Can't keep a rear tube on son's bike

[2strokerfun]

Maybe this should go in pit bike/minis or maybe vintage, so I chose neither and put it here !!
Have 1974 Honda XL70 I rebuilt for my son. It has chrome 14" rear rim. No rim locks on this bike. For some reason, I cannot keep a tube in it. Tire/tube shift and I get valvestem leak. Thought about drilling a few small holes in rim and putting in small screws like we used to do with drag cars, but I really don't want to ruin this rim. Tried really tightening the valvestem nut. No good. Tried loose valvestem nut. No good. Anyone ever faced this problem and have any suggestions?? (And I've decided that the smaller the wheel, the more I hate changing tires!!).
Thanks

 

[IndyMX]

Can you drill a hole and add a rim lock? That'd be the best bet..

 

[2strokerfun]

I may have to try!!

 

[mideastrider]

Indys right just install a rim lock. Its not a big deal just make sure you get one for your width rim and you will be good to go. If you don't want to install a rim lock just run more air. If its necessary to run low air pressure the rim lock is the only way to go.

 

[2strokerfun]

Ya know, I never really thought about running more than 15 psi because that is what I do. But with a smaller wheel/tire/tube maybe I should run something like 20-25 pounds.....

 

[COLEMANAPP]

One of my son's riding buddies always does the same to his DS 80 with no rimlock. Rather than change his tire all the time, I make him run 40 psi and we haven't had any problems. He doesn't notice the extra tire pressure.

 

[Bonehead]

You can get a rimlock cheeper than a tube. I had to put them in all my sons 50's and 70's it ends the problem and you may not have to help them up that slimy hill if you run lower air.

 

[pesky nz]

you will be able to read the rim width stamped into the rim close to the valve hole and get the correct size of rim lock (I advise one with a solid alloy centre) and I agree with bonehead that high pressure is an unnesessary handicap to put on a young rider