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About kenpowell

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    dirt bikes

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  1. kenpowell

    Sedona 907

    This has turned into one of my favorite tires for rocky single tract. I run it at 6 PSI with Tubliss on my '03 YZ265WR and my '03 KX223WR.
  2. kenpowell

    the irreplaceable carb gasket/oring

    The jet-block o-ring for the screw top PWK's from Jets-R-Us (http://www.jetsrus.com/individual_parts/021_532_su.html) is a start to the 'fix' but the little o-ring is in the wrong position and is to large. The smallest o-ring in this set on Ebay (Traxxas 4047 Carburetor,O-Ring Set) does fit. Cut the small o-ring off the core and substitute the small Traxxis o-ring.
  3. kenpowell

    KYB / SSS Fork Lug Measurement

    Hi Glenn, I found the center of the lug by running a string from the top compression screw to the bottom rebound screw. I found that the non-brake fork has a grub screw on the center-line as well as a cast-in mark on the lug itself - this is the mark that you see in my measurements. Note that my template has an offset (it is "L" shaped) so I can keep the measurement in the same plane. Armed with my own measurements I went back and made the measurements according to your directions (included below for everyone else). I never did figure out Dim B (you list as = height of the small casting rib on the rear of same foot section, approx .25mm) but the other measurements were the same as yours so I agree that your method works wonderful - pictures would be nice to help get the correct measuring points. Your original directions follow: ------------------------------------------------------------------------------------------------------------------------------------------ Do it this way, measure the following carefully with a good caliper (example dimensions are from my KYBs): Dim A = dia of the lower thin wall part of the foot, should be 33mm Dim B = height of the small casting rib on the rear of same foot section, approx .25mm Dim C = axel bore. easy at 25mm Dim D = the distance from the inner ID surface of the axel bore to the top of the small rib on the rear of the foot, approx 36.5mm The idea is to get good numbers on easy to measure surfaces and calculate the tough one to actually measure accurately. Offset is the distance from fork tube center to axel center, so we use the dia of the foot and axel to calc them, and reference with D minus the rib height. The KYB is much easier due to the smooth casting, but same principle applies. Offset = D-B-A/2+C/2 =36.5-.25-33/2+25/2 = 32.25mm Older natural, heavier cast lugs will be 35mm offset, newer brown color thinner wall lugs will be 32mm offset. There are different lengths as well. ------------------------------------------------------------------------------------------------------------------------------------------
  4. kenpowell

    KYB / SSS Fork Lug Measurement

    I made a template to make this measurement on SSS forks. This 'L' shape template allows a measurement to be made in the same plane - 32mm is correct for these '07 YZ250 forks.
  5. kenpowell

    KYB / SSS Fork Lug Measurement

    I just measured a '07 YZ250 fork leg by 2 different methods: one using a plumb bob and the other using a 1" dowel in the axle hole with a centered mark formed on my lathe. One measurement was 32.5 mm and the other was 32.4 mm. Close enough to the measurements provided above. Even SHARP pencil marks will cause more error than than the difference found in my 2 measurements. The only problem is that it was stated that the earlier SSS forks has a lug offset of 35 mm; that doesn't seem to be the case with the '07 YZ250 2-stroke forks.
  6. Fork Lug Measurements for SSS forks - There are some well known measurements for Honda's (33mm) and KTM's (35mm until 2016 when KTM changed to 33mm and a smaller axle). But what about YZs? I read 30mm, 32mm and 35mm depending on year and whether 2-stroke (YZ) or 4-stroke (YZF). My crude attempts to measure with a plumb bob showed 30mm for my 2008 YZ250F forks (forks were off the bike and held vertical). I have NO confidence in this measurement - it's just to imprecise. Most data on the Web (yeah, I know!) gives this measurement as 32mm. If you have made this measurement please post how you did it (if you did it mathematically I can follow that logic as well). If you got the info from a tuner or manufacturer that is good to. Any data for brand would also be welcome.
  7. kenpowell

    Jetting with the Zook NECJ

    Did anyone mention that a failure of the carb jet-block o-ring can cause really awful running and spooge issues? Anytime I see a thread of excess spooge that can't be fixed on an older bike I would recommend replacing this o-ring as a first priority. It's cheap and easy so you might as well remove the possibility of a failure from the equation.
  8. I have run stock with the ball, no ball, with a thicker washer/spacer and with 2 washers. I can't tell much difference but settled on 2 washers. I suspect that with 2 washers the ball does not engage the shaft but I didn't check - in that case it's the same as no ball. I have at least 100 hrs in this configuration so no harm is done. This is on a '03 kx125 with a '95 kdx200 motor bored to 223cc with Eric Gorr mo-betta porting.
  9. kenpowell

    Shock interchangeability

    The shocks will not interchange. The lower shock mount for the KX is shaped like an upside down 'U' and the YZ shock is shaped like and upside down 'i'.
  10. kenpowell

    KTM convert to new Yam - turning issues

    I never did get that statement right but I think you understand what I was trying to say (even if I am not communicating very well!!!). A static sag with a LARGER number indicates that the spring is stronger; i.e., a static sag of 38mm would indicate that the rear spring is firmer than a spring that would give a static sag of 24mm. With all other variables equal a bike with a firmer rear spring will turn better than a bike with a softer spring. The firmer spring holds the rear of the bike 'up' which both decreases the effective rake of the steering head and also decreases trail. The front can also be tuned using spring rates. A softer front spring (or one with less preload) will settle into a corner while compressing the forks. This decreases trail and changes the effective rake both of which help the bike to turn. Go to far with (or all) of these and the front will 'tuck under / knife'.
  11. kenpowell

    KTM convert to new Yam - turning issues

    I see where I wasn't clear; I stated 'I prefer higher static sag and lower rider sag.' which isn't clear at all. I MEANT to say that I prefer LESS static sag (example: 38mm instead of 24mm) and also LESS rider sag (example: 103mm instead of 110mm).
  12. kenpowell

    KTM convert to new Yam - turning issues

    Sam, let's go back to basics. The front is 'pushing'; how do we fix that. Holding the rear up and lowering the front end decreases trail. Here are some suggestions (we are basically trying to get LESS trail as we initiate and carry thru the turn): 1. Less rear rebound 2. Less rear sag (I run 102mm to 103mm on my YZ's) 3. More rear compression damping 4. Move the forks higher in the triple clamps 5. More front rebound damping 6. Less front compression damping 7. Stiffer rear spring 8. Softer front spring On the YZ's I want 30 to 40 mm static sag and 101 to 105 mm rider sag. I prefer the higher static sag and lower rider sag. I then revalve the shock to work with the static sag amount. BTW, I weigh 195 lb ready to ride and use .43kg front springs (regardless of make) and whatever springs it takes to get the above sag numbers.
  13. kenpowell

    KTM convert to new Yam - turning issues

    Sam, I had never seen that article in MXA - it's excellent. The very first bullet notes what I said above and conversely, also what you said: 1) Less fork offset (20mm as opposed to 22mm) increases trail and, on paper, should make the bike steer slower and improve stability. Yet, for some reason (perhaps the wide number of factors involved in bike handling), less offset often results in a bike that turns sharper and is more accurate. I was suggesting that you try the 25mm offset because it usually (but not always, as your KTM example proves) causes a bike to turn quicker because of less trail. Note that 3mm in offset is a bunch. KTM uses a rake of 26.5 degress and the YZ uses 27 degrees on the 2-strokes (Yamaha has been changing the rake on the 4-strokes in recent years and it's hard to know what year is what??? - some recent years of the 450F also use the 22mm clamps); as an owner of both brands I've found that what I like on one brand does not always carry over to the other. The YZ 2-strokes have stayed with the 25 degree clamps; haven't the 4-strokes gone back to the 25 clamps for '17?
  14. kenpowell

    KTM convert to new Yam - turning issues

    Does the '16 have the 22mm triple clamps? If so, a set of 25mm clamps off a YZ250 will decrease trail and the bike will turn better.
  15. kenpowell

    SSS to WP conversion- who does this?

    Protune Suspension / Corey Smith - 740-988-6673