Anyone have any tips to put an o-ring on a high speed needle. I am attempting this on a carb for a Picco .12 engine. The o-ring sits between two metal 'rings' cast into the needle. When I try to slide the o-ring over the metal ring it breaks due to how wide it has to be stretched

Are ya using the same size and type o-ring as per original?

Usually, I will lube it with a little fuel to help it slip over.

O-rings can be a problem. To work well, they must be tight. This conflicts with ease of instlation. One of the main reasons for O-ring failure on instlation is using a tool that cuts the ring.

For installing on a needle valve, the best way is to use some fuel as a lube as Proptop suggested, then roll the ring up to the edge of the grove it will rest in. Now, pinch the ring with your fingers, you want to stretch a little loop on it. Now, holding the ring pinched, roll the loop over the edge. You want it to just hang on the edge, don't try to get it into the grove. Now, release you pinch and roll the ring up and into the grove, and then roll in around the grove until the whole ring is in place. Kind of imagine it is a tire going on a rim. You have to start it at one point, and the roll it around the rim. If you try to stretch it over the wide spot all a once, you are bound to break the ring.

Don

I am using a sawing needle as a rail to slide o rings into that groove on High speed needle otherwise I cant step up the wall of groove.Put the sawing needle parallel on the needle and try to push o ring on both of them.When you reach the near spot,use sawing needle like lever to slide into groove.
Good luck

Thanks for the info. The method describing it as comparing it to mounting a tire on a rim makes sense. We use to do this when we raced karts. I will try it and see what happens. Thank you again...

You have to be very careful not to let the point of the needle touch the O-ring. It will cut it as quickly as a razor. I used to rebuild hydraulic equipment and O-rings were always an issue. I've broken and damaged many an O-ring over the years. Sharp edged, either on the tools you use to install them, or on the groves they rest in will quickly do in a ring.

You could take a needle and using a very fine whet stone or India stone, radius the point to about 3/4 the diameter of the needle. This will help a lot to prevent damage, but you still have to be careful of damaging it.

Don

First: You are probably using an O-Ring that is to small for that needle valve. Looking at the picture, sliding that O-Ring OF THE CORRECT SIZE into the groove should not be a problem.

Second: Dont get to fancy, you are very likely to damage the oring by using a needle or other tool. Just push it over the ridge and into the groove with your figner and fingernails. If its so tight that you can not, than I say again, you are using an o-ring that is to small.

Third: Maybe you are using an O-Ring that is old and brittle. Bottom line is putting this ring on the needle should not be an issue. If it is, something is wrong with your O-Ring

JettPilot

Guys,I dont use needle after o ring placed on valve,I am using needle as a skid parallel with the valve.So no possibility of needle point damage.After sliding o ring enough close to the groove over both "needles", then using sawing needle as a lever to place o ring over groove
and slowly sliding back the sawing needle to allow o ring sit firmly onto its home.

O-ring is brand new and order as per the stock number as listed in the manual...