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Rough running and no vacuum
Moderators: KeithZ1R, chrisu, paul doran, Taffus
Took the head off today, then removed the barrels. No.1 cylinder looks like it has seized on the skirt and has deposited ally on the wall of the cylinder. No.4 is also showing signs. No.s 2&3 look OK. Don't think its the carbs as the pilot galleries are all clear.
Probably look to re-bore it later this year when time and cash permits.
Probably look to re-bore it later this year when time and cash permits.
Which parts did you replace with new in the carbs?
Ignoring the float height and looking at the fuel level height, yes three mm is correct and needs to be so. In order to achieve this you will likely need to bend the tangs on the floats that shut the spring loaded plungers on the float needles. The reason for the original question is that my parts came in a Keyster box, After questioning them at length, it turns out the bowl gaskets came in the box,... but the other parts were re-manufactured by them and they got it wrong. In this case it was the relationship between the length of the float needle itself and the depth of the needle seat it sits in. Result was that the tangs on the float; hit the needle seat out rim before they shut the fuel off. (opposite problem to you).
Run a bit of clear tube off the drain up the side of the carbs. Turn the fuel on and run the engine. Dismantle carbs and adjust for the readings you took.
See the one on the end
Picture
Short video clip
AL
Ignoring the float height and looking at the fuel level height, yes three mm is correct and needs to be so. In order to achieve this you will likely need to bend the tangs on the floats that shut the spring loaded plungers on the float needles. The reason for the original question is that my parts came in a Keyster box, After questioning them at length, it turns out the bowl gaskets came in the box,... but the other parts were re-manufactured by them and they got it wrong. In this case it was the relationship between the length of the float needle itself and the depth of the needle seat it sits in. Result was that the tangs on the float; hit the needle seat out rim before they shut the fuel off. (opposite problem to you).
Run a bit of clear tube off the drain up the side of the carbs. Turn the fuel on and run the engine. Dismantle carbs and adjust for the readings you took.
See the one on the end
Picture
Short video clip
AL
1981 J1
Replaced everything in the kit. I did have to bend the float tangs a long way from where they were to get the book figure of 18.6mm. Gravity fed the carbs last night and had 20mm fuel height from the carb split line. Will try again and open the tank cap just to see if the breather is blocked. If the fuel level is low it explains why the bike doesn't idle properly.
If youre using a piece of clear plastic tube as above then the dynamic fuel level is what you see in the tube. I run the engine to make sure it doesn't fall.
When you take the float bowl off by releasing the screws as the bowl and fuel in it drops off it may open the float valve and empty the contents of the fuel pipe and cross (balance feed tube) tube into that particular bowl making the level look higher than it actually is.
There should be two tabs on the float.
One is to set the fuel service level and the other limits the amount that the float falls to, as a maximum.
Which ones have you bent and in which direction.
Guessing at the one that contacts the needle valve and you bent it towards the needle valve and its seat!!!!! In other words it is shutting off too early.
Not forgetting that everything is upside down and back to front until you re-assemble; if its at 20mm now then it likely wants to go the other way.
AL
When you take the float bowl off by releasing the screws as the bowl and fuel in it drops off it may open the float valve and empty the contents of the fuel pipe and cross (balance feed tube) tube into that particular bowl making the level look higher than it actually is.
There should be two tabs on the float.
One is to set the fuel service level and the other limits the amount that the float falls to, as a maximum.
Which ones have you bent and in which direction.
Guessing at the one that contacts the needle valve and you bent it towards the needle valve and its seat!!!!! In other words it is shutting off too early.
Not forgetting that everything is upside down and back to front until you re-assemble; if its at 20mm now then it likely wants to go the other way.
AL
1981 J1
If I drain the fuel from each bowl I am getting about 60ml of fuel out of each carb.
Looking at the tang with the carbs fitted to the bike and the bowl removed the tang is bent towards the floor.i.e away from the needle valve, so the float has to rise further to shut the valve off. Increasing the fuel height in the bowl.
Looking at the tang with the carbs fitted to the bike and the bowl removed the tang is bent towards the floor.i.e away from the needle valve, so the float has to rise further to shut the valve off. Increasing the fuel height in the bowl.
To get some idea of what we are talking about this is the situation with mine as of today.
Ignore the 'cranked' nature of the tab. I did it that way so that the tab acts on the needle rod perpendicular and not on the angle.
As you can see they are more or less flat to the surrounding material of the float part its pressed out of, give or take.
When measured, up side down, my float heights measure 21 mm where they should be 18.6mm. Again ignore this because of the miss match of needles and seats that i have.
Looking in the manual another possibility exists. It says that if you cant get a correct reading from adjustment of the tabs then the floats may be punctured!!!!!
AL
Ignore the 'cranked' nature of the tab. I did it that way so that the tab acts on the needle rod perpendicular and not on the angle.
As you can see they are more or less flat to the surrounding material of the float part its pressed out of, give or take.
When measured, up side down, my float heights measure 21 mm where they should be 18.6mm. Again ignore this because of the miss match of needles and seats that i have.
Looking in the manual another possibility exists. It says that if you cant get a correct reading from adjustment of the tabs then the floats may be punctured!!!!!
AL
1981 J1
Thanks for the info. Checked the float valves against the old ones and the new ones are about 1mm shorter. The depth of the drilling in the brass bit is shallower. So I guess this allows for it. The floats aren't catching on anything.
I put one of the floats in water last night and it seemed fine. I have checked the airways in the carbs and they all seem clear.
Now it has different barrels, pistons, rebuilt head, I might try and run it again to see if that has made a difference.
I put one of the floats in water last night and it seemed fine. I have checked the airways in the carbs and they all seem clear.
Now it has different barrels, pistons, rebuilt head, I might try and run it again to see if that has made a difference.
Had the bike running again today and it does seem a bit better.
The main problem I found initially was that the plastic air filter cap didn't sit down properly. It looked to be in position, and I had the bike ticking over at 1000 rpm. I then pushed down on the filtercap and the revs suddenly shot up to 3000 rpm. Adjusted the tickover and was ticking over fine again. Now pulling a vacuum of around 14cmhg rather than 22 stated in the book. Difference between cylinders is approx 2cmhg across all four.
I think the cap might be a bit deformed so will tanktape it in place tomorrow to see if it makes another difference.
The air filter is a brand new kawasaki part.
Still have the issue with the fuel level, which I don't understand at all.
The main problem I found initially was that the plastic air filter cap didn't sit down properly. It looked to be in position, and I had the bike ticking over at 1000 rpm. I then pushed down on the filtercap and the revs suddenly shot up to 3000 rpm. Adjusted the tickover and was ticking over fine again. Now pulling a vacuum of around 14cmhg rather than 22 stated in the book. Difference between cylinders is approx 2cmhg across all four.
I think the cap might be a bit deformed so will tanktape it in place tomorrow to see if it makes another difference.
The air filter is a brand new kawasaki part.
Still have the issue with the fuel level, which I don't understand at all.
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