1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Need help with dirt bike

Discussion in 'General' started by Eck, Sep 12, 2020.

  1. Eck

    Eck Older, wiser, but still addicted to roadracing

    2021 Honda CRF250RX (bone stock except for Pro Taper clutch & brake levers)

    I'm new to dirt bikes but hoping the collective can help me out. This bike probably has 10-15 hours on it. I've checked the chain slack, lubed the hell out of it, but I've come to the conclusion it's not the chain. I'm wondering if I've already burned through/damaged the clutch somehow or something else. Before I tear into it, I'm hoping someone might be able to say, "oh, it's X or Y" which will help me not make things worse. "Take it to a shop" is also something I'm prepared to hear. Thank you in advance if anyone can diagnose!

     
    Last edited: Sep 12, 2020
  2. Subaruzi

    Subaruzi Total hack

    Sprockets have all their teeth?

    Sent from my Pixel 4a using Tapatalk
     
  3. Eck

    Eck Older, wiser, but still addicted to roadracing

    They do. Surprisingly, that's one of the things I've thought to check. Sprockets look good - no missing, broken, or damaged teeth.
     
  4. Venom51

    Venom51 John Deere Equipment Expert - Not really

    What does the sprocket alignment look like? That looks like it's trying to jump off on occassion.
     
  5. Eck

    Eck Older, wiser, but still addicted to roadracing

    This video was taken before I touched anything. I measured the slack and it was at roughly 45mm. The acceptable range is 35-45mm so I tightened it up slightly and tried to make sure it was aligned. I don't have an aligner tool like the Motion Pro tool, but using the marks on the swingarm, it is as close as I could make it so I'm pretty sure alignment isn't the issue.
     
  6. turner38

    turner38 Well-Known Member

    What does it do when actually riding it?
     
  7. Dom17

    Dom17 Well-Known Member

    It might just be a bad chain with a really tight/loose spot. Does this happen while riding? It's probably just harmonics.

    Sent from my Pixel 2 using Tapatalk
     
  8. ClemsonsR6

    ClemsonsR6 Well-Known Member

    Measure the swingarm from the center of the bolt at the front to the center of the axel.

    If those measurements are different, then your wheel is crooked.
     
  9. Eck

    Eck Older, wiser, but still addicted to roadracing

    I can hear the "clicking" which I think is that sound when riding. It's typically only at low rpm and it is only the sound I hear. I can't feel it if that makes sense so I wasn't overly concerned until I put it on the stand and it almost jumps off. A friend recommended I get an aftermarket chain anyways. I'm really just concerned that it was something in the clutch/transmission but no one has indicated that could be the case. I'll definitely measure, @ClemsonsR6, just to verify the marks on the swingarm - good suggestion.

    Another semi-related question - when I pull the clutch in, is it normal for the rear wheel to not stop? As soon as I click it into neutral, the wheel stops, but even with the clutch lever pulled in, the rear wheel still moves at a decent rpm when it's in gear. My track bike doesn't behave this way which is why I have "clutch problem" in the back of my mind when I'm looking at this chain thing.

    You're all awesome, thank you for helping out!
     
  10. Venom51

    Venom51 John Deere Equipment Expert - Not really

    Yeah..that mostly oil drag between the plates and steels. Don't sweat it.
     
  11. Rising

    Rising Well-Known Member

    Is the chain guide bent or is there something stuck in it? Did you try spinning the wheel by hand to see if you can more easily see what the cause might be?
     
  12. Kurlon

    Kurlon Well-Known Member

    No tool method: Spin the rear wheel by hand a couple times, then look at the chain on the rear sprocket at 3pm or so, aka the furthest away from the motor spot on the sprocket. Is it sitting centered with gaps between the teeth and chain on both sides, or hard against one side? If it's not centered, loosen the axle and tweak the non chain side adjuster only. Moving it back will move the chain right, pushing it forward will move it left relative to the sprocket. Keep tweaking till the chain naturally centers when you spin the wheel after retightening the axle.
     
  13. Eck

    Eck Older, wiser, but still addicted to roadracing

    I've spun the wheel by hand but didn't seen anything wrong. @Kurlon will take another look with your method and see if I can pick anything out. @Rising I couldn't see anything that jumped out rotating by hand but will take a closer look with this new info. I wish I could buy you all beers! :)
     
  14. Greenhound386

    Greenhound386 Well-Known Member

    Is it not just the chain intermittently catching on one of the guards? With the bike on a stand, that chain is super loose. It would tighten up considerably when you sit on it and it sags.
     
  15. pscook

    pscook Well-Known Member

    Dirt bikes aren't designed to be run on the stand, so the "problem" might not be a problem. Consider that it's a single cylinder with a power pulse every other revolution. On a multi-cylinder engine the pulses overlap(ish) to smooth out the drive, but the single hiccups and farts, causing bumps in the rotation. This is why bikes have rubber dampers in the clutch basket. At low RPM the irregular power pulses are magnified, making it feel like it's missing or misfiring, but it's in the nature of the bike to not run perfectly smooth at low load/low speed/low RPM. If it clears up when riding, then it's a non-issue.

    Regarding the wheel turning with the clutch in, again, you are on the stand and not in the bike's natural habitat. Clutch drag is really really common in any wet clutch engine; like a street bike that doesn't want to find neutral at the stop light is wet clutch drag. Don't troubleshoot the drive train on the stand. Clutch drag (to a point) is normal, especially the condition you describe. Put your hand or your foot on the rear brake and I'll be that it takes almost zero pressure to stop the wheel. If it takes too much pressure, adjust the clutch cable slack.
     
    turbulence likes this.
  16. fastfreddie

    fastfreddie Midnight Oil Garage

    It's definitely chain related.
    A lot of dirt bikes do this on a stand, but I swear I see a kinked link. Follow it spinning around from the :03 mark, you can predict when it's gonna skip again at the :17 mark. Looks like it could be related to the master link.
     
    Last edited: Sep 12, 2020
  17. Resident Plarp

    Resident Plarp drittsekkmanufacturing.com

    Oh, hey Eck - welcome back.
     
    Eck likes this.
  18. Eck

    Eck Older, wiser, but still addicted to roadracing

    Went riding today and I loosened the chain just a bit and while the sound is still there it seems better or maybe just seemed better based on everyone’s feedback. I think I’m good to go. Thank you all!

    Oh, hey Plarp! When we going endurance racing?
     
  19. TurboBlew

    TurboBlew Registers Abusers

    one way to check wheel alignment is measure from the swingarm axle to rear axle.You can run some 1/4" metal dowels thru and use a tape measure to get axle even. About $7 at home depot
    I wouldnt trust the embossed hash marks to be accurate.
     
    Eck likes this.

Share This Page