I have a good background in car engines mostly with EFI which is what I plan on installing on the raptor in the future.

I was thinking about installing a O2 sensor in the tailpipe right before the muffler so that I could hook a Air/Fuel misture meter up for carb adjustments. I could also leave the O2 in for a couple of open road runs to help dialin the mixture. Once set I would remove the O2 and install a plug until next time to tune. Would this be a good idea and is the correct air/fuel mixture the same as with a car. I would be using a heated O2 so I do not have to worry about exhaust temp like you do with a one wire O2.

This is just the start of my EFI plans. Also could someone please remind me of the carb MM sizes. This is going to guide my research in a Throttle body selection.

Thank You in advance

 

The raptor stock carb sizes are 33mm, If thats what you wanted

 

just hooking up an o2 won't do anything, the carb is not computer controled so if the o2 shows that your rich it will always be rich because there is no computer to cut back the fuel. the air/fuel ratio is the same as cars with the most power being around 13to1. now once you go to fuel injected you can get rid of the carb and go with injectors, then you'll need an o2 sensor. if you just want to dial in your carb, and if you have access to a 4 gas analizer then what i did was to drill a small hole in the head pipe just big enough for my exhaust probe to fit in, fire up the dyno and presto you can load the motor and see what fuel ratio is at idle, cruise and full throttle. no more guessing. but not everyone has access to a dyno or a 4 gas machine.