5 free horsepower

Yes it will work on the 03 450 as well.

Rev, that is the only place you can do it just un plug the carb TPS and let her rip.

Satch 0922,

What did you think of the TPS mod on the 426? :)

The bike ran strong all weekend (until I crashed it!lol). Can't give you numbers obviously but I will say that two days of riding at the GMB planning/ride at Splendora and I have ZERO complaints on how it ran. Watched Kirtwell clear the big triple step up several times on my bike with no problem!! (I am not that brave)

Did it feel like it changed the power band, was there anything noticeably different?

If i get my tires mounted this week i am going to give it a try this weekend. :)

It wasn't a night and day difference. But i think it helps smooth out the powerband...comes on ealier.

Cool, i'll have to give it a try this weekend on the trails

:):D

I'm going to practice wed. at Podium1 (IN) so I'll unplug then. Race this weekend at Muddy Creek (TN). Looking for any advantage I can find.

I'm with you on the triples. I'm too old and slow for that. Sure is fun to watch though. :)

Hi,

are you guys all racing the outdoor nationals that you need 5 additional hp for your YZ450???

I`m very pleased with my peak hp und my power delivery, so I`ll do the f#@% and change anything on my YZ!!!!!!...maybe you remember from the OLD SCHOOL DAYS of Huskys 610 and HUSABERGS` 600 that more power doesn`t mean automatically that you can go faster!!!??!!! :)

.....and why does Yamaha put on the TPS......only to spend more money building the bike and making it slower???? :D

ride.race.live

The reason I liked the mod is because it seemed to give the bike more bottom end making it more ridable not less ridable, I don't have to shift down to second as much bike seems to have more torque down low.

I have a power now also and am very pleased.

it's more about the delivery Bergi600.......... and some of us are posting in regard to 426s.

Hi,

are you guys all racing the outdoor nationals that you need 5 additional hp for your YZ450???

I`m very pleased with my peak hp und my power delivery, so I`ll do the f#@% and change anything on my YZ!!!!!!...maybe you remember from the OLD SCHOOL DAYS of Huskys 610 and HUSABERGS` 600 that more power doesn`t mean automatically that you can go faster!!!??!!! :D

.....and why does Yamaha put on the TPS......only to spend more money building the bike and making it slower???? :)

ride.race.live

Yamaha didn't have much choice...the TPS comes with this particular carb. If you would read all of the posts, it wasn't so much about gaining HP as it is about smoothing out the hit...see that dip in the Dyno graph? Thats the HIT! Easier to ride, the faster you go.

The jets are pretty small on any motorcycle. Given the conditions we ride in (DIRT), It never hurts to do a little preventive maintenance... :)

...see that dip in the Dyno graph? Thats the HIT! Easier to ride, the faster you go.

FF, that's an excellent point - and something that frequently trips up folks in streetbike applications as well. Classic example is a Ducati with oversize exhaust and without big cams or porting. The larger exhaust actually creates a hole in the torque curve. The result is a perception (from the seat) that an upper-mid "hit" is created by the exhaust change - a signficant improvement. Dyno data proves it wrong, and in fact the opposite - there's a falloff approaching the hole that was created. When it recovers from the hole, the curve rises steeply and this is what riders perceive as the improvement - when in reality they've created somewhat of a problem... :)

It's an interesting twist on the "booty dyno" vs. the "real" dyno. IMHO, it's best to tune a bike to have a characteristic you like and is compatible with your riding style and usage. In cases like this one, where actual dyno comparisons are available, it's hard to argue with the data. Particularly when the seat-of-the-pants agrees... Thanks to FF for posting the graphs and for everyone chiming in with their experiences.

i call it D&D syndrome.

:)

Can you tell me what the air box mod is all about? Or where I can ge the information?

Thanks!

What I want to know is who out there rides 03 YZ450s and did this mod? Was there an actual gain or did the power just change? Same with those of you who ride the 04 YZ450.

You do realize the the ignition map was changed to deliver smoother, more linear power for 04 right? A lot of people I talked to who got of their 03 and onto an 04 complained that the motor did not feel as potent. I wonder if by dissconnecting the TPS on the 04 the ignition map becomes closer to the 03 map. Just a thought. Who out there runs race fuel or premium pump gas after doing this mod? That will make a difference. Because the purpose of the TPS is to allow the higher compression motor to run as well as it does on pump gas. There is a purpose for it.

The only people Ive talked to & noticed on here who report significant power gains were on the 04 YZ450. I tried it on my 02 YZ426 and did not notice a thing other than it started to knock when I started to lug the motor on some hill clibs on a hot day. (running 91 pump gas)

The CDI takes in information from throttle position & engine RPM and computes it to for a 3D map for the ignition.

Why would Yamaha put so much R&D in developing 3D ignition map when you can just unplug it and get more power? When you unplug the TPS you are removing a variable that the computer uses to calculate the ignition timing & spark duration for more efficient combustion. Its kind of like having a vaccuum advance distibutor & an MSD ignition box on your small block chevy, but its all digital.

Oh, and if yamaha wanted to make the FCR without the TPS they could do it no problem. You would not believe how many variations are out there of that carb serving other applications.

Im not saying that dissconnecting it doesnt give you more power. But think about your application, and how the sytem really works & what it was meant to do. :thumbsup:

Because the purpose of the TPS is to allow the higher compression motor to run as well as it does on pump gas. There is a purpose for it.

I would love for you to explain this one...

There is absolutely no way for a TPS to know what gas you are running...

Sure no problem..... :thumbsup:

The TPS does not know what fuel you're running.

Lets look at it in terms of compression ratios & octane ratings. I am reffering to unleaded fuels only here. Basically, the lower the octane rating, the faster/easier the combustion. Typically when you have a higher compression motor and are running a low octane fuel you run the risk of preignition. Preignition happens when the temperature of the fuel being compressed reaches the ignition point before the piston in in the powerstroke. Too early of a spark can also contribute to this. Obviously you wouldnt want to run 87 in your YZF unless you were up at high altitudes (say 7000 or higher) So you run 91-92 pump gas. This is enough to prevent preignition due to compression under mild loads. Now lets focus on the timing of the spark. The YZF's computer with the TPS attached allows the spark timing of the spark to be altered to compensate for a lower quality fuel to be used in a high compression motor and actually have it run damn good! What the TPS does is control the spark by sensing throttle position at a given RPM. At low RPM with a large throttle opening there is a big load on the motor, the TPS adjusts the timing accordingly to aid in efficient combustion. Therefore, the motor doesnt ping & can accelerate out of the low RPM condition much faster & with more power.

If you are running some type of race fuel with the TPS connected, then the timing adjustment made by the TPS may be unnecessary due to the different combustion characteristics of the race fuel and may actually hinder performance. So in some cases it it might benefit to disconnect it. It all depends on the ignition map of the bike.

Remember the ignition map on the YZFs are not programable and must be held constant. Jetting, fuel, rpm, altitude, air temp, & throttle postion are all the variables the computer has to deal with to make the bike run. But the computer only takes into account the engine RPM & TP directly. The rest is up to the operator to get it right :awww:

Hope that helped you out. :lol:

On standard 2D ignition map, the timing is a function of RPM only.

I don't know why they put the TPS sensor on the bike, it seems logical that it was so the bike would run well on pump gas. For me with the way I have my bike setup with the power now and the 47 tooth rear sprocket my bike seems to run better than ever.

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