What Mods To Smooth Power Delivery

14 replies to this topic
  • bcs001

Posted July 24, 2004 - 04:25 PM


Looking for recommendations on how I can smooth out the power delivery at part throttle. I was out at a North Georgia ORV Area (Beasley Nob for those who are familiar with this area)with SERIOUS hill climbs and elevation changes. Trails were filled with ruts, roots, rocks an boulders. These were the toughest trails I have ever ridden.

I was having a real problem keeping the front wheel down even while practically sitting on the gas tank. When additional speed/power was needed, it was comming on way too quickly. For this type of hill climbing it would seem like the power needs to come on smoother.

The only mods I have made so far is the throttle stop and air box cover removal.

For this kind of riding I am thinking a larger rear sprocket would be a big help. I am also thinking some of the carb mods may help with the abrupt power delivery while hill climbing.

Thanks for helping,

  • Indy_WR450

Posted July 24, 2004 - 04:49 PM


I climb extensively. The WR450 will hit its limits on long steep pitches and wheelie out before running out of power. If you have a WR then your power delivery is already pretty smooth. If you have a YZ then a flywheel kit and WR exhaust cam may be a better choice. The next thing is to make sure you add a link to the standard chain length on your next chain purchase. This will make a noticeable difference on reducing wheelies. Make sure your rear suspension is set up to track on nasty rutted loose rock hill climbs. Too stiff and you will hop up the hill and wheelie more. Lower rebound dampening helps on the rear so it returns to full extension quicker. Power delivery can also be softened with richer jetting if you think it is still too abrupt. But a smoother Hydraulic clutch is still your best choice for steep climbs. :thumbsup:

  • Hamish

Posted July 24, 2004 - 09:51 PM


Not sure what bike you have. If you have a 400 or 426 I believe that fitting the WR450 exhaust camshaft will smooth things out a lot.

  • endurodog

Posted July 25, 2004 - 01:38 AM


We need to start with what bike you have. If you have a 400/426 that you bought used then there may have been some work done to it that causes it to hit harder, i.e. YZ cam rotation.

Tell us about your bike.

  • mtrablue

Posted July 25, 2004 - 05:06 AM


how long have you had the bike? these things have a lot of torque and demand throttle control in tough situations. don't be afraid to play with gearing.

i know this is an expensive solution but, the z-start auto clutch made that stuff alot easier for me. i warn the guys i ride with that if the up hill is bad, i may slow down and then take off again. don't follow too close. they may charge up a hill to carry their momentum so they don't have to shut off and get back on it. the auto clutch lets me do what i want.

one way or another, ride the bike a bunch.

  • Fryboy

Posted July 25, 2004 - 03:27 PM


Install a DRZ engine in the frame and then start perfecting a comb 0ver with your hair. :thumbsup: :devil:

Seriously though, like everyone else said, it would be nice to know what bike you ride and what has been done to it. The first thing that I thought was going up some teeth in the rear sprocket.


  • blue_beast_wins

Posted July 25, 2004 - 06:33 PM


Going by previous posts, i'd say he may have bought a 426 :thumbsup:

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  • gloft

Posted July 26, 2004 - 11:33 AM


I've went to a 52 tooth rear sprocket for riding tight stuff in Ga. It helps a bunch and bike will still run over 80 mph. I ride the same trails a lot and try and ride a gear higher on hill climbs to stay away from the mid range hit. Your bike has plenty of bottom end torque to carry a gear taller in most situations :thumbsup:

  • bcs001

Posted July 27, 2004 - 05:24 PM


Seems I did leave out some important info on the bike.....It is a brand new '02 WR426. I bought it used from a guy who only put 10 miles on it before he decided it was too big/heavy for him.

It was completely stock when I got it a couple of months ago. I cut the stop screw, pulled the air box cover and installed the GTYR silencer. Afer this weekends ride I have 52 miles on it. Did one oil change at 20 miles and thats it. Due for a valve check before the next ride.

The one thing that I figured out very quickly was you have to sit on the tank to get any weight over the front wheel while hill climbing.

I am leaning towards a larger rear sprocket initially but I was wondering if he BK carb mod would make much difference in how the power comes on.

Can I go up to a 52 tooth sprocket without a new chain??


  • KTM-Lew

Posted July 27, 2004 - 06:11 PM


You will be much happier with the bike if you change the gas tank for an IMS or Clarke. The stock tank sucks bigtime.
You should be able to pick-up a used one fairly easy.

  • mtrablue

Posted July 28, 2004 - 02:01 PM


i think you'll be better off with a new chain. even if you could pull the axle far enough forward to make the sprocket work, you would shorten the wheel base. it would be even more wheelie prone. just to check the results, you can go down one tooth on the counter shaft sprocket a lot cheaper than a new rear and chain combo.

  • Bandit9

Posted August 10, 2004 - 03:57 PM


To answer your question, add a heavier fly wheel weight. Like an 11 or 13oz from Steahly Off Road. It will smooth the power delivery even more. Adding a larger rear sprocket will only make the front end come up quicker. If anything, you should try a smaller rear sprocket.

  • the426master

Posted August 11, 2004 - 01:42 PM


when I take my 426 trail riding I put a 13 tooth front sproket which helps torque and it won't die as easy :thumbsup:

  • Indy_WR450

Posted August 11, 2004 - 01:44 PM


Ditto I run 13/50 & 14/50 with the same chain and just switch fronts for the terrain. :thumbsup:

  • dale

Posted August 12, 2004 - 06:26 AM


I cut the stop screw, pulled the air box cover and installed the GTYR silencer.

With the GTYR insert it should be pretty smooth. Adding the 450 cam made mine have more power with less hit, but my CRD exhuast is better than the GTYR and only a little louder.


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