm carbs...then by all means...fill 'er up. You'll have that stock carb, stock airbox affect you're searching for.

With a 1075, 0.365 cams, RS34s and high velocity ports (yes, they have epoxy but are essentially brought back close to stock volume). I’ve got 94rwhp & 65lb.ft Pulls from 3K to redline and runs 7.51 in the 1/8 and 11.79 in the 1/4. This from the heaviest KZ1000 they made (600lbs) with a shaft. These numbers are far from stock and the timeslip numbers are uncorrected with me foot shifting.

larrycavan wrote:

The cams in that motor are not midrange cams.

I disagree. Look at duration at 0.030 lift for the following
Web 0.365 lift – duration 262 (This is what I’m running)
APE 0.410 lift – duration 266
APE 0.435 lift – duration 266 (Marks cam)
That cam should provide loads of mid range in a 1200 or 1300cc motor if set up properly. Pulling 5th gear at 3000RPM should be no problem. In fact, it should be scary.

larrycavan wrote:

34mm carbs are way overkill on a 1075cc street motor. I don't care what the Mikuni charts says.

I disagree. I’m very happy with the RS34s on my 1075 – They ran just as good at 1015 before installing the kit. They should work great on a 1200 or 1300cc engine.

larrycavan wrote:

People piss around with 34mm CV carbs because they are broke. Run a real carb on your motor, you'll never go back to those things again.

I’d bet a lot of guys on this forum with strong running 100+hp engines breathing through a rack of BS34s would disagree

larrycavan wrote:

The cams and carbs you choose will decide where the power comes in. Timing can be tweaked to some extent to assist that but duration is the key factor.

I agree. Duration is a key factor as noted above

larrycavan wrote:

Crisp throttle also comes from compression. Cool....crank it up and buy race fuel every day....

I disagree. A crisp throttle comes mainly from a good signal at the carburator jet. Or a carburator that is capable of responding to a weaker signal. Or a combination of the two. Maintain velocity in the intake port and you’ll maintain a good signal at the carburetor jet.

davel wrote:


larrycavan wrote:

The cams in that motor are not midrange cams.

davel wrote:[/
I disagree. Look at duration at 0.030 lift for the following
Web 0.365 lift – duration 262 (This is what I’m running)
APE 0.410 lift – duration 266
APE 0.435 lift – duration 266 (Marks cam)
That cam should provide loads of mid range in a 1200 or 1300cc motor if set up properly. Pulling 5th gear at 3000RPM should be no problem. In fact, it should be scary.


my cams are RC400's .0423" lift 260* @ .050"
Acording to WEB cams write up.

www.webcamshafts.com/ Page 69.

There 409 cams seem to be the same as mine.
They say the 109's have "Exellent mid and upper performance for hot street ".
I tried there 493 grind wich is like the K410 . I didnt notice any real diferance.Both were in my 1135cc build.
Personaly i have not found either of them to have much bottom end.

I would like to see someone post the RC400 definition as listed out of a "RC Engineering catalog" (as per Russ Collins)
I would like to see a copy of that catalog page. Does anyone out there have a Catalog????????????

mark1122 wrote:

davel wrote:


larrycavan wrote:

The cams in that motor are not midrange cams.

davel wrote:[/
I disagree. Look at duration at 0.030 lift for the following
Web 0.365 lift – duration 262 (This is what I’m running)
APE 0.410 lift – duration 266
APE 0.435 lift – duration 266 (Marks cam)
That cam should provide loads of mid range in a 1200 or 1300cc motor if set up properly. Pulling 5th gear at 3000RPM should be no problem. In fact, it should be scary.


my cams are RC400's .0423" lift 260* @ .050"
Acording to WEB cams write up.

www.webcamshafts.com/ Page 69.

There 409 cams seem to be the same as mine.
They say the 109's have "Exellent mid and upper performance for hot street ".
I tried there 493 grind wich is like the K410 . I didnt notice any real diferance.Both were in my 1135cc build.
Personaly i have not found either of them to have much bottom end.

Mark you don't seem to have much torque. So certainly at 3000rpm your not going to win any roll-on contests. As the cams were out from intended 110 to 112, when 108 was reccomended your not ging to win any high end contests either, you have nothing to take home. No trophy no reward. Just knee slapping Gremlins. Davel has roll on power at 3000rpm. He prefers not to shift down but he does know how. Here u come up next to him on the highway with spanky new 108 to 109 lobe centers. Your cruising next to him at 70. The scar from your operation is promiment across the top of your skull and theres a bandiad on your right index filnger. He looks over at you and smiles, showing that gold tooth. It's weak, there's something transparent about it. Like a man that knows he's at the end of his rope. He's out of his element and knows it. He shifts down to 4rth, you shift down to 3rd, he's taching 57000rpm and your taching 6700. Your motor comes alive with intense ferocity, pull's to redline and away from gavel, you look ahead and grab 4rth gear, gavel leans over the handle bars gritting his teeth his engine vibrating, out of steam and just winding on. After running out to redline in 4rth gear you glance back into the mirror, Gavens reaching underneath the gas tank with a long screwdriver jamming it into the carb openings trying to gouge out the epoxy. Mark stops at roadside bar to wait for gavel. Twenty minutes Gavel walks in looking through the dingy smoke filled air he can't feel his butt from the vibration he was just subjected to, and he can't find mark. Finally he recognizes the him by the logo on the back of his t-shirt, (DA MAN),as he walks over, Mark turns around and on the front of shirt are the words NADS.com. He looks up at mark while a tear rolls down his cheek and sniffles, "should have known". Mark takes the toothpick out his mouth, and staring straight ahead again tells him, "Told you - can't run wihtdabigdogs with lobe centers like that. He says quietly, Mark? Will you help me tear out the expoxy? He says sure lset's have a beer first. Never did know why you put that stuff in there in the first place.

Well after nads post, I just don't know what to say. I guess we last left off with Mark getting his head freshened up and the exhaust valves being sunk deeper into the head, so he can use different timing choices without "valve to valve interfearance". His intake ports will be clean so he can keep an eye on the stains caused by the intake reversion. Mark after you get it running and dialed in, I hope you will consider trying a couple of different exhaust pipes. I know that you have a nice pipe on it, you may find a little more hidden free power. Perhaps someone will be willing to loan you one or give you an old beat up pipe or two. You have come to far, to settle for second best!