When your back in the carb verify the jet sizes, just to cross that off the list in case the new needle and seat doesn’t work
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carburetor spring weight
- Thread starter Spoody6677
- Start date
Spoody6677
Member
Sorry guys, this is a less 1 hour on this needle and seat, just came across my ski records, I remember putting in a Silver
spring, other damages, should of been black.
spring, other damages, should of been black.
Spoody6677
Member
maybe a pirate version, who knows
Spoody6677
Member
That's what I was afraid of, crooks
Spoody6677
Member
I hope that I wasn't to order 2.0, but should of order the 1.5
Spoody6677
Member
I don't have the right spring, and can't locate, you said something about washer under spring and highest gram I can find
Yes, it’s something I read somewhere, never had to try it myself but your spring is supposed to be 130 gram spring, it’s not available anymore so you could try te heaviest spring available which I believe is 115 gram and then put a washer beneath the spring in the carb. I think the washer should increase your pop off but I’m not 100 percent sure, again this is just from something I’ve read but I would add 1 washer then do pop off test, see if it gets you within the right range, if not add another washer and test again. Since you’ve lost the original spring this is the only thing I can think of doing except for going with a completely different set up with different jets, spring and needle
Spoody6677
Member
I ordered the 2.0 needle and seat from OSD, not sure what to do on spring, I have several, maybe play in and out after test
If you don’t have the 130 gram spring which you say you don’t you are not going to achieve the proper pop off with any of the other springs. I’ve been looking this up a little and cane across a thread similar to yours. In the thread the poster stretched the spring to achieve higher pop off, I wouldn’t recommend stretching the spring but I would try a spacer beneath the spring ,
Spoody6677
Member
I wonder if they meant 2mm instead of .2 what about bending lever arm, a little upward, not sure about that
Maybe, .2mm isn’t very much
BrianMoore
Member
mikidymac is correct about springs. There are two basic things about springs regular people should understand, preload and spring rate. If you don't understand, read about it a little. Adding a washer or bending the arm or bending the spring (shudder) are changing the preload. Wire diameter, number of coils, spring diameter determine the rate. if you wanted to increase the rate, cutting a few coils off would increase the rate, but at the same time it would shorten the spring and decrease the preload for the same height.. Then it would be required to shim it for the correct preload. These springs are so tiny, it would be impossible for me to accurately measure the things I would need to know to calculate how to do this. Sure sounds a lot easier to find the correct spring.
Spoody6677
Member
I got those check screens in mail, thanks again, waiting for OSD needle and seat, should be here Friday, I going to put back together, I have had several springs in this carb, and one was close to 36 pounds on pop off, no never
found a genuine 130 gram spring.
Spoody6677
Member
Nope, maybe buy BINGO roller, and throw in all my springs and pull one out, and try it Lol
Yes, I’m not grasping the preload and spring rate premise. But basically the spacer thing won’t work then? I will try searching for information on the preload and spring rate but if you come across any good articles in it please send a link
BrianMoore
Member
Think about diving boards. Long board will sink a several feet from the base when you stand on the end. It feels soft under foot. So you adjust the board up with an initial arch so you only sink a foot from the base. This is adjusting the preload. However it will still stay soft under foot. This is the spring rate. Shorten the board. Now it sinks down a foot when you stand on the end and it will feel stiffer when you jump on it. Coil springs are just a diving board in the shape of a helix. Pop off pressure is how much it takes to open the poppet. But after it opens, it is the spring rate that determines how far it opens. Gosh I wish I could explain it better without a piece of paper and a no. 2 pencil.
I have a better idea now if the terms, Let me see if I have it, let’s just use the actual spring in the carburetor as a reference. If a spacer let’s say a washer was placed beneath the spring that’s going to stiffen up the spring making the spring harder to compress let’s say the 1/8” needed to lift the needle to open position. So when the spring is moved up with the spacer increasing the tension on the spring as it now sits in an area that is the width of the spacer shorter the PRELOAD has been increased. ? Is that correct thinking? Would it be fair to say that if the preload is increased the pop off would be increased ? Not sure I understand the usage of spring rate, is it being used to mean the distance the spring will travel? Since it has been spaced up the force needed to compress it has increased (PRELOAD), And with an equal amount of force applied it will no longer travel as far (SPRING RATE) ? The springs are rated in grams 65, 80, 95. 115, 130 . Is that the actual weight of the spring, No right? I’m thinking back to when I was a teenager , no way that spring actually weighs 65 grams. So is grams referencing the force/weight needed to compress the spring a certain distance? I’ve been wondering about that for awhile now.
The grams are the stiffness of the spring. Increasing the preload will increase the pop-off but not the spring rate.
Keep in mind Pop-off is just a test of the spring, arm and needle/seat, it is not how the carb actually works.
When the carb is on the ski and you open the throttle butterfly there is a negative pressure inside the carb and a positive pressure with the atmosphere, this pushes the big rubber diaphragm against the lever arm, overcomes the spring pressure and opens the needle allowing more fuel into the carb. This diaphragm has a range of motion so changing the spring tension changes how much the diaphragm moves the lever arm and needle. So adding preload will change the opening pressure but not really the range of motion, this is why you change spring weights and not just adding more preload.
The stronger the spring the leaner the fueling will be since the diaphragm needs more vacuum to move and allows less fuel into the carb. A lighter spring will allow more fuel in under less vacuum and make the carb richer also a large needle and seat with a lighter spring and the engine vibration can cause the carb to dribble fuel and cause a rich bog and flooding, this is why high pop-off pressures are used.
Keep in mind Pop-off is just a test of the spring, arm and needle/seat, it is not how the carb actually works.
When the carb is on the ski and you open the throttle butterfly there is a negative pressure inside the carb and a positive pressure with the atmosphere, this pushes the big rubber diaphragm against the lever arm, overcomes the spring pressure and opens the needle allowing more fuel into the carb. This diaphragm has a range of motion so changing the spring tension changes how much the diaphragm moves the lever arm and needle. So adding preload will change the opening pressure but not really the range of motion, this is why you change spring weights and not just adding more preload.
The stronger the spring the leaner the fueling will be since the diaphragm needs more vacuum to move and allows less fuel into the carb. A lighter spring will allow more fuel in under less vacuum and make the carb richer also a large needle and seat with a lighter spring and the engine vibration can cause the carb to dribble fuel and cause a rich bog and flooding, this is why high pop-off pressures are used.
Spoody6677
Member
Well no holiday on lake, OSD gave me usps priority mail tracking number, not even in system was to be delivered today
Spoody6677
Member
Excellent overview, allot to sink in, so there could be multiple problems, pulse, spring, diaphragm, seat, needle valve, crank leak, maybe smash some holes in the hull and push it off the bank
