Does anyone miss carbuerators?

1/28/2023 11:52am

Give me a 250 two stroke with a keihin and I’m happy. 
 

swapping brass > tunes/ecu/dumb tuning apps

2
mxtech1
Posts
1968
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7/21/2011
Location
Galesburg, IL, USA
1/28/2023 2:03pm
For a race engine, carbs are old but still excellent even with today's computer technology. It has been shown time and time again that carbs normally...

For a race engine, carbs are old but still excellent even with today's computer technology. It has been shown time and time again that carbs normally make more peak power than EFI. The argument is that carbs do a better job of atomizing the fuel than fuel injectors.  The programming on some of the EFI Honda was not so good off the dealership floor. So what is the advantage of EFI if you dont give it optimal programming.  The advantages of EFI is changing conditions such as temperature, altitude, etc.  For people who dont know how to jet a carb or don't want to constantly rejet if they are riding in very different temp and altitude conditions from ride to ride, the EFI is a plus.  EFI on an MX bike is not something that excites me very much. I mostly ride at sea level on warm days.  For a street cruiser, I would probably prefer EFI though.

No one really cares that a carb can make more peak power than an EFI system on a dyno.
 

If you can’t translate engine power into forward momentum, it’s null. EFI and advanced ECU architecture is the reason why today’s bikes can deliver power based on available traction, modifying the fuel rate, fuel timing, and ignition curve based on engine RPM. Carb bikes could never do this…and that’s why they were rode so much differently than today’s bikes (referencing Pro racing here)
 

The AVERAGE dirt bike consumer never played around with jetting a carb, just like most will never get into EFI tuning (outside of selectable maps/switches). Embrace the change.  

3
1/28/2023 4:33pm
mxtech1 wrote:
No one really cares that a carb can make more peak power than an EFI system on a dyno.   If you can’t translate engine power...

No one really cares that a carb can make more peak power than an EFI system on a dyno.
 

If you can’t translate engine power into forward momentum, it’s null. EFI and advanced ECU architecture is the reason why today’s bikes can deliver power based on available traction, modifying the fuel rate, fuel timing, and ignition curve based on engine RPM. Carb bikes could never do this…and that’s why they were rode so much differently than today’s bikes (referencing Pro racing here)
 

The AVERAGE dirt bike consumer never played around with jetting a carb, just like most will never get into EFI tuning (outside of selectable maps/switches). Embrace the change.  

All else being equal, the carbed rig doesn't though. Out of all the OEM test engines we had in the late 80s thru about 5 years ago when I retired, a 250 cc or smaller cylinder had a stock 38mm carb or maybe a 40mm carb on over 250cc. The same engine would run a 44mm throttle body.  Bigger cc say 300+ would be a 44 or 48mm depending on the model.

Tuning EFI is actually simple.  Way back when you had to swap actual chips with different programming(took about 2 minutes), you could manually change "jetting" in less than 10 seconds and somewhat trick the ECU. You could go from lean to blubbering rich as easy as turning an air screw. 

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