Hi Max, I have diamond needle point files here I might have a go at putting a slight taper in the seat with the file in the battery drill I have tried one with the file on the seat and it might work, just taking the square edge off the seat and then polish it with the cotton bud and autosol. So far it seems to be shutting off and allowing fuel to flow with little float movement. Even putting pressure up on the float doesn't seem to be causing the needle to stick in the seat. Time will tell Cheers Norm
I'm not sure if the angle would be right on a file but may work if the angle is right , I was thinking of a grinding stone as you can shape it to any size and angle or possibly an engraving tool , I think the seats are cut at 60 degrees. It shouldn't too difficult to make or get something the right size ,the cut would have to be very small , even to machine up a metal shape the right size in the lathe and use valve grinding paste would work .
What I will try now is file and polish 5 primer caps and with a carby that I know is working properly fit the 5 primer caps and needles and see what results I get with each one. Then I will keep each set in individual containers so I can then fit them to carbys as I need and see if they work after sitting for some time. Very tiring but I have to do this before I commit to picking up another 30 motors. If they don't work I am done with them
The only problem I see Norm is if the angle cut on the seat isn't 70 degrees then the needle will have less contact.
I had a small 3 mm shaft rotary white stone that I would shape the angle of the stone with a bench grinding wheel dresser tool and that worked well to countersink any angle I liked.
The one I had was from an industrial supply shop and was a few dollars.
I advise not to change the 70° chamfer. Last night I have done comparison with the new primer cap untouched and retouched one. I have observed differences and improved on the surface contact (improved sealing property) and needle sticking. I think I need to do this properly on all our remaining stocks. I think this is overseen during manufacturing.
That certainly looks tapered I will have a look at some of the old one I have here. How did you pull the seat out, I have pulled them out before by screwing into them but this would mark the seat so be difficult to see what the seat looks like
I tried to extract the seat Norm but yes it will damage the seat as they are tight so I just filed behind the seat and pushed the seat from the other side as the cap had a broken primer bubble anyway.Only took a few seconds.
I tried that idea MF but the failure rate is too high and it is the hours I waste fighting trying to get a set that work, on and off the bench is driving me crazy. Never in my entire life have I ever had so much trouble with such a simple thing as a float needle
I've repaired G4 carbs since the eighties and any that were leaking I would put a new plastic needle in the carby and had no more flooding issues but we are talking about genuine Victa parts.
It does sound like the caps without the taper is the problem.
Industrial supply shops sell an 80 degree tool for about $20.
Ok this seems to be working, give it a good file in the battery drill, then polish the seat with Autosol. I can put a needle in and push up hard on the float and the needle doesn't stick in the seat and so far they seem to be shutting the fuel off. This was on primer caps that were holding the needle up in the seat so now I will set up a test carby and try a number of caps and needles and see if this has solved the problem. I don't think the file is cutting much off the seat but it is removing the sharp bur on the seat that was biting into the viton and causing the needle to stick. I hope this is the end of this never ending saga. Time will tell
Ok first test new needle, new primer cap that has had the seat filed, no sticking needle, no pissing out the primer bulb, gentle pull and it fired up perfectly. So one out of one is not a real test so I will try some more but I believe this is the answer to all the problems I have been having. Wish I tried this years ago would have saved me a lot of grief Ok now 3 out of 3 working perfectly straight up, no leaking, no sticking, so this is the answer, the seats need filing. I have only tried this on new caps and needles, now I will try using new caps and the needles that are in my reject bin because they either stuck or wouldn't seal. I expect they will all now pass without problems
I think you're on the right track and I have confirmed with microscope. I have removed one seat from a new primer cap. I knew there must be something on the top of the chamfer which you may suspect is a burr which is biting the viton tip and yes, you're right, there is. There is a slight bulging and microscopic burr around the top of the chamfer. This is due to the manufacturing process using manual press. The seat was machined using an advanced 7-axis CNC machine but the chamfer was done the final stage using manual press. During this chamfer press process with center guide, it pushed the top edge outward to create a slight bulge and microscopic burr. I will get back to the manufacturer to give them feedback about this finding and suggest them to improve the seat surface on our next order but at the moment I have to do all the mods myself on our remaining stocks.
Mowerfreak, You may need to modify your new primer cap to improve surface contact and sticking needle. You can follow this easy solution I did below.
My solution: Using a 3.7mm trimmer string rod with flat end for sanding the seat with 3.7mm sanding disc attached. . Punch-hole a 3.7mm 1000gritts sandpaper disc and glue it into one end of the string rod above. Use the rod with sandpaper disc on the tip on sanding the seat surface by spinning the rod by hand. No need to use drill or power tool to spin the rod. Use NormK autosol method for final sanding.
This really works great and shows a big improvement.
With unmodified seat, I can still observed needle sticking even when fitted with the new float lever. When quickly releasing the float, it took a second before the float drops. The sticking needle is holding the float for a second.
When modified and quickly releasing the float, the float will just drops instantaneous from zero to its gravitational fall.
Overall, there's no need to spend to source for special tool. There's no need to chamfer or grind the seat as it's already been perfectly chamfered at 70° for maximum surface contact with viton tip. Do not sand or modify the viton tip rubber. Only use the method above to remove the bulging and burr.
On the attached photos, the tip of the rod with sandpaper, a ring mark concentration on the center is very noticeable is due to the seat bulding in contact with the sandpaper disc.
