Hi Bill,
hope you can offer some advice on a problem I'm having with my S-2500. Now this engine is fitted with an OS 7D carby so will understand if you don't want to offer advice on it but hope you might know what my problem is.

1. The engine is having a lot of trouble starting, unusual for the big ST engines. Once it is running it idles nicely

2, It will not transition past about 1/2 throttle. When you do advance the throttle it is like somebody just cut the fuel right off on it and it dies. If you bring the throttle right back it then will pick up and run at the lower throttle setting.

I have replaced the needle valve and O-ring, o-ring on base of carb, flushed the carby out, replaced all fuel lines and pressure tested for leaks. All ok.

We did adjust the idle mix on the carb to where I could run it at full throttle but it was not very reliable at all and if the throttle was slammed forward it would die.

Next issue: Parts. I'm having trouble getting a piston and liner for this engine, Tower do not have them. any thoughts where i can get them?

SUPG4170 22042115 CYL SLEEVE S2500


SUPG5275 22202201 PISTON S2500

Anyway hope you can shed some light on this for me.
thanks in advance.

cheers
Peter