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Found 157 results

  1. Josh the squash

    yz125 2001 yz 125 build

    I bought a 2001 yz 125 for $700. Plan to tear it down and see what's going on inside this baby. Depending on how bad the engine is I'll ether keep it and have it be my race bike for next season or sell it and try to make a couple hundred and get a little better one. I bought the bike like this with a box of parts along with it.
  2. I have a 1995 yz125 2t and the thing runs pretty good, well at least it seems to have no issues but it does not need the choke to start the bike. I changed the main, idle, and needle jets all to factory specs for my temperature and altitude. The bike will start first kick when 100% cold and will start first kick when warm but it just does not need the choke. So I'm wondering if I'm hindering my bikes performance in a way because it does not need the choke. Suggestions?
  3. Im talking to a guy who's selling a yz125 and he wants $3600, is that too much?
  4. motophill911

    Artrax tires on a Yz125?

    What do you guys think about the cheaper artrax tires off motorsports.com? I see they run narrow in size. Should I get a 110? Are they heavier than other brands? I'm a top C rider in college on a 2015 yz125. Should I just spend the extra $40 for golden Tyre or star-cross 5s? Thanks
  5. So I'm currently 15 will be 16 in September and have been riding for about a year and a half now. Im 5'9 175 lbs and wanna upgrade from my 06 yz125 to a same year or newer yz250 2 stroke. Would this be a good idea. Also 2 strokes 4lyfe.
  6. I would like to know if a yz125 2002 models cdi unit fit a yz250 2003 model if so can you plz say it and would any modifications be needed.
  7. Hey all, just acquired a mint '01 yz125. It came with oversized bars, the problem is the handle bar mounts sit into the stock mounts...which are non detachable from the top triple clamp. Its not a big deal but I'm a short guy and the handle bars sit high. I would like to keep the oversize bars and get back to the stock bar height. Will any newer yamaha top triple fit on my '01 yz? Or is there a cheaper solution? Thanks guys! I'm sure some of you have ran into this before.
  8. Caleb Kittrell

    2005 Yamaha YZ 125 Repairs

    My dumbass made the mistake of cross threading the transmission oil drain bolt in the case, damaging the crankcase threads, the bolt has no damage but now it wont stay secure. Any ideas to fixing the threads besides splitting the cases & buying new crankcases.
  9. Hello, im 20 years old and im from Germany last year I bought my first dirt bike, a 2003 yz 125, i did have no clue about dirt bikes but I have always wanted one so I just bought it. all my knowledge comes from youtube and the internet. Unfortunately I can't go riding very often because of different circumstances, weather sucks here I need my dads car for the trailer etc.... Here is the issue ever since I got the bike it had a problem with the spark plug. When im at the track the bike starts super well, I ride for a couple labs and then it sometimes just dies, the spark plug is fouled, probably because im riding so slow since im so unexperienced and just getting to know riding (im almost never at full throttle, most of the time id say im at half). I put in a new spark plug and it starts again perfectly... after I go for another few laps the same thing happens again. Also one thing I've noticed is that it doesn't run well at idle and often stalls when the clutch is pulled in even after trying to adjust the air screw and the pilot screw. Ive tried a hotter spark plug (br8eix) and it helped a little bit but im not sure how long its going to last. Do you guys thing I can even try a br7eg? Im scared that it might run too hot and blow up or something, or should I try to rejet it. in that case which jet should I replace? Pilot or main jet? since im only 0- ½ gas most of the time. The compression is still good I put in a new top end when I got it and I clean the air filter regularly. I hope some of you may have some tips or answers, Thank you in advance please excuse any typos or grammatical mistakes..
  10. Goon Rides

    2001 YZ125 Dies

    Hey guys, I finally rode my 01 YZ125 properly. So whenever I ride I floor it, and when I let go of the throttle for 2 seconds, and when I try throttling again, the bike doesn't move because it shuts off. Why is that? I think it might be the CDI or the Alternator. What is it? (William1 please don't delete this thread lol)
  11. CHECK THIS VID OUT!!!!! You Will NOT be disappointed! Kid rips. Get stoked to get out and ride...RIGHT NOW!
  12. jayslatt

    Is my yz blown up?

    So I unloaded my 2002 yz125 to go for a ride. I kicked it and it started right up as usual. After 1 minute of riding it started bogging down and died. Couldn't get it started again so after 5-10 minutes of trying, I packed up and went home. I slapped a compression tester on and it read around 140 psi so I thought it was a fouled plug. I replaced the plug and it started right up second kick. It idled perfectly and revved smooth. But as soon as I put it in gear and went to ride, same thing. Bogged down and died and now won't start again. I'm no expert mechanic so I need some help. Could my air:fuel or gas:oil ratio be that bad that I fouled another plug that quick, or is it time for a top end, or could it be something else? Any information would be appreciated
  13. I was riding my bike at full throttle doing slides in the sand and then suddenly my bike started bogging. It seemed incredibly lean like it was running out of gas. Full throttle barley even got it to accelerate at all. I filled it up with gas and no luck. Any ideas what happened?
  14. I'm looking into buying a used bike to ride on trails, which bike between the two would be better to go on long distance trail rides and be the most reliable. Oh and I'm 5'10 175 pounds if that makes anything different.
  15. 05Yz125ForLife

    Increase Yz125 throttle rotation

    Went riding with my nephew and relalized I don’t pin it as often as I need to. Checked my max rpm after my nephew rode my bike (05yz144) and the motor hit 14,640 rpms. I didn’t know to be happy or worried. I normally don’t see anything over 11-12,000 rpms. I got on it and noticed I was leaving some throttle on the table. I wondered if anyone has changed their throttle ratio so that you have less twist to WOT. The trails we ride have been opened up and there is more opportunity to be WOT. You see a lot of throttle tubes with mutiple cams for thumpers but what about 2t? Any downsides to consider? What ratio changes are common or too much?
  16. Hey guys im looking for an opinion. I have an 01 yz125 and its sputtering half throttle right before powerband. I have checked every last thing from jetting to stator ohms to reeds, gas cap etc ive pretty much narrowed it down to possibly the cdi going bad. Now im just curious on what symptoms would designate a bad cdi? Any help is greatly appreciated
  17. Zach7018

    Coolant drip help!

    I recently bought a 2002 YZ125. I just rebuilt the top end and took it out on the first ride. When I got to the trails and went to unload my bike I noticed some drops on coolant on the bed of my truck and a little bit on the frame.(the bike had not been run at all that day). When I started riding I would check every couple of minutes and noticed it was still happening. just a couple of drips a minute coming from the bleeder hose that runs from the top of the radiator. After a little while I stopped and let the bike cool and checked the coolant level to make sure I wasn't losing too much. After checking I went back to riding and it seemed to have stopped so I figured maybe it just had something to do with the radiator cap and somehow taking it off and putting it back on had solved the problem. However today I had the bike in the bed of my truck and once again found coolant dripping from the bleeder line coming from the top of the radiator(bike had not been running). Has anyone else had this happen? Is it a problem? If so how much is it going to cost
  18. Hey guys, someone came to take a look at my bike. He sounded like he really wanted it. He checked everything, saying it was a perfect bike. Also in my ad I said $2400 firm, but then he offered $2200 and I accepted. Anyways, when he asked to take a test ride, I allowed. He tried popping 2 wheelies and then he said "I don't know man fist gear doesn't feel right". Then he said "The bottom end doesn't feel right". Why is that? I am new to dirt bikes so I don't know what to do. I took down the ad and don't want to sell it anymore, I just want to fix those problems. Thanks.
  19. Hi All, I was wondering if anyone knew which fuel petcock assemblies with reserve fit on the stock tank for a 2000 YZ 125? 2HR-24500-02-00 sound right? Ebay says 1989-2018 fitment. Sounds a little wide. Can anyone confirm?
  20. Patrick Ahern

    YZ125 second gear issue

    I just bought a 1997 yz125, lots of racing parts, bike runs AMAZING, starts first kick without choke. Only issue I have is I went out to ride today and when I shifted to second, I hear a clanking sound and can feel the bike trying to grab but it won't. I just replaced the clutch oil filled correctly with 10w-30 oil of the right grade, and the sprockets and chain are good. It's not the clutch because it rides perfect in all the other gears, 2nd is just garbage though. I know I have to split the case for this, but has anyone had any experience with an issue like this, or have any tips to share? I've found both gears on ebay for 2nd, and can get them both for under $100 combined, just don't want to pay $300 for my shop to split the engine. What specialty tools do I NEED, and what can I make do without? Thanks in advance!
  21. Goon Rides

    Clutch Help

    Hey guys, I wanted to wrap my clutch cover, well it was a major fail. Anyways, when I was done, I went to install it, but for some reason the "long screw thing" with the gear kept getting locked. Well I was able to get it moving after 2 and a half hours of fiddling with it, but now it's really loose and easy to move. Plus the cable gets pulled towards the back of the bike when pressed. I don't know how to fix it, I'm pretty pissed since I "broke" my bike. There's also no "compression" when the clutch lever is pulled. What should I do? My only option now is to take it to a mechanic and rent a truck to do it, and it's gonaa cost me $200 for sure someone help please
  22. Hello, Thought I would share something that I thought might be helpful to other Athena 144 users since I used this forum to help troubleshoot my bike. I bought a used 144 bike this winter that had really good parts on it. Blue Talon hubs, black excel rims, hinson clutch, renthal levers and a bunch of other goodies that appealed to my son. We already had a good running 05 yz125 with upgraded SSS suspension. The Idea was to see how this 144 would do at the track(novice rider). When we bought the bike it started right up, but we never really gave it a proper running test because we met up at a gas station in a town I was unfamiliar with, and there were cops around. That was my fault for not checking things out properly. Now that the weather is better here in Illinois I decided to test the bike, but it was running poorly. It would break up at higher RPM, not getting into the power, and have trouble idling once warmed. I initially thought it was jetting and started the process of getting it dialed in. I ordered up some pilot jets and started leaning it out because the air screw was ineffective. After getting down to 35 pilot i decided to look at timing and compression. Timing was a bit advanced and I corrected that to factory spec. The compression check showed 125 PSI and so the cylinder and piston came out. Ring gap looked good so I checked squish. Squish came in too high at 1.5 mm with HF calipers on solder. This kit is the newer kit with the rubber coated steel head gasket not the o ring type. I could not make sense of the improper squish because the athena instructions say to run a thinner base gasket if the squish is too high. I could see that the Athena gasket was being used for both head and base. Thankfully the seller provided an additional gasket kit, and I found they provide 2 gaskets. 1 Thick rubber one and one thin paper one. Whoever put this kit on used both and caused excessive squish clearance. I corrected everything and got squish back to 1.1 mm using just the thicker base gasket and picked up 30 PSI on the compression test. I have not run the bike yet because it is late now, but I am hopeful we can begin some jetting and get this bike running good.
  23. So i went riding today, bike was running great. Noticed a substantial top end rattle, and a loss of power. Bike ran and rode out of the trails. Pulled it apart. It's got an Athena big bore kit and cylinder. Piston was scored by I believe the power valve. Cylinder fared pretty well. Rod has no up and down movement. The wrist pin and bearing was very sloppy when the jug was taken off. Took the piston off. I have some questions about the power valve, pics may help. There are wear marks on the power valve parts(see pics) so what next? Obliviously a new piston and cylinder honing. I've never taken apart a power band before, I want to make sure it isn't just gonna hit the new piston and ruin it.
  24. Hi. I have a concern and a few questions regarding my piston and cylinder in my 2006 YZ125. Here it goes. Ok so i bought this bike off a friend about 2.5-3 months ago as my first dirt bike. First thing i did to the bike was put a fresh top end in it. I put a wiesco Pro-Lite Standard piston off of rocky mtn atv because that is what everyone recommended and what the website recommended. I followed a tutorial and consulted the manual when installing the new piston, ring, and gaskets. When i put the piston back into the cylinder for the first time i was told to put some premix on the piston and on the cylinder head. I did not put a ton but i put some on. I put it all back together and everything was running great, did a break in as well. Starts on 1st or 2nd kick to this day. I have probably ridden 10-15 times on this new piston. Ok so here is my concern. I took my pipe off today because it was rusty and i am in the process of removing the rust (vinegar and steel wool works great btw). With the pipe off a take a look into the cylinder and see this... (see pic). Looks like blowback on the piston. Anyone know why this might be doing this? I was thinking maybe i got the wrong size piston because with some research i found that the YZ125s have different cylinder letters and pistons to correspond with the letter. Rocky mtn didnt mention this and gave me no option to choose from except the one i got. My cylinder is a B cylinder. It also might be hard to see in pic but there is some scoring on the piston. I felt the marks with a long wooden pick and they just seem to be marks and not actual scratches or scrapes as i did not feel any when rubbing the pick over them lightly. I would just throw in a new top end but i have only really probably but 15hrs on it max since the rebuild. I am also not a racer and this is my first dirtbike so im not constantly winding it out. The main thing that is confusing to me is that i rode this bike yesterday and it was running great, no issues at all and will probably run great if i rode tomorrow. On a final note im running Klotz Super Techniplate 2stroke oil full synthetic with a BR8ES plug. I had a post on here earlier about fouling plugs and what fixed it for me was a hotter plug and better oil (yamalube is trash lol). I have also ordered a compression tester to see what the compression is. Any words of advice or insight are appreciated. Thanks!
  25. Eric Peach

    92 YZ125 shift shaft

    Hey I’m new to this page and am looking for some help I bought a 1992 YZ125 and the shift shaft is bent anyone know how to repair or where I can get a new one and what years are comparable?