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2011 250sx

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Well I've had the bike for a bit now got it alot more sorted out than when I first had it . I do like the bike you just cant beat the lightweight . I'm coming to terms with using the clutch alot more than I had to on my Honda 450 .

So anyways I put on a new mx 31 tire for the race last nite . Its a sand track but mixed with clay . I'm finding honestly the bike has to much rear bite now and its bogging the engine a bit also I find over 4th gear jumps I can feel the rear end is out of balance you can feel it in the air like a bad wheel balance . Does anyone ever balance their tires or perhaps rotate on a spindle of sorts then possibly rotate the tire away from the heavy side for balance ? I really liked the stock bridgestone tire alot more as it allowed a bit more spin and allowed the engine to get in the powerband easier . Ps this bike is a holeshot machine In all my motos except for one I've gotten holeshot . I know in the past I had some negative things to say about this bike but I'm really starting to get it sorted out to my liking now . Ps I just love the hydraulic clutch . :thumbsup:

Ktm250sx002.jpg

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Did you stick with stock gearing and jetting?

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One thing that may help with bogging down is setting the PV to open just a tad sooner.

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I put a 40 pilot in needle on second clip and 160 main I think I could go bigger on main seems a bit lean up top . Stock gearing which is kinda off as 2nd to low and 3rd to high for the track I'm riding mainly sandy soil so hence that might be the next thing to address . I have fmf pipe green power valve spring which I like as calmed down the wheely issue in second gear . Main this is would be the gearing for the most part .I have wire disconnected as well as this helped alot on the harder pack tracks but the sandy track I may have to go the other way perhaps ? and a 9oz flywheel weight . the flywheel really helped with the stalling issues I had coming into corners so its staying on . the bike needs to work both on hard and soft tracks so the wire gearing and pv spring would be the only changes perhaps I would make .

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I put a 40 pilot in needle on second clip and 160 main I think I could go bigger on main seems a bit lean up top . Stock gearing which is kinda off as 2nd to low and 3rd to high for the track I'm riding mainly sandy soil so hence that might be the next thing to address . I have fmf pipe green power valve spring which I like as calmed down the wheely issue in second gear . Main this is would be the gearing for the most part .I have wire disconnected as well as this helped alot on the harder pack tracks but the sandy track I may have to go the other way perhaps ? and a 9oz flywheel weight . the flywheel really helped with the stalling issues I had coming into corners so its staying on . the bike needs to work both on hard and soft tracks so the wire gearing and pv spring would be the only changes perhaps I would make .

Sounds like a lean bog to me. Try 42 pilot and 3rd clip on the needle. Air screw adjust as needed. Start around 1 1/2 turns out and check throttle response.

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Put a 14 tooth up front and the red spring in. Then unplug or turn the map switch on the "soft" setting. Run a bit longer silencer-like from a 250xc. This will broaden the powerband and keep the revs in a more comfortable spot. I would ditch the FWW as soon as you are fully acclimated with the bike. You can balance a rear tire,but it is hard to do with a nobby. If the rim is true/balanced and everything is seated properly-it shouldn't be a big deal. What FMF pipe? The bike makes tons of power.Its a matter of just taking that power and shifting it to where you prefer. You may want to even try advancing or retarding the ognition timing a hair. 1mm either way can make a huge difference in power characteristics.

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I put a 40 pilot in needle on second clip and 160 main I think I could go bigger on main seems a bit lean up top . Stock gearing which is kinda off as 2nd to low and 3rd to high for the track I'm riding mainly sandy soil so hence that might be the next thing to address . I have fmf pipe green power valve spring which I like as calmed down the wheely issue in second gear . Main this is would be the gearing for the most part .I have wire disconnected as well as this helped alot on the harder pack tracks but the sandy track I may have to go the other way perhaps ? and a 9oz flywheel weight . the flywheel really helped with the stalling issues I had coming into corners so its staying on . the bike needs to work both on hard and soft tracks so the wire gearing and pv spring would be the only changes perhaps I would make .

You are riding an amazing bike and most of the issues you are talking about are not bike issues, they are purely riding technique issues. My thoughts...

1. Wheelie issue: its not gearing, its 100% technique. 1. Improve modulating the clutch when accelerating instead of using the throttle power delivery. With your 450 4-stroke, there wasn't much need for this, as the power delivery is smooth from top to bottom. Also, come into the corner with the clutch pulled-in while keeping the throttle cracked open, dont chop the throttle, then use clutch to control delivery. 2. Lean forward over the bike whenever you accelerate, that'll keep the front down. Watch the pros, whenever they accelerate hard they are over the bars (standing and sitting) and they are riding 4 strokes...good technique will be rewarded with faster lap times and far less fatigue.

2. Bogging: Unless you are riding at altitude or on really hot days, you should have left the jetting alone...its perfect out of the box...says everyone!

3. Gearing: Again, its perfect out of the box. Improve your technique and you wont need to make any gearing changes unless you enjoy trying to lug a 2-stroke around

4. Wheel Balance: Maybe its something. Check that your sprocket bolts are tight. You may be feeling the chain play since the chain is much looser on the KTM's compared to linkage equipped bikes.

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agreed on the riding technique for sure as Having to relearn how to ride a two stroke all over again . But I do find the bike between gears sometimes as in second you have to basically shift asap right out of corner and it wont pull third without a ton of clutch slipping . it really depends on the track. As per jetting its good now on the bottom it was to rich before on bottom but still a tad lean up top . again depends on location and tracks you ride . Ps I have been riding for 35 years used to be a top level B rider in the late 90s .

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