Topic: Question for the Sandcast/ KO guys

[guitarkev66]

I purchased a new throttle cable from Z1 enterprises .  It is the stock 1 to 4 cable setup.  I didn't adjust anything else and when I started the bike its idle was pegged at 3,000 rpm. I checked all the cables to make sure they were free moving , turned idle screws all the way out , and re started with the same problem. Do you think that the carbs need to be re synced due to the new cable?  It idled and ran perfect with the old cable I wouldn't think there would be so much of a difference between cables.  Is there something I am missing?

[Johnie]

You will need to resync the carbs. Figure the old cables were stretched. The new ones will be a bit tighter. Sync and you should be good. Don't forget to sync the slow idle now that you turned those down too. Let us know how you come out.

[trueblue]

Don't quote me on this but if I remember correctly there are 2 different lengths in the throttle cables for the K0's, if you had the longer ones and then installed the shorter ones you would have a high idle because the slides would be held open.  But I'm only guessing as I have no experience with the K0's and I'm only going on what I have read.

[Johnie]

Trueblue is correct...there are 2 long and 2 short cables. At least there are on the OEM cables. I am not sure what the setup is on the aftermarket.

[lucky]

I purchased a new throttle cable from Z1 enterprises .  It is the stock 1 to 4 cable setup.  I didn't adjust anything else and when I started the bike its idle was pegged at 3,000 rpm. I checked all the cables to make sure they were free moving , turned idle screws all the way out , and re started with the same problem. Do you think that the carbs need to be re synced due to the new cable?  It idled and ran perfect with the old cable I wouldn't think there would be so much of a difference between cables.  Is there something I am missing?

You have the good carbs.

That 4 into 1 cable arrangement is slightly different than the carbs with the lifter arms and shafts etc.,. With the lifter arm arrangement the idle turns up the idle on ALL FOUR CARBS at once.
On the 1969 carbs EACH CARB IDLE IS ADJUSTABLE.

Make sure the 4 into 1 box (tube thing) is well lubricated before putting it on the bike.

Install the cable so that the 4 into 1 box is centered over the top of the engine.
Do not cable tie it at all. It will cause big problems.


Make sure that all 4 slides are all the way bottomed out.
Look in the intakes.
Turn the adjusters on the top of each carb out untll the cable has no slack on all 4 carbs. Make sure the two long cables are on the outside carbs and the two short cables are on the inside carbs. You knew that right.

Then look at the idle screws. Each one has a letter T on it on the shaft.
Make sure that letter T is lined up with the mark on the carb body.
But more important make sure the idle screw is NOT lifting up the slide.
There is a photo in the Clymer's manual . The top of the letter Tshould be very close to the carb body,but in sight when looking down.

Then feel the throttle and id there is any slack in it take it out with the adjuster near the throttle grip.

Next turn the throttle very slowly and feeling the slide with your fingers make sure that as soon as the throttle starts to turn that the slide starts to lift up.
Do the inside carbs first. Get all 4 like that so that when you turn the throttle and let go you hear it snap closed with ONE CLICK not several clicks . Several clicks would mean the slides are all closing at different times.

Once that is done and works right you can move on.

Now start the motorcycle and get it warmed up with a fan blowing on it.
Turn each idle screw the same amount Just start with one outside carb and once it idles just make all the other idle screws the same amount.

NOW you can sync the carbs.
Turn the engine off and let it cool down. It is easier to have a cold engine to install the sync tubes. Then start it up and get all 4 carbs to be the same. DO NOT touch the idle screws.
USe the adjusters on the top of the carbs to get the sync gauges to be the same.

Now you are done.
You amy have to go back now and adjust the idle screws on some of the carbs. just watch your tach and turn each idle screw until yo see the idle go up a little and then back it off. Then you will know there is no slack in the throttle cable and the slide is touching the idle screw when the slide is bottomed out.

You will finally understand that on these carbs when you adjust the idle screw it is actually raising and lowering the slide a few thousandths and is actually SY"nc''ing the carbs.
The reason you adjust the cable adjusters on top of the cabs is to make sure there is no slack on any of the 4 cables to the 4 into 1 box.

Remember do not put cable ties on this cable that are tight on the cable! You can put them on loose to restrain the cable a little, but thats all.

Also make sure that the 4 cables from the carbs are pushed all the way into the round aluminum tube.

CLICK on the photo to enlarge it.

[lucky]

Trueblue is correct...there are 2 long and 2 short cables. At least there are on the OEM cables. I am not sure what the setup is on the aftermarket.

The two outside cables are longer to reach the outside carbs.

[lucky]

The forum member 754 knows about the 1969 cables.
There are longer ones  and shorter ones but all of the 4 cables are longer on the newer  sets to allow easier adjustments.

Also he said that some of the cables the newer ones were larger diameter as well.
Earlier ones were smaller diameter. Correct me if i am wrong.

[754]

 I have seen at least 2 types of junction 4-1  box or tubes.
 Also I am thinking here that the plastic throttle sleeve may be a bit different on the KO's  The early only had one hole for the cable end, and later had a second hole for the return cable.
 And some throttle cables had a wingnut to tighten the elbow to the switch housing, at least that is shown in the partsbook.

[Brantley]

My prevailing habit when reinstalling the tank on mine is to snag #4's cable out of the adjuster with the petcock so that it sits right on top of it and not in it. Same symptom. Sounds like you checked that, but it's easy to do and not notice (at least for me). One maladjusted or snagged cable will make the engine race. You could pull one spark plug wire at a time and see if yr revs drop and take it from there... And I don't care if you work in an open field at high noon with unlimited visibility with a coal miner's lamp strapped to yr head, the "T" on the #2 and #3 throttle stop screws is IMPOSSIBLE to see when the carbs are on the bike. Put a small corresponding mark on the knurl with a sharpie, white out, model paint- it'll make future syncs WAY easier.

[lucky]

My prevailing habit when reinstalling the tank on mine is to snag #4's cable out of the adjuster with the petcock so that it sits right on top of it and not in it. Same symptom. Sounds like you checked that, but it's easy to do and not notice (at least for me). One maladjusted or snagged cable will make the engine race. You could pull one spark plug wire at a time and see if yr revs drop and take it from there... And I don't care if you work in an open field at high noon with unlimited visibility with a coal miner's lamp strapped to yr head, the "T" on the #2 and #3 throttle stop screws is IMPOSSIBLE to see when the carbs are on the bike. Put a small corresponding mark on the knurl with a sharpie, white out, model paint- it'll make future syncs WAY easier.

Interesting point about snagging a cable when installing the tank.
But as far as the T mark on the idle screws you are not correct.
It is clearly visable . Unless the carbs are dirty with grease.
The photo in the Clymer's Manual is EXACTLY what it will look like.
Of course some of us may need to put on our eyeglasses to see it.
 Luckily I am nearsighted so I can see details without my eyeglasses.

[lucky]

I have seen at least 2 types of junction 4-1  box or tubes.
 Also I am thinking here that the plastic throttle sleeve may be a bit different on the KO's  The early only had one hole for the cable end, and later had a second hole for the return cable.
 And some throttle cables had a wingnut to tighten the elbow to the switch housing, at least that is shown in the partsbook.

There is no return cable on those 1969 models 754. It had not happened
yet at that time. The only thing I can think is that some company may have produced a two cable throttle cable for the 1969 carbs?

Horrible idea - that would really foul things up.

[754]

 I am not suggesting that the KO ever had a return cable..I am suggesting that IF YOU USE a 2 cable throttle  handlebar sleeve, with a 4-1 single cable setup.. then your freeplay will be altered.

[lucky]

I just wanted to add one little tip.

When you adjust the idle screws when you are are all finished you will know that
all the slack in the throttle cables is out between the carbs and the 4 into 1 box,when you turn the idle screw and it immediately effects the idle.

If you turn the idle screw and it seems to have no effect then that can mean that the throttle cable for that carb to the 4 into 1 box has a lot of slack in it.

Back in those days we did not use a vacuum gauge on those carbs for tuning the bike.
The vacuum gauges were used to trouble shoot the engine for more serious problems.

On the 1969 carbs we just used the adjusters on the top of the carbs to get all the slack out of the cables so that when you turned the throttle that all four slides would begin to move upwards at the same exact time. Then we adjusted the idle. Thats it.

We did not do a vacuum sync.

When you adjust the idle screws on those 1969 carbs you ARE syncing the carbs!
The idle screw lifts the slide to let in more air. That is why many mechanics got good at adjusting the idle screws because you were adjusting the slides up and down thereby syncing the carbs. The trouble is that with the 4 into 1 box if you tighten one of the cables for one carb then the other three will have slack in them.
So the carbs will have perfect equal vacuum at idle but as the 4 slides start to move up further the slides would get further and further uneven.

Anyway what it boils down to is, yes it is nice when all 4 vacuum gauges read the same and the idle is perfect, but it is also important that all the slides move up together.

The thing to remember is that with a vacuum sync the slides are only moving up a few thousandths of an inch when adjusted. Maybe about a .010 thousandths difference.

Do your vacuum sync on your 1969 carbs but remember with these carbs that after you have done you vacuum sync and you turn the idle screws you are effecting the sync at idle. So make sure you are turning the idle screws the same amount.

On the NEWER style carbs when you turn the ONLY idle screw it adjusts the idle for ALL 4 carbs at one time.

[lucky]

I am not suggesting that the KO ever had a return cable..I am suggesting that IF YOU USE a 2 cable throttle  handlebar sleeve, with a 4-1 single cable setup.. then your freeplay will be altered.

OK.. Got it.
That is exactly what I have. Because I do not have the original KO throttle sleeve.
Now that you say that I realize why I had a brand new throttle cable and I had to add 4 small 1/4 inch brass sleeves into the adjusters on the top of the carbs to get all of the slack out of the cables. I was lucky that the adjusters were deep enough to accommodate the sleeves and the throttle cable and be deep enough for the sleeve to be added.

You are sharp 754!!!

[guitarkev66]

Update, resynced the carbs and it runs perfect!!!! Thanks for all the advice greatly appreciated. 

[Johnie]

Amen brother!!!