Jump to content
Sign in to follow this  

01 YZ250F Mods for Trail Riding

Recommended Posts

I recently bought my 01 YZ250F from a guy who used it to race and scout tracks before his Vintage races.

The majority of my time on the bike will be shadowing my 7-yr old who just got his first bike. Im not planning on racing at all...having said that I realize that the WR may have been a better choice but I got a wicked good deal on the YZ.

I know most people are looking to mod their bikes to get more power and speed but I actually need to tone my YZ down so I can run it safely at slower speeds, in short bursts, with more than usual idle time while Im watching.

The YZ might be too much bike for what Im going to be doing with it - anything you can toss my way to tame it down would be great!

Share this post


Link to post
Share on other sites

You are correct when saying the WR would be a better choice, but you can make the YZ work.

1. Start with jetting.

Getting your bike jetted correctly will help with starting.

2. Cooling

This is were you are going to have the most problems with the YZF. The YZ is not design to sit and idle. It needs to be moving with air going through the radiators or it will over heat in as little as 3-4 minutes. You can run a better coolant like Waterwetter, Engine Ice or Evans coolant and these will help. I am currently using engine ice. Its easy to find and I live in MN where the distilled water and Waterwetter would freeze in the winter.

I have found that it is best to turn off your bike while you are waiting for someone. That is where the correct jetting comes in. Starting your bike with one kick saves you alot of effort.

You may also want to run a WR radiator over flow tank. That way if you start to over heat, you will not lose any coolant on the trail.

3. Gearing

You can add two teeth the rear sprocket to get a better low speed crawl. You will need to purchase a new chain to fit on the new size sprocket.

Rockymountain sells some cheap chains and sprockets for testing. When you decide what works for you, go back and buy an o ring chain and sprockets then.

4. A Flywheel. This will change the power curve to slow and smooth. It will also help prevent stalling. Here is a good place to start. steahlyoffroad.com I would recommend buying a the complete flywheel instead of the added weights. As you get to be a better rider and you son gets older you will want to go back to the stock weight and you can sell the heavier one.

I played the waiting game for over 4 years with both of my sons. Lots of great memories. The sad part is they are starting to wait from me know

Share this post


Link to post
Share on other sites

I echo Dano's comments. I have a done a few YZ's for people and that is basically what I have done. Instead of increasing the rear sprocket, I went down a tooth on the front (is almost the same as three on the rear). This did not require any chain mods, was cheaper and easier to swap back and forth of needed.

Flywheels can also be had from TrailTech. Note most aftermarket flywheels do not have the TDC mark on them. I rec. scribing it when you put it on.

Share this post


Link to post
Share on other sites

1. Start with jetting.

Getting your bike jetted correctly will help with starting.

Any guesses on what the correct jetting should be? I dropped a post in the Jetting Forum but didnt get suggestions. Currently Im set up: 178 main. 40 Pilot. 105 leak. Needle is on 4th groove

2. Cooling

This is were you are going to have the most problems with the YZF. The YZ is not design to sit and idle. It needs to be moving with air going through the radiators or it will over heat in as little as 3-4 minutes. You can run a better coolant like Waterwetter, Engine Ice or Evans coolant and these will help. I am currently using engine ice. Its easy to find and I live in MN where the distilled water and Waterwetter would freeze in the winter.

Thanks for the heads up - Ill be picking up a couple gallons sooner rather than later!

You may also want to run a WR radiator over flow tank. That way if you start to over heat, you will not lose any coolant on the trail.

Again, thanks! Ill start my search now!

A Flywheel. This will change the power curve to slow and smooth. It will also help prevent stalling. Here is a good place to start. steahlyoffroad.com I would recommend buying a the complete flywheel instead of the added weights. As you get to be a better rider and you son gets older you will want to go back to the stock weight and you can sell the heavier one.

I started looking into a FWW, but cant seem to decide how heavy to go. It sounds like +8oz isnt really going to make much of a difference, but is +11oz too heavy?

I played the waiting game for over 4 years with both of my sons. Lots of great memories. The sad part is they are starting to wait from me know

Im actually looking forward to that day! Its gonna be a while since he's just 7, but I cant wait until he has to wait on the "Old Man"!

Thanks again for all the insight and tips!

Share this post


Link to post
Share on other sites

There are base lines for jetting, but it is very bike specific and needs to be tested. Do search there is a ton of post about it.

Since I knew nothing about jetting when I started, I purchase a JD kit.

Here is what I am running now

MJ = 180

PJ = 40 - 1 1/2 turns out

Needle at 4th po

Also changed the leak jet to #60 and added the o-ring mod.

As for the flywheel. I know of a few eduro riders who like the 10oz for racing. I would not think a 10oz will be to much.

Share this post


Link to post
Share on other sites

I would purchase a JD jet kit for your 01 YF250F it will make a big difference.

Share this post


Link to post
Share on other sites

Regarding William1's post I am one of the fortunate to have had the opportunity to benifit from his generosity and knowledge base. I have a 2003 YZ250F that via william's suggestions is now a wonderful trail bike.

My 1st mod was changing the leak jet from 100 to I think around 48, this got rid of a huge bogging problem almost instantly. We also added the trailtech 10oz flywheel. We chose DrivenRacing Sprokects and I run 12/48 this is very nearly perfect for tight woods trails and is still fun on a mototrack.

The WR overflow for the rad was also added.

I bought the bike used with a "fresh" top end. With out an hour meter I'm guessing between my son and myself we put something over 100hrs on it. The bike started smoking at startup at the end of last fall and it was worse when we started about a month ago.

Once again via W1's generosity the head was taken off and shipped to Jesse at Williamsmotrwex.

There is a rumor via Jesse that the new head is enroute as we speak.

My rebuild was all about durability and increasing low end and mid range power.

The results are yet to be determined but I'm exicited by some early reports of his work.

Enjoy your YZ you will have a blast on it.

As for me, my rotten 16yr old son has claimed the bike for himself and I play chase around on my trusty DRZ 400.

Infact it's good that my son is strong and the bike is fast, I don't have to wait so long for him to come back and lift my bike off me when I fall.....

Happy riding

Share this post


Link to post
Share on other sites
Anyone have any luck or experience with the Fluidyne Power-Flo Radiators? Wondering if its worth the money to drop in the YZF to help prevent overheating?

Even with larger radiators the bike will still over heat if you are not moving. I would look into a better flowing water pump like Boyesen Water Pump Cover and Impeller Kit. The good thing about a water pump is that it will not get bent if you crash or should I say when you crash.:thumbsup:

Share this post


Link to post
Share on other sites

We chose DrivenRacing Sprokects and I run 12/48 this is very nearly perfect for tight woods trails and is still fun on a mototrack.

Isnt the OEM Rear 48 already?

Share this post


Link to post
Share on other sites
how does the tube from the tank connect to the yz radiators?

Connect the over flow tube to the tank. AVs website described it step by step. The process is the same whether its a WR or YZF

Share this post


Link to post
Share on other sites

so could i just get a wr tank from ebay and bolt it on without modding fenders or does it taking modding the fenders with a wr radiator tank?

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×