Need some bottom end hit.

20 replies to this topic
  • 328somewhere

Posted July 07, 2008 - 04:51 AM


I have searched this to death and have came up with no answers. Here goes I just got a low hour 06 yz450f. It has a PC TI4. The jetting is stock as far as i know. The power is great in the mid to upper but low end is lacking alot. I just got off a crf250r and switched to the yami. I swear the little crf had more lowend than this thing. The power is nice and linear but there is just no hit. Seatbouncing doubles out of tight corners is almost impossible. So how do i get some low end out of this thing? Is it a jetting issue? Do i need a new pipe? The bike doesnt bog it just doesnt have that 450 snap that almost every other 450 i have ridden has. I will check the jetting tonight to get the numbers. Also it has stock gearing which seem fine. I had a couple other people ride it and they felt it was lacking a ton of lowend. Like i said before the throttle has no bog it feels good. Please give me some help.

  • MX926

Posted July 07, 2008 - 05:09 AM


The 06 YZ450 had quite a bit of bottom end, sounds like you got something going on there. What gearing does it have on it? Stock is 13/49..Definately double check the jetting. If all of that looks correct maybe this beast has something elso internal going on.. Hopefully you can just do some tweaking of the jetting and get the fire back into the beast. If not, might have to tear it down and find out what condition the top end is in.

  • 328somewhere

Posted July 07, 2008 - 05:52 AM


The bike has at most 15hours on it and that is pushing it. I know they are suppose to have one of the best bottom ends in the business but mine seam to be lacking.

  • ncmountainman

Posted July 07, 2008 - 05:55 AM


drop a tooth on the countershaft sprocket,you'll find what you need for $15:thumbsup:

  • 328somewhere

Posted July 07, 2008 - 06:30 AM


That would make it a 12/49 which would be like running a 13/52 correct? I really dont believe its the gearing. It would help but not solve. Lowering it that much would hurt me around the rest of the track. The only other thing i can think of is rear tire. Its worn not horribly but worn. I have a new set of Michelins on the way. I am just wondering if its the pipe. I had similar issues when I had one on my crf. Anyone got a ti-4 on there bike that would like to share there input?

  • MX926

Posted July 07, 2008 - 06:37 AM


The bike should have plenty of bottom end power with stock gearing. If you have a 13/49 gearing is not the problem.

  • Ga426owner

Posted July 07, 2008 - 06:40 AM


This could be from several 15hrs this is perplexing
1. The bike may not have been properly broken in......the rings may have not sealed correctly. A incorrect breakin procedure will affect overall power output
2. the jetting may be off.
3. the carb may have issues
4. the pipe is too restrictive for lowend power

the bottomline is this there is plenty lowend torque and power on a 06 YZF450 compared to any 250f. If it were me and it is not #2,#3 or #4. I would be getting a new top end and break it in correctly:thumbsup:

  • 328somewhere

Posted July 07, 2008 - 06:40 AM


It has a brand new twinring Renthal 49tooth with a 13 up front and a DID oring chain.

  • 328somewhere

Posted July 07, 2008 - 06:58 AM


If i had to compare it to something it would be like putting a top end pipe on a two stroke. The motor pulls like a monster once it hits the mid. I can make the doubles if i clutch the crap out of it. Which is something i want to avoid which is why i move back to a 450. The bike starts and runs good. Doesnt eat oil. I just dont really want to have to buy a new exhaust which is what i am worried is the problem.

  • Anssi

Posted July 07, 2008 - 07:00 AM


With a bike that has been ridden only 15 hours in three years, I would definitely take a look inside the carb (accelerator pump, float bowl, clean jets and passages). Something may have gummed up.

I drained the carb and cleaned the plug where the jets get their fuel and the gunk in there was filthy(though not really gummy). This was on a zero hour -08 that I got a few weeks ago.

We have a nice step-up right after a (barely) second-gear tight off-camber, and my bike blasts out of there like a bat out of hell.

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  • Drfletcherdc

Posted July 07, 2008 - 07:18 AM


If it is stock jetting then you need to rejet. Do a search and you will find that one of the problems with the 06 was the jetting. Having the correct jetting is like adding 3-5hp on the bottom, especially the pilot jet. I ran a 45 or 48 depending on the time of the year.

  • 328somewhere

Posted July 07, 2008 - 07:54 AM


hmm that could be it. I will look into the jetting tonight and see what i got.

  • Slinkyman16

Posted July 07, 2008 - 07:54 AM


its not the pipe.. i have the full Ti-4 gp exhaust on my 07.. i would look into jetting. the bike should have a big improvement with that pipe. (not a whole much) since the power is made in the mid to upper range. but you should still be noticing an increase...

  • 328somewhere

Posted July 07, 2008 - 08:17 AM


I am really hoping its as easy as jetting that would be great. Now if i could get it to quit vibrating me to death I would have the world by the tail.

  • Ga426owner

Posted July 07, 2008 - 09:48 AM


I am really hoping its as easy as jetting that would be great. Now if i could get it to quit vibrating me to death I would have the world by the tail.

huh this bike is super smooth in fact it was designed to be super smooth- you should not be getting much vibration if at all.
Something is not right here - check the motor mounts

  • 328somewhere

Posted July 07, 2008 - 10:03 AM


will do. this thing vibrates horribly compared to my honda. After some searching I was thinking the motor mounts are loose or the bar mount cones are worn. Its got some gremlins that i have to fix from the previous owner. the bike sat alot just hanging out. It was bought late in 07 as a leftover so its not to old.

  • ncmountainman

Posted July 07, 2008 - 04:08 PM


i run 13/51 on my 05,i know you have a extra gear but i'm pretty sure 1st and 2nd is about the same. yamaha 450 is not really known for its arm ripping bottom end,in fact it took alot of time and $ just to get mine where i thought it shoud be;but thats just me:busted:

  • TapptOut

Posted December 04, 2008 - 09:44 PM


Did anything you try work?

  • finthat

Posted December 05, 2008 - 08:18 AM


If you have alot of vibration I think you need to find the source of that problem first. When you solve that I have a feeling your power problem will be easily solved. Low hours doesn't mean the bike is minty, it could mean the previous guy screwed it up and dumped it. I know more guys who buy these high performance bikes and wreck them by runnig them like some old half worn out trail bike they had when they were 8 years old.

  • ryzman

Posted December 08, 2008 - 09:35 AM


do the A.P mod with a 50 leak jet that'll make a good bit of diffarence.. did on my 07

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