Overheating from (probabily) untuned carb, what other options are there?
Hey guys, a while ago I got my santaja sj410 engine's rebuild and after fixing some electrical problems something else showed up: temperature fluctuations with the pedal pressed. To be clear, this is not the engine's temperature going to the top and staying there, it's raising to around 2/3s of the scale when pushing the engine hard-ish and coming back to normal (1/3) after some time.
Things I ruled out:
- faulty thermostat (both I tried are opening and closing at the correct temperatures),
- faulty sender (there are actual fluctuations near the sender and in the oil filter, I tested it with a thermometer),
- problem in the head (there is no mix of oil and water), problem in the cooling circuit itself (no leaks).
What I couldn't rule out:
- something INSIDE the cooling circuit, even though I purged it again and again (the level of coolant raises and plunges quickly in the expansion bottle),
- the radiator is too big for the car/newly installed water pump (I installed it before engine rebuild and it actually stopped the car from overheating when idling, so I don't see it making any sense unless the water pump that was there was stronger than the one they rebuild it with, which I doubt)
- The final carb tuning was badly done and it's too rich when revving, which would also explain some (burned) gasoline smell and higher than expected emissions when revving.
Have any of you had a similar problem before? What of the 3 possible causes do you find most likely? I do know how to tune carbs but I'm more used to smaller/simpler engines, so I don't want to mess with it unless I'm positively sure that that's the cause.
Thank you!