Author Topic: FYI if ordering slow jets for roundtop carbs  (Read 1467 times)

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Offline evanphi

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FYI if ordering slow jets for roundtop carbs
« on: November 16, 2016, 09:24:30 AM »
I got a nice forum member to send me jets from jetsrus.com. I live in Canada so they won't ship to me.

I got them yesterday and I noticed no K stamp on them. My heart sunk as I thought the order was placed wrong, but there is only one option for ordering for the roundtop carbs on their site.

They are aftermarket only!



The only place you'll be able to get genuine Keihin slow jets, OTHER than stock, would be through honda dealerships (if they are available).

FWIW, size 42s were stock on the CB400F model bikes.
« Last Edit: November 16, 2016, 09:47:19 AM by evanphi »
--Evan

1975 CB750K "Rhonda"
Delkevic Stainless 4-1 Header, Cone Engineering 18" Quiet Core Reverse Cone, K&N Filter in Drilled Airbox
K5 Crankcase/Frame, K4 Head and Cylinders, K1 Carbs (42;120;1 Turn)

She's a mix-matched (former) basket case, but she's mine.

CB750 Shop Manual (all years), searchable text PDF
Calculating the correct input circumference for digital speedometers connected to the original speedometer drive

Offline harisuluv

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Re: FYI if ordering slow jets for roundtop carbs
« Reply #1 on: November 16, 2016, 09:49:49 AM »
Any Honda dealer can look up the nationwide database to see if they have any NOS 42 jets--they may or may not be available.

The 400F uses a #40 slow jet, and the 350F uses a #35 slow jet.

Offline evanphi

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--Evan

1975 CB750K "Rhonda"
Delkevic Stainless 4-1 Header, Cone Engineering 18" Quiet Core Reverse Cone, K&N Filter in Drilled Airbox
K5 Crankcase/Frame, K4 Head and Cylinders, K1 Carbs (42;120;1 Turn)

She's a mix-matched (former) basket case, but she's mine.

CB750 Shop Manual (all years), searchable text PDF
Calculating the correct input circumference for digital speedometers connected to the original speedometer drive

Offline flybox1

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Re: FYI if ordering slow jets for roundtop carbs
« Reply #3 on: November 16, 2016, 10:52:43 AM »
http://www.partzilla.com/parts/detail/honda/HP-99124-076-0420.html
Yes, they are obsolete, but there still may be some around.
you sure you need 42s?

'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

Offline evanphi

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Re: FYI if ordering slow jets for roundtop carbs
« Reply #4 on: November 16, 2016, 10:54:36 AM »
http://www.partzilla.com/parts/detail/honda/HP-99124-076-0420.html
Yes, they are obsolete, but there still may be some around.
you sure you need 42s?

Yes I am only 1/4 turn out on my idle screws and very lean at idle.
--Evan

1975 CB750K "Rhonda"
Delkevic Stainless 4-1 Header, Cone Engineering 18" Quiet Core Reverse Cone, K&N Filter in Drilled Airbox
K5 Crankcase/Frame, K4 Head and Cylinders, K1 Carbs (42;120;1 Turn)

She's a mix-matched (former) basket case, but she's mine.

CB750 Shop Manual (all years), searchable text PDF
Calculating the correct input circumference for digital speedometers connected to the original speedometer drive

Offline flybox1

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Re: FYI if ordering slow jets for roundtop carbs
« Reply #5 on: November 16, 2016, 10:58:30 AM »
http://www.partzilla.com/parts/detail/honda/HP-99124-076-0420.html
Yes, they are obsolete, but there still may be some around.
you sure you need 42s?

Yes I am only 1/4 turn out on my idle screws and very lean at idle.
Tell us about your setup. . .
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

Offline flybox1

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Re: FYI if ordering slow jets for roundtop carbs
« Reply #6 on: November 16, 2016, 11:01:35 AM »
What could be really confusing is there are press-in and screw-in type pilot jets listed on the jetsrus 400F page.
The 400f's take the screw-in type.
Just throwing this out there....could it be that your US buyer purchased the (wrong) press-in type by mistake, when you really should have the screw-in type?  :-\
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

Offline flybox1

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Re: FYI if ordering slow jets for roundtop carbs
« Reply #7 on: November 16, 2016, 11:04:17 AM »
More confused...400F's dont have roudtop carbs.
So what bike did those carbs originally come on?   ;D
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

Offline evanphi

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Re: FYI if ordering slow jets for roundtop carbs
« Reply #8 on: November 16, 2016, 11:48:11 AM »
What could be really confusing is there are press-in and screw-in type pilot jets listed on the jetsrus 400F page.
The 400f's take the screw-in type.
Just throwing this out there....could it be that your US buyer purchased the (wrong) press-in type by mistake, when you really should have the screw-in type?  :-\

Nope. They're correct for my bike.

More confused...400F's dont have roudtop carbs.
So what bike did those carbs originally come on?   ;D

These are correct. It is how Honda designated the jet part numbers.

http://www.siriusconinc.com/pro-detail.php?pid=&product_id=1947

https://jetsrus.com/a_jets_by_carburetor_type/jets_keihin_99124-076_slow.html

 

http://www.partzilla.com/parts/detail/honda/HP-99124-076-0420.html
Yes, they are obsolete, but there still may be some around.
you sure you need 42s?

Yes I am only 1/4 turn out on my idle screws and very lean at idle.
Tell us about your setup. . .

In my signature. Checked new plugs after five minutes of idling under fans. They look brand new.
« Last Edit: November 16, 2016, 11:53:40 AM by evanphi »
--Evan

1975 CB750K "Rhonda"
Delkevic Stainless 4-1 Header, Cone Engineering 18" Quiet Core Reverse Cone, K&N Filter in Drilled Airbox
K5 Crankcase/Frame, K4 Head and Cylinders, K1 Carbs (42;120;1 Turn)

She's a mix-matched (former) basket case, but she's mine.

CB750 Shop Manual (all years), searchable text PDF
Calculating the correct input circumference for digital speedometers connected to the original speedometer drive

Offline flybox1

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Re: FYI if ordering slow jets for roundtop carbs
« Reply #9 on: November 16, 2016, 12:21:31 PM »
What carb model do you have?
...so confused with the 400F jet mention in your first post  ::)
« Last Edit: November 16, 2016, 12:24:47 PM by flybox1 »
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

Offline harisuluv

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Re: FYI if ordering slow jets for roundtop carbs
« Reply #10 on: November 16, 2016, 12:27:06 PM »
I'm sorry but the #42 just isn't stock on a 400F.  I think what's happening is that you're seeing that the #42 is listed under the CB400F parts list/fiche, but it's normal that they will list 1-3 jet sizes to accomodate for users making modifications.  If you look again at the link you will see that the #40 is also listed in the list.  Also listed is 38, and 42.  Same goes for the main jets listed for the 400F:  #72, #75, and #78.

The stock size for the 400F is #40 slow, #75 main.

http://www.partzilla.com/parts/search/Honda/Motorcycle/1976/CB400F%20A/CARBURETOR/parts.html

« Last Edit: November 16, 2016, 12:29:33 PM by harisuluv »

Offline harisuluv

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Re: FYI if ordering slow jets for roundtop carbs
« Reply #11 on: November 16, 2016, 12:35:29 PM »
Flybox, he's saying he has roundtop carbs on a cb750.  He looked up the jets for the cb750 and didn't see 42 listed in the parts list.  So looking around for other models saw that #42 is an option in the 400F parts list.

The #42 jet association with the CB400F is just arbitrary, so he can use that in his cb750 carbs.

I don't like how jetsrus will liberally use the term "OEM".  When people are looking for jets and start talking about jetsrus and this is brought up to them, they are resistant and insist they are all OEM jets because they are kind of misleading on their site.


Offline flybox1

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Re: FYI if ordering slow jets for roundtop carbs
« Reply #12 on: November 16, 2016, 12:56:53 PM »
Now i'm following  ;D

'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

Offline evanphi

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Re: FYI if ordering slow jets for roundtop carbs
« Reply #13 on: November 16, 2016, 03:41:35 PM »
Glad we're all on the same page now. Haha.

Jetsrus makes a good distinction with their main jets, but doesn't explicitly state the slow jets are non-oem.
--Evan

1975 CB750K "Rhonda"
Delkevic Stainless 4-1 Header, Cone Engineering 18" Quiet Core Reverse Cone, K&N Filter in Drilled Airbox
K5 Crankcase/Frame, K4 Head and Cylinders, K1 Carbs (42;120;1 Turn)

She's a mix-matched (former) basket case, but she's mine.

CB750 Shop Manual (all years), searchable text PDF
Calculating the correct input circumference for digital speedometers connected to the original speedometer drive