07 YZ450F Bottom Power


31 replies to this topic
  • Yamkifour

Posted August 17, 2008 - 02:20 AM

#21

[quote name='Boricua']I like my 07' YZ450F, but the bottom power sucks compared to my frind's 07'CRF450. QUOTE]


I felt the same way. I rejetted with the JD jet kit and got the bottom end I was looking for. I also got tons of mid and topend I wasn't looking for. I went down one tooth in the back sprocket and now love the power delivery to the rear wheel. I got what I was looking for and can control it well.

  • bigred455

Posted August 17, 2008 - 10:09 AM

#22

I never tested the OEM exhaust, It was bend when I got the bike. So I can't tell if the current set-up is the problem. The jetting still stock. I did try the 50 sprocket, but I got more out of the 51.


Try a 155 main,with a 42 pilot.What is the altitude in Puerto rico?

  • loudarbs

Posted August 17, 2008 - 05:27 PM

#23

Keep in mind you want "tractable" power. You can have all the power you could want but if it doesn't move you forward the best it's doesn't equate to fast lap times. Hence sometimes de-tunning a bike for better traction control.
But big power is addicting.
I nice new sharp tire does good things for acceleration too.

  • red7

Posted August 18, 2008 - 08:16 PM

#24

I run a MRD full system ,carb jetted for the MRD
1 tooth up rear
I can keep my bike in 3rd gear on most track
every once in a long straight ill go to 4th .


Ditto on the MRD full system. The thing is so small you hardly see it except for the blue anodized cap sticking out and it also is one of the nicest sounding exhausts out there if you're into the deep throaty sound. I just sold my 2006 YZ450 and took the pipe off and am going to sell it separately. If anyone is interested I'm going to post it in the classified so PM me.

If I didn't destroy my wrist and have to retire I'd put the MRD on any future bike. You can order them with a header designed for bottom or top end and I went for the bottom as it seemed to lack stock. What a difference over stock!

  • 801pe

Posted August 19, 2008 - 09:21 AM

#25

Try adjusting you fuel mixture screw, you should be adjusting it daily.

  • Aka.Goose

Posted August 22, 2008 - 01:24 PM

#26

Try adjusting you fuel mixture screw, you should be adjusting it daily.


Really? Anyone else adjusting this often???

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  • grayracer513

Posted August 22, 2008 - 01:35 PM

#27

Nope.

  • djs383

Posted August 22, 2008 - 01:41 PM

#28

I would agree. I've only ever used an aftermarket once and that was on a 250f. i took it off to trade it and ended up riding it one more time and felt stock was better. I just let my 07 yz450 go. I thought the honda was more powerful and thats why I liked the yamaha. But I'm about 140-145 lbs.....

  • Justin89

Posted August 22, 2008 - 01:55 PM

#29

Really? Anyone else adjusting this often???


Heck no.:worthy: ..I seriously never adjust that thing very often...:thumbsup:

  • grayracer513

Posted August 22, 2008 - 02:12 PM

#30

I would agree. I've only ever used an aftermarket (fuel screw) once and that was on a 250f. i took it off to trade it and ended up riding it one more time and felt stock was better.

I have no use for the stock fuel screw, and I do reset the idle mix 4-5 times a year for changing conditions, but nowhere near daily.

  • clutchless

Posted August 22, 2008 - 02:32 PM

#31

Really? Anyone else adjusting this often???


i do.

based on the air temp, humidity, altitude, and style of riding.

going from Amago when it's 65 degrees and damp to Ocotillo or Superstition where its usually 78 degrees and dry.

i warm my bike up for 3 min then crack to about 1/2 on the throttle listening for poping as i let off. if it pops a lot more then usual i adjust to fix.

as stated some poping on decel is normal but excessive needs to be adjusted.

i dont remember what i am running for jetting but i called Zip Ty to set it up.

  • bigred455

Posted August 22, 2008 - 05:23 PM

#32

You know the fuel screw is talked about like it is magic,it is not that sensative of a circuit. I leave mine(oem screw) set at 1.5 and move my pilot from summer to winter. The needle, main,AP and pilot are sooooo much more WORTH TO GET RIGHT.Really the fuel screw is so overated,it is not that intricate.





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