honda big red problems

floger70 · #1 03-17-2011, 02:34 AM

hey guys. new to this forum. ive tried a bunch of other forums and havnt found the issue yet so im trying here to.

2007 honda trx450er
aftermarket parts:
slip on pipe
big bore kit
stage 2 hot cam
r&d quick jet kit
air box lid cut open and put lizard skin top on it
k&n filter

heres the problem
when i start the bike, it idles fine no problems at all running smooth. i can give it quick shots of the throttle and it revs up and down like a normal bike no problems. when i try to ease into the throttle to slowly accelorate at all the bike bogs and shuts off. if i push the throttle wide open and hold it it revs up then bogs and shuts off.

i have tried the following to fix this.
tried these main jets, 130,135,155,162,188. the slow jet is a 45 and leak jet is stock.

tried moving the clip on the float needle to every spot on it.

i have tried every setting i can set it to on the fuel screw. from all the way in to all the way out and everything in between. tried moving the accelorator pump screw in and out and everything in between. still nothing. does the same thing for any of these settings.

also i bought a dyno jet kit and tried that with the new needle and jets and set those accordingly and still the same thing.. im running out of options and cannot figure it out. below i will post a pic of the carb with the quickjet and a video of it running and what its doing.

thanks
brett

YouTube - 450r problem

90vfradam · #2 03-17-2011, 02:42 AM

When did it start doing this?? before or after a mod??

floger70 · #3 03-17-2011, 02:45 AM

sorry i should have mentioned that. i bought the bike about a month ago with all the mods done to it as is. it came with the 155 jet in it and then i tried everything else on it.

Here 2 help · #4 03-17-2011, 02:31 PM

Your problem appears to be in the throttle position switch in the throttle housing. I am guessing that when you ease into the throttle the ignition loses spark. This can be verified with a timing light. If you lose spark as you ease into the throttle, try adjusting the free play in the throttle cable. If adjustment fails to solve the problem, try unplugging the switch from the wiring harness (it will solve the problem or it will not start and run at all). Last try, the throttle position sensor on the carb. It can be tested with an ohm meter. I don't recall ever seeing one fail, but inexperienced mechanics can damage the unit or set it improperly.

Let me know if this helps.

floger70 · #5 03-17-2011, 07:31 PM

when i unplug that the bike shuts off. there is no free play in the throttle cable at all. im going to check the ohms on the tps tonight and see what it is

Here 2 help · #6 03-18-2011, 02:23 AM

Honda specifies about 1/4 inch of free play on the thumb lever. no freeplay might be the cause of the problem?

floger70 · #7 03-19-2011, 02:53 AM

hmm. ill have to see and try that. i checked the tps sensor. bike off between pink wire and yellow and green wire it was 5 ohms on the 20k setting. i belive this is right where i want to be. ill try that adjustment on the throttle cable though

trx2fiveO · #8 03-19-2011, 11:43 PM

measure the resistance between the pink and green/yellow wire on the sensor side of the connector. (unplug it)

Standard : 4-6 ohm at 68'F

Calculate the throttle position resistance at idle speed.
A x (0.13 - .015)= B
A= pink and green/yellow wire resistance
B= Throttle position (light green - Green/yellow) resistance at idle

EXAMPLE: if the pink and green/yellow terminal resistance is 5 kohms then throttle positionsensor light green- green/yellow resistance at idle speed is: 5kohm X (0.13 -0.15) = 650 - 750 ohms

Adjust the TPS so the resistance between the terminals (light green and green/yellow) is at what you calculated from the above equasion.

If this don't solve your issue then there is an issue with your Closed throttle position detection system. Which that is an ignition cut-off system that will prevent the engine from running at any speed beyond Idle while the throttle lever is closed, just incase the throttle drum sticks so to speak. I think your TPS is bad personally but it could be that also. Check for a bad micro switch at the throttle. Good luck