Templar X Sprocket re-size
Okay, I know there is information here and there in different threads about this but I'm hoping to get the pertinent info in one place if possible.
My stock Templar X is pushing about 54-55mph at 7k rpm. My bike will be only on roads long enough to get dirt. But for example, it is about a 30 mile ride to get to the bottom of the WABDR on a 60mph road. I want to keep all the good torquey goodness of the bike as I can for fire roads and trails but I would love for the bike to be able to cruise at say 64mph at 7k rpm. I want that extra room in the rev band for when I load it down with gear for a couple overnights and perhaps some extra fuel. In your experience most cost effective way to get this done? I saw the thread with the 42T rear that is inexpensive but I like to examine all my options...that seems like a big jump down to me. |
What sprockets are currently on it and is this a 6 speed bike? Everything I know about the 6 speed 172 engines and their gearing tells me 55mph at 7k rpm doesn't make sense. With a 13/49 set, 6th gear at 7k would theoretically be doing around 85mph.
Maybe I am mistaken, or the gearing info I have is wrong. Doesn't look wrong, but who knows. |
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Here it is: https://www.chinariders.net/showthread.php?t=31046 I always called the 6 speed a 2022-1/2 Templar X (or beyond) |
...well, there I go learning something. I still would appreciate any regearing recommendations/what gear inch should I be aiming for.
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The formula is very simple.
If 7k is your desired rpm, and your current speed is ~55 mph, and you want to be doing ~65mph at that rpm, Your ratio change will be: 65/55= 1.182 You can either multiply the ratio with front sprocket tooth count, or divide the rear sprocket tooth count with it. 13x1.18= ~ 15T - 16T up front, or 49/1.18= ~ 41T - 42T rear. You'll have to look and see if you can physically fit a 15-16T sprocket up front, or if you can find a 41-42T rear to buy. Alternatively, you can also put a 14T up front, and a ~45T rear; though the easiest swap is the front sprocket. Swapping out the front sprocket with a larger one, will mostly only affect first gear start from a stop. It does affect all gears but it'll be harder to notice. You still will have plenty of torque in the higher rpm ranges, save for final gear (5th or 6th), where torque is traded for HP; meaning your acceleration will be slower, but your top speed reached will be higher.. a taller final gear ratio, results in an increase in HP, but it only works, if the bike makes the torque necessary to pull at the speed you want to go. Hence you'll lose top end speed with taller gears if the engine isn't powerful enough to pull the gears. A 150cc engine with carburetor usually reaches about 60-65mph tops. A 250cc will reach about 75-80mph tops. A fuel injected one will reach 5-10% faster than the carburetor version. |
Obviously there are a variety of ways of getting there. Now you have a few ways to calculate/estimate your preferred gearing, and make your decision. I put a smaller sprocket on the front because I ride off road and love to have rpm at low speed. So I can't tell you what might fit (bigger) up front. But you don't have to even change the front sprocket since there are many rear sprocket choices:
https://www.jtsprockets.com/catalogue/sprocket/JTR210/ In fact, these are the sprockets they are making today. There is lots of old stock apparently, like the JTR210-51 I got for my X, still available. Just google JTR210-XX (where XX is number of teeth you want). These sprockets are low cost, and they are durable sprockets. |
If a 16T will fit up front, that would be the best/easiest way to go about it. Simple front sprocket swap and you can likely keep the same chain length. Don't like it, then swap it back and get a rear somewhere between 49 and 42, as suggested above.
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There's a 13 tooth sprocket up front. I think a 14 tooth sprocket would work if it fits. That'll get you about 8 percent increase. You can do the math on 15 tooth gearing if you think it'll fit.
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I have no firsthand experience with larger front sprockets on the Templar but I recall reading others state that a 14t requires some clearancing of the side case/cover and that a 15t can fit. I wouldn't even consider a 16t and I chose a 44t rear for my 5spd. YMMV
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I have no experience at all on the Templar, and I can't seem to find any accurate gear information. If somebody can provide that it wouldn't be hard to plug it into gearingcommander to really dial in exactly what would be needed to meet said goals.
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Fwiw... I swapped to a 40T rear, but unfortunately failed to get an accurate top speed. 13/40 made 1st too tall for trail riding. So I swapped back to the stock 13/49.
My top speed is only 50 ish indicated...but a gps check reveals land speed to be well over 60 mph(62-64). Bottom line, don't trust that speedo until you check it. If you only need to cruise at 65, a small change to the rear sprocket should be enough to get you there. Say a 47 tooth perhaps? but really, if it is a 60 mph rd...you're probably fine to leave it as is...as to not compromise the trail worthiness. |
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The Honda Rebel 250 did 80 (sometimes 85 MPH with a tail wind), and 75MPH with a headwind. It's a parallel twin, so it's got more HP compared to a thumper.
So I'd say, a 250 should top out at least around 70MPH, level ground, no wind. |
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