yz250 OEM silencer question. Have Shorty.

[rjpjnk]

I recently bought a 2011 yz250 and the previous owner put an FMF shorty silencer on it. I realize this is a good option especially for low end, but I like to keep my bikes as close to stock as possible and would like to replace it with an OEM silencer. I understand that beginning in 2011 the silencer grew about 3 inches in length to conform with the European standard. I am wondering if this additional length comes with any performance hit. Would I be better off getting hold of a pre 2011 model?

 

There seem to be many of both versions for sale on ebay.

 

Thanks,

Rich

[SmokinJoe90]

I would go with the 10 n older I thought the 11 plus hindered power why everyone swapped it out. I myself have two of the 10 n older silencer and pipes.

[rjpjnk]

Yeah, a 2010 or older might be the best bet. I searched but couldn't find any discussion as to whether the 2011+ silencer was impacting power. Can you provide a link?

 

I think that in addition to making it longer they also made the perforated tube a larger diameter, so maybe it is actually better? Ride reports would help.

Edited August 31, 2015 by rjpjnk

[Bremer120]

If you're going for a stock OEM look then go with whatever you feel would look best. You will be giving up performance in one way or another by ditching the shorty anyhow so splitting hair on the two OEMs shouldn't matter much. Personally the shorter OEM pipe looks better in my opinion. Whether it performs better or worse then the current equipment I wouldn't know.

[numroe]

... but I like to keep my bikes as close to stock as possible and ...

That sounds like you want your bike kept stock just on principle. Which is fine, but it would be something that makes no sense to me personally.

Firstly I never ever buy a bike for myself with any care about resale value. I just want to make the bike work as best as possible.

Stock bikes are built to a price, and for a mythical rider and his "average" needs.

Your stock 2011 YZ250 can be so much better, for any rider.

Targeting a mix of MX tracks (almost never groomed) or fast trails, in rough order of preference, I'd fix these things on a stock 2011 YZ:

1. Up one rate in the fork springs. 0.44 dive too much for 165 lbs me.

2. Same 4.9 rate but constant rate quality steel rear spring. Ti spring hurts traction under power.

3. Rear shock re-valved to soften the horrid compression spikes.

4. Adjust the clickers and sag. Adjustable for a reason.

5. Head corrected squish. Broader power and consistent, instant response. Less gear shifting.

6. Jetting. Remove that blubbery then delayed hit "stock" feeling. Want a clean linear pull from the motor, always.

7. Gearing (for my needs). Once the power is broadened, a 49T rear works fine.

8. Dunlop MX32 tires. I like them.

9. Flywheel weight. After all of the above mods.

10. Lower offset triple clamps. More agile in tight turns. More planted front in flat sweepers.

11. Oversize 270mm front brake rotor.

12. Fork re-valve. Stock is great, but I know how to make them much better - for my needs.

13. Lighter pull clutch lever. Call me soft.

Edit: The best thing about a shorty muffler, is that when you crash they don't get broken so easily. Mods 5 and 6 above will do far more to boost the bottom end power.

Edited September 1, 2015 by numroe

[rjpjnk]

Stock regarding things visible (like the exhaust, plastics, seat covers, engine covers, and assorted bling). I'm definitely ok with modifying suspension, jetting, fww, etc. Ok, maybe arc levers too, but mostly stock and clean is the look I prefer.

 

I immediately noticed the blubbery rich mixture you mentioned and swapped the 50 pilot for 45 (since I had a 45 on hand in my shop). It is much better now, but still seems to have a little down low transitional blubberiness. I hear the No 8 slide is the fix, but think I'll play with the jetting a bit more since it's cheap and fun. I think I may try 42 and 40. Tried moving neadle leaner 1 pos, not sure if I like it better or not yet. What jetting did you settle on, and under what riding conditions? 

 

The bike came with a 13oz Stealthy fww from PO. Seems ok, wondering if the GYTR might be better?

 

I think I may need to go heavier on the shock spring (190 lbs). I have a 5.1 in the shop, so I may give that a try.

 

Deffinitely dissagree with the .44s being too light in the forks. You must be a super agressive rider!  Stock springs seem to sit just right for me, but the valving is so harsh!  Right now I have the C all the way out and R at about 15 out and it is just tolerable. Could this be because the suspension has only 3 hours ride time on it? Was thinking of sending to FC for revalve as I've been very happy with what they've done for my other bikes. The shock seems to need more rebound damping. I am at 7 out now and surprised I may need to go even lower. Hmm... again maybe the revalve will help, but I'd rather just ride it for a couple months and see what I think.  Yeah, know what you mean about the anoying compression spikes.

 

EDIT: Forgot to mention the timing. Initially it was at .0125" (1.5 deg adv). I moved it back to .003 (2 deg ret). I like it better there. Of course I will correct the squish. I haven't even had a chance to measure it yet. I've read entire squish thread and more. Looks like 50-ish is a good target? Now these 2011+ have a lower compression head as you know from the factory, so I am wondering if it might be possible to correct squish without CC adjustment? I supose it will depend how much has to be shaved off the head. Maybe I will measure this wekend. What did you set yours to?

 

Thanks for all your helpful suggestions btw!

Edited September 2, 2015 by rjpjnk

[numroe]

OK understood re your preference for the stock appearance.

At below 1000 ft, I don't think going smaller than a 45 or even 48 pilot jet will work well with the Yam needle. The pilot feeds fuel beyond 3/8th throttle, and at 3/8th the Yam needle is too lean, so with the small pilot you will end up with a nasty hesitation then a a delayed hit. Not good if you care about lap times.

I'm a big believer in the #8 slide. I hate that 1/8th blubber. The slide cutaway fixes it nicely. A needle with leaner straight section can help, but I found the straight section does more at around 1/16th throttle (that is does not change much).

This post describes my best attempt at jetting the 250, using two Zook needles: https://www.thumpertalk.com/topic/1138942-how-to-stop-spooging/page-2#entry12620211

I cannot comment on GTYR flywheels. I have a 11oz TMV (or TVM?) FWW. Works great for traction under power.

The stock shock valving is harsh for sure. Stock 2007-14 reb damping is a little light/fast but not too bad. The real issues in the stock rear suspension is that the high speed comp is way too harsh for anyone not riding groomed tracks. Even with the HSC adjuster wound fully out the shock wont compress enough on fast impacts and that upsets the front end and the whole bike. Also the stock Ti spring is too progressive, so you'll never find a reb clicker setting that seems to work everywhere. The stock rear shock will kick hard on some big bumps, but with the reb clicker in the wheel will hang up and slide out under power exiting flat corners.

I'm not super aggressive. I just don't like too much dive, do brake late, and I do keep my weight forward. The 0.44 springs stay low for far too long under brakes. Then it's easy to tuck and crash.

Yeah, the SSS 2 stroke forks can be a bit harsh for some uses, even after being run in. With the stock valving, you need the reb clicker out to get traction, but the side effect of letting the tyre follow the ground closely, means that: 1. you feel too many spikes on the next comp stroke. 2. The bars bounce back at you too fast.

For rough MX tracks you might like what I do in my forks. That is:

- Base valve: Softer low speed via inserting a 26mm x-over shim half way between the face shims. Softer high speed via a smaller 15mm clamp shim (stock = 16). Soften the bleed stack a lot.

- Mid comp: Remove 2 of the face 20mm shims. Keep the float tight at 0.25mm, but replace one of the 17.3 cup shims with a 15.3 so this stack is a lot softer on very fast hits.

- Reb: Speed up the low speed via smaller 11.12 (or 11.15) x-over shim. Slow down the high speed reb via a large 11mm clamp shim and also a thicker 12.2 shim above the clamp. This more progressive stack gives the front tire a very connected responsive feeling, and is much smoother on rough tracks, but might not be as good on some tight/rapid woop sections.

If you dial in your forks (valving and springs), then you might find you can sit or lean forward a lot more. Then you wont need a stiff rear spring, also you can run more sag in the rear for gains in rear traction.

I've not measured my timing. I just set it to where the motor works best. Broadest power, and still plenty.

My 250 squish is 1.3mm. See also https://www.thumpertalk.com/topic/1152457-2015-yz250-pinging/#entry12621199

[rjpjnk]

This post describes my best attempt at jetting the 250, using two Zook needles: https://www.thumpertalk.com/topic/1138942-how-to-stop-spooging/page-2#entry12620211

 

I see you ended up using a 168 main. (down from 178 stock) Is that typical for these machines?  I didn't even begin to look at MJ changes yet as I am still trying to work out PJ. The MJ shouldn't have any effect of the low rpm blubber, right?  I'll look into the different needle. Thanks.

[numroe]

No it's not typical to use a 168 at sea level, but the air fuel ratio remains the same. Let me explain ...

The Suzuki NExJ needle is visibly shorter and also thinner at the pointy end. Thus it needs a smaller main jet size.

At wide open throttle, I cannot tell the difference between the stock Yam N3EW needle (on clip 3) with a 178 main and the Suzuki NEDJ (on clip 3) with a 168 main jet.

Some people change the main jet last. But if you are going to use any needle for a while, then you might as well get the main jet size right as soon as possible. It's the easiest to get right, the easiest to change, and the cost is about $5 each.

Correct, the MJ size wont effect the 1/8th throttle open rich blubber.

[rjpjnk]

Ok. That makes sense. I am currently reading everything I can find on jetting this bike, but I can tell you have a tone of experience here, so perhaps you can advise me on the following.

What jetting do you think would be best at 1000 ft while still using the stock slide and needle? (also stock exhaust as mentioned).

[numroe]

With the stock needle and slide at below 1500ft in moderate temps with stock (wide) 1.75mm squish clearance, the best I had it was with the needle on clip 3 to provide more fuel at the 3/8th lean spot. Then a 50 pilot and a 178 main.

With tighter squish it might run better with a 48 and 175.

A 180 maim was too rich and gave up a lot of power.

With the yam needle, no matter what jets you use, the 1/8th rich blubber and/or 3/8th lean hesitant spots will still be there. Many people assume that the blubber misfire and then delayed hit is "that 2 stroke feeling". Actually on most tracks it's just slow and hard work to ride.

Since one Suzuki needle costs just $10 I don't see the point jetting without it. The #8 slide costs $50 but it is so nice when the motor pulls clean and strong the whole way through the throttle turn. You can power through and into corners without upsetting the bike.

[rjpjnk]

Since one Suzuki needle costs just $10 I don't see the point jetting without it. The #8 slide costs $50 but it is so nice when the motor pulls clean and strong the whole way through the throttle turn. You can power through and into corners without upsetting the bike.

 

I am wondering why, if this simple change in needle and slide is so effective at transforming the bike, that Yamaha has not made this change themselves. I believe the 250 has not been rejetted since Yamaha fine tuned their setup in 2007. (well other than the euro-spec efforts that is). Why on earth would they continue to sell a bike with the wrong slide, wrong needle, and too wide squish for 10 years? I would think that these issues could be corrected for less money than it takes to design new graphics.

[rjpjnk]

Btw, I fouled two plug in one hour riding with the OEM jetting (178/50/N3EW-2). Since I switched the pilot to 45 last week I have put 4 hours on it and not fouled a plug. The plug is no longer black either. It is a dark brown. Probably should be lighter, but it's a big improvement. Early throttle response is much better as well. But yes, there is still that burbble as it comes on the pipe. I am not sure what to do with the needle clip position. Do you think I should try pos 3 with the 45 pilot or stay at 2? Also, I still seem to need at least 2 turns on air screw to get max idle speed. Doesn't that indicate that 45 pilot is not too lean?

 

Did a quick squish check (solder through plug hole) and got about .077. I was going to send it off to Eric Gorr for head mod, but after speaking with him on the phone he didn't seem to think it was worth the trouble if I only intend to run pump gas. He also didn't seem to comfortable with cutting the dome to bring compression back down. He said he typically alters the angle and extent (radial) of the squish area to deal with the compression increase. I think I might rather keep the band intact and just CC the dome if I do anything. Thoughts?

[numroe]

I am wondering why ...

I assume stubborn corp policies and conservative marketing. Why for 9 years have Yamaha been so reluctant to change the bike at all? eg. No suspension setting changes, until perhaps this year. Perhaps their market dept holds the majority of decision power and their thinking is "If the bike sells then leave it". Jetting also depends on many factors (ride conditions, usage, engine state, fuel choice) and perhaps Yam made a blunder in the past and lost some sales. Short answer I dunno. But to assume stock is perfect for anyone is a bit deluded IMO. Plastics is just the look. A conservative easy change. Don't put Yamaha up on a pedestal for doing all things great. If they were truly great then they (and the other Jap brands) wouldn't have handed their market over to KTM.

[Kinger317]

RJPJNK you may find the suspension is harsh because the springs are too soft. I am 185 pounds and run .48 upfront and 5.6 in the rear. Very soft ride. The forks keep me up in the upper/plush/softer part of the travel and the rear lets me set the SAG with little to no preload on the spring. Trust me, Stiffer springs give you a softer ride. If the bike sits low in the front with you on it you're already starting off in the mid stroke. thank U Tapio!!!!

As for jetting, I have been very frustrated for a while but I am now happy with 48 pilot, 40 power, stock n3ew-3, 175 main (@1200'). Thank U Eric!!!

[rjpjnk]

RJPJNK you may find the suspension is harsh because the springs are too soft. I am 185 pounds and run .48 upfront and 5.6 in the rear. Very soft ride.

 

Kinger, I definitely agree with you about the stiffer springs with less preload providing a softer ride, but the valving can work some magic too.

 

I just got the suspension back from a Factory Connection revalve and it is like a whole new bike! The harshness is completely gone. The rebound is incredibly smooth. The high speed chop is gone. They really did a *very* good job.

 

I am still running the stock .44 in the forks, but upped the shock spring from the 4.9 to a 5.1 (simply because I happened to have a 5.1 in my shop), so I am still undersprung on the shock I realize. I am currently running 10mm preload and achieving 110 race sag with 25 static sag, so obviously a stiffer spring is needed. FC wants to run the bike at 108 sag and reccomends 5.4 Kg/mm shock spring for me (no change in forks). I found a 5.5 Ti and plan to put that in this weekend. I expect it will give me 108 sag with about 32 static and only 4-5mm preload. Should be even smoother, but hey, it's already amazing!

[Kinger317]

Nice, don't you love it when a plan comes together! I forgot to mention my valving and Pistons are all set up for me and you're right that helps a lot too. I ride 90% woods so I have very light compression damping. I think having the valving done this way allows me to run stiffer springs which gives me a very soft smooth ride.

[rjpjnk]

Yes. Stiff springs + light compression damping + heavy rebound damping = plush ride. ?

[TN Dirt Rider]

If you are interested in an OEM silencer, I've got an 08 YZ250 with the stock silencer....maybe we could trade??

[rjpjnk]

If you are interested in an OEM silencer, I've got an 08 YZ250 with the stock silencer....maybe we could trade??

Thank you for the offer, but I already found one of the new euro-spec ones. Man are these things huge! I think I'll try it back to back with the shorty and see what I notice in performance when I get a chance.