So many folks have reported problems with the Robin engines and cold starting. I feel for you guys. This is a real problem. I'm not going to expound on the virtues of my Kohler engine, but this is what I do to it year round. It seems to work and may be worth a try on the Robin engines.
1. I always keep a trickle charger on the battery, year round, so it is always topped off. I use a small, 500ma motorcycle battery charger. I installed a cigarette lighter socket in the engine compartment and a 12v male plug on the charger, so it is just plug-and-go each time I return the PT to the garage. I drape the cord across the seat so I do not forget to unplug it.
2. I always use Mobil1 in the engine oil. I think the very light weight of it when cold really helps the engine crank easier. I have no scientific proof of this, but the stuff pours pretty easily out of the can even in winter.
3. I usually go 3/4 to full throttle and full choke when cranking the engine when cold. I crank for no more than 10 seconds. If it does not fire by then, I let off the key and wait a minute or two so I do not cook the starter. Then I try it a second time. If it fires up, I start adjusting the choke to get it to run smoothly. Sometimes I have to sit there and back the choke out for close to a minute, but usually by the time I get to 1/2 choke, it will continue to run on its own. I shovel the area around the garage doors and sidewalk by hand, listening to the PT. If I hear it slow down, I go back and adjust the choke some more. I usually let it run at 1/2 throttle for at least 5 minutes to get the hydraulics warmed up a bit. Longer on very cold days.
4. If the engine does not fire after two or three attempts, I do not keep attempting, as all that will do is get the engine flooded or the battery dead. Instead, I open the choke, open the air cleaner and give it a one-to-two second shot of starter fluid. Then I close the choke, 3/4 to full throttle and give it a crank. It fires immediately and keeps running. I have to back the choke out soon thereafter and follow the above procedure until it runs smoothly.
If the engine does not even POP on a small squirt of starting fluid, there is most likely an ignition problem that will have to be addressed first.
If the engine POPs on the starting fluid, but does not continue to run, there is most likely a fuel issue or problem with the carb.
Our Kohler cranks really slow below 5 degrees and really, really slow when it hits 10 below zero. I can pretty much count on having to use starting fluid at that point. But it always fires up.
