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My 13t experience

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I recently picked up a used lrp in immaculate condition with 500 miles on it for a ridiculous price, and like any good owner of anything, I went and found a forum to learn about all the mods available. After reading a multitude of threads and always in the pursuit of power, I decided on my first mod: 13t sprocket. At 14 bucks shipped it was cheap enough to do, and being that I am a pretty handy fellow, it was also exceptionally easy.

So I slapped that bad boy on, adjusted the chain accordingly, fired up my GPS, and went for a ride. My first impression was good: the bike certainly had more torque at the wheels, it was a good bit peppier at the low end, and was easier to deal with The low speeds. My second Impression was: hmm that's interesting. With a good understanding of gearing and how systems are affected, I expected my speedo to be a bit off, but not that far off... 7 miles an hour off at 25 mph. So I cranked it up to speed.... Again, the pep was great on the lower end of things... A the way up to a GPS reading of 60mph (a speedo reading of 69), then things died off. Going an Actual 65 meant the bike was at 76, and I maxed things out at 72mph GPS, 83 on the speedo. (and that was down a hill at WOT).

These were not the results raved about... And being that I use the bike as a daily commuter, I need to go 65 - 70 without much trouble, which the stock gearing gave me. I've even had it up to 80 on stock gearing, on flat ground....

After my riding around, I went home swapped the 14t back in and called it a day. With results like this, the engineer in me kicks in, and I am trying to figure out the discrepancy between people claiming a higher sustainable speed and what I have just experienced. So far I have come up with 2 possible conclusions :

1. Being that my bike is bone stock, the system cannot even reach the upper Rev range.

2. People are not verifying their speed with a GPS and are reading their new, remarkable speeds off the Guage.

Final remarks : given that 95% of my riding is pounding pavement at Highway speeds, the 14t is for me. Since it only takes 5 minutes to swap, I am going to keep the 13t for the times when I do go off road.

Please do not take this post as an insult to anyone's intelligence, this is one data point, and may not be representative of other people's experiences.

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Yeah, most of us use the speedodrd to calibrate afterwards. Also, I think size of rider has something to do with it. Stock 6th gear was utterly useless to me, bike would literally start slowing down the instant I hit 6th, at any speed. Adding a 13t made 6th barely usable. I could maintain a speed usually, but couldn't gain any. Adding a 42 to the rear helped immensely, now 6th is usable. I'm 6'3" and 230lbs and with my mods, 13/42 gearing, can hit low to mid 70's mph easy.

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around here .......... I do not think there are very many people that just added a 13T only .... most have the stage 1 kit with a 13T added so those results may be different. And as mentioned the rider weight makes a huge difference.

 

All the mods we do is to get what works for us as an individual ....  :thumbsup:

 

 I love my bike and have many mods that suit me well but, it is not for everyone nor is it mean't to be. If I was more of a road rider I would have took the route of the supermoto concept with my mods rather than the off road version... :ride:   But, then again if I was more of a road rider .... I would not have bought a 250 and I would have probably went with the CB500X that is one sweet looking ride in my opinion. 

Edited by gnath9
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Yeah, most of us use the speedodrd to calibrate afterwards. Also, I think size of rider has something to do with it. Stock 6th gear was utterly useless to me, bike would literally start slowing down the instant I hit 6th, at any speed. Adding a 13t made 6th barely usable. I could maintain a speed usually, but couldn't gain any. Adding a 42 to the rear helped immensely, now 6th is usable. I'm 6'3" and 230lbs and with my mods, 13/42 gearing, can hit low to mid 70's mph easy.

 

 

around here .......... I do not think there are very many people that just added a 13T only .... most have the stage 1 kit with a 13T added so those results may be different. And as mentioned the rider weight makes a huge difference.

 

All the mods we do is to get what works for us as an individual ....  :thumbsup:

 

 I love my bike and have many mods that suit me well but, it is not for everyone nor is it mean't to be. If I was more of a road rider I would have took the route of the supermoto concept with my mods rather than the off road version... :ride:   But, then again if I was more of a road rider .... I would not have bought a 250 and I would have probably went with the CB500X that is one sweet looking ride in my opinion. 

 

Thanks for the replies.  I think you guys hit it pretty well... I am 5'8" 190lbs, so the stock system can move me around pretty well.  Gnath, you bring up another interesting point related to a possible cause I listed earlier: I am now wondering if (at stock) it is even possible to use the upper Revs while under load.  There definitely seemed to be a rev ceiling that I was hitting, but it was not the limiter considering I probably did not even hit 8000 RPM.  Also, I picked the 250 for the gas mileage, price point, and the off-road fun factor when I have the opportunity, all of which I have been very happy with so far. 

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Thanks for the replies.  I think you guys hit it pretty well... I am 5'8" 190lbs, so the stock system can move me around pretty well.  Gnath, you bring up another interesting point related to a possible cause I listed earlier: I am now wondering if (at stock) it is even possible to use the upper Revs while under load.  There definitely seemed to be a rev ceiling that I was hitting, but it was not the limiter considering I probably did not even hit 8000 RPM.  Also, I picked the 250 for the gas mileage, price point, and the off-road fun factor when I have the opportunity, all of which I have been very happy with so far. 

 

You may want to look into getting the EJK and doing the airbox mod to uncork her up some ....  :thumbsup:  ... there is a ton of info around here. I put the FMF full exhaust but, lots of guys want to keep it quiet and have seen good improvements keeping the stock exhaust.  

Edited by gnath9
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I was very late to change sprockets (currently on 14/42 with big bore) but what I found is I could consistently hit higher top speeds in 5th than I could in 6th (on 14/40), so I believe the reports of people stating getting higher top speeds with 13/40. The only time 6th was actually faster was with a tail wind or travelling down hill, every other time I found 6th to be 2 to 4 mph slower than 5th.

I performed these test on numerous occasions literally over thousands of miles, many times chasing down road bikes.

I only weigh 170 pounds and still found 6th to be almost useless above 65mph unless travelling on completely flat ground.

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my 2cnts

 

mechanicaly,, the lower gear ratio will lower your top speed.

But ,,,because this engine is geared so hi and does not make the power/torque in  stock form to actually pull the hi gears with a rider over 200lbs (approx)

by lowering the gear ratio ie: 13/40 or 13/42 a rider feels the engine pulling the higher gears and this allows the engine to rev higher and for some get a ligher top speed

 

I was running a 13/42 on my bike for about a week, I did not like the lack of freeway ease (higher top speed)

 but it did pull the gears easly

I went to 13/40 and it gave me back my reeway speed and still pulls good enough through the gears

 

My bike recently broke in at about 400 miles and I felt a noticable power increase (FYI)

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I've been hesitant to switch sprockets too. It's my commuter bike first and foremost, and while I'm sure I'd love lower gearing for off-road, it's geared about perfectly for normal street and highway use (I'm 5'11" and 185 lbs). It usually tops out at 75 mph in 6th gear, just runs out of torque and can't fight the air resistance anymore, but it isn't super revved-up either. I think someone around here recently said at stock gearing it's pretty much 1000 rpm for each 10 mph in 6th gear.

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Hmm, 14/40 at 8200rpm = 80mph, 13/40 at 7900rpm = 72mph

 

Strange, you had the power to pull 8000rpm+ with the 14/40 combo on level ground, but then couldn't reach 8000rpm with 13/40 gears on a downhill.

 

:excuseme:

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You really need to perform these tests over a period of months like a few of us have under various conditions to draw a real conclusion.

My top speeds would vary around 8mph depending on the conditions just wind direction alone (even the subtlest breeze) makes a significant difference to your top speed and obviously the slightest incline decline will affect the speed too.

In addition to that temperatures, altitude, humidity etc also effect top speed.

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You really need to perform these tests over a period of months like a few of us have under various conditions to draw a real conclusion.

My top speeds would vary around 8mph depending on the conditions just wind direction alone (even the subtlest breeze) makes a significant difference to your top speed and obviously the slightest incline decline will affect the speed too.

In addition to that temperatures, altitude, humidity etc also effect top speed.

Exactly, with such a small motor, EVERYTHING plays a part. Some days I can only get 70mph top speed (according to my speedo with SpeedoDRD at -11.6%) and other days I can hit 84mph (with 13/42 gearing).

Even my little truck has those issues because it's a 4 banger. I turn the AC off when I pass people lol. My truck is so gutless that every little thing helps. Same with these bikes.

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with my 305 and 13/44's I feel as my top speed is pretty consistent now but, I do not really push it or hold it there as I can now reach much higher rpms in top gear. I think I get about 77-79 mph but she is wound up tight and I would not hold it there for more than a mile or so ..... at 65 I feel I can hold it there all day long even tho it feels like it is just starting to be wound up  ... 60-65  mph is a nice cruise speed for my gearing 

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Different big bore kit than Gnath's, but I'm running 13/42 and feel the same. Between 65 and 70 it's just fine, anything over that and she is wound pretty tight.

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Hmm, 14/40 at 8200rpm = 80mph, 13/40 at 7900rpm = 72mph

 

Strange, you had the power to pull 8000rpm+ with the 14/40 combo on level ground, but then couldn't reach 8000rpm with 13/40 gears on a downhill.

 

:excuseme:

This is very strange to me... perhaps environmental factors.  It has been fairly humid here recently in Mississippi.   Thanks for the input all, it is very interesting to see what speeds people are getting out of their rigs. 

 

Another interesting point i have noticed with my bike (which may relate to a ceiling) is that my power seems to fall off if I go over 7/8ths (ish) throttle.... for example, when I am going up a hill I slowly increase the twisty handle to maintain speed, and if I go past that throttle point I feel power drop off until I back the throttle off slightly again and it comes back.  I'm sure the answer I will get for this one is to add an EJK, but I was just wondering if anyone had experienced the same thing.  

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Another interesting point i have noticed with my bike (which may relate to a ceiling) is that my power seems to fall off if I go over 7/8ths (ish) throttle.... for example, when I am going up a hill I slowly increase the twisty handle to maintain speed, and if I go past that throttle point I feel power drop off until I back the throttle off slightly again and it comes back.  I'm sure the answer I will get for this one is to add an EJK, but I was just wondering if anyone had experienced the same thing.  

 

I believe that comes from dogging or lugging the bike to low for the situation at hand. And that is why I say this bike is so over geared  ... you should be able to slip the clutch and spin that rear tire up the hill. 

 

I wish the manufacturers  would give us a low geared 5 speed tranny with a true over drive 6th gear for highway use ...  :thumbsup:

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This is very strange to me... perhaps environmental factors.  It has been fairly humid here recently in Mississippi.   Thanks for the input all, it is very interesting to see what speeds people are getting out of their rigs. 

 

Another interesting point i have noticed with my bike (which may relate to a ceiling) is that my power seems to fall off if I go over 7/8ths (ish) throttle.... for example, when I am going up a hill I slowly increase the twisty handle to maintain speed, and if I go past that throttle point I feel power drop off until I back the throttle off slightly again and it comes back.  I'm sure the answer I will get for this one is to add an EJK, but I was just wondering if anyone had experienced the same thing.

I've never had that issue on my bike.

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i have tested this on my bike...  i think there are a lot of variables to this, but mine pulls right up to the stop....  i understand though that if you are deep in the lug lug lug, a little less throttle will get you moving a little faster...    but in general, i have stage 1 with a 13t and she pulls all the the way through...   i hold her around 75-85mph for a good bit on my hour commute..

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Something interesting that was pointed out to me this weekend was the issue that swapping to a smaller 13T front would have on wearing down the rubber chain guard under the swing arm – eventually even digging right into the swing arm itself. He rides the WR250R but said it's a universal issue that many people often don't take into account. Low + behold as soon as I checked the rubber on mine (with the 14T stock sprocket) I could feel where the chain has chewed almost right through the rubber. Does anyone have any input or familiarity regarding this? fyi, my chain slack is bang-on according to model specs. I'm a little hesitant now in throwing on the 13T + then chainsawing right into the swing arm.

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Ive had my 13T on for over 500 miles and i think you buddy is blowing smoke--OK yes the chain wears on the plastic a little but i'm betting it would take 50k miles to wear thru to the metal with proper chain lubing--Not to worry grasshopper :thumbsup: :thumbsup: :thumbsup:

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