I got a 1986 Suzuki 230lts, but lately I've had some problems with it, it seams to running bad when it gets to running for a while, When you really get after it for a while like running down a long strait away or racing at high rpms around our track. It has a very low idle, if you blurb the gas it will stall most of the time but it will usually start back up, The valves were re-adjusted, air filter cleaned and carb cleaned, should i try some thicker oil? right now im running 10w 40, any help will be greatly appreciated. Thank you

 

The 230 has a defect where the main bearing will starve for oil if ran at high RPM for extended time. I had a kid seize mine once by riding in 1st/2nd gear wide open... You don't mention exactly how it starts running poorly, but I would advise against extended WOT runs with this motor anyways. The stalling when hitting the throttle from idle can usually be resolved by adjusting the mix screw or jetting since you state the carb is clean. Some carbs are pretty prone to this and will do this even when jetted spot on.