ATV Florida Forum

I've been hearing a slight rattling vibration sound coming from the crankcase/tranny on our CRF50 when we ride it. The vibration happens in any gear under any rpm as long as you're accelerating. It's been happening since we rode it through the sugarsand in our yard a couple days ago when it kept getting stuck and bogging down pretty bad.

 don't know if those bikes have a kick starter or not but sometimes they'll rattle/vibrate. While bike is running hold foot against kick starter to see if it stops. If it stops kick starter needs rebuilt. If it doesn't stop call Mike & Melissa @ A.T.P. Racing in Apopka, Fl.

I'll try it tommorow, I was just thinking about that while I was riding it. That might be it. What would it cost to get that rebuilt? I'm just hoping it's not some internal engine problems, pretty sure it's not the top end too. It's deffinately a noise coming from the bottom/rear end section. And will it cause any damage to the bike if that is it and I keep riding around on it without rebuilding the kick start?

Does it only rattle when it's hot?

Or does it begin rattling as soon as you start it?

Or does it only rattle when it's in gear?

I would for sure call Mike & Melissa @ ATP (Nightbreed & Mrs.Nightbreed) IF IT'S JUST THE KICK STARTER RATTLING IT SHOULD STOP AS SOON AS YOU PUT YOUR HAND OR FOOT AGAINST IT. They sell kick starter rebuild kits for a few dollars. I'm hoping your this lucky & that's all it is. If not then call ATP, they have kids and are probably familiar with this kinda bike.

Yes, it only rattles when after a few minutes once it's hot. It'll do it in neutral I think, just not as loud.

And holding the kick start doesn't stop the noise.

It's almost like a scraping noise. I checked the oil just in case and the oil is fine.

I don't want to be the bearer of bad news, but...

It sounds like it might be a gearbox/transmission issue, but you won't know what's wrong with the transimission gearbox until you take it apart, or reach catastrophic failure.

You can drain the transmission oil, and look for discoloration or metal bits in your tranny fluids.

You can also put your hand on the tranny casing and see if you feel excessive vibration when you rev coming directly from the trans.

I would take this problem to the shop.

Does it shift correctly?

It's doing everything as good as always, including shifting. Just got that scraping/rattling vibration coming from the right-side of the bottom-end. Not sure if it's coming from the crankcase or the tranny. :/ I've drained the engine oil before but never the tranny oil, are you supposed to drain that regularly like engine oil?

Been trying to convince my dad the noise is there but for some reason he can't hear it. Me and my bro can clearly hear it..

well there is this thing called exhaust on the right side that makes noise. it gets louder as you rev it up too. lol. j/k. maybe sumthin came loose and rattles now.

Here's the clutch parts for the 50...

If you don't feel comfortable taking this many parts off your bike, then take it to the shop.

 

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What? The clutch is fine. Nothing seems to be wrong with the bike besides that noise. I'm gonna check for loose bolts later just to make sure.

Something funny is, you were right. Figured out that it wasn't coming from the crankcase and that it was actually coming from the exhaust right next to it. The exhaust guard is rattling and vibrating.

Fox SOLVES ANOTHER One!

Nice Job Homeschool, you should be like a master mechanic or something.


Congrats, that's a much cheaper fix than a gearbox/transmission.

(The picture of the clutch parts was an illustration to say, "If you can't deal with simple clutch parts, don't take apart the tranny.)

Who da man?