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XR to XRL primary drive & tranny swap

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This has been rattling around in my head for some time now. Can the primary drive and tranny from an XR600 be swapped into an XR650L? I'm pretty much at the limit with final gearing (14/48) Any smaller on the c.s. and it's too hard on the chain. Any larger on the r.s. and it gets too wheelie prone on the hillclimbs. Plus, I'd love to tighten up that 1st to 2nd gear leap. Current gearing has me at the upper reaches of 2nd gear on most trails and i'd like to be in the meat of it in 3rd. Well... I'm waiting!

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I'm pretty sure that it would pop right in,

They are basically the same engine

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A 13 tooth sprocket is not really that much harder on the chain.

What happens is, the 13 tooth sprocket itself wears a bit quickly, and then that wears the chain fairly quickly.

If you run a 13 tooth and change it as soon as it visibly wears or hooks (its pretty cheap and easy, I don't even loosen the chain to change it) the chain life is not really shortened.

When I sit on the bike, the chain clears the swingarm slider, so the 13t doesn't shorten life on that either- for me, anyway.

I don't know about swapping the primary drive, I do recall that they are different ratios- but if the case holes arew the same distance apart that means changing both gears, I think.

After 2nd gear I think the 600R and XRL ratios are the same- they've been posted here once or twice, search and you'll find them.

If you lower the gearing, it does not matter if you do it by the primary drive ratio, the front sprocket, or the rear sprocket, I think it will be just as wheelie prone.

Dave

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You need the XR600 clutch basket and crankshaft gear. Keep in mind that the higher torque multiplication at the clutch will be harder on the transmission....that's why the Baja prepped 600s had the numerically lower 650L primary drive.

The manuals I have show these gear ratios:

XR600:

1st - 2.385

2nd - 1.647

650L:

1st - 2.666

2nd - 1.647

So actually the ratios after 1st are the same. That means the 600's closer 1-2 ratio is due to 1st being taller than the 650L's, not because the primary reduction is more aggressive.

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Well, the taller 1st gear and higher number primary does sound like the answer I'm looking for. Most of my riding up here is fast woods and as you know with the current 14/48 setup 1st gear is next to useless except for throwing out the anchor down cliffs. I've looked around a little and it appears that you can get bottom end w/clutch for next to nothing. I'm not looking for extra torque rather just better flexibility w/ the ratios. Can I mix & match without pain? Thanks for the replies, guys.

P.S. Come up here if you want to learn how to ride woods.

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They will swap. The 85-87 600Rs had different sprocket spline width and spacing, so you should look for 88 or newer if you want to use your existing sprocket.

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Well, the taller 1st gear and higher number primary does sound like the answer I'm looking for. Most of my riding up here is fast woods and as you know with the current 14/48 setup 1st gear is next to useless except for throwing out the anchor down cliffs. I've looked around a little and it appears that you can get bottom end w/clutch for next to nothing. I'm not looking for extra torque rather just better flexibility w/ the ratios. Can I mix & match without pain? Thanks for the replies, guys.

P.S. Come up here if you want to learn how to ride woods.

If I could get to idaho to ride, I'd be a happy guy.

We do have woods out east, too, though :)

Dave

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P.S. Come up here if you want to learn how to ride woods.

You mean come out to good ol' southwest PA for some woods riding:p

If you would just plan on replacing 1st gear i think it would be easier to just buy the 2gears that make 1st gear up and just diassemble the motor to replace the gears, instead of buying a whole new bottom end. Just my opinion but i would go that route

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Thank you gentlemen. Yeah, the the bottom end would be used as an organ donor. Straight R & R, that's the way I like it. Just finished this winter's project, grafting an XR600 tank. This may be next winter's project. The snow really does need to go away for now though.

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I would leave the 650L primary alone and only change the transmission. Tehe tranny is already the weak link on a 600. If you add more torque with the 650 engine I think that the L primary would help for longevity. If you are so inclined you can also add a kickstart with a few more parts.

They will swap. The 85-87 600Rs had different sprocket spline width and spacing, so you should look for 88 or newer if you want to use your existing sprocket.

Actually that went up to 90. The new countershaft splines came in 91.

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You mean come out to good ol' southwest PA for some woods riding:p

If you would just plan on replacing 1st gear i think it would be easier to just buy the 2gears that make 1st gear up and just diassemble the motor to replace the gears, instead of buying a whole new bottom end. Just my opinion but i would go that route

If I recall right one of first gear's gears is machined into the counter or main shaft.

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Ok, is the 600 mainshaft interchangable w/ the 650 c.s. & cases? Or would I start descending into a wormhole here?

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Ok, is the 600 mainshaft interchangable w/ the 650 c.s. & cases? Or would I start descending into a wormhole here?

Like was said, yes it all fits. Do some searches as it has been discussed before on a few occasions.

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Everything is the same between the bikes. If you go this route it will also give you a chance to check every little piece of the motor in case you need to replace anything

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Alrighty then, I'm satisified. After 12 yrs of trail, Elsinore Grand Prix's and now endless forrest, this'll be a good reason to go thru it after this season. Hell, I might even repaint the frame and everything. Thanks again for the replies gentlemen.

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