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301cc Complete Big Bore Kit
301cc Complete Big Bore Kit
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Originally developed for my racing endeavors on a CBR300R, this kit has dozens of race wins, two class championships, and one lap record to its credit. With tens of thousands street and off-road miles logged, this is a proven and reliable setup for improving your CRF's performance, capability, and fun factor.
This piston and cylinder kit turns your CRF300L into a true 300 with an additional 14.8cc while also increasing compression from the stock 10.7:1 to 11.5:1. When combined with the required Stage 3.0 parts which include a high-flow air filter, hi-flow velocity stack, CBR cams, performance exhaust, and Stage 3.0 ECU tune, you get a massive increase in torque (+25%) and horsepower (+34%). Throw on a CNC ported cylinder head and Stage 3.5 ECU tune for even more gains (+30% torque and +39% horsepower).
To ease installation, we now pre-set ring gap, install and orient the rings on the piston, install the right (cam-chain side) wrist-pin circlip, lubricate the piston and cylinder, and then slot the piston into the cylinder. This greatly reduces the work required for installation; just drop the whole assembly onto the con-rod, install the left circlip, and press the cylinder down.
With our 301cc piston kit and full Stage 3.0 parts package you can expect faster acceleration, snappier throttle response, and easier highway cruising. See dyno charts and performance comparison below.
This piston and cylinder kit includes:
- Forged 78mm piston, 11.5:1 compression ratio
- Piston ring set, properly gapped
- Wrist pin and circlips
- New, OEM Honda cylinder bored to match piston
- Cometic head and base gaskets in custom thickness to optimize quench clearance
- Upgraded Class 10 stud nuts
- Click here for install tips and break-in guidelines
PLEASE NOTE: This is not a standalone mod! You must run the full Stage 3.0 parts package and ECU tune. 91 octane (R+M)/2 (95 RON) gas is required. This kit should be installed by a professional mechanic or someone of similar experience following steps outlined in a service manual.
Warning: This product is for closed-course competition use only and is not intended for street use or use on public lands. This product is not legal for sale or use in California.
I've now put over 6000, fully loaded for travel with camping junk, BDR type miles on the bike Ari built for me last winter. It's been stellar.
I average 70mpg with the way I ride. I even saw 82mpg once!
I try to stay off fast highways for the most part, but with this type of riding, sometimes you're forced to and the 301 handles sustained 65-70mph just fine if needed. It doesn't burn any oil.
The bike becomes a bit of a sleeper, too which is kinda cool. I was stopped in a section of the SEBDR last week checking my GPS. A rider pulled up on a KTM 690. "oh, is that a 450?" No, it's a 300. You could see the look on his face as he was looking down on the bike. I came up on him shortly after while he was struggling through some rocks. Stopped to ask if he was ok, and blew past him laughing in my helmet. Ha!
Where the kit really shines is in on/off road riding all day at anything below 50mph. It'll climb the toughest rocky uphill stretches, and scratch along in twisty sections, all while carrying your gear. With this type of riding, I'm the limitation, not the bike, with the reliability of Honda and Ari Henning.
Thanks, Ari, for building this bike, and supplying a reliable kit to get this platform to the next level.
This will be a winter project. i have great confidence in the Big Bore kit.
This was the single best upgrade I’ve done for my CRF300 Rally. This big bore with the support mods and 3.0 ECU from 550 Performance has made my bike what it was meant to be all along.
Kit went on easy due to rings being on the piston and in the bore, thank you verymuch
Nice complete kit. Prompt service. Have not installed yet, but can't wait.
I've now put over 6000, fully loaded for travel with camping junk, BDR type miles on the bike Ari built for me last winter. It's been stellar.
I average 70mpg with the way I ride. I even saw 82mpg once!
I try to stay off fast highways for the most part, but with this type of riding, sometimes you're forced to and the 301 handles sustained 65-70mph just fine if needed. It doesn't burn any oil.
The bike becomes a bit of a sleeper, too which is kinda cool. I was stopped in a section of the SEBDR last week checking my GPS. A rider pulled up on a KTM 690. "oh, is that a 450?" No, it's a 300. You could see the look on his face as he was looking down on the bike. I came up on him shortly after while he was struggling through some rocks. Stopped to ask if he was ok, and blew past him laughing in my helmet. Ha!
Where the kit really shines is in on/off road riding all day at anything below 50mph. It'll climb the toughest rocky uphill stretches, and scratch along in twisty sections, all while carrying your gear. With this type of riding, I'm the limitation, not the bike, with the reliability of Honda and Ari Henning.
Thanks, Ari, for building this bike, and supplying a reliable kit to get this platform to the next level.
This will be a winter project. i have great confidence in the Big Bore kit.
This was the single best upgrade I’ve done for my CRF300 Rally. This big bore with the support mods and 3.0 ECU from 550 Performance has made my bike what it was meant to be all along.
Kit went on easy due to rings being on the piston and in the bore, thank you verymuch
Nice complete kit. Prompt service. Have not installed yet, but can't wait.