What is off topic p nut? I'm still talking about slide action. My question to you has to do with your statement that the slide couldn't be lifted all the way with the hole covered.don't take this thread off topic WER
What is off topic p nut? I'm still talking about slide action. My question to you has to do with your statement that the slide couldn't be lifted all the way with the hole covered.don't take this thread off topic WER
Use finger nail polish/super glue at the slide and diaphragms junction. Make sure you have the slide oriented before applying.
Use grease/vaseline at the where the diaphragm seals to the body.
Thank you for the edit. Makes a lot more sense now. Well, can't take a picture as I am currently at work. So let me just make sure I understand this correctly.
The proper way to test my brand new diaphrams that I installed from JDM is to lift the slide with my finger, while it is lifted up, block the vent hole. If it drops, then there is a leak or the seal is not perfect. If it stays elevated in the air and does not drop then there is nothing wrong with the seal and it is working perfectly. This would make sense.
I read some older posts about the JBM diaphragms and there being issues with them not sealing correctly and in some cases the slides would twist out of place. It's hard for me to understand HOW I'm going to get the diaphragms to stay put. When the diaphragms caps are off you can easily pull the diaphragms off of the seal as you go in a circle around the diaphragm body. Should I be super gluing them or something? I don't see Vaseline working that well....
No do not glue them.
Look ... place a drinking a straw in a glass of milk and suck the milk up to the top of the straw. If you place your finger on the top of the straw the milk stays where it is ....why is that? It is because in order for the milk to drop something (air) must take the place of the milk. But nothing can get into the straw because you've blocked the top off with your finger.
However if you lift your finger off the top of the straw slightly the air rushes in allowing the milk to drop. That is the principle.
Now the Mikuni carb has a small hole in the slide which allows a very small amount of air to move from above the diaphram to below and visa versa. This tiny hole regulates how quickly the slides moves up and down which in turn regulates the amount of fuel drawn through the needle jet from the fuel bowl.
The air leak is probably absolutely miniscule ...much less than the size of the hole in a drinking straw . By smearing vasoline around the edge of the diaphram it can prevent tiny air leaks from slight imperfections on the carb body or cap. You shouldn't need to put anything on your new diaphrams if they have been fitted properly.
I think some put a dab of Super Glue between the slide and diaphragm so they don't twist in one anther. I don't think the JBMs have a locating tab on their outer edge like the originals did. You just have to get the slide oriented correctly before you screw the top on.
amazing ....all the hard work is done already but now everyone and his Mother wants to have some imput
As 5twins says on the original diaphragms there is a tab on the edge to help you get the slide facing the right way when you put them back in the carbs.
The little hole in the bottom of the slide must face towards the engine . Do you remember checking this on both your slides ?
just ignore weekendrider.... he is only here to wind me up and to try and take credit for someone elses hard work as usual.
You don't Super Glue the outer edge to the carb body, you do the inner ring to the slide. The top, once screwed down, is more than enough to keep the diaphragm from turning in the carb body. I answered your question about slide drop in post 35.
there is your problem right there !
great vid by the way.
Your diaphrams are not sealing somewhere. I had a similar problem and couldn't afford new diaphrams so I smeared vasoline around the edge of the diaphrams where they sit in the lip and a little on the covers and now they are perfect.
The reason that your engine is bogging or going flat off idle is because when you twist the throttle open your slides are leaping up the slide well which is creating a huge immediate low pressure in the venturi. This means your engine cannot draw the extra fuel it needs .
You must hold your thumb or finger over the top vents when the slides are raised up before testing the diaphrams for leaks. (thanks 5Twins)
If your slides do not stay up then you have a leak somewhere either round the edge or at the centre