89 Yamaha Big Bear 350 4x4

[MrSchaeferPants]

Im used to build threads coming from the 4x4 truck world. Im sure not as many here have older quads, but its my first, it is what it is. Im going to rock this thing

I like modifying, making the things the best they can be so Ill try to do that with my quad. I know theres only so much I can do, but my main focus is reliability. I dont care so much about power or speed. My trails around here are crawling trails anyway, so Im in 1st-3rd most of the time.

So I have an 89 Big Bear, full time 4x4, auto clutch, IFS, solid rear axle, drive-shaft, "disc" rear, drum front. Thats all I know for now, still learning, only had it two weeks or so. Ive bought a stock used air box since mine was broken and wasnt sealing anything, no filter. Got a new filter assembly, tore apart and rebuilt the carb. Oh ya got it for $900, has a winch too. About $100 into it currently.

Carb rebuid kit is on the way, few more misc parts for the carb. Its missing the little clip/housing for the throttle cable, and the baffle that goes in the float bowl. Also ordered a new ignition cylinder, I currently turn it on/off with a random key, screw driver, etc. Also the on/off switch on the left handle bar is stuck and doesnt work.

Read a later model big bears front disc setup will bolt on, or mostly bolt on. Mud and dirt dont mix with drum brakes, so Ill look further into that. It would also need a new master cylinder.

Took the muffler off, it was leaking all over. The baffle was rattling around inside the body of the muffler. So I welded it all up. One day Ill change it. Ive only seen two other "after market" muffler systems thatll hopefully work. Theyre supposed to fit later model big bears. Ill get to that one day.

Ill post pics and edit this later. Its dinner time

Edited August 23, 2013 by MrSchaeferPants

[oxidized_black]

i have a 91 Big Bear ... reliable and mostly bulletproof ... same drum set up for front brakes.

if you find out more info on bolt on from newer models, do share ...

[MrSchaeferPants]

Yeah thats what Ive read. When I find a good deal on a entire front brake assembly Ill give it a try. Currently my front brakes do nothing, so some steep hills are kind of a hairy situation. My only real complaint is being a solid rear, when I traverse a hill horizontally one of the rear wheels lift off the ground, and I pucker up a bit hoping it wont tip over. But today I went everywhere my neighbors newer fully independent quad went so

The day I brought it home

The exhaust, towards the right you can see where it came undone, I just welded it closed.

The baffle was just rattling around inside, so I pulled it to where I believed to go, and welded it in place, and closed around it. I the wife noticed a big change, and the first thing my neighbor said after my test drive was asked if I bought a new muffler :smilielol5c:

Heres after the welding. Didnt grind and clean the welds cause... I dont care Functional, not pretty. Believe it or not its closed/sealed. The case is welded to the baffles collar. So it just looks like theres a 1/8" gap.

You can see to the right where the frame is black with carbon. All welded closed now. My right leg/foot is much cooler now as well.

Its a temporary fix. The baffles inside are worn and broken and partially missing. One day itll see a new one.

Also replaced a valve stem/core in a tire. Thought it looked low, so I stepped on it and sure enough it was empty. I guess the tires are such a thick ply it rides w/o air in it. As soon as I looked at the valve stem I knew, filled full of silicone, as well as the outside threads. I guess someone filled a cap full of silicone and screwed it on to stop a leak. I was like really? $1.99 pack of 4 valve cores and you could of fixed the problem. So I had to remove the core, rip out all the silicone and replace it. Simple as that. Ridiculous. I guess theyre good tires? My neighbor said so anyway, Carslile Tracks Max. I know nothing about ATVs

And as it sits now. Ripped all that junk off the front. All together probably took 20-30lbs off the thing.

Guess Im all caught up now.

Edited August 23, 2013 by MrSchaeferPants

[MrSchaeferPants]

Got my new ignition cylinder in the mail yesterday, so no more turning it on/off with a screwdriver or random key that falls out while riding.

Got a tire gauge that reads low enough, someone had them things at 20psi :shock2: Hell says on the tire not to exceed 15psi to seat the bead, 5psi running. So I lowered them all to 10psi and drove around for a bit, then down to 5psi. What a huge amazing difference it made in ride comfort Not to mention Im sure the traction is way better, Ill find out.

Still waiting for more parts to come in. Forgot to get an oil filter in my last order of parts, so maybe Ill go down to the local dealer and find one. Who knows the last time it was changed, and I wanna put some compressed air through the oil cooler to make sure its still flowing.

Might take off the front drums and see if I can get it working, not having any kind of brakes really kinda sucks on long hills and steep areas, and always having to look for a place to stop on a trail so I can get off w/o it rolling.

[MrSchaeferPants]

Got the rest of my carb stuff in today. Had the kit for the last week, but waiting for the throttle cable retainer clip thing, and the plastic baffle plate that goes in the carb bowl. Hopefully it wont want to cut off on the steep stuff anymore.

All went well, kit came with everything. Tearing it down and reading my manual, there was a lot of things missing. Either way, my vacuum issues should be fixed. My pilot screw is set at 2.5 turns out now instead of the 4.5 it was previously, and runs well. The main needle was set at its most lean setting (kit came with a new one also), book said 3rd from the top, or the middle rung, set it there instead and it made it super rich, so put it back where it was.

Main problem still, otherwise everything is just fine- still dies as soon as I push the choke in/off position. No idea why, stumping me and pissing me off If it dies with the choke open, sounds to me like a lean issue. But every things fine, its clean, rebuilt, everything else is perfectly fine. Just have to run with the choke on. Starts up great, off-idle is great, part throttle is great, WOT great...etc.

Just finished taking it for a test run, once it cools down Ima check the plug to see what it looks like, but I remember previously it was just fine, tan color.

Still need to do an oil change. Just have to get a filter. I do have to put oil in here and there, its leaking around the gearbox area somewhere. Strange thing is, if the engine and gearbox share the same oil, and the dipstick can read it needs oil, but above the oil filter, theres a plug, if I take that out it gushes oil like crazy. Im confused perhaps. The trans is seperate from the 4wd part of the gearbox, using different oil, or is it all one big unit.

[oxidized_black]

the engine oil shares everything that im aware of ....

[bigbear93]

The "final gear" right behind the engine runs the same type of oil but is its own reservoir, drain it by pulling the bottom left bolt on the rear of the casing and fill it from the fill plug on the top as you would a differential, just until it reaches the bottom of the threads. I'm not sure what plug exactly you are referring to hut I hope that helps

As for the filter, I would recommend changing it if you don't know how long since last changed. But after that, as long as it isn't damaged you can clean it with some solvent and a soft bristled brush. Just let it dry before you reinstall it. Just change it every second or third oil change depending on the interval

[LokoLobo]

I picked up an 89 last fall. I traded a snowmoble for it.

I dont thing the front rack is original, but it works. Front lights were replaced with fog lights, I got a set of original lights off ebay for $30. Just rebuilt the carb last night, was going to put it back on today but its raining pretty good right now. I also would like to upgrade the front breaks to disk someday so I will keep an eye out here for info on that.

[schmeck]

MrSchaeferPants: Did you ever get your idling problem fixed.

My 89 with a rebuilt carb is missing the baffle and it surges like heck on low gear when accelerating. Also i dont get any response from the pilot screw on the bottom of carb but put it at 2 3/4 turns per manual for 4X4. Adjusting the idle speed screw gives very little response. I can idle but it is not very steady, kind of surges slightly. Like Mrschaefer I cleaned it properly and carefully rebuilt.

any suggestions?!

thanks in advance,

schmeck

[gopher]

my 1990 big bear runs and starts well even in our cold weather, however in order for it to keep running I have to choke it or set up the idle too fast to put it into reverse. Takes about 30 to 40 min running fast before it will idle slow enough to use the reverse. Any ideas of how to idle before such a long warm up time. I use it to push snow off my big driveway here in the north.

Edited March 22, 2015 by gopher
request help

[schmeck]

Found this in another link:

http://www.quadcrazy.com/atvforum/vs/13301-pine-sol-vs-berrymans-chem-dip.html#post85741

Am going to try bot will be about 10 days before I know for sure.