Help...125m grinding noise

[Pendl303]

I just picked up a 125m that hadn't run in a few years, after I got the motor running I realized after shifting into first a grinding noise appeared and seem to put a strain on the motor when driving. I tried to run through the gears and it was apparent in all of them.
I brought it back in the garage and the noise seemed to come from around the sprocket behind the high low sub transmission case. I took that all apart as the high low gear didn't seem to be engaging properly. It looked as everything was in there and nothing really beat up except a slight chip on one gear in the H/L case. I spun the main shaft coming out and thats where the noise would come from, I believe that one goes through the sprocket.
I am no mechanic but would love to hear what you guys think, thanks for the help and hope I am in the right section.

[DohcBikes]

You are definitely in the right section, welcome to 3 wheeler world, there will likely be some 125m gurus coming your way soon!

[Pendl303]

Thanks, I hope to get another wheeler soon but trying to get this one running in the mean time

[tri again]

Hi and welcome
Try the search key for tons of info in one click.
I usually read all the stuff that pops up, even if it's not my particular machine.
I have a 125m with a shifting problem.
Shift drum stopper broke off but I got it that way so no idea if it makes noise or not.
Fairly common problem and nice to fix efore it gets worse IF that's your issue.

Someone will surely chime in soon.
Yeah, see if you can get the search key to work and PLEASE let us know what you find.

[Pendl303]

Thanks again, I have been searching for a while but I haven't run across the exact same thing that I have. It thought it might be the stopper also but wasn't sure and have never dug that deep into a engine.

[shortline10]

Pull the clutch cover and inspect !

[Pendl303]

Is that the opposite side of the pull start right? If I pull that whole cover will I need A new gasket?

[tri again]

There are some great pictures.
search key for:
shift drum stopper
should get you tons of info and pix

I have one apart but can't seem to walk today but surely pix
are still up, I'd bet.
Yeah, lots of folks report loose mounting bolt, or broken bolt and a few with broken aluminum boss that Holds the bolt so for whatever reason, seems like they get wierd or noisy or symptomatic enough to look into them beFORE they get semi terminal, requiring internal heliarc welding of the case.

Not to scare you and maybe that's NOT your problem.

Sure wish I knew more.
My guess is that you'd have a mystery shifter before that shift drom stopper bolt
came loose enough to break.

[tri again]

ps - gaskets are cheap and very nice to have.
If not , I usually VERY carefully, use blue silicon and put it on the case super thin and kinda tapered to the outside of the case and LET IT DRY completely, like a rubber band.
Reeeally don't want gasket sealer globs floating around the engine.
Doesn't take much to plug oil passages, especially to the head and cam.

My other preference is to glue a gasket to the case (contact cement) , nice and perfect,
face down on something perfectly flat, so that it stays on the cover in case it needs to come off again, the gasket will stay on the case.

Yeah, let us know the the search key and pictures don't work. and / or wait till you hear from kb or any of the others who have been through this.
There MIGHT be a reverse thread bolt in there somewhere depending on how deep you need to go.
Hopefully it's an ez fix.
If I had another 125m? I'd most likely address that drum stopper and an updated parts or shoulder bolt or whatever makes them better as prevention.

[tri again]

http://www.3wheelerworld.com/showthr...t+drum+stopper

see if this opens for your 125m info
I really want to know what the do long before they break .
Most likely funky shifting but lots of people borrow these things and if they don't shift right, the STOMP on the poor tiny little shifter.
Once you've been in there, a braefoot click shift is all they ever need.
and then again, some people riode these things and use the shifter like a bless'ed footpeg.

[kb0nly]

Hmm... If the noise is coming from the output shaft area when you spin it inside the sub trans i would think it might be the drive sprocket bushings making the noise.

But, before we explore that option... You removed the jack shaft correct? The small shaft in the sub trans with the gears on it? I wanted to be sure your only spinning the drive sprocket on the motor output shaft. The main noise makers that i have come across in these 125M's is worn bushings in the drive sprocket, the sprocket the chain goes around and rides on the outside of the motor output shaft, also the three roller bearings in the sub trans, two in the cover and one in the case side that the jack shaft sits in.

Does the drive sprocket have play in it? If you can wobble it and/or that oil seal around it is leaking and you have a lot of oil buildup around the drive sprocket then chances are the bushings are shot. It makes kind of a dragging grinding noise when they wear out. But so do the bearings in the sub trans.

If its shifting in and out of gear and not dropping out of gear or anything weird like that, just the noise, then the shift drum stopper and clutch should be fine on the other side. Wouldn't hurt to get a gasket set though so you can pull the right cover off and inspect the shift drum stopper and clean the oil screen as well since it hasn't run in years. You can also pop off the cover on the clutch and clean out all the accumulated sludge from the years as well.

Main thing is to figure out exactly which part is making the noise by the questions i asked you first.

[Pendl303]

It actually has popped out of gear once or twice but no apparent play with the shaft. Seems like it's almost missing 2nd gear sometimes. I did take everything off and was just spinning the main shaft.
Kind of sounding like the stopper drum? Or sprocket
It definitely sounds like a dragging grinding noise. Where can I grab gaskets? And or other parts that you guys think it might need.


Again appreciate the help guys

[kb0nly]

Ok, its its popping out and missing 2nd gear you likely have a broken shift drum stopper... STOP RUNNING IT NOW... Get the right side cover off and check it. If your lucky its not done any severe damage yet, but there could be loose bits rattling around and grinding between parts on the right side. Definitely go through it FIRST.

All you need is a good hand held impact driver, the type you hit with a rubber mallet, to get the philips head case screws out on the right side. You will also have to pull the exhaust off to get some working room. When you pull off the right case cover you have to watch out for losing parts, mainly the clutch adjust parts that the screw and nut on that cover adjust inside. Lay it on its left side, make sure you shut the fuel off first, then you can take it apart without much trouble.

The shift drum stopper is upper left corner behind the large gear, now generally what happens is the roller tip of that stopper arm breaks off, sometimes it gets stuck behind that gear and just gets ground between the gear and the case. To get to the stopper and repair it however, provided your just suffering from a broken roller tip, you will need gaskets and a clutch nut socket. All pretty inexpensive really. You can buy a bottom end gasket set to get everything, you will need a new gasket for your sub trans now anyway, and you will need right cover gasket, clutch cover gasket, also a new o-ring on the clutch adjust screw couldn't hurt they like to leak there as well. I have taken quite a few of these apart to replace the stopper, its not terribly hard, remove the case cover, remove the clutch cover, remove the clutch nut, pull the entire clutch assembly off, then you have to remove the snap ring from the gear and pull that off, the shift stopper and the shift drum it engages is behind it. Oh you will need snap ring pliers for that. But thats the end of the specialized tools.. LOL

www.dratv.com has the stopper and the gaskets, and he also has the clutch nut socket, not hard to get at all. But before you order parts, tear it apart and see whats broke. And get the service manual if you havent already from my website.

[Pendl303]

Awesome thank you... Everything I need and more.

On a side note what does a 1986 250sx go for? Relatively good shape and runs great with everything in working order ?

[kb0nly]

Awesome thank you... Everything I need and more.

On a side note what does a 1986 250sx go for? Relatively good shape and runs great with everything in working order ?

Thats actually a hard question to answer... These things seem to be differently priced by region, demand, etc. The best answer i could give on that, its worth what you think it is. An 86 250SX would be a nice find!