Topic: K0 - new acquisition, fueling issues

[Justin]

Hey all,
I'm on a hiatus from building my K1 because I'm mostly tapped out for cash and the engine building is expensive . That, and I'll be gone for four months until the end of December so I don't want to scatter any more pieces about the garage. 

So, needless to say, it being beautiful riding weather here in sunny California, which is totally devoid of water because of the drought...
I came across a K0 in okay shape, 1 hour from where I live. And I couldn't pass it up... 
So it came home with me and I got it running in less than an hour with some fresh petrol and some poking and prodding with the nonsense that the previous owner had caused...

http://forums.sohc4.net/index.php/topic,136912.msg1717754.html#msg1717754
this shows a video of it running after I had warmed it up and run it up and down the street at work. It lacks a clutch cable so I didn't ride it far or long, don't want to be unnecessarily hard on the transmission.

[Justin]

So, seeing the state of things, I decided that the first things that it would need is a proper carb rebuild, being that I brought it up to 2000' of altitude from down in the valley, and that it looked like the poor bugger had been sitting a while. Not to mentioned that carb #3 was spilling quite a bit of fuel from it's float bowl and drain.

The main jets were absolutely knackered... full of orange-y crud and gummy fuel deposits. The carb bodies were caked with nasty oily #$%*e all over. I got out some wire brushes, wire reamers and bought 8 cans of brake parts cleaner. It appears that the local Wally World doesn't have standard carb cleaner any more, though I'm sure that I bought it there only months ago, as I had the remainder of an aerosol carb cleaner can on the shelf in the garage..
ALL of the float heights were different and buggered up. I replaced only the float bowl gasket and the o-ring at the float bowl drains with new gaskets, I did not change the float needle or seat or the jets, but cleaned them as well as I could, quite thoroughly.

[Justin]

I disassembled the rack, wire brushed and cleaned as much as I could.. It took about 2 hours each carb.... which I suppose is good practice for when I have a go at the K1 carbs, which I intend to do a bit more thoroughly.. I only want to get the K1 running decently to putt around on until my K1 is finished, then I'll have a go at restoring the K0.
I reamed all the passages in the carb with wires and then blew them out both directions with the brake parts cleaner, did the same to the jets

I also took an emery cloth and lightly polished the brash jets, and the slide needle to clean some #$%*e off of them.
While I rebuilt each carb I soaked the float needle and seat in a strong Simple Green solution.

Additionally, and quite oddly, ALL the idle air mixture screws were set very differently, so I set them all to 1 turn out. These are the type with no holes, solid tips.

The carbs all had the original brass floats (which gave me great glee) and the original Keihin 120 main jets, 40 pilot jets, and the floats seats were stamped 2.0 or 20, I suppose I didn't look close enough....

[Justin]

This last picture shows one rebuilt carb next to the rest, which were not yet done..

This leads me to this point... I have the carbs rebuild and eyeballed the slides to visually check for approximate sync and saw that they looked even, not atrociously set. I have not yet brought out the syncrometer tool to check their sync..

When I put them back on the bike and set the gas tank down on the bike, I hooked up the fuel lines to the petcock/tap. Is there a specific order to which tap feeds which carb set??

It also appears that I am cursed with ongoing fuel issues. It seems to me that the bike ran much better with the carbs all buggered up than after the thorough cleaning... I suspect that I'm not getting fuel to the 3-4 carb set... the exhaust on those two pipes doesn't feel like they're giving off as much heat as cylinders 1 & 2. My K1 suffered the same thing, and it seemed like I had a bad petcock that caused it but I tore the bike down for a rebuild before I could verify what was really the issue..

at any rate: does any one have input as to what I should be tinkering with to try to alleviate my issues? I know I should probably remove the tank and rebuild the petcock to check for blockage.. and perhaps remove the carbs again and attempt to clear the petrol passages again.. perhaps I missed something?

[754]

Those are K1 or 2 carbs..not sure if 73 has brass floats.
Gas lines should not matter what hose goes on which barb.
 I would not use emery on any of the brass.

[Johnie]

Are you sure it is a KO? It has the K1 side covers on there too. Be sure to check those brass floats. They usually start to leak and draw in fuel making them heavy messing up the height. Take them off and shake them and listen for fluid inside. I got rid of all the brass floats in mine for that same reason. If they are not leaking yet they will. I put in the updated plastic ones. If you really want to get her running great do the 3,000 mile tune up...points, condensers, timing, valve and cam chain adjustment, carb sync and make sure that tank is clean. I see you are running pods and no OEM exhaust...that could change up the jetting and someone else will chime in about that.

[Justin]

Those are K1 or 2 carbs..not sure if 73 has brass floats.
Gas lines should not matter what hose goes on which barb.
 I would not use emery on any of the brass.

The VIN tag is missing, so I can't know for certain, but the stamp on the frame indicates that it's a (late?) K0. I can post the specific numbers if anyone is interested. That being said, the carbs on it are identical to the ones on my K1 (which has a build date of May 1971 according to its vin plate and frame stamp) and the both contain the brass floats. I do have brand new plastic ones that I was saving for my K1.

I'm in the middle of building my K1, so I bought the K0 to have something to ride, while K1 is being built..

It was a well-worn, green 3M pad that I used on the jets to brush off the black marks and caked on stuff. Thanks for the tip, what should I be using to clean the brass jets/floats instead?

[Justin]

Are you sure it is a KO? It has the K1 side covers on there too. Be sure to check those brass floats. They usually start to leak and draw in fuel making them heavy messing up the height. Take them off and shake them and listen for fluid inside. I got rid of all the brass floats in mine for that same reason. If they are not leaking yet they will. I put in the updated plastic ones. If you really want to get her running great do the 3,000 mile tune up...points, condensers, timing, valve and cam chain adjustment, carb sync and make sure that tank is clean. I see you are running pods and no OEM exhaust...that could change up the jetting and someone else will chime in about that.

well, I can't be totally certain, but i'm 99.9% certain that it's a K0. It's a 1970, and the frame number is in the K0 range, before the beginning of the K1 group. The VIN plate is removed , so I don't have the build date... I think that it's outfitted with a later side cover because the originals were broken. It looks to have a 19L tank: two tanks came with it when I bought it, one was on the bike, the other one was handed to me and went into the garage for spare.

I did check the floats for any holes, and I do have a set of plastic ones that I can use, but the brass ones seem to be holding up after 45 years..
I plan to do the 3000 mile service, but I would like to get it firing on all four first . I have a 4-4 exhaust set for my K1 that's not installed on it, but the K0 is a bit too rough for me to put $1500 worth of pipes on it  just yet anyway.

It came with someone's really stupid idea of pods on it.. two UNI foam types on the middle carbs and 1 with a cheap china pod filter, and 1 carb with no filter at all. I'm using a complete set of pods at the moment because it didn't come with an airbox.. I didn't really want to give it the one from my K1 unless I break down and buy CR29s for the K1 .

[Justin]

Thanks Frank and Johnie for your input! I'm glad to have a little help here....

[754]

KO ended at number 44,***... So under that is KO  they went to 44,6 or 44,8
Carbs were often changed as your type was deemed less trouble than  the 4 cable KO type.
 Any KO is worth having..I have a frame motor that is less than 200 from end of run.

[Justin]

KO ended at number 44,***... So under that is KO  they went to 44,6 or 44,8
Carbs were often changed as your type was deemed less trouble than  the 4 cable KO type.
 Any KO is worth having..I have a frame motor that is less than 200 from end of run.

Cheers, Frank

I'll double check the frame's serial # when I get home and let the mutt out for a tinkle on the lawn.
I'm wondering if the issue isn't related to the petcock? I wish Honda had only had one barb leading off the petcock and put a T in the line somewhere downstream... Whenever I take any tank off and drain it, the fuel only flows out of the one barb, this is true even of my wife's CB360 tank.

Is the slow flow to #3 & #4 a common issue? I'm wondering if something is blocking one of the balance tubes..? I should remove the carbs again and triple check each bit but I'm not feeling like it, what with all the heat. It's been about 40 degrees every day and the garage is too hot

[Justin]

CB750-1037663, puts it solidly in the K0 range. After the K1 is finished I'll start working on restoring this one to an original K0 condition