Just as I had suspected!!!! (TPS Must Read!!)

I posted about the elation I had after I rode my NOS 2004 450 after I uncorked it about a week or two ago. This bike rocks! I have absolutely fallen in love with it.

I did have one problem that was bothering me. I had a mid throttle stumble that worried me a little. I hated the fact that I had to lug it for it to be smooth when transitioning from trail to trail on fireroads or rip along at full throttle Half throttle would send the bike into a surging/stumbling pattern that felt like the CDI couldn't make up its mind which timing map to use. Knowing a little about TPS problems on fuel injected vehicles, I thought that this was the problem on my bike. I read about one guys experience with his TPS sensor on his WR on this forum and it really made me wonder. He said that his wasn't set correctly from the factory and just by adjusting it, it made all the difference in the world. I thought to myself that Yamaha would never let a bike out the door with a TPS that wasn't adjusted correctly. Then I thought about the tuning gymnastics that would have to be pulled to make this bike run in the massively restricted stock form. Could Yamaha actually set these up incorrectly just to make them run? Naah, I thought. As my conspiracy theory brewed, I thought about my experience in manufacturing and the thought that this thing wasn't set up correctly reallly started to gel. I finally had the gumption to check it out. I used a couple of paper clips to stick into the leads and tested it per the owner's manual instructions. Much to my surprise, the reading was .48 volts. This was out of spec. I adjusted it to spec and took it for a little spin. Woohoo! this bike only gets better. ?

The moral of this epic monologue is for all of you that have disconnected your TPS or still are having weird mid throttle position problems. Adjust it per the Owner's manual instructions. I reallly think that these aren't setup correctly from the factory. I also believe that by disconnecting the TPS, you are losing some of what makes these bikes so alluring. The technology that changes the timing curve for the throttle position at any given time is what makes this better than an old air-cooled no technology thumper.

I'll report the full ride report after Sunday but I know that it is going to be a changed bike.

THat is very interesting...im gonna have to hit the manual this weekend and learn how to adjust the TPS.

What is the TPS specification for an 04 Wr450 carb? I got an 04 carb off of eBay last year and have been running it in my 99 WR since then, but I haven't checked the TPS and do not have an 04 manual. The bike runs great but there is a little bit of mid throttle surging just like it always had with the old carb. Thanks in advance.

THat is very interesting...im gonna have to hit the manual this weekend and learn how to adjust the TPS.

DITTO! ?

wow,

ill be very interested to here how it all goes!!! since my 04 450 was fitted with a yoshi pipe and the jetting changed i started getting massive cruise speed spluttering... obviously disconnecting the tps fixed my probs but if we are able to find a mid-way or corrective measure for the tps all the better please keep us all posted as i'm sure there is a tonne of guys with the same probs...

in a nutshell, what needs to be adjusted with the tps? i don't have the book with me until next week ?

First, you loosen the little screws that hold the TPS it in place, then rotate the TPS until the resistance reading is where it's supposed to be. Finally, tighten the screws back down to lock it in place. It's very easy to do. There may be a need for security-type torx keys to loosen the screws, but I haven't checked mine yet to see if that's the case.

thanks, i'll take a closer look tonight ?

What is the TPS specification for an 04 Wr450 carb? I got an 04 carb off of eBay last year and have been runnning it in my 99 WR since then, but I haven't checked the TPS and do not have an 04 manual. The bike runs great but there is a little bit of mid throttle surging just like it always had with the old carb. Thanks in advance.

Rich - I too have picked up a 04 carb for my 99 WR400. What else do I need to hook it up to my bike? Cables? Boots? Thanks.

Looky here Scotty, thinking outside of the box will get you in deep trouble some places, but not here! Good find. ?

BTW, I can't wait to see how f'ed up the FI will be on the WR to meet EPA standards. We'll be dealing with AIS TPS MAPS and probably a few other tricks to fix the EPA restritions. It's gonna take a lot of thinking outside of the box to get it to run.

Rich - I too have picked up a 04 carb for my 99 WR400. What else do I need to hook it up to my bike? Cables? Boots? Thanks.

When I got the carb off of eBay, it came with the throttle cable/throttle tube and the remote hot start cable/lever. All I had to do was mount it on my bike. I put the hot start on the right side of the handlebars. The boots still work with the new carb. If all you have is the carb, you'll need the throttle and hot start cables and the hot start lever.

Okay, adjusting it is not like a car. You don't set it by resistance. You set it by output voltage. The range is .54 to .7 volts DC at idle or something like that. I inserted some paper clips into the boots of the yellow and black leads in the plug and hooked up my trusty fluke 12 voltmeter. I started the bike and the voltage output wasn't even registering. I knew that there had to be some voltage present so I dug around with the paper clips until it read .32 volts constant. I loosened up the Torx screw that holds the TPS in position and rotated it until it read .62 to .64 volts and tightened her down. Rechecked it afterward and disconnected it. Oh yeah I almost forgot. The red lead on the voltmeter to the yellow wire and the black goes to the black. LEAVE THE TPS HOOKED UP!! I still think I have a little surge but I think that I can work that out with jetting. I am going to try my JD blue needle. I dropped in the red needle per the jetting sticky but JD is pretty adamant about the blue needle for my situation (0-4000 ft, 60-80 degrees, very low humidity). I am wondering if a lean condition could lead to a stumble. We'll see this weekend.

Does anyone know what pilot jet a 2004 US model came with? I didn't even check it when I installed my JD jet kit. My 0-1/4 throttle seems a little fat and It is only out 1 1/4 turns. (Zip Ty screw of course)

good find scott v. i"ve been riding my 04 w/ tps disconnected for quite a while and have been happy even though my mileage has suffered and the hit is a little flatter. bike is plated and i couldn't handle the stutter on the street. stock pilot is 45 on the 04. i'm in western WA and my jetting is good to about 4500 feet, even in summer. 170 main, 48 pilot, jd blue #4, 72 starter, 35 leak jet. anyway, after reading your post i ckecked my tps and got .40 v. i had to adjust counter clockwise all the way to get a .60 reading and i do notice a big improvement. thanks. i do wish i had a more accurate voltmeter for small readings. jetting specs is w/ fmf ti-po pipe.

When I got the carb off of eBay, it came with the throttle cable/throttle tube and the remote hot start cable/lever. All I had to do was mount it on my bike. I put the hot start on the right side of the handlebars. The boots still work with the new carb. If all you have is the carb, you'll need the throttle and hot start cables and the hot start lever.

Thanks. Does the bike run any better with the newer carb?

...Does anyone know what pilot jet a 2004 US model came with? I didn't even check it when I installed my JD jet kit. My 0-1/4 throttle seems a little fat and It is only out 1 1/4 turns. (Zip Ty screw of course)

If I recall, the WR's is a #70. You can get one for a YZ or a CRF (sometimes a dealer can get the honda parts quicker), which is a #100.

Yamaha part # & description:

5TA-14943-27-00

JET, MAIN (#100)

or

Honda # & description:

99104-MEB-1000

JET, SLOW AIR (#100)

If I recall, the WR's is a #70. You can get one for a YZ or a CRF (sometimes a dealer can get the honda parts quicker), which is a #100.

Yamaha part # & description:

5TA-14943-27-00

JET, MAIN (#100)

or

Honda # & description:

99104-MEB-1000

JET, SLOW AIR (#100)

That's PAJ!

PJ was 45 ?

Thanks. Does the bike run any better with the newer carb?

It runs much better and I really like the remote hot start. The bike feels like it has much more motivation to move forward compared to the bike with the old carb. But I didn't get a new carb for performance reasons. The original carb went through two carb sliders and I got sick of always worrying about it breaking another one. The performance boost is just gravy to me.