MDS 40

I have just bought an un-run MDS 40 2-stroke on Ebay for £30. Also, I have been reading some forum topics on MDS engines (generally from some time ago when they were available). There was a majority subscribing to the view "... they're junk ..." but also some who thought they were great!

I have put through 3 or 4, 4oz (110ml) tanks full on a running in regime and it has become much better over that time but still not reliable enough to commit to a plane.
The biggest problem seems to be throttling up to max speed from a period on idle or a bit above (4-stroking).

I would appreciate any advice or comments with regard to the engine and it's settings.

Thanks,
Phil.

Hi Phil, I had one a few years ago, at the time, "MDS" was reckoned to stand for Metal Door Stop. My engine was OK at starting, but throttling was unreliable. Finally I took the problem to Just Engines, they recommended one of their twin needle carburettors. After swapping the original carb for the J'EN one, the engine was transformed. I can only say that the MDS .40 was the easiest starting and the most flexible running two stroke i ever had. I don't know if Just Engines still have a suitable carburettor, but it would be a good place to start.

Thanks Brian,
The more running in it gets, the better it becomes. I note in the instructions they recommend not adjusting the low speed needle until at least 3 hours of running./ I'm not there yet and I'll see how it is then before looking to change the carb. Thanks for the advice re Just Engines; I have found them very good in the recent past.
Kind regards,
Phil.

Engines do tend to improve during the first hours of running. My MDS was an early model from RipMax(I think). Initially, the throttle response was so erratic, I locked the throttle open, sleeved the intake, and used the engine in a control line model. The final cure was the J'EN carburettor, the engine is now in a Gangster "somewhere in the South of England". The last I heard of it, it needed two flicks to prime and one flick to start. The new owner never uses an electric starter.

I had an MDS 58 in a .40 sized propjet. Never had any problems and with stock carb. Probably a later variant though.