97 or 98 Yamaha 350 4x4 big bear

[Sam Shelley]

I've got the opportunity to buy a running big bear for $130 from a guy I work with, has a winch, electric start, lights work, but the axles are screwed I guess, he says the rear is stripped on the inside (whatever that means) and I guess the front pretty much (or did) snap in half. My question is before I even go and take a look at it, is it worth it? And how difficult/expensive is the fix? Dont have any experience with driveshaft driven wheelers. 

[Frank Angerano]

$130 bucks is worth it.  As long as it’s running, the engine parts alone could be worth double that.  And if the plastics are in good shape then that’s worth another $150 for both front and back even if there faded.  And if the metal racks are not too banged up they are worth money also. Easy $60 bucks a rack. So you would get your money back.

Now having said that, if your looking for a project then you can go to eBay and find some used axels for a fair price and play around with it as a project but your probably going to spend about $250 on parts and some time. As far as experience goes well that’s another story.  If your mechanically inclined and have some knowledge about cars and things of that nature then you will be good. The seat is an easy fix and cosmetics are as well.   Try and get the price down more. It’s basically a dead bike as it is. Offer him $75 bucks. He will come back at $100.  

[wanrep]

I guess it's worth $100 IF you've heard it run and it sounds ok.  If it doesn't run, tell him you'll give him scrap price ($25) and get it out of his way.  That way if it turns out to be a total mess, you can get your money out of it.

From what you said, it'll need at least a rear diff. ($200), rear axle ($100), front axles ($50 each), maybe a front diff. ($200).  Those a used prices.

From the picture, it looks like it needs tie rods.  Then you've got the unknown....brakes, transmission, clutch, etc.

It could be a money pit.  Then again, it could be worth sinking $500-1000 in.  One thing it has going for it, it's a Yamaha 350.  Those engines are like the Energizer bunny.

[Sam Shelley]

Appreciate the response guys, I do have a video of it running today, as well talking him down to $100. I've got "some" mechanical background, more small engine then automotive from what he's described and I've seen it looks like the joints in the front are fine and the shaft itself broke, (he was backing up with only the front tires under power and snapped it I guess i dont really know and in the rear I guess it's not hooking up inside the rear diff which gives me the idea that either the splines inside the diff are stripped or the splines on the shaft are stripped but I dont know which is more likely or if it could be something stupid causing the rear end to not be under power, he doesnt have alot of mechanical knowledge and I'm pretty sure he hasn't looked at the rear diff or shaft at all he's just assuming its "stripped" is the word he used. Anyway for 100 bucks I might as well get it out of his yard, but is there a chance that rear diff or shaft issue could be something stupid? 

[wanrep]

Not likely.  Most likely...the ring gear in the diff. AND the axle splines are stripped.  It's caused from the diff. seals going bad allowing water to get inside.  Seen it too many times.

[Sam Shelley]

What can I do first? Can i rebuild the diff?

[Frank Angerano]

Start by spraying everything down with WD 40 to loosen things up. Then taking it apart. Let’s see how bad things are. Maybe it’s bad maybe not.  Only one way to find out!!!!

[Sam Shelley]

Can you run these as 2 wheel drive? Say I fix the rear drive issue before fixing the front, could i still ride it without causing damage? 

[Frank Angerano]

My guess would be no.  The best thing to do If you do buy it is to get all the wheels off the ground. With the bike in neutral spin the tires and see what spins and what grinds and makes noise. Go from there.  

[Ajmboy]

Sounds like a cheap and good project. Great advice from @Frank Angerano and@wanrep! For $100 I would buy it just to mess with it.

[Frank Angerano]

Thanks @Ajmboy  I agree. Just to mess around with it would be fun.  

[Sam Shelley]

Alright I've got the wheeler in the air, in neutral, spinning the tires and I'm hearing nothing, no grinding, nothing. I can spin the front shaft and can hear the rear shaft spinning but when I spin the rear tires the only noise I hear is coming from my brakes 

[Frank Angerano]

Take the fill caps off the differentials and check the oil levels as well as if any metal chunks or shavings are inside.  Start to inspect the drive shafts and universal joints. Take the inspection plates off of the drive shafts. Don’t forget to spray the bolts down ahead of time so nothing snaps.   Use a good penetrating oil spray.  

Put the bike in gear and try to spin it and see what happens as well. 

[Sam Shelley]

Had it in gear and spinning the rear tires there was no difference, where can I find the inspection plates? Its connected in the front of the rear shaft, that I can tell but I can't tell how to check the rear connection without tearing the rear end off completely 

[Frank Angerano]

The rubber boots at the ends of the shafts. Loosen the clamps and pull them back.  Inspect the connections and watch them rotate.  And check the differential fluids for metal etc.   

[Sam Shelley]

I'll check the diffs after work tonight for shavings but the rear shaft only has the one boot on the motor side and then it runs through a tunnel that bolts to the rear diff, I dont know how to check that side of the connection, I know what's wrong with the front, the very front yoke broke and everything else with the front seems fine. 

[Frank Angerano]

That’s what I was thinking as far as what broke. I have a feeling the rear may be fine.   If that’s the case then it’s a score.  Going to take some labor but worth it.  

Were you able to figure out the year ? If not find the vin# and you can search it. 

[Sam Shelley]

Should I drop the rear swing arm so I can see why it's not hooking up or is there an easier way? 

[Frank Angerano]

No I would pull that plug on the top left rear side of the differential housing. You will be able to see the ring and pinion gears inside with a flashlight. Spin the rear tires and see if anything is moving and pull that rubber boot back By the engine/axle housing to expose the yolk and see if they all move together. If not it may be a broken drive shaft or the gears in the rear.   

[Frank Angerano]

If you wind up having to dropping the rear:

The four bolts right in front of the differential housing come out so you don’t have to pull the yolk and drive shaft housing off at the engine.    The shocks unbolt, the swing arm bolts and all that’s left are the brake and vent lines. Some times I leave the shocks bolted and take the swing arm bolts off and swing the rear out of it’s in the air.  The rear hangs from the shocks.   

 

Edited March 28, 2019 by Frank Angerano

[Sam Shelley]

Awesome that's just what I needed to know, I'll post what I find out after work tonight 

[Frank Angerano]

Good luck.  

[Sam Shelley]

Okay so on the exposed axle side in the rear I can grab ahold of the tire and lift it up and down and watch the shaft move up and down where it connects to the rear diff, the diff is filled to the brim with oil and water I assume. Anyone tell me what this means so I can look up replacement parts? 

[Frank Angerano]

Sounds like a bearing or seal or both went bad. Can’t see the video for some reason.  Maybe post some pics.  

[Sam Shelley]

Sucks the video wont play, it shows the movement well, these are the best I could get, it's got almost a 1/4in gap between the axle and the diff. Definitely seems to have water in the diff, dont know if that helps. 

[Frank Angerano]

Yep that’s a bearing seal and bearing.  Going to need to swap it out and might as well do both sides. Or see if you can find a rear diff if it’s shot on eBay.   I believe  that is one continuous axle and that bearing assembly for both sides would be about $50 bucks.   Have you found anting else ? Anything chewed up like gears or the yolk ? Is everything spinning for the most part ?

[Sam Shelley]

I'm thinking the bearing went and it screwed the splines on the axle, but I can't drain the rear diff fluid the allen plug is stripping on me, the yoke and the rear drive shaft seem fine I believe it's the axle not connecting with the diff 

[Frank Angerano]

That’s ok. Loosen the right side diff cover bolts and drain it that way.  6 bolts maybe ? But spray them ahead of time.  

Edited March 29, 2019 by Frank Angerano

[Sam Shelley]

Didnt even think of that! They're soaking now, I'll give her a try a little later 

[Frank Angerano]

Go slow! Easy snap of you go to hard.