I recently bought 2 Turnigy Nitro RC cars to have a little fun with, whilst being fully aware of them having a problem with the starter mechanism I hoped that HobbyKing would have resolved them by now, but unfortunately not.
I bought a Truggy for £50 and a Buggy for £70 and managed to start them both twice before the pull starter began to slip. I took the buggy engine apart and found no obvious problems, but there was a lot of oily residue covering pretty much everything, even the pull starters chord and this seemed to be the reason it was slipping.
Searching online at the HobbyKing website I found various posts about replacing different engine parts but the most promising said that a Graupner 92600.117A back plate was the ultimate solution and stops the oily residue from the fuel seeping everywhere.
All in all it looks like a design flaw with the engine, but two new back plates are on their way from Germany, £30 inc postage and should be here in a few weeks.
Update 16/08/2015 –
The new back plates fits nicely and the engines have both turned over flawlessly since. The pictures below show briefly how it was done to the buggy engine, the same steps were repeated for the truggy engine too.
A video will be attached soon showing the cars in action.