Quick question: rear sprocket difference 1985 250r versus 1986 250r

[Dammit!]

I know they're slightly different but not sure what the difference is. Every basket case 1985 I've had has been rigged in that area so I'm not even 100% certain what a stock 1985 setup is supposed to look like.

I know you can use a 1986 sprocket on a 1985 but what exactly needs to be done to make it work and line up properly?

Somebody I know is trying to get his '85 ride ready which is why I'm asking. It had a 1986 rear sprocket on it and it sheared all four bolts off yesterday. His R has a few things that were cobbled together before he got it. It's even got a front end that I'm fairly certain is off a 1983 or 1984 R.

[JohnR.]

The hole in the center of the sprocket is larger on an 86 type so that it can fit over the fingers on the hub it mounts too since it sits on the swingarm side of the sprocket hub and the 85 fits on the tire side of the sprocket hub. Secondly, the holes in the 86 sprocket are tapered to match the bolts that hold it on and I believe the tapered head bolts are used to make sure there is sufficient clearance between the bolt heads and the axle carrier. I know of people using a 1985 sprocket on their 1986 in order to run the 33 tooth rear that is available for the 1985. It just requires that you remove the axle or sprocket hub to swap the sprocket

The closest you could do to make it fit properly is to use the tapered bolts that were used on the 1986 but I think they might be larger than the 1985 ones so they won't thread into the 1985 sprocket hub.

The front fork/wheel/brake set up on an R before 1985 is very different than the 1985-1986 style. Look at some pics of both types online and you'll see what I mean.

John

[Dammit!]

I know for 100% certain the front end is not off a water pumper. Pretty sure it's second gen. Single piston brake caliper, brakes on the opposite side, triples are not 3rd gen. Can't think of anything else they would be from. Way too long to be from a 200x. Definitely not 350x. That leaves 83-84 R. :lol:

Sounds like I'm going to have to go have another look at the axle/sprocket in person. I might have some spare 86 tapered bolts. He had it on there before so it fits over the sprocket hub. My fear would be making sure it's lined up right so he doesn't throw a chain and ruin his engine case.

[JohnR.]

. He had it on there before so it fits over the sprocket hub. My fear would be making sure it's lined up right so he doesn't throw a chain and ruin his engine case.

If the trike has an 85 sprocket hub then the sprocket doesn't have to go over the hub. The sprocket bolts on from the tire side so the only thing it has to go over is the wheel hub. The side to side alignment won't be an issue but if the tapered bolts aren't used it could have a problem with the sprocket moving up and down which would play havoc with the chain tension.

John

[Dirtcrasher]

Bear in mind that the 83/84 250R has the same fork diameter as a 350X so you may have something odd put together there.

BUT, like you said, it has a single piston and I'm fairly certain that the 350X always had 2 pistons.

Now a heavier 450R has a single piston, go figure??!!

Your good with pics, get some up for us :D

[Dammit!]

I've only seen it once and didn't have a camera with me. If the guy can get it running before this weekend we might meet up for some desert riding. I'll get some pics of the mystery front end if that happens. I'm pretty damn sure that it's second gen R though. It's got a 350x front fender on it but the mounting holes have been drilled to the wider mounting points of the R. For a minute I thought it was a 350x front end just flipped around.

[Yamahondaman]

i have some Stainless Tappered washer's to adapt the "86-89" Sprocket to the "85"... they work GREAT !! 10MM TO 8MM inside to out .. DANG HONDA'S !!! :-)

[Dammit!]

Well the 86 bolts I gave him definitely don't fit.

Is there any difference at all between the 86 and 85 axle/sprocket hub besides one is threaded for the sprocket bolts and the other just passes through and tightened down with nuts on the other side? I have an axle that came out of a clapped out 85 here and sitting next to a known 86 I can't see any difference. The hub isn't even threaded so it's either been drilled out or it wasn't the original axle (very likely).

[JohnR.]

I really think you should go on one of the parts lookup sites so you can see the difference between the two years. The 1986 sprocket goes on the swingarm side of its hub (i.e. up the axle and over the hub) and is held on with bolts and nuts with the bolt going in from the swingarm side and the nuts on the tire side. The 1985 sprocket goes on the tire side of the hub and is held on with 4 bolts that get threaded into the hub from the tire side with no nuts, the hub is threaded. They use different diameter bolts in the two years (smaller in 1985 and larger in 1986). The only thing between the two that is the same is the sprocket bolt pattern.

John

[Dammit!]

I worded my previous post poorly. The sprocket thing is already figured out. Thanks for the help.

I was trying to ask if there's a way to tell the 85-86 axle/hub apart other than one having a threaded hub. The threads could just be drilled out. Is there a more definitive way to tell the difference?

Only reason I'd like to know is I have an axle for sale that came out of an 85 but there's no threads. Up until this subject came up I just assumed it was a legit 85 axle. I can't see any difference at all between the one I thought was 85 and a known 86 that I have.

While I'm on the topic, is there any difference from an 86 atc axle all the way up the 89 quad axle? It would be easier to sell if they're all the same.

[JohnR.]

I think you're missing an important part of my last couple of posts but I don't know how to make it any more clear. If the sprocket goes on the swingarm side of the hub then its an 86 hub. If the sprocket goes on the tire side of the hub then its an 85.

The 86 ATC axle is the same as the 86-89 TRX one as is the bearing carrier, rear caliper, and in the case of 86-87 TRX's the swingarm.

John

[Dammit!]

I finally found a clear pic of a real 85 hub. Makes sense now. The basketcase I just parted out was all wrong and had me all screwed up. Sorry about that. :lol:

[JohnR.]

No sweat. So it didn't actually have an 85 hub on the rear?

[Dammit!]

My basketcase R definitely had an 86+ axle/hub with a 85 sprocket rigged on there. The dude I'm trying to help get his trike running, his must be a real 85. I only saw that trike once and didn't pay close enough attention to the hub. I was too distracted by the mystery front end on it. :lol:

I should be able to post some pics of that front end after this Sunday's ride.