I recently had my 2F engine rebuilt- new water pump, thermostat etc, radiator flush and heater - radiator is a littleover a year old I also replaced the sending unit for the stock gauge - the engine was timed by the rebuilder- but it runs on the warm side of the gauge- at the 3/4 mark particularly on a climb. In tearing apart my old engine prior to rebuild I discovered that the thermostat had been stuck open-which according to SOR would register the engine heat as cool,but fry some cylinders. I evdently had been driving it that way for years. Question what is normal? Should the temperature fluctuate climbing and settle down as the terrain smooths out? or should the temp be more consistant? I've got way too much invested in this stock rebuild to fry it.

The rebuilder thinks I need to change water tempt gauge, I am not convinced it is a gauge isssue. any input would be helpful.

Fearful in Driving....

I don't see how running without a thermostat would register an engine cooler than it really is. I thought all a thermostat did was to help in heating up the engine faster...especially on cold mornings.

I would install a new temp gauge that has degrees on the gauge so you know exactly what temps you're running.

Yes, you engine temp can vary depending on the engine load.

I'd check for a lean condition at the spark plugs. Verify that the timing is within spec.
What compression ratio was the 2F built to?
Did you go thru the carb also?

In my experience, the temp guage for a 2F should not go beyond the halfway point unless towing in 100 deg temps uphill. Not even then, really. YEMV.

Until you put a real gauge on it there is no telling what temp you are really running. If you had the head shaved it is going to run hotter than stock.