I have a ofna hyper 7 and for some reason i keep breaking the strings in my pull start.... I have been in this hobby now for about 7 years and have not ever seen this.... but i seen on youtube that a guy put a metal pull start string on his 1/5 scale so i got to thinking it should be the same principle for nitro pull start so i went out to the building and cut the shift cable off an old mountain bike... same thickness as the string but a whole lot stronger....

I have not tried putting this on yet but has anyone else done this? will it work?

Not sure the recoil spring would be strong enough to roll up the cable.

no reason metal can not work but think you need to need to find something a little thinner or that is less rigid so that it will recoil back in.

The other thing to check into make sure you are not getting too much fuel into the engine before pulling the string. I know on the engine that was in the car I bought I broke the string pretty quickly and I didn't feel like replacing it so I used the bump starter - after throwing the rod in that engine I replaced it with an Axial .28rr2 and I quickly realized I was getting too much fuel in the engine on cold starts - Now I just prime it enough to see fuel reaching the fuel nipple on the carb and then I stop. Will take me one or two more pulls with the ignitor on it and she fires right up. I never re-prime on hot starts

True, cannot rule out a hydra-lock situation on the engine.

Guitar/harp/piano wire? Don't know if it has the right sort of 'memory' for rolling back up though.

Agreed with the hydra-lock possibility.

You may want to try and loosen the glow plug a little so it doesn't 'lock' so easily (I'm talking about a 1/4 turn loose from wrist tight). Once it's running, tighten the glow plug back down.

spider fishing line the braded type works great.