KX250 flywheel weight

[shafty1172]

Well, I finally decided to put a flywheel weight on my 2004 KX250 (2 stroke). After talking to a few people I've been leaning toward the 11oz Steahly. I weigh about 145lbs not including riding gear so power isn't much of an issue for me but I want to smooth out the delivery. I ride mostly tight technical single track and quad trails, but a few of the places I ride are pretty open. I've never had a flywheel weight on any of my bikes, can anyone offer their opinion on what weight to go with?

[krazyinski]

I run a 14oz stealthy, on my 05 along with a FMF Gnarly and G2 throttle cam with the 500 cam . smooths the power delivery out nice. Warning the FWW will come loose over time you must check the thing every 20-30 hrs.

[dav3406]

I've got a 9 oz weight on my 05 250, also have a gnarly pipe. The flywheel weight definitely makes a noticeable difference, especially in technical riding. I was concerned about losing off the line performance and acceleration, but my starts in the desert races out here haven't been affected. The weight does make the bike much more manageable. I outweigh you by about 30 lbs, and if I had to do it over again, I'd probably go with a bit heavier weight than 9 oz, but I'm cheap and don't want to drop another $100 on another weight when I'm pretty satisfied with this one.

They have a chart on the Steahly web site that gives recommendations on the correct flywheel weight taking into account the size of bike, your riding ability, etc. That's helpful, if you haven't already looked at it.

[razornpc]

any opinions about how the gnarly make the bike feel?

im thinkin about getting 1

[makKX250]

I just had my first ride with the Gnarly last weekend on my '06 KX250. I also have a Steahly 11 oz FWW and the G2 throttle cam #200. FMF says that the stock jetting works fine. I'm a step leaner then stock and I would say the jetting is spot on with the pipe at ~90 degrees and less than 1000 ft elevation. I'll probably have to go back to stock jetting for the cooler months. Quality and fitment are top notch.

The ride: ?

I was a bit disapointed. I guess the power delivery is what they advertise - more on the bottom and mid range. But I was expecting even more on the low end than what I got over the stock pipe. The gain is very noticable but from how people talk about it I guess my expectations were set too high. And I wasn't expecting the top end loss to be as much.

Would I change back to stock? For tight woods/XC riding the answer is it is a keeper. For higher speed riding at higher RPMs I would definately put the stock pipe back on.

Was it worth the money? I don't know. For the bling and low end gain I would say yes. But is it so much better than the stock power delivery that I couldn't live without it? I would say no.

Hope that helps.

Back to the original question about the FWW. I have an 11oz and really like it. I have not had any problems with either it or it's set screws becomming loose. I check it around each 20 hours of riding anyway just to be sure. Just be sure to follow the directions and torque it to the correct specs during installation and you shouldnt have any problems.

[Jeekinz]

Do all the newer KX250's have a "hit"? My 2000's and even my 98 just rolled on the power with no noticable hit. I rode my friends YZ and there was a slight delay in power delivery when you twisted the throttle, it seemed to really come on at 1/4 and past.

[Outlaw525]

Do all the newer KX250's have a "hit"? My 2000's and even my 98 just rolled on the power with no noticable hit. I rode my friends YZ and there was a slight delay in power delivery when you twisted the throttle, it seemed to really come on at 1/4 and past.

My '05 had a monster hit in the mid range until I tamed it with a 13oz. FWW and Gnarley pipe. I went from a top end pipe (Pro Circuit Race Pipe) to the Gnarly and it made a world of difference in bottom end lugging. Took away a little from the top though.

My main riding partner has an '03 KX and its much smoother stock than my '05 was. It doesn't have the power of the '05 anywhere in the powerband but its more smooth from bottom to top. The '05 keeps reving long after the '03 tops out even with the Gnarly.

I first thought his bike had more bottom but after riding it several times on the same obstacles/hills as mine, it doesn't have more bottom at all. Its just a smoother transition from lugging to getting on the pipe.

I rode an 07 a few weeks ago. Same exact feel to it as my '05. Powerhouse of an engine - The 05-07 KX250!

[KDXGarage]

Mine has a noticeable midrange hit. If the traction is there, I am not looking to roll on anything, "except the competition" AKA (my fellow slow riding buddies).

On most MX bikes, the pipes do more of a powerband shift and slight increase instead of a monster add-on of HP.

[krazyinski]

I would say the top end loss would be due to gearing and or jetting. I leaned mine out on top smaller main and of course the top end is short with 13/50 gearing but bottom end is solid much better that the pc works pipe but I never ran a stocker and I have heard good things about the stock pipe.

I do all my riding in tight technical trails and when it does open up l like running it in one gear 4th most but 5th comes on quick.

I would love to keep my gearing the same and just add a 6th gear and the bike would be perfect.

running 5th all out on my 05 gets my pucker drawn up so tight you couldn't get a brad nail in there.

[shafty1172]

thanks for all the input guys, I ordered the 11oz last night, can't wait to get it on and test 'er out. haven't ridden in a few weeks so i'm having severe withdrawals

[hodgkins]

keep in mind if you think it's too much weight any local machine shop can turn off a smidgen and make it 9,10 or whatever you want.

[Kx_Ryan21]

Did ya get that FWW yet?

I'm interested in one as well

I'm hoping it will help with some hill climbs, since they take an awful lot of clutch work to keep the RPM's high so the bike doesn't stall.

So whats the verdict?

[scalejockey]

I tried a 3 degree retard on the ignition plate on my 03.It's real easy to go up the nasty hills now and the top end feels the same.

[starrman]

I tried a 3 degree retard on the ignition plate on my 03.It's real easy to go up the nasty hills now and the top end feels the same.

So here is a question: when you retard the ignition timing, do you end up with less burnt fuel? I'm asking because my bike seems to be running richer (or at least spoogier) since retarding the timing.

[llamaface]

if I had to do it over again, I'd probably go with a bit heavier weight than 9 oz, but I'm cheap and don't want to drop another $100 on another weight when I'm pretty satisfied with this one.

Save all the packaging. I put a 6 oz on my ktm, and a few months later wanted more, so I went with a 10oz, and put the 6 oz in the package with instructions and everything, and sold it for about 3/4 of new price (and shipped for free). So it only cost me a few bucks.

How is the install on the kx? On my ktm it was a piece of cake (assuming you use the plastic lockup tool), but I hear on the yz's you have to bend the clutch arm to clear it.

[djm]

How is the install on the kx?

I bought the lockup tool and it was very easy.

(2000 KX250)

[gixxer_76]

I just installed a 13oz on my 2007 KX250. It took about 15 minutes since I was taking my time. I do have air tools though.

I'll reports back with how it feels...

[scalejockey]

So here is a question: when you retard the ignition timing, do you end up with less burnt fuel? I'm asking because my bike seems to be running richer (or at least spoogier) since retarding the timing.

I didn't notice a difference, i change it depending where i ride for the day.

( We have open desert on one side of the valley and tight woods on the other.? )

How ever one would think retarding the ignition would make it run a little cooler,thus not burning "out the pipe"as completely?Resulting as a little more "drool"?

[The Spanky]

Ignition timing changes won't affect the air/fuel ratio, which is what determines combustion temperatures. Changing the timing won't fix rich jetting, or cure spooge.

Retarding the timing will transfer more heat to the pipe, raising the wave velocity in the pipe, which in turn will shift the power to slightly higher rpm.

[gixxer_76]

So I did a 4.5hr tour today in my usual area. Nasty single track not meant for the faint at heart.

The luggability is improved. First gear is no longer useless (excessive wheel spin): I can start off on a semi-steep, loose, slimy hill in first without nearly the wheel spin of previous. I also found myself clicking down to first to clear some obstacles. In first I was doing with little to no clutch what I did in second with a tonne of clutch before. Still making it but in a different manor.

On regular trails that pose no issue to me but would be trouble for a newb, it drives better. Less clutch work, improved traction. I even found myself not covering the clutch at time. Completely unheard of before the weight.

On the nasty climbs, I'm not yet sold. It feels like the power is harder to reach. Since I only have a few hours to adapt to a substantial change (13oz weight) I will just need some more time I guess. I kept finding myself powering out. Going over known obstacles I know how much clutch and throttle I need to feed to make what I want to happen, happen.

Well, I was finding I needed to slip the clutch more and add more throttle. Quite frusterating but very overcome able. The power is still there to loft the front or to get a quick zap to clutch over a root step-up.

I guess I was just hoping for more result without having to change my riding style. I was extremely happy with my bike in 95% of the terrain but I was hoping to have a magic wand wave over my bike I guess. I'll give it more of a chance before I give up. The pro's are quite nice but if I can't adapt to the con's she's gotta go.

BTW, I'll check it for looseness in the coming days. I'm not a big fan of aftermarket crap killing my motor!!!!!!

Another thing I'm considering is switching the gearing. I've got the stock 13/51. Maybe 13/52 or 53 will make me happier. We'l see how it is after another ride or two.

I ride the same nastiness every weekend so I'll keep ya'll posted.