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  #1  
Old 12-03-2004, 07:16 AM
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Default 1987-1996 Yamaha Big Bear

     

Hey everyone,

I just picked up a 1989 Yamaha Big Bear 4x4 (YFM350FWW) last night and was wondering if anyone had any tips on them, things to watch out for, etc. It's primary mission will be utility functions like towing my log splitter into the woods, dragging logs, hunting, and maybe the occasional recreational ride. The latter will be very rare as I've got a small fleet of dirt bikes for "real" recreation. OK, it will also haul the beer cooler during a friend's annual cookout/dirt biking weekend, but that's not recreation, but rather a highly important practical function.

Does anyone have a front rack on their Big Bear? Mine doesn't have one, but I think Yamaha used to offer one as an option.

Thanks in advance for any advice you can give.
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Old 12-03-2004, 07:19 AM
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Default Re: 1987-1996 Yamaha Big Bear

I'm pretty sure the ol'd big bears had racks, but I could be wrong. I can't think of any issues those quads had, just do regular maintenance and you should be fine.
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Old 12-03-2004, 08:15 AM
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Default Re: 1987-1996 Yamaha Big Bear

They were pretty much a bullet proof bike when properly maintained. I don't recall any big bears except the special editions being sold with out front and rear racks. They were likely removed at one point in time to remove the front plastics and the rack was just never re-installed. It would not be hard at all to have one made up, they were only light steel and attach/bolt on at 4 points.

The front limited slip differential left a bit to be desired but was not really an issue unless hoggin' through snow or mud. A simple and cheap fix to help it hook up a little better is to change the differential and transfer case fluids and use Amsoil 2000 75W-90 gear lube. It contains friction modifiers (not to be confused with energy saving anti-friction modifiers) to help reduce limited slip differential clutch slip and put the power to the wheels. The other great thing about this oil is, it never needs to be changed EVER. Just drain it, filter it through a coffee filter and re-use it.

Lubricate the cables using a good cable spray and a cable luber tool. Don't forget the shift cable and shifter lock out cable that attaches to the rear brake.
Keep the valves in spec, check them once a year or at every oil change, its easy and cheap insurance.
Use a good quality oil. Don't use an overly heavy oil. Again I use amsoil 0W-40 for all season use and change it once a year. Anything heavier then 10W-40 will just shorten the life of the engines top end components.
These air cooled bikes run super HOT thanks to Yamahas designs and there lean jetting. Keep the oil cooler clean and free of mud. Chang the spark plug fairly often or switch to an iridium plug and even though it's a low compression engine use a mid octane fuel 89-92. This will help lower the combustion temps and eliminate any detonation or pre-ignition.

The Big Bears equipped with CV carbs were horrible for sticky slide valves do to a very tight fit and that can cause a bit of low end hesitation. In colder weather the carbs would freeze up easily and the slide would stick open or shut. The simple fix is to remove slide every few months and spray a shot of cable spray into the slide bore and the slide.
If it does not have the CV carb and still has the low end hesitation or backfires through the carb in tight woods riding etc adjust the float level a 1mm little lower (higher fuel level) turn out the mixture screw another 1/4 ~1/2 turn and again thank Yamaha for using such lean jetting.

The only other beef I have with these bikes is the less then water proof front drum brakes on bikes so equipped. Take some time and pop off the drums, lubricate the auto adjusters with an anti-seize compound or good quality silicone brake grease (sil-glyde) and make sure both pistons in the wheel cylinders are free, the top ones like to seize up. If they are sized up or sticky you can often use a C clamp to hold the one then apply some brake pressure and pop the other free. Then lubricate them with wd-40 and work them back and forth until they move nice and freely. Replacing these parts is costly so a bit of preventative maintenance will save you a lot of headache and cash

The rear brake is a little better, the caliper is adjustable from the outside by adjusting the large bolt. Just loosen the lock nut and turn in the bolt for more adjustment.

Last edited by hardlydangerous; 12-03-2004 at 08:48 AM.
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Old 12-03-2004, 09:05 AM
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Default Re: 1987-1996 Yamaha Big Bear

Quote:
Originally posted by mtk
Hey everyone,

I just picked up a 1989 Yamaha Big Bear 4x4 (YFM350FWW) last night and was wondering if anyone had any tips on them, things to watch out for, etc. It's primary mission will be utility functions like towing my log splitter into the woods, dragging logs, hunting, and maybe the occasional recreational ride. The latter will be very rare as I've got a small fleet of dirt bikes for "real" recreation. OK, it will also haul the beer cooler during a friend's annual cookout/dirt biking weekend, but that's not recreation, but rather a highly important practical function.

Does anyone have a front rack on their Big Bear? Mine doesn't have one, but I think Yamaha used to offer one as an option.

Thanks in advance for any advice you can give.
Man, Michael, that sounds perfect for what you are doing! As we are from the same neck of the woods (I was born and raised in upstate NY), we had to resort to snowmobiles to gather wood and, of course, the standard tractor to skid the logs. I would have loved to do those chores with an ATV.

I must confess that at times I would be sorely tempted to go AWOL on the wood detail and engage in some serious forest exploration and hill climbing though . . . .
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Old 12-03-2004, 01:33 PM
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Default Re: 1987-1996 Yamaha Big Bear

Not quite perfect; that would be the Grizzly 660. More power = bigger logs = more fun when you've got all four wheels spinning trying to drag it through the woods. But I could buy three of these for the price of a new Grizzly, so the Big Bear will have to do. Big ticket off-road vehicles have two wheels in my playbook.

As for going AWOL on wood detail; that's not possible. Since we're in command, it's impossible to go AWOL; I make sure to grant myself leave before I start screwing off. Not to mention that the whole idea behind getting an ATV is to make the job easier and allow more time for screwing off in the first place. We just make sure no one finds out about the screwing off, back at HQ.

Now if I could only find someone to run the chainsaw and do the loading and unloading for me....

Steve L, thanks a bundle for the in-depth advice. I'll be pulling the front brakes apart for sure because they definitely have some kind of issue already. The lever comes all the way back to the grip right now, so something is clearly amiss. I've got four new tires on the way (ITP Mud Lites) anyway, so while the fronts are off I'll be giving them a once-over. Thankfully, I have a good source of Yamaha parts so if I need a wheel cylinder or two (or three or four), I won't be paying the $66-68 full retail price for it.

At lunchtime (it's still in the back of my truck, parked here at work ) I figured out that the intake boot is almost broken in half, which explains why it only runs while on choke. Got a new one on the way. It compression tested at 150psi last night (sucking through the whole intake tract), so the engine is still healthy.

I don't know if it's a CV carb or not as I haven't looked that closely. I had planned on putting a washer under the needle (assuming it's a non-adjustable needle like used on streetbikes)when I had the carb out to replace the intake boot and probably fiddling with the low-speed mixture while I was at it. I assumed that this would be like most other bikes and be jetted on the lean side. That washer/mixture screw thing seems to work about 90% as well as a jet kit, so we'll give it a whirl and see what happens. I'm also going to work on straightening all the fins on the oil cooler to get more airflow through it. It's a tedious job, but what else are you gonna do all winter?

I'll also go through the valves as soon as I get a Service Manual. I'm assuming they are screw adjusters, but I don't know the specs for them. Thankfully, there are only two of them.

On the front rack, did the mounts come through the front fender, towards the nose of the quad? Mine is grey and the fenders don't have any holes in them, but he had a brown Big Bear fender in the "extra plastic pile" that was clearly a Big Bear fender and it had two holes that looked like they were where it mounted. He also had a beige one, but I didn't check it too closely. My front fender is broken, so I'll probably be buying that brown one anyway. Any idea on where I can find a used front rack? I'd like to have a front rack on it since that's twice as much space to carry "stuff" when I'm using it. I checked Ebay, but no luck so far. I'd also like to find a new front bumper for it, if I can find one for a reasonable price. The current one has "bumped" a few too many things, if you know what I mean, and is pretty dented up. It's so small that I figure it can't be all that expensive to find a used one. If not, I've got a couple welders and I've got friends with torches, so I'll either straighten the old one or weld up a new one.

Besides, I was eyeing up a winch on Ebay.... Can't be getting stuck, now can I?
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Old 12-03-2004, 05:32 PM
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Default Re: 1987-1996 Yamaha Big Bear

This is one of my customers bikes. Looking at the pic it looks as though there may be 4 holes for the rack to go though at the very least there are two for sure. The front bars may come down in front of the plastics. I don't remember exactly.






Yeah you deffinatly have at lest one siezed up wheel cylinder in each wheel, possibly all 4 have one or more pistons locked up. No amount of bleeding the brakes will get that lever to stop hgitting the bar.
On nearly 90% of all the ones I have worked on I was able to pop the rubber boots off the wheel cylinders and free up the pistons using the c-clamp method and never had a leak or a problem again. I also pack a bit of silicone grease under the rubber boot before I put it back on. Re-bleeding is also a must.

Yeah I had forgot about the intake boot until you mentioned it. They are often almost too short of a fit depending on the type of carb you have and are prove to cracking. you can loosen the air box slightly and move it forward an bit if there is a fit problem.

Valve clearanace is
Intake .06 ~.10mm (.003 ~ .004")
Exhaust .16 ~ 20mm (.006" ~.007")

float level is usually 12.5-13mm however I prefer 11.5 mm and not shim the needle.

Last edited by hardlydangerous; 12-03-2004 at 05:34 PM.
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Old 12-03-2004, 09:12 PM
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Default Re: 1987-1996 Yamaha Big Bear

Hey Hardly;
You ever check your PMs??:
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Old 12-06-2004, 08:58 AM
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Default Re: 1987-1996 Yamaha Big Bear

Steve,

That's a dead-ringer for the one I've got, except for the front rack and optional recoil starter, which is still available from Yamaha and on my "soon to be added" list. I've got a thing about being stranded in the woods with a dead electric starter as my only option. I also don't have the nerf bars behind the footpegs, but I'm not completely sure it ever had them in the first place. The BikeBandit listings for the 1989 don't show them, but I thought 1989 was the only year grey was available. Who knows, maybe that guy added them from a later model.

I'll check out the wheel cylinders this weekend, once my other parts arrive. Hopefully I can resurrect them using the methods you mentioned and save myself some money on that end.

As for the intake boot, I'm don't think my problem was anything to do with length. It looks like someone tried to pull the carb out sideways and practically tore the boot off of the engine.
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Old 12-07-2004, 05:13 AM
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Default Re: 1987-1996 Yamaha Big Bear

Quote:
Originally posted by 2fun
Hey Hardly;
You ever check your PMs??:
Actually.......................
no

sorry

(makes note to self, to check PM's)
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  #10  
Old 12-07-2004, 05:19 AM
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Default Re: 1987-1996 Yamaha Big Bear

mtk

The bike in the pics is a one owner 100% bone stock 89
Nothing was changed or added. I would doubt if the tires have even been changed.
The re-coil is a treat with out a decompressor. Make sure your not wearing any rings on the hand you use to pull start it, because they have a nasty habit of "catching" and rippin' the pull cord out of your hand.
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Old 12-07-2004, 07:49 AM
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Default Re: 1987-1996 Yamaha Big Bear

Steve,

The front rack is definitely an optional extra, as is the recoil starter. At least according to the BikeBandit.com parts listings and my friend who's family has a Yamaha shop. Both are Yamaha parts and were probably put on it by the original selling dealer. About the only reason it really matters is that the front rack and starter are hard to find used because they were optional extras. After 1991, the front rack became standard equipment and Yamaha still sells that one, but it's different than the one in the photo (it's shaped more like the common front racks you see today) and runs around $200. But Cambridge Metals and Plastics makes an aftermarket rack and it's only $90 so it looks like it's aftermarket parts for me.

I also can't find the nerf bars that are shown in the photo on BikeBandit.com for the 1989 models. Hopefully I can find a microfiche and get to the bottom of it as I'm curious more than anything.

As for the recoil starter and being a treat to use, while I can appreciate what you're saying, you have to admit that it does beat having having a dead ATV, stuck in the mud, with a non-functioning electric starter and no other options to get it running. That's the only reason I want one. Hopefully I'll never need it, but it's nice to know it's there if I do.

Last edited by mtk; 12-07-2004 at 07:52 AM.
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Old 12-09-2004, 01:54 PM
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Default Re: 1987-1996 Yamaha Big Bear

Steve,

Those photos you've posted are really puzzling me. I've checked two different websites (the aforementioned BikeBandit.com as well as a Yamaha corporate parts website) and neither one shows those nerf bar footpeg mounts. They show up on the 1996 model, but not on the 1989.

I wonder if Canada got slightly different trim on theirs or something? I didn't realize you were in Canada until I was typing this post, so that could explain it. I know that ATVs for Maine and New Hampshire get rear brake lights (there's a separate listing page for those two states on both sites) so maybe the Canadian models got the front rack, recoil starter, and nerf bars as standard, while the USA didn't. Go figure.

On a more positive note, my intake boot should arrive tomorrow so the Big Bear should be back in business on Sunday.
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Old 12-09-2004, 04:07 PM
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Default Re: 1987-1996 Yamaha Big Bear

flippin' eh! no doot aboot it
I'm like 100% canadian eh!

I started working for Yamaha in like 92 or so and at the time the racks were all standard equpiment. Pull start was I believe too but an option for the warrior. I had no idea the front racks were an option in earlier years...maybe I did and just forgot. I did know that the (special addition) came with out racks and slightly differnt cosmetics..ARGGGGGGG now I'm confused
lol
As for the heal guards/pegs I don't know. I'll try contacting the owner and see if he had then replaced or if there were OEM equipment.

I was under the impression the 96 bigbears only came in Charcoal/black and Green and the owner always told me it was an 89. Who knows maybe He's wrong about the year??? Maybe he changed the plastics? I'll have to check into that. I'll also check the canadian dealership fishe cards and see if the heel guards were avaialable and for what year.
I do know we had some bikes and options not available in the US
And the other way around. You guys still have some quads available that we don't like the Wolv etc. It came to the US before it came out here, it's still available in the US for 05 but not in Canada.


EDIT.. I caled my local dealer and they can't find a fishe card for a 4X4 in 89 only 96 up haha. I'll keep looking

**EDITED for content, spelling a swear word different is not be allowed**

Last edited by Woody_YZF; 12-09-2004 at 10:26 PM.
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Old 12-09-2004, 05:48 PM
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Default Re: 1987-1996 Yamaha Big Bear

The 1989 is definitely grey as it says that on at least one of the sites I checked, along with "discontinued" (at least on the front fender).

As for the nerf bars, the real kicker is that the online fiche drawings don't even show the mounting point on the frame for them. The 1996 page, on the other hand, shows the mounting flanges on the frame for them. In my experience, the microfiche drawings are detailed drawings and actually reflect the part in question; they're not just generic schematics. For example, the front rack on the ATV above is a dead-ringer for the optional accessory one listed for the 1989 model. The later 1996 page shows a completely different rack on that page, one more like what you see on later Big Bears.

In all honestly, it's not a big deal by any stretch of the imagination. I'm more curious than anything at this point. I've been looking over the 'fiche drawings mainly in an effort to see what, if anything, is missing after the past 16 years. So far, it's all there, it just doesn't match your version of a 1989.

Speaking of microfiches, I'm still looking for a 1989 version myself. I don't know if Yamaha still sells them, but I'd like to get one from somewhere. I've got a 'fiche reader so I try and make a habit of buying a 'fiche for every bike I own. Makes life much easier when I need parts for it. So if you come across a microfiche which includes the '89 model, please let me know.
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Old 12-13-2004, 12:02 PM
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Default Re: 1987-1996 Yamaha Big Bear

Update:

I put the intake boot on over the weekend and it's better, but still only runs on the choke, so clearly a carb cleaning is in order. The old intake boot was nice and brown inside from gasoline deposits so I'm sure the carb is equally gummed up. So the new boot will have to come back out so I can clean the carb and that should hopefully resolve all the running issues I have at the moment.

That and checking out the wheel cylinders will hopefully happen this week, along with mounting up a set of four 25" ITP Mud Lites.
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Old 12-20-2004, 08:34 AM
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Default Re: 1987-1996 Yamaha Big Bear

Ok, here's the latest:

Over the weekend, I replaced all the fluids in it and got the carburetor cleaned up. The pilot jet was plugged completely, which explains why it would only run with the choke on. Some carb cleaner took care of the deposits in the jets and got most of the funk out of the carburetor itself. I haven't been able to test ride it as of yet because the four wheels are still sitting in a stack because my buddy's neighbor wasn't home all weekend and he's the one with the tire machine. But it runs OK sutting on the stands, which is an improvement.

Speaking of the carburetor, it's definitely not a CV carb on my Big Bear. In fact, it's unlike any carb I've ever seen before. The carb uses two throttle cables to operate it. One cable moves a butterfly valve set-up like you'd have in a CV carb. The other cable moves a slide valve assembly, complete with a needle, like you'd have on a normal dirt bike carburetor. The slide valve is in a location similar to where you would have a vacuum slide in a CV carb, but this one is cable-actuated. What advantage this design has over a conventional carb design is beyond me. It's certainly complex enough, that's for sure.

I haven't dug into the front brakes as of yet. I'm going to save that until after I actually get to take it out and ride it a bit, once I get the new tires mounted up. I couldn't get the drums off of the spindles so I'm sure that will make for an enjoyable afternoon once I start digging into them.

Oh yeah, any suggestions on how to remove the drain plug from the ring gear housing in back would also be appreciated. I got the front plug out, but the back one didn't want to cooperate for me. I ended up sucking out the old oil with a vacuum pump and refilling the housing until I can get it fixed. I replaced the front drain plug with the fill plug since it has a large hex head on it. Unlike the socket head drain plugs, the large hex fill plug never strips out. I replaced the fill plugs with some oil drain plugs I had laying around for the race bikes. Why Yamaha didn't do that in the first place is beyond me.
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Old 12-22-2004, 03:18 AM
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Default Re: 1987-1996 Yamaha Big Bear

Thanks for the report.
Sounds like you've got most of the carburator problems taken care of?
Anxious to hear how it ran once you get the tires mounted!
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Old 12-22-2004, 07:25 AM
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Default Re: 1987-1996 Yamaha Big Bear

Me too.

OK, I'm actually anxious to see how much mud it can throw from four new ITP Mud Lites spinning at once.
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Old 12-22-2004, 11:16 AM
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Default Re: 1987-1996 Yamaha Big Bear

Quote:
Originally posted by mtk
Me too.

OK, I'm actually anxious to see how much mud it can throw from four new ITP Mud Lites spinning at once.
LOL!!
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Old 12-22-2004, 11:57 AM
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Default Re: 1987-1996 Yamaha Big Bear

What can I say, I have a dream.
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