The official XT225 thread!

How much easier can a chain have being on a 225?
With a 13 still get 10,000 miles plus, that's a lot of riding on an xt.

hh
wwm

Agreed. I'm inclined to go as big as will fit on both ends. Here's my thought process. While F/R determines gear ratio, larger drive sprocket reduces chain stress. Larger rear can deliver more torque to road with less chain force. Possible win-win if the math works out right.

While replacing the chain today I got a fresh look inside. Combined with recent interweb clues, and focusing on JT Sprockets, it looks like JTF1263.xx front and JTR1842.xx rear will bolt up to late model XT225s ('96-07 I believe).

http://www.jtsprockets.com/catalogue/part/JTf1263/
http://www.jtsprockets.com/catalogue/part/JTR1842/

Those rear sprockets are indeed flush on the back side not dished. That's actually what I've been running for the past 14k miles. Back then I just shimmed between the sprocket and hub with washers. Alignment was close enough.

Availability will surely be a challenge this time...

Please don't use a flat sprocket. Here's a new sprocket for you.
https://www.ebay.com/itm/192363878546

So if you go 16 in front and 55 in back, you will certainly need a longer chain.
So you’re going one bigger in front and 10 bigger in back. So you are gearing it down from stock approx. 7 teeth. A 13 in front is approx 6 teeth so very close.
Same size stock chain will accommodate a 12-16 front with a switch time of 10 minutes max.
By doing it the way you want you need to buy new rear sprocket, front sprocket plus chain.
Then the only way to gear it up is to change rear sprocket and put on a smaller chain.
Where is the savings, NONE!!
When camping and traveling carried 12 and 16 with me.
Rode with the 16. 1,000 miles down Great Basin Hwy to Vegas then home on Interstate 15.
Left other sprockets inc 15 in Idaho, oops!
Bike was geared to tall with my fat ass and 80lbs of gear, 35 mph winds, 100 plus temp,
Worst ride ever. On the hills between Vegas and my house, 38 mph max in the emergency lane, got passed by all buy the slowest trucks.
Spend $18.00 on 13, buy a new chain in 7500 miles.
Happy riding!

hh
wwm

Obviously longer chain.
Actually, if a 17T squozes in front I'll pair that with 55T rear.
I think it's great how versatile these bikes are to accommodate very different ways we use them.
And I'm happy to report back and share my experiences for anyone interested.
Rock on!

Okay, you got me curious. Why not? What do you know?

I assume that your reason for wanting large sprockets is for reduced friction and wear on the chain/sprocket set, so misaligning the sprockets will work against you.
Spacing the sprocket out with washers, which would probably require longer studs in the hub, could easily lead to damage to the hub, and failure.
I believe the Serow was originally designed with a 50 tooth sprocket, and sold that way before coming to America, presumably the 45 tooth was to aid in meeting emission standards. If you look at the plastic chain guide on the swingarm you'll notice that it hangs down well below the 45T sprocket, with a 50T it lines up well. Obviously if you fit an overly large sprocket the chain guide will be of no benefit since the chain will run below it.

Please do.
17 a NO GO!
If your chain is loose, (by the way you are thinking this I would say never), it will hit case with a 16.

hh
wwm

Wow! I didn't think my initial post would generate such activity.

So, here's the whole story.
1) I found a dished 50T sprocket from Chapparel and its on its way. So that confirms this animal is readily available.

2) The 14T sprocket from ProCycle arrived today.

3) I picked up 2 boxes of 100 link 428 chain at a swap meet year before last @ $5 each so I'm all set with chain.

Why? Well, I just want to putt around my property with my just acquired '92 XT 225 just to get used to it. Want slow speed with less chance of stalling, riding slow speed cone slalom maneuvers, tight woods, log hopping; stuff like that.

Interesting that the original Japan Serow had a 50T. I hadn't heard that before.

When I replaced the stock "dished" rear sprocket with flat and shimmed behind with washers (14k miles ago) the studs did reach but just barely. But since one stud actually broke, they were all replaced with bolts instead.

I appreciate the early history of 45 vs 50T gearing. That explains the geometry points noted. Thanks!

I wasn't thinking about friction. Just tension on the chain. Basic physics: Torque = Force x Radius. For fixed torque, larger sprocket radius means less chain force.

Sure looked like a 17T would squeeze in there. Bummer. Sounds like personal experience talking. Sorry you're stuck with a part you can't use but thanks for looking out for others.

What benefit do you hope to derive from reduced tension on the chain, assuming you're using a chain of more than adequate tensile strength?

I

In theory, less stress, less wear. Spread over a few more links. Or maybe I just I like to experiment.

I’m very happy with the stock gearing for my style of riding.

Second will climb most, first will climb anything, and sixth is capable of highway speeds. Couldn’t ask for more from the little bike.

I think the tension would be spread over fewer links with big sprockets, not that I think it matters (weakest link and all that). In your giant sprocket scenario I think you would be increasing the load on the splines on the transmission output shaft, I don't know by how much but you'ld probably rather change sprockets than a transmission shaft.

The wide ratio six speed gearbox is one of the things that make the 225 special.

When I first had the opportunity to purchase my xt225 I started researching it and the six speed really interested me. While I haven’t done a lot of highway cruising with it yet, it has proven to be a sweet combination. All stock, except for the jetting, I rode it from 8,000’ to 12,000’ today running above the speed limit and even passing an RV uphill at over 11,000’ without missing a beat. The stock gearing seems to be a good all around combination for my type of riding.
I think it’s great that tinkering with this bike is easy and inexpensive and you can customize it without breaking the bank or having buyers remorse for having bought something that you decide doesn’t work for you.
It’s a great small bike.

+1 on stock gearing works the best, i tried a 16t front, and the bike cant pull it in any headwind or slight inclines, you actually lose speed and have to drop down to 5th gear.

Agreed. When I bought my 06 in 2008 with low miles I rode it home ~150 miles. To hold 55mph on hills I had to drop to 5th gear. Going through everything I found mouse nesting packed around the air cleaner. Once that was cleared she pulled hills in top gear. Near sea level anyway. It seems the engine hits peak torque around 6,500rpm and peak power around 8,000. I don't have the math in front of me so I'm going from memory but IIRC with stock gearing 6,500rpm in 6th works out to 63mph. One thing I'm correcting now with lower gearing is indirect upgearing from stock. Last time I replaced the rear wheel I upsized from 120/80-18 to 140/80-18; so about 5% longer legs. So that pushes 6,500rpm in 6th up to 66mph. I'm waiting on sprockets ordered. I can report back with actual results after I get a chance to install and exercise a bit. That could be a few weeks. Meanwhile...

Issue #2. My starter may be dying at 38k miles. I'm curious how long others' last(ed). I know it'll depend on average ride length or starts per hundred miles, say. Still. Anyone have experience with starter replacement and life expectancy? Thanks!

I don't see the logic. I mean, fixed engine torque seems like fixed spline stress, to me. But that's an interesting thought...