Yz450 Tps


10 replies to this topic
  • JP147

Posted November 22, 2004 - 05:12 AM

#1

I recently purchased a YZ450 & the Throttle position sensor is un plugged, the guy that sold me the bike says this helps to make power come on smoother. Is this true?

Thanks for all the input I am going to hook the TPS back up, also purchased big gun exhaust system.

  • Chris_from_Oz

Posted November 22, 2004 - 05:19 AM

#2

Use the search function at the top left of the page. Type in 'TPS', or 'unplugging TPS', something along those lines, you will find more info' than you care to know about unplugging your TPS. :cry:

  • SureBlue

Posted November 22, 2004 - 07:17 AM

#3

http://www.eskimo.co...g/tpsdanger.htm

Hello fellas, above some interesting reading about TPS...

  • grayracer513

Posted November 22, 2004 - 09:09 AM

#4

Mine is still plugged in. When I got the bike, it already had an FMF Ti4 system with a Power Bomb header, and I couldn't figure out what people were talking about when they kept mentioning a "hit" at about 8000 rpm's.

One day, for fun, I started swapping the OEM exhaust back on the bike to see the difference the FMF made. When I rode it with the full stock system, there was the "hit"! And with a narrower feeling, less controllable power delivery, too.

I also tried both combos of mixing the OEM header with the FMF pipe, and vice-versa. It looks like it's mostly the header that gets rid of it, but the best setup is the full FMF system.

With the stock system on the bike, disconnecting the TPS does get rid of the "hit", but the bike tends to ping when lugged a little. With the full FMF, unplugging the TPS did nothing to smooth anything out, the pinging at low speeds was back, and I felt like the part throttle response wasn't as sharp.

So, I am led to conclude that even though disabling the 3-D ignition mapping by unplugging the TPS at least hides the problem, what it really is is a mismatch between the camshafts and the exhaust system causing a "foggy", or "flat" spot in the power curve. The recovery of power as the engine passes through this is seen as a "hit"

I could be wrong about conclusions as to the technology involved, but not about my bike runs. I'm leaving the TPS hooked up.

  • gonzo

Posted November 22, 2004 - 09:24 AM

#5

And how your bike rides with the FMF system is exactly how the 05 rides stock. Does your bike feel slow? I have the same system. I love it.

Try riding a CRF with the same system. The power is EXACTLY the same. Its amazing. Everyone says the Honda was so much different motor. I wonder if it was just he pipe all along.

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  • grayracer513

Posted November 22, 2004 - 12:37 PM

#6

And how your bike rides with the FMF system is exactly how the 05 rides stock. Does your bike feel slow?



Eh, NO! :cry: :cry:

I have the same system. I love it.

Try riding a CRF with the same system. The power is EXACTLY the same. Its amazing. Everyone says the Honda was so much different motor. I wonder if it was just he pipe all along.


MXA said of the CRF, after putting a full Factory 4 (a fancier, but otherwise identical system to the Ti4) on it, that they never knew the bike was slow until they tried with that exhaust. :cry:

  • condog_aus

Posted November 22, 2004 - 07:35 PM

#7

The TPS effectively advances or retards the spark dependant on RPM and throttle position. In effect it generally advances the spark at higher RPM. This is because at high RPM if the spark occured at top dead centre the combustion lag would mean youd lose power out the exhaust. If your weapon is way to powerful for you than this is a poor, but available option, but be prepared for a lack of mid to top as part of the combustion power is blown out the open exhaust valves. Also at low RPM you will most likely expect to hear knock , with too much advancement of spark. Personally id be worried about engine detonation, and would not do it. Fork out the money for an exhaust to spread the power, its cheaper than a new motor.

  • Chas_M

Posted November 24, 2004 - 11:42 AM

#8

http://www.eskimo.co...g/tpsdanger.htm

Hello fellas, above some interesting reading about TPS...



Regarding TPS function, I don't agree completely with the description supplied in this article. According to Dale Lineaweaver, Husaberg guru on the Husaberg.org site. "The ignition timing is viewed as a 3D map consisting of load (as indicated by the TPS), engine rpm and ignition advance. All else remaining equal, most often the case with high output four cycle singles, is that ignition timing is advanced during light load to compensate for a less dense and often times exhaust diluted fuel mixture. By unplugging the TPS, timing will go to the default setting thereby eliminating light load advance with a consequent reduction in throttle response.

  • SureBlue

Posted November 24, 2004 - 12:51 PM

#9

Anyway, true or partly true, information or misinformation, I have done enough reading to keep my TPS plugged, since I do not consider myself wiser than the japs who in their great wisdom supplied the bike with it. :cry:

  • FFRacing79

Posted November 24, 2004 - 01:07 PM

#10

Have posted this dyno graph many times...

http://www.allthings...rycenew-med.jpg

  • grayracer513

Posted November 24, 2004 - 01:07 PM

#11

Regarding TPS function, I don't agree completely with the description supplied in this article. According to Dale Lineaweaver, Husaberg guru on the Husaberg.org site. "The ignition timing is viewed as a 3D map consisting of load (as indicated by the TPS), engine rpm and ignition advance. All else remaining equal, most often the case with high output four cycle singles, is that ignition timing is advanced during light load to compensate for a less dense and often times exhaust diluted fuel mixture. By unplugging the TPS, timing will go to the default setting thereby eliminating light load advance with a consequent reduction in throttle response.

Yep, that's pretty much it. If you're lucky, the CDI unit will see the unplugged TPS as WOT (this is usually the response in the automotive world) and continue to control timing as to RPMs, assuming full throttle. Worst case, it could shut down and default to static timing. As stated, this will affect part throttle engine response adversely.





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