Honda CBR250R Front Sprocket - 13 Tooth

[WingNut]

http://www.ebay.com/itm/JT-Sprockets-Front-Sprocket-13T-Honda-XR250R-96-04-/231249125429?pt=Motorcycles_Parts_Accessories&vxp=mtr&hash=item35d785a035

US$20 including shipping to Thailand. Around 650 Baht.

[Happy Grumpy]

http://www.ebay.com/itm/JT-Sprockets-Front-Sprocket-13T-Honda-XR250R-96-04-/231249125429?pt=Motorcycles_Parts_Accessories&vxp=mtr&hash=item35d785a035

US$20 including shipping to Thailand. Around 650 Baht.

600% increase on one that's barely used.

Barely used one for the experiment, then if want to keep that set up, get the new one. Clearly the more intelligent option.

[WingNut]

Sure. Whatever pleases you.

[DLang]

I've had my experiment 13T on now for the last few days. It's the same brand as the one in the OP.

Some okay pros, some big cons.

Obviously the pick up and acceleration is better. Good for city riding.

Changing gears quicker, not really an issue.

the Speedo is now out by 20%, instead of the stock 10%. I had guessed it would be about 15%. 20% is a bit much.

The massive con is that is out of breath at 7k rpm, which in 6th gear, is, wait for it................ 120kph indicated and 100kph real speed.

It starts to feel breathless at 80kph (real) and is almost out of breath at 100kph (real).

Now obviously this just isn't cricket. Not acceptable.

Doing a long highway ride must be like pulling teeth.

Good pro, terrible con.

My riding is 95% city, so I might, just might keep it like this. Doubt it though.

[WingNut]

Give it a try on a long ride before you decide to switch it back. I think you'll find on the highway on an open road it will eventually pick up the lost speed at the top end. I think the power is still there at the top. It should only be a net 10% loss.

Sent from my iPhone using Tapatalk

[WingNut]

I must say, I've had it for about 4-6 months and wouldn't switch back. I do pretty much only city driving with it and the extra acceleration at low speeds, even though it only another 10-20%, it's still quite useful.

Yes, the bike gets up to the 7,000 rev range very quickly. But that's really the point of the 13T sprocket change I think. The bike has no power until you hit its power band sweet spot at 7,000-8,000 revs. So the faster you get up there then the faster your going to get some usable torque out of the bike. I reckon if you switched back to the 14T your going to feel a distinct drop in the acceleration.

[DLang]

I took her out for a 400km weekend trip at the weekend and she is shockingly bad with 13T when it comes to the highway.

No way I will do that again.

It's only 50 baht to change the sprocket and adjust the chain at the Honda shop at the front of my village, so will get them to change it back should I ever take her out of the city again. The poor little engine was almost hopping out of her with the RPMs. Topped out and the GPS showed 140kph where previously 150kph. But none of that is sustainable. 110kph GPS is sustainable for long times but above that the poor thing is buzzing breathlessly and going nowhere.

Would be interested in trying out a 15T for highway riding. then swapping back to the 13T or 14T when back to city use.

Anyone ever found one available here?

cheers.

Edited July 20, 2015 by DLang

[Crowleys]

I took her out for a 400km weekend trip at the weekend and she is shockingly bad with 13T when it comes to the highway.

No way I will do that again.

It's only 50 baht to change the sprocket and adjust the chain at the Honda shop at the front of my village, so will get them to change it back should I ever take her out of the city again. The poor little engine was almost hopping out of her with the RPMs. Topped out and the GPS showed 140kph where previously 150kph. But none of that is sustainable. 110kph GPS is sustainable for long times but above that the poor thing is buzzing breathlessly and going nowhere.

Would be interested in trying out a 15T for highway riding. then swapping back to the 13T or 14T when back to city use.

Anyone ever found one available here?

cheers.

I think i saw 1 in 320sp shop months ago. not 100% sure that was it for cbr300 cos back then i was only looking for 13T

[WingNut]

I think a 15T could turn the bike into the slowest 250cc bike off the line. I also don't see how it can increase your top end. Maybe just reduce revs a bit on highway driving so that you can get it up to its full speed of 163KM at lower revs. The power of the bike's HP won't change. So it won't make the top speed any faster. Just different gearing and slower acceleration in my opinion. When I got my bike up to 163 a few times it wasn't the revs holding me back, but the bike ran out of power. Can't change that. If your really aren't happy with what the bike can do then just put it back to the factory spec 14T and forget out it. You can really change the bike from what it is. If you really need more power then think about upgrading to a 500cc or a 650cc bike. Otherwise just accept it's fine for running around in the city and your better off with the 13T for that I think.

Edited July 20, 2015 by WingNut

[DLang]

Thank WN, but your advice and emotive posts about things really aren't that useful.

[WingNut]

No problem. In that case I will stop here and leave it with you. Best wishes.

[JimMorris]

I think WN's advice is very useful. He is simply noting the fact that you don't like the stock 14T, you don't like the 13T you tried, he is also telling you that the 15T isn't going to solve your problems either. And his conclusion that the problem is that you don't like the bike itself because it doesn't have the right combination of torque, acceleration, and top end speed, and concluding that you need a bigger bike is your best answer. You are trying to get big bike performance out of a small bike which wont work with only front sprocket changes. You simply need more HP.

Edited July 22, 2015 by JimMorris

[Happy Grumpy]

He is simply noting the fact that you don't like the stock 14T, you don't like the 13T you tried, he is also telling you that the 15T isn't going to solve your problems either.

I don't see where DLang has mentioned not liking the 14T, not liking the 13T other than on the highway, and only see him wanting lower RPMs than the 13T gives when on the highway, thus his interest in experimenting with a 15T for highway riding.

This is actually an excellent way to set up one's bike for one's type of riding.

If you will be in the city for a long period of time, set it up best for city riding (shorter gearing). When you are going highway riding, set it up best for the highway (longer gearing). This is regardless of make, model, engine size, if the parts and ability to change are all close at hand.

What 'problems' are you talking about?

Perhaps I missed a few posts.

Edited July 22, 2015 by Happy Grumpy

[Crowleys]

And takes you around 10 minutes to change the sprocket even at home, so easy to keep swapping between city riding sprocket and touring 1.

[Happy Grumpy]

And takes you around 10 minutes to change the sprocket even at home, so easy to keep swapping between city riding sprocket and touring 1.

At least somebody gets it.

Thank God, the forum isn't completely lost.

[DLang]

^ lol.

Yes, I think some posters don't know much about bikes, let alone what people are discussing.

There's nothing wrong with being a newb that's excited with a mod they've made, even if it isn't fully understood, we've all been there and the excitement feels good. So roll on with it.

Ride on fellas.

Edited July 23, 2015 by DLang

[DLang]

Of course another thing to change is your mirrors.

I use Koso mirrors for my city riding. Slimmer than the handlebars and lower then every car's side-mirrors, so they're perfect for lane filtering.

When going for a day's highway riding the stock mirrors are far, far superior and better suited to the terrain. A simple two minute job.

Just a tip for the inexperienced who consider altering one's bike for different types of riding as an alien concept.

The best days were back with carbies, tuning them for altitude when hitting the mountains for a few days.

[Vogele123]

I must admit I changed the sprockets on my old XLR and found an improvement, however I would be very reluctant to change the front sprocket on the CBR, I would have preferred to change the rear sprocket if anything.

One thing I would say that will make a difference to your acceleration if that is what you are looking for is to change your rear tyre from the 140/70/17 to 150/60/17, it definitely gives it a bit more oomph, without over stressing the output shaft.

Mine can get 154KMH even with this tyre - but you have to lie on the tank looking like an idiot. - probably get 158 without a wind.

[Vogele123]

Thanks for checking that out. So no need to ever change the speedometer if you are worried about speed accuracy once you roughly how much it is off by.

I wonder though if that 10km difference, which is also about a 5-6mph difference, is the same at all speeds? Perhaps the gap widens or lessens depending on how fast you are going. Did you test it at various speeds?

I'm wondering if you were going only 5km in actual speed if the speedometer on the bike would read as much as 15km for example.

Taken from my Garmin Nuvi 255W, your speed error increases the faster you go compared to your speedo indication, i.e. it is not a linear thing.

[DLang]

I switched modes at the weekend as was doing a quick 200km trip.

What a breath of fresh air the 14T is. In the the city too. The longer gearing (so far less shifting is fantastic). The gears are actually useable now and not just for shifting, shifting, shifting, getting you into 5th where you can do a massive 80kph.

Would be surprised if it wouldn't beat the 13T to 100kph (and of course beyond) because of the length of gears.

[eeeya]

Cb300f top speed with 13T sprocket. Speedo says 168..GPS says 141

[DLang]

Cb300f top speed with 13T sprocket. Speedo says 168..GPS says 141

Ouch.

CBR250 top speed was 151kph GPS with the stock 14T sprocket (165 indicated)

With the 13T it was around 135kph (GPS) but completely unsustainable as the poor little engine was popping out of her frame, wouldn't even want to go there..

With the 14T you can pin her all day no bother.