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Discussion Starter #1
Hi to my fellow Cbr300r, CB300F, and CB300r owners!!

My name is Mike_on_bikes and I've owned a 2017 cbr300r for 3 years, with 25,000+ kms all done by myself.

Here is my story of a search for more power and top speed. Without buying a new bike.

I love the cbr300 and want to own it as long as possible, and in the process make it usable for commuting and back country twistys. I ride with mostly 650, and 300 class sport and naked bikes- and every bit of performance counts.

Heres my non scientific review of the bike stock:
Tires, brakes, transmission and chassis are adequate, and great. The motor is geared too short, too restricted, and the speedo reads 10% optimistic. Top speed is gps verified 160km/h +- 5kph.

UPGRADES:
IRC roadwinner Rx 02 tires (small step up from stock)
Dobeck EJK fuel controller
Slip on exhaust w 2 baffles (the back pressure is needed)
K&N intake air filter
15T front sprocket (+1 ,tooth from stock)
X ring chain (replaced stock o ring)

Review after upgrades:
GPS verified top speed of 170km/h +-5 km/h
Reduced fuel efficiency, gobs more torque low down
More accurate speedo reading (only 3% optimistic!)
First gear is way more functional and less choppy at slower speeds.

10,000kms with upgrades and very happy! Yes I'm a slow poke(comparatively) but this bike can really push it in twistys and in the city has incredible maneuverability.

I am now as fast as a Ninja 300, and more competitive with r3 s and rc 390s, yet more comfortable.

All in performance upgrade cost? Ejk $450, slip on $75, sprocket $10, x ring chain $200.

Best of luck to all and I'd highly recommend the ejk, slip on, intake, +1 front sprocket upgrade.
 

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Nice write up Mike. I think that 2017 colour option is one of the best for this bike. Like your mod list. With hind sight I should have fitted a fuel controller or flashed the ECU on my old CBR and gained that extra 10kph.
 

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Discussion Starter #3
A few things to note: the powerband of the engine peaks HP at 8500rpm, and peaks Torque at 6500rpm. Why does this matter?

1) the engine keeps identical HP and Torque curves after the ejk
2) what this means is with a stock gearing setup, the engine is past it's peak power at 160km/h, running on momentum basically; you do not gain any top speed with just an ejk!!
3) the extra power from the ejk, slip on, and k&n intake is needed to achieve the full potential of the gearing (15t front, aka +1 front tooth),
4) without the extra ponies, the extra tooth setup can even take away top speed, and is not recommended
5) the x ring helps surprisingly, as it creates less rolling resistance and is a lighter chain with less friction. Throw that o ring garbage out at 10,000km
6) I've tried endlessly to have an open pipe, or one baffle but the engine just runs better at "high compression" aka with 2 baffles installed. I've heard it's high compression (11:1) and loses torque when you free up airflow too much.
7) these engines are lean, and even with an ejk, they can run lean if you have a straight pipe. The injectors are just a wee bit too small, and let's be real- it's only 286ccs

Cheers to maximizing the potential of these chainsaws!!
 

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Dropping weight off them helps performance too. Did you see my long running thread where I striped over 13kg off the stock curb weight?
 

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Discussion Starter #5
Dropping weight off them helps performance too. Did you see my long running thread where I striped over 13kg off the stock curb weight?
This is great! But I often ride 2 up and I need all the passenger stuff. Definitely looking into a lighter battery and bar end mirrors. The stock mirrors create so much drag!!
 

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:LOL: "These chainsaws"

My experience with my CB300F was largely the same as yours, Michael, save for a big one: I went -1 in the front, to try to gain acceleration (and occasionally work on wheelios). As you'd expect, there was no first gear or top end... but the middle was nice.

Also followed kiwi's experience and shed the easy weight from the bike.
 
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