wanrep

LOL....Is it a Textron, Arctic Cat or Tracker?.....Yes.

The ATV market gets more & more convoluted every year. It's getting where I can't keep up with who makes what any more.

Axle comes out from the right side. You'll need a long rod/punch to knock those bearings out.

If the springs are too weak to hold the rollers in, it's good you ordered new ones. They are probably too weak for the clutch to work properly even if you got everything together. I'd wait until you get the new springs. When you're ready to install it, put the gear into the starter clutch first. Then slide it on the crank as a unit. Before you slide it all the way on, you'll have to fit that small gear (cog #1 in your picture) into place.

View File 2000 Yamaha Big Bear YFM400FWNM Service Manual Factory service manual for the 2000, 2001 Big Bear 400. Submitter wanrep Submitted 01/18/2019 Category Yamaha ATV

I uploaded the Yamaha service manual for your Big Bear. Covers 2000 & 2001. First time I've done this so I hope it downloads correctly.

Without getting an accurate measurement of the cylinder, it's just guess work as to what piston to buy. I'd take the cylinder to a bike shop or machine shop and have them measure the cylinder.

Awesome

That's it.

I think the mystery part in the diagram is still inside the clutch. If it came out easily, there'd be a part # for it. The dowel pin, in the diagram, is the big roller that you have. They didn't draw it to scale. Looks like all you need is one of those spring caps.

Someone would have to remove them. Not like they can fall out. Here's a pic of what it should look like. When the sleeve part of that gear is in the clutch, it'll spin free in one direction but lock up in the other direction.

Yes, the starter clutch bolts to the back of the rotor/flywheel. It has 3 rollers in it that grab the big gear when turned in one direction but freewheels in the other direction. Usually the rollers and/or springs go bad, allowing it to slip instead of grabbing that big gear.

You need a starter clutch. It bolts to the back of the flywheel. It's a one way clutch that locks up cog 2 when cranking. You'll need a flywheel puller if you don't have one already. Be sure to loctite the screws that hold the starter clutch to the flywheel.

That's correct. Yamaha didn't start using replaceable ball joints until 2000. Good news is, all the Big Bears used the same upper A-Arm from '87 through '98 and there's plenty of good, used ones on Ebay.

Post a new thread and we can help you figure it out.

Yes, stock head works fine with the Athena 98mm kit. I don't know how much milling would be too much. There's a couple guys over at www.yfzcentral.com that could tell you. There's different thicknesses of base and head gaskets available to compensate for a milled head but I'm no expert when it comes to that.

The rear brake disc is on the same shaft as the driven clutch so with the belt on, stepping on the brake will slow the engine. If you have a 4x4, you'll have 3 chains turning at the same time. Try to isolate where the binding is taking place. Take the middle chain off, jack up the rear and run it to see if it still binds. If not, the problem would be in the front chains or front diff. If it still binds, then it could be the rear axle bearings but more likely in the transmission.

How's the chain/tension? If it's too tight or has tight spots it'll put things in a bind. Should be about an inch of free play just sitting.

Pretty sure that's the original head. You'll have to take the head to a competent machine shop and have the head milled a few thousands to get a good sealing surface again. Get the head gasket from Athena for the 98mm piston. BTW....that piston has 12:1 compression. Be sure to use one of the aftermarket coolants or distilled water and antifreeze. Coolant in the oil means water pump seal is leaking.

Unless it sat in subfreezing temps with straight water in the cooling system, it's doubtful the head is cracked. Worse case, the head might be warped if it really got hot. More than likely you can get by with a new head gasket and I'd definitely get that fan switch working properly. It's all in the factory service manual.

I've had 3 atv's in the shop with the "1 spark" problem. 2 of them were regulator/rectifier. The other was a loose ground cable. To check the ground, I take a pair of jumper cables and attach both clamps on one end to battery neg. and the clamps on the other end to the motor and frame.

Your Yamaha has a limited slip front diff. When they get low on oil, they will tend to growl in a tight turn. I'd drain the oil and refill with a good 80w90 gear oil. The other thing that helps is adding 1 ounce of friction modifier, made specifically for limited slip diffs., to the oil. Some of the gear oils have the friction modifier in the oil already. Royal Purple is one of them. If you can't find one, the auto parts store should sell a 4oz. bottle of friction modifier. The early Honda 4wd's were bad about chattering front diffs. also.

Yep, been there too. Most times it's not enough slack in the throttle cable that causes the problem. The other thing that causes problems with spark is that rev limiter box. You just unplug the black wire to eliminate that.