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How much dashpot fluid is needed?

2K views 23 replies 10 participants last post by  rayjoe 
#1 ·
Does any one know how much dashpot fluid (50,000CST silicone fluid) is required in the tachometer?

And How does one put the fluid in the tach? Where does it go?

I have the tach apart.
 
#4 ·
May as well check the air pressure in your speedometer while you are in there. Nitrogen fill if it's low.
 
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#5 ·
dashpot fluid

Dashpot fluid is used in some older carbs. Not in the carb per se, but in a little can or pot attached to the throttle plate shaft. I believe it was used to prevent throttle plate flutter. And he might be referring to fluid used to dampen the tach needle. Older tach and speedos used fluid as a means to prevent the needles from bouncing.


That's my story and I'm sticking (pun intended) to it!


Rayjoe
 
#10 ·
The gauges that I've seen use fluid in a "can/pot" that is attached to the needle shaft. I not sure if you can get fluid into it thru the cable hole. Anything is worth a try.


Rayjoe
 
#11 ·
Ken
You are probably correct in that the tach does not use fluid.


Rayjoe
I hate it when I am reading some one else's post and they do not state what they are working on. I am very guilty of not stating what I am working on.
It is an 83 gl1100.

I have the tach apart. I see the can/pot on the needle shaft.
Now I will try to figure out how to refill it.

I have had 3 tachs on this bike so I tried to research and get one to actually work. I have replaced the cable.
I assumed that the tachs had fluid in them as they say not to store them face down.
When Honda sold them in the box. The box stated to keep this side up.
 
#13 ·
Ken

I have the tach apart. I see the can/pot on the needle shaft.
Now I will try to figure out how to refill it.
How about a picture of the tach with the "can" showing?

Can you move the needle with your finger?

Going to an X-mas party now. Check in with you later.


Rayjoe
 
#17 ·
Had one apart and it was driven by the cable and what I would call a magnatic spinner inside a cover that looked like the round thingie.
 
#18 ·
I have taken apart many speedometers from old cars just to see what made them tick. There is a spinning magnet inside that can that is spun by the cable. The clearance is very critical so everything works correctly, probably why they are boxed 'this side up'.
 
#20 ·
fluid

Back from the party!! Nice evening.

So, back to your tach. I tend to agreed with bike and Dennis. Looks like a standard setup.

What is the tach doing, or in this case, not doing?

Have you checked that the drive is working?

Did you replace the whole cable, or just the inner?

Later,


Rayjoe
 
#21 ·
Here's a discussion of this topic. The CB750K does have a dashpot containing silicon oil. You may find your answer reading all 3 pages. There are URLs to other threads too.

http://forums.sohc4.net/index.php/topic,78890.msg880290.html#msg880290

I think Wilcoy is correct. I thought the thing was a bearing but apparently it's a dashpot and storage of these gauges is supposed to be face up to retain the fluid in the dashpot
 
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#22 ·
I replaced the whole cable. I pulled the new one by taping it to the old one and pulled the old one out. So the cable is routed as the old one was. I also replaced the seal at the fuel pump.


One of the tachs shows 3-4000 at idle. When ridden it goes all the way around to the peg and falls back to between 6-8000 rpm's and bounces all the time.


The second tach makes a terrible racket and jumps all over the dial.


I am trying to learn how these tach's work
 
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