Topic: 064A carbs from what year(s)

[HondaMan]

Just unloaded into my garage super early build F0, number 400 something, build date 1/75.  It's real dirty but ls mostly complete and under 20k on the odo.  Worst thing is someone swapped a 77/78k tank on and painted a really ugly shade of single stage red.  Got it from a junk hauler who was smart enough to get a title for $400  It will be fun to see what these carbs have.  I already saw the little plastic restrictor caps are gone from the pilot screws.  I think I got a set of the caps stashed.  Pretty sure this is gonna run fine with the carbs cleaned.  Almost hope not because a damn F tank is gonna cost more than the whole rest of the bike.

Wow!
The F0 engines had Stellite valve guides like the K0/1. They last over 100k miles.

[newday777]

Worst thing is someone swapped a 77/78k tank on and painted a really ugly shade of single stage red.

Those were the ugliest tanks ever to foul the appearance of an SOHC, IMHO. Any tank would look better. Frank fit a 400F tank onto a 750, with only minor hammer work on the underside.

yeah, I can't argue with that.  I got a couple cb200t tanks that somehow came into my possession...cant imagine they are gonna fit too easy, but who knows    was just looking at f tanks on eBay  How is total rusty garbage worth $600?!?  And then a clean or restored complete running riding cb750f tops out around $4500?!?!?

I was also looking at ebay for a F tank the other day as I picked up a 78 F roller a week ago without a tank, motor, carbs and some other stuff. At those prices it may be sitting for a while....

[newday777]

I had a minute to look again this morning.
The 064A carbs do have the plastic limiter caps, all 4! And they have the float valves with the screen filters.
The 7A carbs must be from the K1, didn't have the extended air screws for the limiter caps.

[PeWe]

064A carbs on 1975 F according to Honda CB750 shop manual.

Mine had plastic caps on air screws too.
I do not use them.
I think my  086A had those too from the beginning.

I gave my CB750 K2 a set of those last year.
They work really fine, better than the K6  086A it had earlier.
Choke for start only.

The K2 has CI +0.50 mm K7/K8 (392) pistons, K7/8 cam. K6 head wich will fit K2 1975 as we had here.
Yamiya no numbers 4-4, K&N filter in stock airbox.
Pilot 40
Needle clip middle (good needle model)
Mains 120

The needle model the 064A has can be a good upgrade in the others

[seanbarney41]

PeWe, what needle number is stamped on your needles?  Is it not 27201?

[HondaMan]

It's likely #271301 or #271304?
The F0/1 needles run leaner below 2000 RPM than the regular #27201. The thick section near the top (by the clip grooves) is straight for about 1/8" or so. This corresponds to the late-opening intake valve (0 degrees BTC) of the F cams.

[PeWe]

PeWe, what needle number is stamped on your needles?  Is it not 27201?

I cannot find my notes.
Maybe 271307

It is not easy to check without taking it apart.

[seanbarney41]

Yeah, I don't expect you to tear your carbs apart...but I know you are a meticulous tuner and thought you might have it written down somewhere easy to check

Reason I am curious is I don't think I have seen anything but 27201, but have not been meticulous about noting the needle number for very long.  And my long owned orange F0 has always carbureted so wonderfully despite numerous intake changes without jetting adjustments.  Basically, if gas and air are somehow getting in there, its gonna run great.  I have always suspected that it had something to do with the needle profile, but really don't know.  To be sure, I also need to check, but I am about 70% sure it has 27201 needles.  Or could it be the Kerker 4 into 1 with street(quietest) baffle.  I am hoping to find a way of finding this extreme flexibility for all my 750's.

[PeWe]

It would be nice to know. I remember that I saw same numbers in an old post on the forum.

Not this thread that is very informative
http://forums.sohc4.net/index.php?topic=153577.msg1755847.msg#1755847

[newday777]

That's great information guys. Thanks!

[newday777]

It's likely #271301 or #271304?
The F0/1 needles run leaner below 2000 RPM than the regular #27201. The thick section near the top (by the clip grooves) is straight for about 1/8" or so. This corresponds to the late-opening intake valve (0 degrees BTC) of the F cams.

Mark
Would the # 27201 actually be #271201? (going by the #271301 or #271304 numbers?) Or is #27201 correct as you, Per and Sean have all said?

[seanbarney41]

Yeah, I need to fact check that number.  I came up with that from memory and am notoriously dyslexic.  I think I got it right because when I came up with this theory about the flexibility of the 064a needles, I started checking all of my spare carb racks (I have lots!),and that was the only number I found.

[PeWe]

Yeah, I need to fact check that number.  I came up with that from memory and am notoriously dyslexic.  I think I got it right because when I came up with this theory about the flexibility of the 064a needles, I started checking all of my spare carb racks (I have lots!),and that was the only number I found.

Which needles in your 064A carbs?

[seanbarney41]

Yeah, I need to fact check that number.  I came up with that from memory and am notoriously dyslexic.  I think I got it right because when I came up with this theory about the flexibility of the 064a needles, I started checking all of my spare carb racks (I have lots!),and that was the only number I found.

Which needles in your 064A carbs?

pretty sure...27201
I will try and check my notes and post back

[PeWe]

Yeah, I need to fact check that number.  I came up with that from memory and am notoriously dyslexic.  I think I got it right because when I came up with this theory about the flexibility of the 064a needles, I started checking all of my spare carb racks (I have lots!),and that was the only number I found.

Which needles in your 064A carbs?

pretty sure...27201
I will try and check my notes and post back

I have to remember this post and hopefully write down my needle numbers when I have a reason to remove carbs. Or if I'll find my notes.

[newday777]

I haven't pulled the 064A carbs apart yet to get the needle numbers on my set. I'm off at a friend's playing with his Norton.

[seanbarney41]

Yeah, I need to fact check that number.  I came up with that from memory and am notoriously dyslexic.  I think I got it right because when I came up with this theory about the flexibility of the 064a needles, I started checking all of my spare carb racks (I have lots!),and that was the only number I found.

Which needles in your 064A carbs?

pretty sure...27201
I will try and check my notes and post back

I have to remember this post and hopefully write down my needle numbers when I have a reason to remove carbs. Or if I'll find my notes.

just checked my notes...2 out 3 of the cb750s I have on the road right now specifically mention needle number 27201.  Ironically, the notes that don't include needle number are the notes for my orange F0...but like I said before.  I have not actually ever seen a cb750 needle that was stamped anything else.

[PeWe]

I found my note on my phone.
Not in the directory I thought. Had to view them all to the date when I adjusted needles last time.

As I thought which also verify the 064A thread I linked to.
271307