cenracer1

I have an OS 18tm motor in my tmaxx and it has about 1.5 gallons thru it.. My problem is the engine suddenly started running very hot and stalls at high speed. It will start fine and most times will go from idle to upper midrange fine then stalls.. It will restart every time without fail even when its hot. I can't seem to find a fix for it. I've replaced all the rubber O rings in the needles, replaced the carb O ring and insulator, replaced the backplate O ring.. I even replaced the fuel line, tank and fuel tank O rings in the lid. I went as far as replacing the exhaust manifold gasket as well.. I'm done spending money on this motor.. Any thoughts.. Even when running as bad as it had, it never got above 300 degrees.. I also have tried new plugs and the Head is on tight with the correct shim for 20% trinity MH fuel.. The only thing I can think of is the piston and sleeve, but it does restart even when its hot, so I give up..

Bax

My Feedback: (11)

It sounds like the engine is just a bit too lean. This would cause it to overheat and quit. You cannot depend upon temperatures for getting your engine properly-set. Too much reliance on temps will eventually cause your engine to be ruined. You have to go by sound and performance. Temps are only a quide.

It's not possible for us to give you an actual temperature or temperature range for your engine. The specific temperature is determined by too many factors. There is only one way to determine at what temperature your engine should be run. You have to run it first and then find out what temperature the engine reaches.

Make sure your engine is operating properly with the performance you expect. Use the exact setup every time...fuel, exhaust system, plug, measurement location, and so forth. If you change anything, the temperature will change. Once you have the engine running the way you want it. Take your measurement. This is your starting point. You will have to take measurements over time to find out how the weather affects it. As the air temperature and humidity change from day-to-day, the operating temperature will change. Eventually, you'll find a temperature range that you can work with.

Engine temperature is not an absolute number for setting your engine. It is only a guide, and can help alert you to potential problems. The only sure way to make sure your engine is running correctly is to see how it's running. An engine can be operating at "correct" temperatures, but not running well.

Finally, use any temperatures you read about, or people tell you, as rough information. The only useful numbers are the ones you actually measure when your engine is running correctly. If your engine is running correctly, then what you measure is correct, even if some else says it's too high or too low. Don't worry about the differences. Each engine is in a unique installation with a unique set of circumstances, so there can be wide variances in engine temperature.

cenracer1

I know its lean..... but nothing I do will richen it up..This engine worked perfectly for a long time and now its not responding to any tuning. Maybe I wasn't clear on my first post. It has symptoms of an air leak, but I can't seem to find it.. The needles don't have any effect on the motor.. once it gets warmed up, it leans itself out quickly and shuts off..

Bax

My Feedback: (11)

Very likely, the piston/cylinder fit is no longer any good. You may need to replace the piston/cylinder assembly to get back any performance.

cenracer1

I was on the phone the other day with your tech department.. I still have some pinch left, not what it had when new, but the compression is still strong with the plug and head on.. The tech guy seems to think I may have something clogging one of the needles on the carb. most likely the high speed needle as it runs fine up to that point but will stall if given too much throttle. If I roll on the throttle it usually gets going..

I'm hoping its not the piston/cylinder as I don't want to sink any more money into this motor.. Its been great for a few years but its not made anymore... and with the piston/cylinder you still need a couple of other parts that will bring the total to over $100...