Hi everyone, new member and new dt125b owner. I just really noticed this tonight after getting home. When I start the bike and the clutch is released there is a very unpleasant grinding noise (hard to describe sort of like a rattling) coming from the left side cover where the clutch cable goes into it.

I’m pretty green outside basics so I wasn’t exactly sure what to search for other than “grinding noise” so please excuse the stupidity basically of probably creating another post about something that has been discussed.

Could this possibly just be worn clutches? It does seem kind of weak from a stop sometimes, especially in loose dirt. Or do you think this is more bearing related? I want to fix it just not exactly sure what my plan of attack is.

prior to tonight it hasn’t made this noise, when the clutch is engaged the noise goes away. It also starts a whole lot easier all of a sudden with the clutch lever in than not.

Thanks in advance, I really appreciate it.

john

I don't know the answer to your question, sorry! However, if you are able to make a short video of it (with audio!  ), post it to youtube or similar and then post a link to that here, it will help other members id what the noise is.

Thanks.

Welcome, & as Gr8uncleal says above--we love videos with audio if possible. But looking at Partzilla i guess your is electric start which is the early style motor & clutch mechanism on the left. 175's changed the complete motor design in "74 so just want to be sure. In saying 'that', i'm no help. There's nothing in there to make a noise. Run it without the left cover, not just the outer points cover but the one with the cable so you can run it & see if the clutch pushrod is gyrating wildly rather than doing nothing. Could put pressure on the pushrod while running. Just a piece of wood or hammer handle, just to get an idea if there's something going on the other end--pushrod damage where the ball bearing sits against it. Unusual though. Check the 3 screw triangle cover is still there above the sprocket & sits over the selector drum. Can get wiped off along with the end of the selector drum if its thrown a chain & its bunched up there & smashes the drum end completely off. Also is the sprocket nut in place, not undone or trying to drop off. That'll keep ya busy.

First thing I'd do is make sure there is oil in the transmission.

MarkT post=127631
First thing I'd do is make sure there is oil in the transmission.

RT325, Umm, never thought of that lol.
ps, tried to use the quote button but came up Error.

Have oil but the level may be somewhat low, that said the bike was on its kickstand and the majority of oil may have been not leveled. I’m going to do a drain and fill today just to make sure I don’t have any metal going on.. I don’t think it’s bottom end related just because the kick is very smooth and it runs fine.

I’ll try to get some video or audio going on at some point today. Also after reading obsessively last night I need to clear things up I guess in what I meant. When the clutch is engaged in neutral (lever is out) the noise is present. When the clutch is disengaged in neutral (lever in) noise goes away.

it sounds like it’s gear noise possibly accentuated by a rough idle, I did notice my intake manifold boot might have some slight cracks in it and is spongy, new one on the way when I replace the reeds and gasket.

or it’s just clutch basket noise and I guess that’s “normal” for a lot of bikes. I do have new clutches and springs, so I’ll probably dig into that soon anyway. I think the bike is all original so I wouldn’t doubt the clutch plates are too. I’ll check the basket out for notching but I don’t have any weird lever feel and it shifts great so I’m assuming that will be ok too.

what weight oil would you recommend? I can exactly remember what I used but it was what the factory manual wanted or at least close to it. It had plenty of clean oil in it when purchased but I figured I’d change it since I knew nothing about the guy who had it.

thanks again for the help, have a great weekend!

Also I’m going to explore the difference between load vs no load. Pretty sure the noise goes away no matter what when a load is placed on it, I couldn’t really tell yesterday with my maniac dogs chasing me and barking lol

another thing... typically speaking it’s kept in my garage and the weather has been colder up here than it has just this week. I had the bike out in the sun, could the heat possibly on the case have thinned the oil out causing the noise?

It’s just weird it’s all of a sudden, nothing has happened and I’ve barely ridden the thing. I think I have 10-30 in SAE or whatever the manual wanted, but maybe I put the wrong stuff in idk.. frustrating haha

If the noise is occurring with the clutch lever let out in neutral, and goes away clutch lever pulled in, then it's transmission related, should have nothing to do with the engine or starter/generator. Bearing, or chipped gear, or debris inside. Clutch plates don't rattle in the baskets with wet clutches.

That said, it could be normal depending on the severity of the noise, which is why a video would be great!

You'll need to upload your video to a YouTube account, then post the link in using the little link icon above, second row in the middle/left above this text box.

Ok i'll have a up to date read later but talking basket there's a heavy large Oring that will dampen the rattle out if it 'is' that doing it. Shown here as number 2. Stretches over basket & into the gap between gear & basket. 175's were bad for rattle at idle--CT2 & CT3 models. If yours already has one then doubt that's the noise but is just a thought.

www.partzilla.com/catalog/yamaha/motorcycle/1975/dt125b/clutch

youtube.com/shorts/G5xoFwxZJik?feature=share



hopefully this works.. I’ve never uploaded to YouTube (I sound old wow). Kind of hard to hear the noise but I think you will be able to. I ended up monkeying around with the idle adjustment and brought idle up to 3k and that seemed to lessen the noise.

I have a new intake manifold on the way, the one on there now has some surface cracks that could be creating a vac leak, wouldn’t hurt to get some fresh rubber on their anyway.

also just running a uni off the back of the carb (oiled). I haven’t tackled putting the airbox on (missing when I got it, also no filter at all when I got it).

thanks everyone