Installing a Ryobi/Ryan/IDC duckbill into a McCulloch 250 fuel cap

[promac850]

Well, long story short, Eccentric's babbling about duckbills in another thread reminded me that the cap on the 250 needed a new (or lightly used) one installed.

So... I dug around for some old fuel tank caps. I happen to have a small pile of old string trimmers that aren't doing anything but residing here. Found a cap off of an older 80's or early 90's IDC trimmer fuel tank. Had a good duckbill in it...

Then I took a punch and carefully tapped the bronze filter out of the 250's cap. Used a small screwdriver to remove the old gooey crud from the long gone duckbill that left the factory in said cap.

Next, I pried the top piece of the IDC's cap off. Again, the small screwdriver is used for this. Pull the duckbill valve out and check it and make sure that it is not starting to turn into goo.

Here are the caps, the Ryobi/Ryan/IDC cap is on the left, while the Mac cap is on the right.

Once that is done, set the duckbill into the recessed part of the McCulloch cap, notice it doesn't go in. Grab a punch and gently push it in... bottom it out in the cap.

Then find a tiny brass nut and drop that in there. Line the hex up with the hex that is formed in the duckbill valve flange.

Now you drop the bigger nut (no idea what size either one is... I just happen to have all kinds of random hardware laying around. I took a lot of stuff apart when I was younger.)

Then carefully tap the bronze filter back into place on the top of the cap. All done.

Dimensions of the duck bill valve will be in the next post...

 

[promac850]

 

[galde]

It is a given that all duckbills, as well as all fuel & oil lines, primer bulbs, carburetor diaphragms, etc.. will eventually have to be replaced. I try to fix every saw that I intend to keep so that the fuel tank and oil tank vents are easily replaceable. I don't like vent holes that are partially closed with small cotter pins or pieces of wire. I seal off such openings with J-B Weld and modify the oil caps and fuel caps by drilling a tiny (#80 drill bit) hole from the outside and a larger shallow hole from the inside to hold a stub length of brass or stainless tubing which is long enough to be secured with J-B Weld onto the cap and to hold a Homelite duckbill slipped onto the other end. The brass ink refills that came in ball point pens years ago are ideal for this purpose.

 

[promac850]

It is a given that all duckbills, as well as all fuel & oil lines, primer bulbs, carburetor diaphragms, etc.. will eventually have to be replaced. I try to fix every saw that I intend to keep so that the fuel tank and oil tank vents are easily replaceable. I don't like vent holes that are partially closed with small cotter pins or pieces of wire. I seal off such openings with J-B Weld and modify the oil caps and fuel caps by drilling a tiny (#80 drill bit) hole from the outside and a larger shallow hole from the inside to hold a stub length of brass or stainless tubing which is long enough to be secured with J-B Weld onto the cap and to hold a Homelite duckbill slipped onto the other end. The brass ink refills that came in ball point pens years ago are ideal for this purpose.

I have read about such modifications around here. However, it does permanently alter the cap.

This saw is almost entirely original, thus why I did not do anything that is permanent.

I did some research and it appears that this fuel cap (came off of an IDC 520) is obsolete. I will need to figure out if there is a different way to use the Homelite duckbill that doesn't require any permanent modifications to be made to the cap.

Now that I think about it... it sounds kind of hypocritical... here I am with a ported PM850, a soon to be built ported 790, and I want to keep a fuel cap entirely original. I must be nuts.