Problem, is it intake reversion?

Good reading guys, thanks:woohoo:

Larry: By "g'awful 33 flatslides" do you mean the TM33´that came on GSX750R in ´85? I got that set in my bike and it really is far from being civilized:laugh: Is this what you mean or are they as difficult to dial right as they seem?

Z1109R Fin wrote:

Good reading guys, thanks:woohoo:

Larry: By "g'awful 33 flatslides" do you mean the TM33´that came on GSX750R in ´85? I got that set in my bike and it really is far from being civilized:laugh: Is this what you mean or are they as difficult to dial right as they seem?

Hey how are you? Good to see you!

No, I was talking about the old Mikuni VM33 smoothbores.

Isn't your bike punched to 1170?

larrycavan wrote:

Z1109R Fin wrote:

Good reading guys, thanks:woohoo:

Larry: By "g'awful 33 flatslides" do you mean the TM33´that came on GSX750R in ´85? I got that set in my bike and it really is far from being civilized:laugh: Is this what you mean or are they as difficult to dial right as they seem?

Hey how are you? Good to see you!

No, I was talking about the old Mikuni VM33 smoothbores.

Isn't your bike punched to 1170?

Howdy, LC

Nope, it´s a GPZ1100 block with 1 oversize bore and Kawi pistons. Should make around 1109cc if i calculated it right. Developed some issues with carbs lately, somehow started running a bit lean and very har to start when cold. Well, it´´s a awfully long winter to figure that out.

excellent information larrycavan

flow goes to hell after 300 feet per second.

every thing we are discussing here is complex theory.

carb size is determined by the intake valve diameter.(Carb dia. = .85 of int. valve diameter)

same as the porting diameters and a "D" shape. 0.85 is a venturi cut into the intake runner walls also to keep velocity up. bigger is not better!!
Old joke> would you rather flow 1 bowling ball or 100 B.B.s' through your intake runner??

stock kz head 68 cfm on average but a mild port job and suzuki intake valves(38mm) can yield a 88~92 cfm head that can handle a set of 34mm carbs really well. even on a 1015 bottom end. and be very smooth powerful and streetable.

kz stock in valve 35.5mm = 30.1 mm dia carb is optimal
gs in valve 38.0 mm = 32.3 mm carb.
bigger is not always better as carbs go for smooth even power.

popularity of 29mm and 33mm smooth bores to wake these engines up is a matter of matching the physical traits of the part combinations.

answer 100 B.B.s' you figure it out.

you may have multiple areas of reversion if you have many mis matched parts on your engine.

1.carb diameter
2. total intake length
3. intake diameter
4. exhaust pipe diameter
5.exhaust pipe primary length
6. lobe centers on both camshafts
all have trig calculations to match all details for a desired power band at a specific R.P.M.

if all these are matched together you will have 1 reversion event just under the torque peak. if they are mismatched you will have 3 or 4 low spots in the power delivery.
sound waves on the 2nd and 3rd harmonic are powerful forces that help or hurt smooth power.

Great post guy's. I love this stuf. i'm enjoying ,taking all this in.
Thanks.Keep it up.

V&H PERFORMANCE BAFFLE HELL YEAH!! I took the baffle out and ran straight megaphone. WOT in high gear at 2500 rpm and it coughed and sputtered (barely ran) to 4K then ran with improved mid and top end. So I ordered a V&H performance baffle and WOW! Finally the right combo. Roll on the throttle in high gear at 2500 and it pulls like crazy to 11K. Best mid and top power yet, and no flat spots at any rpm. The noise level is considerably higher than the street baffle but way quieter than open exhaust. I don't like loud exhaust and I can live with this one. It is a nice deep growl that screams at high rpm.
Will Piatt

Thats good to hear Will. I notice more bottem end when i went from an open pipe to a 2" baffle in my Kerker too.
check your PM's.

Exitpupil wrote:

WOW! Finally the right combo.

Glad it worked out. Sounds like you've got a good complete package now.

My experience was similar with baffles. I wasn't able to get the stock baffle to run well at all so I ran an open megaphone for about 1/2 a season last year. It produced good top end power but bottom end power, gas milage, and my ringing ears all suffered. The comp baffle was the answer.

IMO the gains you've just experienced with the baffle will far exceed any gains to be had from a 3 angle valve job. It's not worth tearing your top end apart for the valve job alone.

Enjoy and ride safe!

@ Mark1122... "2" baffle in my Kerker"

I purchased the 1.5" baffle for my Kerker for I was concerned with the loudness of the 2"... The 2.5" was rated for racing only, blow your friggin ear drums out.

Is the 2" too loud to talk with a passenger while driving?

OMR

I bought a 2" perforated , baffle from a bike shop. It was too long, so I just cut it down to length .Then I cut a 2” hole (with a grinder) in my Kerker’s end cap. Then I had it welded to my Kerker’s end cap. I then wrapped it in fiberglass . It is pretty quit at low rpms. As a matter of fact it passed the cops test. It does get loud as the rpms approach 6000.
Davel has a post showing his home made baffle ,but i cant seem to find it. It refers to the baffle size and its effects on reversion. I have pm'ed him for a link that i will post for u .

trippivot wrote:

excellent information larrycavan

flow goes to hell after 300 feet per second.

every thing we are discussing here is complex theory.

carb size is determined by the intake valve diameter.(Carb dia. = .85 of int. valve diameter)

same as the porting diameters and a "D" shape. 0.85 is a venturi cut into the intake runner walls also to keep velocity up. bigger is not better!!
Old joke> would you rather flow 1 bowling ball or 100 B.B.s' through your intake runner??

stock kz head 68 cfm on average but a mild port job and suzuki intake valves(38mm) can yield a 88~92 cfm head that can handle a set of 34mm carbs really well. even on a 1015 bottom end. and be very smooth powerful and streetable.

kz stock in valve 35.5mm = 30.1 mm dia carb is optimal
gs in valve 38.0 mm = 32.3 mm carb.
bigger is not always better as carbs go for smooth even power.

popularity of 29mm and 33mm smooth bores to wake these engines up is a matter of matching the physical traits of the part combinations.

answer 100 B.B.s' you figure it out.

you may have multiple areas of reversion if you have many mis matched parts on your engine.

1.carb diameter
2. total intake length
3. intake diameter
4. exhaust pipe diameter
5.exhaust pipe primary length
6. lobe centers on both camshafts
all have trig calculations to match all details for a desired power band at a specific R.P.M.

if all these are matched together you will have 1 reversion event just under the torque peak. if they are mismatched you will have 3 or 4 low spots in the power delivery.
sound waves on the 2nd and 3rd harmonic are powerful forces that help or hurt smooth power.

The thing with the Suzuki Valves is they are .050" shorter than the KZ. That works in your favor when you have to sink them for 1.110" b/c cams though. You're only the second other person that's even mentioned using those valves.Nice to have you in the neighborhood.

Using the 36mm stock kz valves we commonly get 86-88cfm. With 37.5 my head, [stock manifolds installed] is flowing 97CFM for my street bike. 91CFM with TB installed. 270FPS dead down the middle of the runners. I could choke it up with epoxy and push the velocity to 300 but I have no reason to do so.

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I know a guy with a 1045cc Z that runs low 9's with OLD 31mm Keihin CR smoothbores. And that was foot shifting the thing.

I'm no mechanical genius here, but I do have two observations for you.
Years ago when I used to drag race motorcycles, one of the guys I raced with ported many heads. He really believed in D shaped ports, and it worked for him. His best run with no nitrous was 8.20 with a '78 2 valve suzuki motor.
Second, I work on F-18 aircraft in the military. The intakes are D shaped. Guess there has to be something to it.