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Help gearing a woods bike

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:thumbsup::confused:Sorry if this is a repeat! I am rebuilding a 96 rm250 to try some woods racing. I have only been on a bike again the last 2 summers (out of sport for 17 years). I have been riding an 85 xr200 1st summer & 02crf 450 chassis with xr200 motor at a local mx track last summer. I want to try my hand in the woods. I'm 43 years old 6ft tall and 295lbs my riding skill from 1-10 is maybe a 4. I want to gear my rm for the tight woods and do not know what to do. Someone please help!!!!!!!

Thanks for your time & knowledge.

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I bet that XR200 romps in the woods! Those bikes were bad ass in 85!

go up 2 in the rear sprocket and see how ya like it. Other than that unless you ride it in the woods you won't know what you'll want.

Good luck.....

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The 85 ran good but the 02 has a big bore kit, stroker crank, and powroll cam. It runs better. Thanks for the info.

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I think flywheel weights mellow out the "hit" so you can ride it easier.

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a FWW is an excelent choice for any 125/250 mx bike that wil be ridden in the woods. had one on my 125 and it was awsome! made it a much more enjoyable ride

it lessens your likelyhood of a stall at low speeds, and gives you more low end to work with. it does this because the added weight on the flywheel gives the crank more inertia, so the crank wants to keep moving under low speed strain.

it really is worth the $150 for the weight, i would go with the mid level weight- so you still have plenty of over rev.

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I got back into things a couple of years ago too, after a break of more than 20 years. It's been fun!

I want to gear my rm for the tight woods and do not know what to do.

I figured I'd just re-gear my RM and CR for the woods, and off I'd go! I was mistaken. :thumbsup: I'm talking about tight woods, not 10-foot-wide paths with trees flying by.

Here's the problem, as I see it: a 2-stroke MX bike's 1st gear is a true 2t woods bike's 2nd gear.

You can bolt stuff on and see if it works, but I prefer doing the math first: 1 (one) divided by the overall gear reduction in 1st gear to rear wheel (I needed my owner's manual for the ratios) x engine rpm where the motor's actually making some power = usable minimum rear-wheel rpm; multiply this times the rear wheel circumference (roughly 7 feet, give or take) to get feet per minute of usable minimum forward speed. Then, convert to mph or feet per second (which I prefer, since you can easily simulate it by walking). Long story short, neither of my bikes could go slower than 13.5 mph (@ 20 feet per second) and still have any power to pull a hill. Surely Bubba could banzai some of the walking-pace sections in my woods at 13 mph, but I can't.

I tried gearing down, starting from a 14/49 final gearing and giving up at 12/58 (!). The bike still couldn't pull the hill from a slow start, and top speed dropped to about 45 mph. I was shifting so much I thought my left foot would fall off. :ride:

My current woods bike (MR) has excellent power at 5.6 mph (@ 8 fps) in 1st gear, which is much more my speed in the nasty stuff. If you run the numbers above and come up with more than 10 mph/14 fps as a usable minimum speed, you may want to consider an auto clutch, which I still believe is the best way to turn a MX bike into an enjoyable tight-woods bike, making full power available at low speeds even if the gearing is too high (if adjusted properly). I realize they're not cheap, or maintenance-free.

Ray

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I have a better idea, how you and I just hit the tails as is and then see if a gearing change is needed?

Heck, after I break in both of my bikes I'll let you take them for a spin and then you can decide if you need to regear. But for what it's worth front sprockets are cheaper than rear sprockets, so buy a front sprocket that's one tooth smaller than what you have and go ride. If it's better but maybe too much, then you can go back to the stock front and then get the correct rear ~ or just leave it on there.

But stock I believe that your gearing is 13/49, and a 52 on the rear will do wonders. And it's not like you will ever see 5th gear on any Michigan ORV trail. Especially if you have ever ridden Cedar Creek or White Cloud ~ ever been there?

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i'd start with stock too. Stock is actually what i prefer(190lbs AA/Expert). Some friend i know go two up in the back. Some go one UP on the front! lol

If i had to guess, i'd say 2 up on the rear would be good for your weight...

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off topic: what's the point of changing the gearing?

if you do it too drastically, then 2nd gear becomes first gear, 3rd becomes 2nd, and so forth. The way I see it, you're just riding in a higher transmission gear for the same riding speed/characteristic (& shifting more!)

since all the gears get "shifted" to a different ratio, the only real advantage I see here, is if you want to ride at a slower velocity in 1st gear, while "on the pipe". You could effectively use the top end power of a 2t in first gear, without moving too fast...but once you get into 2nd gear and higher, it would be like riding the old gearing, minus the top gear(s)

with that being said, granted I am very new to dirt riding, I rode some (relatively) tight single track in MA on a stock RM125, and good throttle/clutch control with appropriate body positioning seemed to pay off the most. The only way to make it a much easier ride was to switch to a dedicated 4 stroke woods bike (which coincidentally, I have an XR200R as well)

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off topic: what's the point of changing the gearing?

I think that's pretty much right on topic for this thread. :thumbsup: One huge advantage of gearing down in some circumstances - one I never knew about until I tried it - is effectively bringing the gears closer together (the ratio relationships don't change, but the speed ranges for each gear do). If you have a bike with too-large gaps between the gears and can afford to lose a little top speed, gearing down can make the bike easier to ride and accelerate faster in the woods, possibly giving you another usable gear.

When I started riding, I would never have dreamed of gearing my MX bikes down for 'woods riding', since back then it was easy to find high-speed trails to ride, even in SW CT. Today, I'm climbing deadfall, ducking branches, paddling through muck, and wondering if that cop's going for his gun or his radio... it's not always slow-speed stuff, but it sure seems like it sometimes. :ride:

Ray

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i'd start with stock too. Stock is actually what i prefer(190lbs AA/Expert). Some friend i know go two up in the back. Some go one UP on the front! lol

If i had to guess, i'd say 2 up on the rear would be good for your weight...

X2 :thumbsup: ride it stock and se what you think

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I wouldn't change the gearing as gearing down you usually end up shifting far more and first is useless. I really didn't see him say what the problem was as in if it was stalling or the rear wheel breaking loose and if not, he really can't make judgements as to what to change until he has ridden with the simplest being if you are breaking the rear wheel loose to back off on the hit by changing the powervalve. I rode with a FWW being told 'it was it' and then ground it down 2oz and then took it all the way off and that was the best thing ever and if it's stalling you just turn up the idle a bit and for that I always carry a small screw driver whereby I can change the idle or the air screw on the trail in about 2 seconds................

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X2 :thumbsup: ride it stock and se what you think

Yes, I prefer stock also,,,and, most of My riding is woods...Sometimes 1st seemed a little high at first, but, with a little clutch action,,,on the real steep hill climbs, at low speeds,,,no problem....p.s... flywheel weights are Your friend....good luck,, send pics....Dr.D...

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I don't understand a lot of what that guy said.:thumbsup:

Now we know why 4s are so popular as you can get on it and ride and don't have to know a thing about it! Guess you gotta learn yourself on what a lighter or heavier FWW does or doesn't do to decel and accel and idle and even what FWW means. Another good topic is what the air screw does and where it is on a carb. After that you can look into the adjustment and location of the powervalve and learn what that does and can do and what 'hit' means. You can also make adjustments with the addition of methanol and/or ethanol to tame the bottom, too, but you learn this other stuff first.

Back to helping the guy who started the thread and as was said, ride it stock first and see what the 'problems' are. In the woods you'll be WANTING to stay in second most of the time cause if you are dropping to first alot, there's a large increase in unwanted shifting into neutral.

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Now we know why 4s are so popular as you can get on it and ride and don't have to know a thing about it! Guess you gotta learn yourself on what a lighter or heavier FWW does or doesn't do to decel and accel and idle and even what FWW means. Another good topic is what the air screw does and where it is on a carb. After that you can look into the adjustment and location of the powervalve and learn what that does and can do and what 'hit' means. You can also make adjustments with the addition of methanol and/or ethanol to tame the bottom, too, but you learn this other stuff first.

Back to helping the guy who started the thread and as was said, ride it stock first and see what the 'problems' are. In the woods you'll be WANTING to stay in second most of the time cause if you are dropping to first alot, there's a large increase in unwanted shifting into neutral.

Whooaa nelly take it down a couple notches.. I'm trying to learn from this thread just like the author is. I was just asking you to elaborate a little..

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I think that's pretty much right on topic for this thread. :ride:

ha, thanks for the save :thumbsup:

One huge advantage of gearing down in some circumstances - one I never knew about until I tried it - is effectively bringing the gears closer together (the ratio relationships don't change, but the speed ranges for each gear do)...gearing down can make the bike easier to ride and accelerate faster in the woods, possibly giving you another usable gear.

Ray

hmm...I might have to try it to see what you mean

but if the gears are closer together, aren't you just shifting more often?

again, I'm very new to woods riding, but I would think wider gearing (thus, stock) is better because once you get going, you can stay in one gear for longer periods of time, stand up, keep both feet on the pegs, and use the gas/brakes/clutch & your body to negotiate the terrain.

is this tight/slow stuff that you've tried, single track? I only ask because I'm in MA, and I figure the kind of woods we ride in are similar...

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if the gears are closer together, aren't you just shifting more often?

Yes. With a transmission like my MR has (ultra-wide ratio) this was an improvement for me, as I could only use 1st, 2nd, and occasionally 3rd with the stock gearing. Now I use the first four gears all the time, and even get into 5th every now and then. This works much better for me than screaming the motor in 1st/2nd, then lugging it in 2nd/3rd, like I had to do before. On the other hand, gearing down a close-ratio MX transmission did not work for me (just wanted to make that clear, I'm only recommending a big-time gear-down for a unusually wide-ratio transmission).

I would think wider gearing (thus, stock) is better because once you get going, you can stay in one gear for longer periods of time, stand up, keep both feet on the pegs, and use the gas/brakes/clutch & your body to negotiate the terrain.

Absolutely - and with a beefy wide-powerband motor you can also accelerate quickly if need be; if I ever get my KX500, I'll probably just leave it in 3rd. :thumbsup:. The 'stock' gearing on a MX 2-stroke is almost certainly close-ratio; I wouldn't recommend gearing it down too much at all.

I love close-ratio transmissions; 3 of my 4 bikes have (or had) them. If they work well for the type of riding you do, that's great! A lot of the stuff I do now is single track, but some is either 'no-track' or ridiculously tight. To get to my main riding area, I have to descend a steep 20' downhill to a 3'-radius hairpin (usually wet) followed by an equally-steep ruts/roots/boulders climb back up; you stall, you fall. The rest of the place is a much faster and more enjoyable ride, but I have to make it through this section to get there, then make it back out when I'm tired.

Ray

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