Nikki carb OE4215 jet size for Generac 27hp

[Neo7]

I'm working on a B&S 25HP, Nikki at the moment. So with a lots of magnification I read 111 and 114 ... 111 on the "R" Side (Cylinder 1) of the Carb .... Get these the wrong way round and Cylinder 1 runs a lot hotter than Cylinder 2

Sorry, I'm not sure if I recalled this correctly, as this guy says the larger jet is on the "R" side.
Anyway, I know they're correct on my engine because I've checked the temperatures on the cylinders, and they are close to the same.

 

[tjwid]

Thanks for all your feedback. I had a chance to get back after the machine and found that the previous owner had adjusted the valves incorrectly. The Intake valves were adjusted with zero lash, in fact one side may not have been closing at all. After the valves were adjusted properly, the machine ran great, no popping. So, for now, no jet drilling. I'll run and assess spark plug condition after running for several hours.

 

[RevB]

Just a heads up....Generac had a huge amount of air filters that were made in the Phillipines about 5 years back. They were spec'ed to have a fire retardant applied to the element but the Philipinos went nuts and soaked them so they would barely pass enough air to run under load....unloaded they ran fine. The dealers got stuck with these filters and as far as I know were never compensated for stock on hand. Most threw them out but can't guarantee there aren't still some out there. The unit would come up to speed and run under partial load but if an additional load like an AC, well pump, air compressor, etc hit it it would start popping and surging. Discovered this on my own since mine is nat gas it would almost be certainly air related...popped the latches to the filter cover, lifted the filter and ran just fine. Replaced with a WIX brand substitute and never had that problem again.

 

[Auto Doc's]

Thanks for all your feedback. I had a chance to get back after the machine and found that the previous owner had adjusted the valves incorrectly. The Intake valves were adjusted with zero lash, in fact one side may not have been closing at all. After the valves were adjusted properly, the machine ran great, no popping. So, for now, no jet drilling. I'll run and assess spark plug condition after running for several hours.

Hello T.,

Glad to hear you are making positive gains on this project. I have also found many times that verifying all settings prove to be a good thing.

I keep My Generac generator (same engine, just not a mower) connected to my house inlet adapter on my back deck and run it once or twice a month.

I considered a Propane conversion, but these bigger generators are just not as efficient on Propane, so I just keep extra fuel with Ethanol shield on standby as the weather gets colder.

The spark plugs are the ideal way to gauge if you are running efficiently or too lean. Make sure you are running your mower under load for a while before checking the plugs. A faint tan color on the electrode end should be ideal. If they are too white, its lean and that will create excess heat in the cylinder combustion.

I used to ride several iron head Harley's years ago and checking the plugs were always the way to make sure the engine was running efficiently.