Sure Start performance increase?

I find the easiest thing to do is replace the Sure Start Piston and cylinder assembly with a Number 1 cylinder and piston. I have achieved 20K+ RPM with a No 1 Cylinder/Piston assembly, a 5X3 Prop, and a Sure Start backplate (Stainless Steel Reed) using 25% Sig Champion Fuel. You may accomplish the same thing with a Tee Dee cylinder (#4), however, I find the older #1 cylinders better for the reed valve carburetor. Additionally, the cylinder and pistons on the older engines Pre-80 seem to be better. I believe this is because the tooling was newer. I do not know when they stopped upgrading/maintaining the tooling but I read a article once that said the aftermarket companies came into business because they QC at cox started slipping. I imagine that was sometime in the late 70s or maybe early 80s. I have purchased shaved/lightened pistons and they work OK, but I have never gotten over 17K on those. Also the stainless steel reeds work great. I have used them all, and the Stainless Steel reed is really good. I hope this is helpful. Andy

Thanks for the input. The mention of SPI got me wondering if they're thirstier than non-SPI engines. More air in means more fuel too, thus a richer setting.

Another question: Does anyone sell "blank" cylinders, i.e. without ports cut in them, so one could experiment with different configurations?

uncut cylinders are out there. Might have to pry them out of cold dead fingers to get them. Most dont want to sell them.

Good luck finding an uncut one, but I hope you do. For horseshoe backplates just drill out the venturi hole as large as possible and still allow the reed to seat. Also when you press the spray bar in go slightly offset from center so the fuel will atomize better.

Ron

TheotherGeoff wrote:Thanks for the input. The mention of SPI got me wondering if they're thirstier than non-SPI engines. More air in means more fuel too, thus a richer setting.

Another question: Does anyone sell "blank" cylinders, i.e. without ports cut in them, so one could experiment with different configurations?

If you want to experiment with your own porting you might try an older single port cylinder. One small port you will enlarge and one "blank" side.

As for the spraybar angle, I always heard what Cribbs said, set it at about a 15 degree angle off center. However I had two backplates for my tach race engine, one centered and one offset. The centered one ran 300 RPM faster. So try it both ways, you never know what will make a sweet spot for these fickle engines.

Another question: Does anyone sell "blank" cylinders, i.e. without ports cut in them, so one could experiment with different configurations?[/quote]

YES, I have one for sale. Comes with piston.$35.00+ post if you're interested. Contact me further at: pgibeault@shaw.ca

Cheers, Paul