Coughing/Jerking at low rpm

Titan

Registered
I just got back for Diels Gap in Tennessee. It has a lot of curves and 1st gear was to low and wicked to use...2nd gear the rpms were very low out of the corners. This caused the bike to constanly jerk and sputter until about 4000rpm. Is this normal for Fuel Injection or do I have a mapping problem. This bike has a full Yosh and power commander. My friends RC51 was very smooth but its a twin so not the same bike but its fuel injected.
 

Kento-Moto

Hayabusa Immortal
Donating Member
Registered
The stock set up tends to run a little smoother at low R's and with my full exhaust I get a little of that too, do have a tre mod? It helps, and when was your last tune up?
 

SierraFlyer

Registered
It sounds like a need for TRE. Do you have one installed? If not then read on.

If your bike is a little out of tune (fuel map to rich/lean) and there is no TRE, then you might aggrivate the timing retard that a stock ECU has on gears 1-3. The ECU retards these gears up to 5000 RPM to help increase traction and reduce smog. The TRE removes this retarding on low RPM timing and can really clean up the low RPM range stumbles like Hawaiibusa said.

Last year I was riding with friends in the hills. Going into a tight left-hander I shifted down to 1st with RPM's around 5-6000 with the throttle closed. In the middle of the turn I hit a harsh bump and my wrist cracked the throttle just a little at about 4500 RPM. The ECU came out of retard and gave me way more torque than I expected. The front end came off the ground while leaned over hard. The bike went straight for a tree so I closed the throttle hard. That stood the bike straight up and almost highsided. I was puckering up on the edge of the road at about 50 and brought it back in. That experience showed me the need for TRE. Now all my throttle turns give me the same power each time. Yes it is more, but it is predictable and you can get used to the additional power quickly.
 

rubbersidedown

TURBO-BUSA-RIDIN'-BASTID
Donating Member
Registered
This caused the bike to constanly jerk and sputter until about 4000rpm. Is this normal for
a Busa......yes . Change yer gearing if ya want, to get it into a more "Twisty Type " set-up . Even thou the Bird wasnt really designed for the twisties . Go down in front or up in back . This will bring yer arps (RPM'S) into a more usable range .
go get 'em...KILL KILL KILL
 

Titan

Registered
Ahhhhh! :-) the 15k resistor fixed it.Its just as smooth as my R1. Ive only owned 2 bikes in my short riding career of 2 years so I wasnt sure if the jerking was normal for fuel injected or not. But its smooth as silk now...thanx everyone.

p.s. 15minutes after I started riding it with the new setup I got rearended by a S-10...Im not hurt the bike is...Murphy's Law.
 

jwcfbd

Administrator
Registered
Ahhhhh! :-) the 15k resistor fixed it.Its just as smooth as my R1. Ive only owned 2 bikes in my short riding career of 2 years so I wasnt sure if the jerking was normal for fuel injected or not. But its smooth as silk now...thanx everyone.

p.s. 15minutes after I started riding it with the new setup I got rearended by a S-10...Im not hurt the bike is...Murphy's Law.
I'm glad you're ok but how bad is the bike?
 

Daddy Fatsac

Registered
Thank god someone knows what I'm going through!! I've had my busa for 3 yrs and nobody could tell me why in the hell she was so jerky in 1-2. If you have a power command running its 200% worst. Hmm...so I'll just go buy a TRE...the cheapest one I've see is at Hayabusazone/ape for $70 bucks. Anything cheaper?
 

Daddy Fatsac

Registered
Go to aperaceingparts.com then go to Hayabusazone and look under TRE. It will give a discription of what it does and why.
 

Titan

Registered
My bike had the upper/lower tail and the pipe smashed. I rode it the next day up to 175mph...seemed fine. I have State Farm they are going to my bikeshop of choice to checkout the estimate. The %#^*weed that hit me said "Maybe you should push the gas next time" I said "Your getting the ticket you shouldnt be driving" Sure enough no license driving his dads truck...
 

samurai1833

Registered
I get the same kind of on of throttle response and the sputtering engine at low speeds. I usually open the choke to keep the rev's high at low speeds but I don't want to foul the plugs.

The TRE sounds good but would it work on my 1999 Busa? My bike is unrestricted already would I sacrifice my top end to get better low speed performance?
 

SierraFlyer

Registered
Hi Samurai,

No you won't affect your top end. The TRE replaces the signal from the Gear Position Switch (GPS). The "signal" is just a resistance that the ECU uses to figure out what gear the bike is in. It does this to apply the correct timing/fuel map to the engine. The TRE has only one resistance that tricks the ECU into thinking your bike is in 5th or 6th gear (depending on what resistor you select) all of the time regardless of what actual gear you are in. In a stock bike, without TRE, the ECU will retard timing on gears 1 through 3 up to 5000 RPM to help with traction. It reduces power through the timing retard. TREs typically run 6.8K ohm resistance (5th gear) to also remove the speed limiter. TRE with 15K ohms will simulate 6th gear and you don't have a limiter in 6th. So the ECU will work just like it had the GPS signal in 6th gear and won't effect your performance top end at all.

The other thing you might try is to adjust the idle. The "choke" lever we have on our Busa's isn't a real choke. All it does is pull a cable that attaches to a linkage on the throttle body/idle stop which bumps up the idle slightly. You can do the exact same thing by twisting the throttle open slighly and holding it, or adjusting your idle up slightly. The "choke" doesn't limit air like on a carburator. It won't foul the plugs either if you leave it on. The ECU automatically mixes the correct amount of fuel/air for what ever temp the engine is at. All it does is raise the RPMs a little to stop the cold stumbles the engine has. I have ridden around all day with the lever on with no problems simply because i took off the forgot the damn lever. I do that a lot with turn signals too........................ouch!

Hey Titan,

its just like a little punk to try and blame you for being in the way! You need to push the gas?
rock.gif
? He needs to push the BRAKES!!!! and in time - next time. He needs to have his driving priviledge revoked for 10 years until he grows up!
 

malcolm

Registered
Thank god someone knows what I'm going through!!  I've had my busa for 3 yrs and nobody could tell me why in the hell she was so jerky in 1-2.  If you have a power command running its 200% worst.  Hmm...so I'll just go buy a TRE...the cheapest one I've see is at Hayabusazone/ape for $70 bucks.  Anything cheaper?
anyone checked the micro gauze fuel filter/regulator inside the fuel pump feed,block off fuel pipes,2 cross head screws on top of pump,remove screws,pull out little filter with a point end tool,clean,may help.....
rock.gif
for models where fuel pump is connected to the throttle bodies............
 

Daddy Fatsac

Registered
Can't say I've tried that Malcom. But TRE is already on order...too late. If the TRE doesn't help I will try that step next. Thanks for the info!!
 

TJFAST

Registered
Less fuel should jerk or choke at a higher rpm not lower. If the filter or filters are pluged it would kill the top end. I just bumped up my timing in 1st-3rd and it made a big difference.
 

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