Jump to content


  • Content Count

  • Joined

  • Last visited

About mrdsee

  • Rank
    TT Bronze Member

Profile Information

  • Location

Recent Profile Visitors

552 profile views
  1. mrdsee

    WOT sputter

    Also found this: "Yamaha for 01-03 lightened the Pv spring rate, this causes the PV to open to soon and can create a bog like feeling or dip early in the powerband. For 04 Yamaha went back in time to the 00 PV spring and solved this problem." I changed the spring on my 125 for better results. So you might want to explore this further.
  2. mrdsee

    WOT sputter

    Also put the needle clip in the #2 (move up 1, 1 step leaner) slot and retest. Mid range too rich
  3. mrdsee

    WOT sputter

    Check your coil, cap, etc etc per service manual testing procedures. Unplug all electrical connections(even rotate kill switch a little) and reinsert using di-electric grease. Keep us posted on results.
  4. mrdsee

    Head gasket failure?

    Yeah, never bought into this lean on oil kick that some folks follow. Especially with small bore, ultra high rpm 125 mx motors. If factory Yamaha says 30-1 you can bet theirs a valid science based reason for it. Hell, go cart motors that see even higher engine loads than motocross mix as high as 16-1. Of course one must jet accordingly, and since I run in the desert I mix more oil due to the higher sustained speeds. Since my 125 is a 144 I could in theory run a tad leaner on oil as the bigger the bore the less oil is required. But the piston I run weighs the same as a stock 125 so is therefor balanced to the crank and revs like a 125. Most 144 pistons weigh more and therefor sign off sooner due to imbalance loading. My 144 has over rev o'plenty and I run an oil mix that suits this motor. After 45 years of riding I've seen many a fad come and go, and if I was putting around on a trail bike, not working the engine hard, I'd run less oil. But for flat out mx work, I stick to the tried and true well oiled, and enough octane, method.
  5. mrdsee

    Head gasket failure?

    Check timing and run 30-1 Yamalube 2R, plus adding some VP110 or C12 or even VP100 goes a long ways towards reliability/detonation insurance. In my full race YZ125/144 I run 26/28-1 plus straight VP 110 as it's a high compression head with full mid-top porting and a tad of timing advance with carb mods.
  6. mrdsee

    WOT sputter

    What was/will be the air temperature at when riding? Likely requires a drop of 2-3 steps on the main 1/2-1 step leaner on needle(from stock position) check your pilot(likely rich) and effects all jetting ranges, per standard testing procedures octane level is fine consider having Eric Gorr cut your head for high altitude riding to get back some of the compression your losing due to decreased atmospheric pressure. It could be a bad coil, but try the jetting first as your rich @6000 ft
  7. mrdsee

    2 stroke wet clutch sticks every day - plates look ok?

    I have found from decades of owning 2 strokes that ATF Type F works great, is cheap, available almost everywhere, and changes clutches from sticking to not, plus shifts better, and less grabby. Just change the ATF more often than gear oil. Might want to soak the fiber plates in the fluid for a day or two prior to install if their already out of the bike.
  8. mrdsee

    Blown up 2000 yz125

    Yes, oil, oil ratio, and jetting #'s are needed. Plus altitude and temp you ride in.
  9. Yeah, after 450's 125's make them feel like a boat anchor. Not so fast down a straight, nor in high load situations like deep sand. But in the turns, braking, over ruts, putting the bike here and there with ease, and general flickabillity, it's a 125 all the way. By far the most fun bikes I've ever ridden. Besides, who the hell wants the expense and pain of a 4s rebuild. Not to mention how 2s hold their value better.
  10. Working with Eric But the high octane of straight VP110 is what allows for the high compression head, and the timing changes due to the slower burn rate of the fuel.
  11. I've had several over the decades, including a YZ300, plus the whole 450 4s thing. But nothing I've ever ridden is as fun, or handles as well, as a dialed in 125. Especially one that's been lightened almost 20# over a stocker.
  12. On my YZ125/144 I run the V-Force. But I've also got Eric Gorr's 144 kit, his custom speced out single ring forged weisco piston(same weight as stock 125 piston for crank balance) mid-top porting, EG high compression head, FMF Factory Fatty, Titanium 2 Silencer, RB Designs over bored carb with machined in divider wing, aluminum clutch plates, later model power valve governor spring, iridium plug, advanced timing, no toil air filter, straight VP110 gas, 28-1 Yamalube 2R. This combo yields good bottom end, fairly flat mid range, extremely potent(and wide) top end, with over rev o'plenty(thanks balanced piston). Not sure how much the V-Force does on its own. But in this combination it all works stellar.
  13. mrdsee

    Top end rebuild, what happened?

    Yeah, there's people who run less oil, but I'm not one of them since I run in the desert/MX under extreme conditions. Lots of wide open and high loads going on rather than partial throttle trail riding. The extra oil cuts down wear, increases ring seal, etc. Some cart motors run as high as 16-20 to 1 due to the extreme loads of pavement running. On my YZ125/144 I need to run straight VP110 due to the high compression head and advanced timing. On stock'ish 250's I'll mix for a 98 octane rating for detonation protection since sometimes what we think is premium 91 can be 87 if the station is scamming. Plus premium gas often times is much older than the more used, and thus replaced more often, 87. Later model YZ250's have been known to detonate with 91.
  14. mrdsee

    Top end rebuild, what happened?

    Been running Weisco forged pistons in all my racing 2s. Also run plenty(28-1 in YZ125/144 and 30-1 in 250's) of Yamalube 2R oil. Plus the octane required for the engine. The main thing I follow with forged pistons is to "thoroughly" warm them up prior to full load/RPM runs. I let them warm up "extra" at idle, then gradually increase load and RPM's. Cast pistons are much easier, but the benefits of a forged piton is worth the wait.
  15. mrdsee

    Castrol 10w 30 in 1995 kdx 200 tranny?

    Been running ATF Type F for decades. Better shifting and a less grabby clutch.