ST GS 45 paperweight

Jul 31, 2003 7 Replies

I too have had probelms with a five year old GS 45 = paperweight now.



Tried 4 plugs, 3 fuels, 2 silencers, a Conley pump, an an Irvine and ASP mark 3 carb.



The only thing I did not try was onboard glow.



The symptom was always much the same, the engine would idle and top end fine, but quit at about 60% throttle.



I have often wondered if the porting is a bit quirky on this motor and always fuel to build up in the crankcase. I think the earlier 40/45's had more but smaller transfer or boost ports ?



The earlier 45 and a 51 in our club run fine though.


Colin


Sadly, all that was needed was another carburetor. A lowly Perry carb would have sufficed.

It is a shame to witness the masters of engine making decline and then disappear. Perhaps their resurrection in China will bring back some of their former luster.

Ed Cregger

You still can use the method, as it also corrects sloppy manufacturing practice of the later batches of ST carbs, especially the sharpness of the cat's eye milling in the spray bar.

Try a Fox Miracle plug in it.

Did you try rotating the spraybar 30 deg to the rear? That usually helped over rich midranges.

Thanks to you and Pe for your comments.

Yes I did try rotating the spraybar.

Also per my much earlier post I had tried both a late ASP Mk 3 and an early Irvine carburettor, both of which had been OK on other engines. The same symptoms were present, quitting at 50-60% throttle, although reduced. So I ruled out the carb as the cause ....... and as I have also remarked, there seem to be porting differences between the earlier and later GS 40's and 45's.

Also as per the earlier post I had tried various plugs, fuels and silencers. I bought my first Mills 0.75 cc in 1957 and this is the first engine I have given up on - my remaining life is too short !!!!

Regards

Colin

Can I give it a shot? I never had one I couldn't get to run.

Sorry Paul it has been given to a friend with a much earlier ST45 that actually runs quite well.

In due course both will be flown/dismantled to see what the differences are.

C W

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