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Tech Talk

posted Jul 08, 2008 to Featured Articles by FLmx
from the Jul 2008 issue

Tech Talk

By: Chris Reo

I’m not sure if you are noticing but we are again going to see a major change in technology on our motocross bikes. A few years back we had the big switch from 2-stroke to 4-stroke. Looks like the next big thing is going to be fuel injection. It is time to start saying good bye to our trusty carburetors and hello to FI. In 2008, Suzuki was the first major manufacture to race and sell to the general public a fuel injected (FI) motocross bike in the US and it looks like the other manufactures are following the trend. Kawasaki has just posted its 2009 line up and it looks like the KX450 is going to be fitted with FI. Pictures and a short summary can be seen at www.Kawasaki.com. I’ve heard rumors but haven’t seen anything solid from Yamaha or Honda as of press time.

If you think about it FI has some superior benefits over carburetion, but with new technology comes new troubles. Most of the drawbacks of FI are getting use to then new technology. New systems like fuel pumps, Electronic control units (ECU) and fuel injectors are complicated. In order for FI to work well for you the best thing you can do is learn how the system works. There is with out a doubt going to be a learning curve for both the manufactures and riders to get this system to work well. Here is a short list of the benefits and drawbacks to having a unit fitted with FI.

Benefits of FI:

1. NO MORE JETTING

The days of having to switch out a jet because the temp or humidly has changed, FI bikes are fitted with sensors that adjust the fuel mixture as the conditions change. In future articles I’ll address all of the sensors and what they are used for. No need to figure out complicated jetting specks. The system does it automatically.

2. NO LOSS OF FUEL

When you ride your carburetor needs to vent its float bowl. The problem with this is fuel tends to get tossed around and lost out of the vent tubes. When you crash or lay the unit over fuel pours out the vent tubes. Who needs that with gas prices as high as they are now. Fuel tanks on FI bike can be smaller because the FI system is a closed loop. Fuel returns to the tank instead of being dumped on the ground.

3. CRISP THROTTLE RESPONSE / COMPUTER MAPING

It doesn’t matter if you are here in FL at sea level and it is 90 degrees with 100% humidity or in Colorado in the mountains at 40 degrees with 30% humidity your bike will have crisp throttle response. I sure that manufactures will also more then likely have computer mapping available to help with this if you plan on changing your pipe or racing at different tracks. Street race bikes have had this set up for years and it works really well.

Drawbacks of FI:

1. TROUBLESHOOTING

If you are going to purchase a MX bike with FI you are going to need to know how the technology works. FI systems are advance and sometimes a pain to troubleshoot if you don’t have the diagnosis software and the know how to use it. It’s not like a clogged up jet. Sensors can go bad and if you’re not up on electrical diagnosis you could get stuck in a rut. So learn all you can. If you feel it is over your head visit your dealer so that you don’t make the problem worse or replace parts that don’t need to be replaced.

2. COST

FI parts and sensors can be expensive. You will have sensors that your carbureted bike did not contain. Also the fuel pump and fuel injectors are all parts that aren’t on carbureted units and when they break they can carry a hefty price tag. So there could be a cost issue if you don’t take care of your bike or try troubleshooting on your own. Too many times I see riders not use their trained authorized dealers to help on the tech side and it ends up costing way more then it should of to fix the issue.

There is no escaping it FI is going to be here sooner then we think. The best thing that we can do is educate ourselves on the working of this system and embrace the new technology with open arms. If you purchase a FI bike or are currently riding one now send me your story (good or bad) and if it is interesting enough (and technical) I’ll print it in a future issue of FLMX. I’m also in need article ideas. Please send them to me at Chrisreo@bellsouth.net and together we’ll keep Florida riders on top.