Engine. Problems, problems...

[Dandare]

I have an 8th .25 engine which is new, i have run 5 tanks through it, the last race evening it was still set rich for 2 heats then just before the finals the pull start snapped (5th one overall, lol)

Now, i've bought an SMD starter box, set it up fine. I've removed the pull start from the engine but used the plastic housing to cover things up as i don't yet have a backplate.

Here's where things go wrong. When i started the engine on the box in my garage the engine suddenly raced but, the throttle slider was in the idling position ie, 1mm or so gap. i had to close it down pronto before it done any damage. At this point i didn't have the electrics on, i just manually operated the throttle. This happened yesterday.

Today i try again, same thing, though when it fired, the idle was eratic then it raced so i had to shut it off, again, the throttle was either on idle or very near so.

I now don't know what to do, all needle settings are as per the last race evening where it ran 2 heats fine.

Is there something i'm missing when converting from pull start to a box or has some dirt miraculously got into the carb inbetween use? I don't know.

I've had such rotten luck with these damn things lately it makes me want to race 10th electric, lol.

Any suugestions welcome.

Dan.