Tech Forums > SOHC/4 Bikes
So, you want to run pods?
seanbarney41:
--- Quote from: HondaMan on May 01, 2020, 07:08:54 PM ---
--- Quote from: dkihlgren on May 01, 2020, 11:33:37 AM ---I translated this from a swedish site www.braigasen.se
The owner is a real carb-guy
Carburetor with fuel screw
Most common on 4-stroke carburetors (except Mikuni HSR). A fuel screw is always located downstream of the throttle and is pointed
--- End quote ---
Umm...Keihin doesn't make a single carb that I have ever seen in which this is the case. All Kehins use an AIR screw for the idle circuits. A few Harley carbs (notably the old Linkerts) use an adjustable main jet that DOES adjust the fuel orifice, maybe this is what he is referring to? Or, maybe some of the Mikunis he is speaking to have adjustable mainjets, but I have not seen one like that.
Automotive carbs like Holleys, FoMoCo, and Carter, use fuel metering screws for the idle circuits (which is opposite the Keihin method), which confuses some folks who don't know about the differences.
--- End quote ---
diaphragm cv carbs on v4 bikes have a fuel screw...probably others too, but not until the 1980's...sooo, doesn't really apply to sohc4's
dkihlgren:
--- Quote from: seanbarney41 on May 01, 2020, 09:05:43 PM ---
--- Quote from: HondaMan on May 01, 2020, 07:08:54 PM ---
--- Quote from: dkihlgren on May 01, 2020, 11:33:37 AM ---I translated this from a swedish site www.braigasen.se
The owner is a real carb-guy
Carburetor with fuel screw
Most common on 4-stroke carburetors (except Mikuni HSR). A fuel screw is always located downstream of the throttle and is pointed
--- End quote ---
Umm...Keihin doesn't make a single carb that I have ever seen in which this is the case. All Kehins use an AIR screw for the idle circuits. A few Harley carbs (notably the old Linkerts) use an adjustable main jet that DOES adjust the fuel orifice, maybe this is what he is referring to? Or, maybe some of the Mikunis he is speaking to have adjustable mainjets, but I have not seen one like that.
Automotive carbs like Holleys, FoMoCo, and Carter, use fuel metering screws for the idle circuits (which is opposite the Keihin method), which confuses some folks who don't know about the differences.
--- End quote ---
diaphragm cv carbs on v4 bikes have a fuel screw...probably others too, but not until the 1980's...sooo, doesn't really apply to sohc4's
--- End quote ---
Well my carbs on my 650 has fuel screw, or so I thought... Change fuel screw to air screw and the rest is the same
Skickat från min Mi 9T Pro via Tapatalk
PeWe:
My CB750 with 836, 4-1 and original carbs with pods
Pilot jet: 40 (not changed)
Needles: 4:th notch from top. Stock was 3.
My K2 got those carbs and need 4th notch too with stock airbox and HM300 replica. So this is more about the better flowing exhaust.
Main jet: Larger.
CB750 at least 125-130
As said before mostly main jet to change if needles are at 4th notch from top on CB750 K2-K6 carbs. I guess K1 are the same.
Air screw:
This will run bike on low cruising speed on 5th gear, around 60mph.
Open it too much can be easier to get too lean.
With airbox 1.5 turns out (correct 1 turn out) to find way too lean, pods will most likely be leaner.
Then close it in 1/8 steps. Have a screwdriver with you and take a ride and adjust after a while.
I have had a long adjusting period with other carbs where the needle jets had to be changed .
- CB750 stock carbs not.
This jet is also called emulsifier tube and affect at around 3 mm throttle lift over idle and transit to needle heights.
Needle jets must be correct!
I have later understood that my Mikuni Smoothbores were too lean and I tried to fix that with richer pilot that is not possible.
Needle heights can help but bring other issues.
seanbarney41:
--- Quote from: dkihlgren on May 02, 2020, 02:22:51 AM ---
--- Quote from: seanbarney41 on May 01, 2020, 09:05:43 PM ---
--- Quote from: HondaMan on May 01, 2020, 07:08:54 PM ---
--- Quote from: dkihlgren on May 01, 2020, 11:33:37 AM ---I translated this from a swedish site www.braigasen.se
The owner is a real carb-guy
Carburetor with fuel screw
Most common on 4-stroke carburetors (except Mikuni HSR). A fuel screw is always located downstream of the throttle and is pointed
--- End quote ---
Umm...Keihin doesn't make a single carb that I have ever seen in which this is the case. All Kehins use an AIR screw for the idle circuits. A few Harley carbs (notably the old Linkerts) use an adjustable main jet that DOES adjust the fuel orifice, maybe this is what he is referring to? Or, maybe some of the Mikunis he is speaking to have adjustable mainjets, but I have not seen one like that.
Automotive carbs like Holleys, FoMoCo, and Carter, use fuel metering screws for the idle circuits (which is opposite the Keihin method), which confuses some folks who don't know about the differences.
--- End quote ---
diaphragm cv carbs on v4 bikes have a fuel screw...probably others too, but not until the 1980's...sooo, doesn't really apply to sohc4's
--- End quote ---
Well my carbs on my 650 has fuel screw, or so I thought... Change fuel screw to air screw and the rest is the same
Skickat från min Mi 9T Pro via Tapatalk
--- End quote ---
actually no...if you have an air screw, the method of adjustment as described is totally wrong
HondaMan:
I think what is important to remember about the adjustment screws is: in order for a fuel screw to work, there must be fuel PRESSURE. Honda introduced fuel pumps to the Goldwings and many of the later CV carbs, and in some of those there are fuel-adjust low-speed screws.
The old Harley Linkerts had a screw that adjusted the height of the metering needle in the carb venturi, sort of like having manually-adjustable needle clips that you could turn while riding.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version