THE PORTAL HUB - Pinzgauers, Haflingers, Volvo 303s and more!

This fully stock (other than Pertronix) 710K is very cold blooded. It starts instantly even after sitting for weeks, but is very balky until the engine is fully warmed up after about 10 minutes of driving. Once it's fully warm (oil temperature above say 140F) it is fine, but before then it balks when cruising at a constant speed and surges and sometimes wants to backfire. Put your foot into it, though, and it's fine, but it's when maintaining speed and trying to slightly accelerate that it complains.

JimL recently rebuilt the carbs, and advised that these were jetted for Euro3 standards, and thus on the lean side and maybe better for high-altitude than my sea level operation. I asked what the jet sizes were, and he's not responded.

During that warm-up period, the engine mostly wants to be at full choke for smoothest operation.

Spark plugs look good, BTW, and fuel pump is recently rebuilt. When warm, the idle speed is a bit high, close to 1050RPM FWIW.

Whatch y'all think? Is this just a symptom of the main jets being too lean?

I believe my Pinz is jetted correctly, and it is still cold-blooded until it warms up. I think this is a normal characteristic of this engine, but I agree that the choke needs to be left on too long. Perhaps advancing the timing slightly would help.