YZ250X governor spring

[Kinger317]

Does anybody have any information on this? A quick check showed '02 through '16 YZ250 governor spring part number 90501–256L2–00. The new '16 YZ250X governor spring part number 90501–290A2–00. Is this an updated number or a different spring? I would like to try a different spring in my '09YZ250 to smooth out the surge.

Edited October 2, 2015 by Kinger317

[YZDOC]

Did you typo? Same number with a space b/t L and 2?

[Kinger317]

Yes! Corrected. Thanks for catching that

[Treesmacker]

This is from Dirt Bike Test:

The power isn’t tamed much but it is more manageable. Without adding flywheel weight Yamaha got some additional smoothness with less compression but actually boosted the overall power with a raised exhaust port. Additionally the powervalve opens slower and helps smooth the delivery. It is so strong running you hardly feel the wide ratio spacing in the gears in shifts between 3-4-5. The traditional YZ sign-off at peak power is gone in favor of a very long overrev character. Yes, this may be better than the YZ motocrosser for some.

 

Looks like it has a new spring

[shrubitup]

I wonder if they changed the slide on the 250X vs. the 250. That's a known point that causes the 250 to have the aggressive hit. 

[Kinger317]

I believe the slides are the same, they both are 5HC–14340–A7–00 which is the #7. All jetting is the same too, 50, 50, 178, N3EW.

Has anybody tried a different spring on the governor? Or shimming the stock spring?

[mikeylikesit]

$10 is certainly worth a try for the spring. RMATV says 5-7 business days.

 

Update... just ordered it. They say early November.

Edited October 2, 2015 by mikeylikesit

[Kinger317]

After looking a little closer the only other differences I found was the washer plate (4) says (T = 0.8) and has a different part number for the 250X and it says not shipping :-( The valve itself has a different prefix. The 250X is BF1 and the 250 is 5XF. Not sure what the difference in the valve would be but it looks like the washers are a different thickness? any part number experts out there?

[Doc_speeder]

This is from Dirt Bike Test:

 

The power isn’t tamed much but it is more manageable. Without adding flywheel weight Yamaha got some additional smoothness with less compression but actually boosted the overall power with a raised exhaust port. Additionally the powervalve opens slower and helps smooth the delivery. It is so strong running you hardly feel the wide ratio spacing in the gears in shifts between 3-4-5. The traditional YZ sign-off at peak power is gone in favor of a very long overrev character. Yes, this may be better than the YZ motocrosser for some.

 

Looks like it has a new spring

Yes, the motor is fantastic.  That's one thing I'm very impressed with is the total RPM range available.  It tractors down quite low, and revs out to the moon.  Awesome engine.

[Treesmacker]

Here is a link to the Dirt Bike Test sneak peak:  http://dirtbiketest.com/fresh-dirt/2016-yamaha-yz250x-first-riding-impression/

[carver]

The smoother power and better overrev also makes it sound like they fixed the timing, would be curious to hear what it is from someone who picks one up and checks it.

[shaheeb]

I have been reading the CDI is different.

 

BF1-85540-00-00 is the part number according to motosport. & RMATV    $240.

 

 

Would this make much of a difference to a stock 09 yz250???

[carver]

Honestly for most people, probably not. Imho it would be money better spent to just pick up a dial gauge for $45 and make sure your timing is right,

 

which will reduce detonation if you're on pump gas.  Then you can try +1/0/-1/-2 degrees and see which you like for your riding, fuel and conditions. If someone has $240 rattling around

 

and you're curious, sure, try it.  There was one person who tried an adjustable box in the timing thread though who thought just adjusting static was nearly as good.

[shaheeb]

I was just reading the timing thread yesterday.  538 replies is a lot,  I think I got 5 pages in and almost bought the dial already.  The webpage is open on my computer   ?

 

THing is I want to ride the YZ first before I spend any money on it.  Just bought it on Monday,  it has to be shipped so next weekend I should be able to get a ride!

 

for trails I think its ready.   11oz weight, , PC ported and head mod, 13/50 ,  21/18" rear wheel,  15 plastics, and some bling  ?  such a good deal compared to KTM,etc...

 

 

stoked.   Thanks for the tip on timing!

[Kinger317]

Has anyone tried changing springs or shimming the existing spring on a YZ250? Anybody played with the governor spring at all?

[rjpjnk]

$10 is certainly worth a try for the spring. RMATV says 5-7 business days.

 

Update... just ordered it. They say early November.

 

Did you try the new PV spring yet?

[cman962]

Has anyone tried changing springs or shimming the existing spring on a YZ250? Anybody played with the governor spring at all?

Harris performance sells a lighter spring. I have one in my EG295 motor. It let's the power come on about 500 rpm sooner. It designed for a ported 250 or bigbore. Not sure how it would effect a 250 cc motor.

[Kinger317]

Harris performance sells a lighter spring. I have one in my EG295 motor. It let's the power come on about 500 rpm sooner. It designed for a ported 250 or bigbore. Not sure how it would effect a 250 cc motor.

Do you like it? Where could I get one in the states?

[Kinger317]

I found Harris performance products in the UK. Searching their site could find no governor/power valve springs. Any info would be appreciated. Thanks

[SAthump]

Look for him on here