Jump to content


  • Content Count

  • Joined

  • Last visited

About smc704

  • Rank
    TT Newbie

Profile Information

  • Location
  1. smc704

    yz 144 rattling at high RPMs

    Yup ill try that this week as well as dropping the needle clip to the lowest setting. I guess Ill even pick up 440- 460 mains and a new needle just in case. Anyone know handy what the next richer than stock needle is for the 06 yz 125 (I have the stock needle currently). In addition to this Im gonna check the timing as rjpjnk suggested. Hopefully I can find sometime between school this week to get at this before next weekend..
  2. smc704

    yz 144 rattling at high RPMs

    Yes I do have the stock needle and I can only go 1 clip position richer until it is set at the richest setting. I think I will try that along with a 430 main. I can always jet down on the main by trial and error if I think the needle fixed it. I have not checked the timing. I have never done it on a small 2 stroke engine. Id like to say it is okay as the engine runs great minus the pinging. However it could be slightly advanced when it way put back together. How exactly can I check it? Is there a way to tell the exact number of degrees or does the engine have to be running and I manually adjust it?
  3. smc704

    yz 144 rattling at high RPMs

    Previously I had the the needle clip at 2nd position from the bottom and a 410 main in. I threw in a 420 main this morning and went for a ride. The rattle is there but seems to be less noticeable in high gear/high speed under load. Like rjpjnk said I can wind it out at around half throttle too and it will rattle but it is mostly in the higher gears and upon acceleration. Seems to me now that when the engine is under a heavy load it is pinging. Should I try a 430 main and put the needle clip to the 1st posisiton? And for comparison what are you guys with Eric Gorrs 144 running for clips and main jet? P.S. Can I mix 91 octane and stp octane booster that you get from wal-mart to help the cause or is stp octane boost b.s? I heard lucas oil octane boost is a legimate product anyone ever use it? In my city your not allowed to buy av fuel unless your filling an airplane or airport tank.
  4. smc704

    yz 144 rattling at high RPMs

    <p>I checked the flywheel nut all engine nuts and bolts all are tight. The countershaft sprocket nut was very slightly loose but the retainer was holding it on so I doubt that was the cause since it is just dependant on speed but I tightened it up for sure. I took the cover off the exhaust linkage assembly to inspect it. The linkage was tight. I did find oil leaking from the exhaust valve shaft. I suspect it is the o-ring as there is some play in the shaft (I can move the shaft in and out slightly). I then peeked through the exhast port to check the valve itself. The cylinder and piston and valve looked good from what I could see. The exhast valve does have some play within the slide as I can wiggle it slightly within the slide with my finger. So my conumdrum is: 1) Could the o-ring cause a lean condition? 2) Is it normal for the exhaust valve to have some play within the slide? Is this something to be concerned about? I will try a 420 main. I have a 410 in right now (I put it on with my pc pipe before the 144). Now that you mention it the plug was a bit too tan. Better rich than sorry lol.
  5. smc704

    yz 144 rattling at high RPMs

    I got the more mid range to top end porting option. I would say that I have about 2-3 hours on the bike after doing a few races this summer. I havent taken the top end off yet. What should I look for if I were to take the top end apart? Before any of this Im still gonna check the exhaust valve linkage and double check all the simple issues again.
  6. Hello, I sent my 2006 125 engine to Eric Gorr and had him bore it out to a 144 to run on pump fuel. I installed it in the bike around June of this year and it runs great except at really high ( close to MAXIMUM) RPM's there is a rattling noise. It has been doing this since I got the engine back. It sounds like the chain whipping against a plastic peice but this is not the problem obviously. The exhaust assembly is tight, springs are tight as well. I don't beleive it is detonation as I have been racing it and it still runs good! Could it be the exhaust valve linkage chattering at these RPM's? I will look further into it this weekend now that racing is over and I have free time. Any suggestions/help? Thanks!