HONDA F4i

**ls1ohyeah** · 11-23-2009, 03:47 PM

Having problems with a honda f4i engine. Do not know if it is the tuning but we have been tuning the crap out of the engine but it still wont do what we want. Problem is: lack of throttle response. The engine just does not rev up when we open the throttle, it actually slows down and almost dies and then a few seconds later itll rev up to 13,000 rpms.... any tips or suggestions would be greatly appreciated.

**402 Guru** · 11-23-2009, 06:33 PM

Originally Posted by ls1ohyeah

Having problems with a honda f4i engine. Do not know if it is the tuning but we have been tuning the crap out of the engine but it still wont do what we want. Problem is: lack of throttle response. The engine just does not rev up when we open the throttle, it actually slows down and almost dies and then a few seconds later itll rev up to 13,000 rpms.... any tips or suggestions would be greatly appreciated.

ok dont take this the wrong way but did you before you tuned the engine give it a full tune up /Replace Engine Oil & Filter
Replace Drain Plug Washer
Replace Transmission Fluid
Inspect Hoses & Top Up All Fluid Levels
Inspect Tire Pressures, Lights, Horn, Wipers
Inspect Charging System and Belts
Inspect Drive Shaft Boots
Inspect Exhaust System
Replace Air Filter
Front & Rear Brake Service
Replace Brake Fluid
Replace Fuel Filter
Engine Tune Up
Clean Engine
Replace Air Filter ( i did all the spaces so u would not get confused)
Cooling System blow out the front radiator and the most important before a tune you should Adjust valves - Replace valve cover gasket - Replace spark plugs - Replace ignition rotor( only if youre past 35k on the odo.for this one) - Replace air filter - Check timing if you did not do all these listed do so then revert the f4i to its stock tune . it is nesecssary to always save the stock tune did you and if so the bike should run norman then you can start messing with the tune agian knowing that you arent going to pop your engine. those honda engine can take alought of crap but i dont reccomend pushing that engine like you have been doing without doing the things i listed.

**mark21742** · 11-25-2009, 07:20 AM

is it carb or fuel injected? it sounds like your going WAY lean. if carbed I'd try raising the needles and go up a size or two on jets.
if injected check your TPS, AND Map Sensors, if they check ok, reprogram for more fuel

**jiveass** · 11-25-2009, 07:41 AM

i had this problem with a 2000 cbr 600f4...it was carbureted....turns out the carbs were outta sync and had to get em synced up ...cost about 60 bucks...but you are fuel injected, right?

**5abivt** · 11-25-2009, 07:47 AM

Is it carb for fi? Pull the plugs and check them to see their condition. Won't tell you much since its been idleing etc but they will soaked if you are running rich or have a stuck injector etc. Remember Fuel, air spark. Check the ignition system, fuel pump/regulator etc an the air filter to see if it is dirty. I would reccommend checking all the sensors like map/maf (not sure what f4i has), coolant temp, tps, iat etc. The ecm will control timing/fueling based on all of these parameters so if one is off it can throw it off significantly.

Does it do this when it is cold/hot/both ?

**Spikito** · 11-25-2009, 08:12 AM

it depends on what yeah, i may be wrong, but i think the F4i came in both carbed and injected...depending on year

**ls1ohyeah** · 11-25-2009, 08:30 PM

it is fuel injected

**402 Guru** · 11-25-2009, 08:35 PM

ok did u read anything we asked but fuel injection ? did u give it a tune up b4 u tuned it or u could of jacked up ur ride you have major problems if you didnt realize it untill now

**ls1ohyeah** · 11-25-2009, 08:38 PM

generally the engine does not perform well in any stage. cold/warm/hot... It just cant rev up from idle.

We have checked MAP and TPS several times, ripped out a custom fuel tank and cleaned it out and re-did it, new fuel pressure regulator, checked the injectors and plugs. We have done wiring about two times just to make sure everything is connected. I should mention that when we ran in gasoline the engine performed OK, but now we are experimenting with ethanol which just seemed to mess everything up... What are some things I should expect to change when doing ethanol (keep in mind im aware of some of the bad things ethanol can do to rubber and engine parts that werent designed for ethanol)

Question: (I am not a motorcycle engine guru) how likely would timing be an issue?

**Orcus79** · 11-25-2009, 10:04 PM

What mix of Ethanol? If you are running Ethanol you need to totaly redo everything and tune it for such, hotter plugs, bigger injectors a whole new fuel mixture and possibly more compression. My guess is as stated above. simply not enough fuel is getting to the motor.

**5abivt** · 11-26-2009, 07:52 AM

Because everything stated in the above post is true, you also need to increase your timing as well for ethanol. It burns slower and requires more time so Try a few degrees advance at a time.

**mark21742** · 11-26-2009, 08:01 AM

with ethanol your A/F ratio will need to be completely changed.
this is just an average =
gasoline run best at 13:1-14:1

ethanol runs best around 6:1-8:1

so you'll need to REALLY richen it up over a standard gas system.....you should get a wide band and hook it up for the tuning to be sure