Long term KLX250S review

Discussion in 'Thumpers' started by bmwhd, Dec 2, 2005.

  1. CousinLarry

    CousinLarry Ridin Dirty

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    Cool pics!! I'd love to ride out West.

    I have had 351 for about 5k miles with zero probs. I know there's a guy on kawiforum with 8-10k or so and no probs.

    I think it's the best mod for the buck for power by far.
  2. jckid

    jckid Been here awhile

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    That is definitely encouraging!
  3. SamM

    SamM Jeep Overlander

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    Good to know that it has the ability to flash also. I'm adding this to remove a little weight for my bike too. The front signals will be located in the Zeta handguards. Wheeling Cycle isn't located far from where I live, so it's just a short ride up to get parts.

    SamM
  4. RicH2

    RicH2 Ric H2

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    My stock sf got a solid 70 mpg under all conditions.
  5. GaryHarris

    GaryHarris I bent my Flounder

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    Quick question on gearing guys and gals. I'm currently running the stock 14-42 with stock tires and feel I'm way over geared. Since Ill be soon removing the wheels to change tires, D-606 120/90 rear, I might as well change the rear sprocket while I have the wheel off and this would be a good time to add some "Farkle" since I have a $50 coupon coming.

    http://www.rockymountainatvmc.com/p...&navTitle=Drive&webCatId=9&prodFamilyId=22817

    The smallest they offer is a 47T and I have no problem with that since I like the big rear sprocket look, a little color and the old school dirt bike look. The chain guard will be tossed.

    I have a decent idea on how the gearing will feel, but I don't know about the chain length. I assume Ill have to get a new chain. Anybody run this set up and can you give me an idea on how many links the chain will need to be?

    Thanks.
  6. redpillar

    redpillar Been here awhile

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    Why not put on a 13 tooth countershaft sprocket instead? They are much cheaper and no chain length difference.
  7. akarob

    akarob Green Cantern

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    New 250SF owner here. Picking it up tomorrow.

    To the people upgrading to 351 (or 300+) , do you get any head work done? I'd think that some oversize intake valves would be a good idea if your engine gets bigger and carb is getting done and all.

    How do the heads in these bikes hold up? Do the stock intake valves last a while?
  8. ADVwanaB

    ADVwanaB BOLD NEW AVATAR

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    adding the extra 100cc's and retaining the stock pipe and carb is like buying a car witha big 454cu in motor with a 2 barrel carb on it.
    It wont go as fast as a 4 bbl carbed motor but it will have the same torque. Does this make sense? you do not need to go big on the carb and pipe, valves , cam, head bench flowing for max performance. The bike just wasn't made for that and you can buy a KTM, HUsky or Honda if you are looking for race performance. The 351 kit adds bottom end and mid range.
    It is actually the way the bike SHOULD have come from Kawasaki. Adding the kit makes this bike really fun and a true Dual Sport machine that you can ride and just add gas.. I really love mine and just finished a 300 mile dual sport event last week end with ZERO issues. I added a 15 tooth front sprocket to gain some HWY speed without loosing and low speed grunt.
    A buddy of mine was on a stock 250s and we swapped bikes for a bit so he could check out my ride. He is sold on it and will be doing the mod soon i suspect. BTW,, i hated his stock bike as it was so anemic. One more thing, after he got off my bike he mounted another freinds bike, a Husky 450,,, he liked mine better because the husky was a huge vibrator. not so pleasant on a long ride i suppose.
  9. David R

    David R I been called a Nut Job..

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    JUST the 351 makes a huge difference. You get the most bang for your buck. If you want to add a bigger carb or exhaust it will add a little power and quicker response. I ran stock carb with stock exhaust modified by me for a while. It works great. The bug bit me so I had to have the bigger pumper carb which did help with response, but I don't think it added any horse power.

    The 351 turned my Street bike from a weed whacker motor to a true thumper. Torque is way up.

    No head work or anything else for me. Its fine just the way it is. We started out with DOHC and 4 valves.

    David
  10. markk53

    markk53 jack of all trades...

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    The fact is most modern singles will benefit from being "unplugged" at both the intake and exhaust then properly jetted. Unfortunately most exhaust mods make the bike rather loud. It will be nice when someone actually makes a decent flowing quiet muffler. I just wish I had the where-with-all to do the job. It may not be significantly lighter than the stock one would, but it'd flow better and have a bit better tone. There's room under those number plates for sure.

    When I sold Kawasakis the trick I learned to really add power everywhere for the KLX300 was to install a carb kit with a larger carb and a larger ID head pipe freer flowing exhaust. About $450 at the time, to pick it up in a big way with bolt on stuff in a few hours.

    The same is probably true for the 250. Get it to breathe.

    I won't say the big bore isn't a benefit - It absolutely IS. Based on my own experience with only a 27cc bigger engine, the power delivery is pretty much over the same area, but just a lot stronger. It does take more effort and money to do it though in most cases.

    I did the big bore and an exhaust at the same time and, oddly enough, I got a 10 mpg GAIN from 50 mpg to 60 mpg. I use a Dial-A-Jet, which automatically compensated for the changes, thus I don't mention jetting. Good consistent plug color and exhaust tip color from sea level at Daytona to 5000 feet in WV, from 20 degrees to 95 degrees.

    Do the 250s gain mpg when some of this sort of work is done?
  11. TNC

    TNC Candyass Camper

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    Mark, mine gained some mpg with the 300 cylinder. At a 250, I had the full Muzzy exhaust...huge head pipe like you describe...modded airbox, and DJ jetting. Still, I had to rev her up pretty well to scoot, which it did OK. With the 300, those other mods probably came more into their own for a performance increase, and I found I could short shift and lug the bike a whole lot more. I think that's where my mileage increase came from.

    I also have a totally unsubstantiated theory that the later/current 250 is a tiny bit different from the original 250 that won't accept a 300 cylinder wihtout case machining. I'm suspicious that Kawasaki took the basic 300 model and dropped the bore to 250...marketing, licensing, insurance, and a host of other reasons for a street legal model. When you go back to a 300 cylinder or larger, I'm thinking the combustion chamber and valve layout is more optimum for the bigger bore and therefore provides more/better performance due to being a better "match". One reason I think this is how the valve reliefs are located almost down to the piston ring grooves on the 250. While you can see this occasionally on some engines, it is not really an efficient design for ideal combustion. It seems to me that the power increase of just the 300 cylinder is more than the meager 43cc or so would normally yield. Anyway, just a idea I have about it...worth about .01 cent in today's market.:lol3
  12. GaryHarris

    GaryHarris I bent my Flounder

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    Besides the look factor I mentioned about, I want the option to gear lower than just using a 13t up front. I feel the bike is way over geared for some of the riding I want to do and from what I understand changing one up front=three in the rear.

    If I need to gear back up Ill put a 15t up front.

    Ill figure the chain length out.
    Thanks.
  13. rickypanecatyl

    rickypanecatyl SE Asia adventure tours

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    Sorry I'm too lazy to post pictures but had an amazing ride today!

    Just last week I got a motoport airmesh kevlar shirt and pants. To be honest I'm super unhappy with them but they are good for 1 thing and thats riding thru thorns, briars and thickets. Stuff that would rip my tourmaster jacket apart in minutes are no problemo.
    And so, dressed for battle I sought to reclaim miles of single track from the ever spreading jungle. I had a razor sharp machete mounted and it was on.
    Most of the time there was absolutely no path to see... just a memory burned that it used to be right about here. I lost my front wheel over a 60 foot high cliff and bailed by grabbing the branches and vines above me. The bike didn't go over because liana vines and bamboo shoots were clutching the bars and wrapped around my wheels etc.
    Ended up on a motocross/enduro track right next to a river...
  14. Dan888

    Dan888 Been here awhile

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    !!!!!!!!!!!!!!!! Too bad no pics, I'd love to see the cliff. Sounds like you got lucky. :D
    Dan
  15. UtahGuido

    UtahGuido Long timer

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    Hey Gary,

    I can help you out I think. I was running a 13/47 setup right (with the 250) and I like that gearing. With the 250 opened up and making power at 7-9K rpm it was no sweat to go down the interstate at an indicated 70 mph. Yeah it was screaming, but it would also chug around and over things really well. The chain is a 108, which works but it puts the adjusters on about 1. In other words the wheel and tire will be in pretty tight. Doable however. I had a real tall Pirelli MT43 on it but a new 606 is just about as tall. Here's what that looked like:

    [​IMG]

    Has kind of a bobtail look.

    So I wanted to go to a longer chain so I could move the wheel as far back as possible. I had to mod the adjuster pin to make it work and the axle is back to bitter end of the swingarm - maybe not ideal (the ideal might be a longer swingarm!). Here's the 110 chain and modded adjuster:

    [​IMG]

    [​IMG]

    Basically that's just a 10x1.25 bolt and some washers.

    And sorry about these huge pics.

    Another option is 13/45. The 108 chain works well, lots of adjustment, and versatile gearing. Maybe not as rock-crawly but still plenty of low gear.

    But now I have the 351 installed and I need to gear up. The low gear is really cool for poking along but I don't think this engine will rev high enough to make the top gear useful. So I'm going back to a 13/42 with the 108 chain. I may go higher.
  16. GaryHarris

    GaryHarris I bent my Flounder

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    H-Town Texas

    Thanks Guido. I'm thinking the 14-47 set up might be the right compromise for me, but I'm not sure what chain to order.
  17. TNC

    TNC Candyass Camper

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    Gary, I run a 14/47 gearing on my KLX with just a 300 cylinder. With all the other mods and a full Muzzy exhaust, it has lots of low end but still winds out well. I can ride extemely tight singletrack but still cruise at a GPS 60mph all day at a safe rpm. Gearing can be very preferential because we don't all ride the same terrain or the same way. You'll have to take what you hear and try it out to see how it applies to you.
  18. UtahGuido

    UtahGuido Long timer

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    For a 14/47 I'd go 110. I don't think a 108 is long enough. What do you run TNC?
  19. TNC

    TNC Candyass Camper

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    I believe I'm running a 108...wanted to get the wheelbase as short as possible. I'm running on the number "1" snail adjuster. I set it up before I cut the chain, and it works. Most people would probably run a 110.
  20. GaryHarris

    GaryHarris I bent my Flounder

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    Thanks guys. I ordered a DID 116 and don't mind cutting it down. I just didn't want to order something too short or try to be exact since I may run a 15t up front.

    Thanks.

    :1drink