Why Yamaha will not update the YZ-250....good reading

You sir are welcome !! I know there was a thread about this recently and seeing this I knew others would like to read it.

Wow i cannot read this. Most rediculous thing ever. MXA doesn't have a mobile friendly version of their web page. It's 2013 MXA get with the program. I don't have access to a computer for a month!

Edited by CRF450ish

Hell, i love my 02 yz250. Nothing about the newer ones makes me want one. It does great stock for trails and cruising.

Wow i cannot read this. Most rediculous thing ever. MXA doesn't have a mobile friendly version of their web page. It's 2013 MXA get with the program. I don't have access to a computer for a month!

My windows phone pulled it up no problem...which is actually pretty rare for it to do something I want it to.

Great read thanks for the link!!

That article has enough errors and BS in it to make one chuckle and not take it very seriously.

Fork oil "height" 130mm ?? Really??

Add an aftermarket pipe and you will need to increase the main to a 180 or 182? Has that been the experience of anyone on this board?

I subscribe to MXA and I am happy that they support the 2-stroke market pretty well, but they do seem to state things that are counter to what I read hear on TT from YZ 250 owners. For one thing, they state that an aftermarket pipe is worth 3 horsepower. There are many threads done by tuners here that say the stock pipe gives the best overall power, and the aftermarket pipes only move power around a little. I also think the magazines are wrong for bashing a manufacturer for turning out a great product like the YZ smokers simply because they have not altered the look in a number of years. If the bike works as well as it can now, why change it just for the sake of change?

That article has enough errors and BS in it to make one chuckle and not take it very seriously.

Fork oil "height" 130mm ?? Really??

Add an aftermarket pipe and you will need to increase the main to a 180 or 182? Has that been the experience of anyone on this board?

Stock jetting is extremely lean for Michigan Sand MX tracks.

My problem is this:

(1) Exhaust pipe. You can gain two horsepower with an FMF or Pro Circuit pipe. Although you might think that this will help close the gap to the more powerful KTM 250SX, that is only true if the KTM rider doesn't install an FMF or Pro Circuit pipe.

(2) Reeds. As a rule of thumb, MXA test riders who like more midrange choose Moto Tassinari reeds and those looking for more top-end go with Boyesen. A simple mod is to remove the 5mm spacer in front of the reed block for more top-end power.

(3) Gearing. Every MXA test rider adds one tooth to the YZ250's rear sprocket. The goal is to gear it down to get to third gear sooner. The lower gearing makes the bike accelerate quicker.

(4) Jetting. Although the YZ250 is finely jetted for its box-stock configuration, if you port it, raise the compression, add an aftermarket exhaust or try to skimp on fuel quality it will ping. Play it safe and go rich.

(5) Front brake. Drop kick the stock front rotor and go over-size–260mm is nice and 270mm is better.

(6) Clutch: We run stiffer clutch springs. Our basic setup is to install three aftermarket YZ450F clutch springs to get better bite.

(7) Flywheel weight: Although local hotshots will tell you that flywheel weights are for enduro riders, virtually every factory Yamaha YZ250 rider ran a flywheel weight on his works bike. We run a 9-ounce Steahly weight, but Steahly will make you a lighter weight also.

1) Pure dross. The stock pipe out preforms both.

2) See above.

3) One tooth eh? That's crucial.

4) The #7 slide in there is a good part to modify or use on a different motorcycle. But it totally grocks wrongness on a YZ.

5) Honda hydraulics are cheaper (used) and more effective. But both is the way to go.

6) I'll get right on that.

7) The GYTR off-road is an excellent choice.

You jet the bike correctly for conditions, mods, weather etc. That's a given. It really doesnt matter what any article said it should be.

If the bike works as well as it can now, why change it just for the sake of change?

I agree. Looks doesnt do me anything. That's what aftermarket is for. Customize all you want.

In cold weather or sand I think the bike needs a bigger main jet, especially on pump gas. As far as the 130mm oil height they are talking about the oil height in the inner cartridge. Make the fork much stiffer when raising the oil height on the inner cartridge.

In cold weather or sand I think the bike needs a bigger main jet, especially on pump gas. As far as the 130mm oil height they are talking about the oil height in the inner cartridge. Make the fork much stiffer when raising the oil height on the inner cartridge.

There is no "oil height" measurement for the inner or outer chamber. That is most likely a copy/paste remnant from some YZ250 test 10 years ago. Typical MXA.

You cannot alter or change the amount of oil in the inner chamber. It is completely filled with oil and bled to ensure there is no air in it.

Owners manuel states, oil height to be between 145-148mm in the inner chamber. You can run more oil in the inside chamber, I set mine at 140mm. I agree 130mm is quite a lot of oil. The 140 just makes the last couple inches a little more stiffer. In nearly all suspension tuning articles it talks of adding oil or subtracting oil through the bleer screw hole. The bair bleeder screw in located in the inner chamber fork cap.

I will say if you add more oil in the inner fork cartridge you better drill the plastic pistons the extra bleed holes in the article about them here on TT.

Owners manuel states, oil height to be between 145-148mm in the inner chamber. You can run more oil in the inside chamber, I set mine at 140mm. I agree 130mm is quite a lot of oil. The 140 just makes the last couple inches a little more stiffer. In nearly all suspension tuning articles it talks of adding oil or subtracting oil through the bleer screw hole. The bair bleeder screw in located in the inner chamber fork cap.

When the manual states 145-148mm, that is NOT a range of adjustment for altering the performance of the fork. Notice it's only 3mm difference. It's basically just telling you how much oil has to be in there to eliminate the air when you install the damping assembly and bleed all the air out.

Any oil you put above that, say your 140 or 130 as MXA says will just get pushed past the piston when you bleed the inner chamber. It is then above the piston so, essentially, it is not in the inner chamber anymore. Once it is above the piston, it will naturally work out the bleed holes to the outer chamber as the fork compresses, thereby ending up in the outer chamber. Same thing if you put oil in through the bleed screw. It is above the piston and will work it's way through the bleed holes to the outer chamber.

If you put oil higher than the max recommended 145mm and do not properly bleed it, and don't drill holes in the piston as you said, you risk exploding the piston when the extra oil forces its way past the piston seal under high pressure.

Again, that 130mm that MXA states is most likely just a stupid copy/paste mistake from some ancient test on the old single-chamber cartridge forks. You do not adjust the perfomance of the twin chambers by altering the amount of oil in the inner chamber. You alter the amount in the outer chamber to do that.

Ok

Edited by yamahachuck

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