Easy install, very nicely made!
Thanks.

Fantastic invention I ride a lot of rocky trails, have a hairline crack on one side, delighted when I seen them advertised thank you!!

Very nice piece, snug fit, increased velocity, throaty intake sounds, felt a difference. Would recommend

NGL I was thinking about cutting off the peg brackets and beefing up that part of the frame until I saw this bracket on a Facebook group that I'm in. There great easy to install and now it's 1 less thing I have to worry about when I jump it.

Great quality product, really well made, hopefully it will never be used as intended, But I'm sure it will be up to the job if it has to

The work was fantastic! No problems in the process and you get what you pay for! Thank you for doing a great job!!

Firstly, Ari’s customer service and communication is top shelf. He’s a busy dude, but was always there if I had a question. Now…the bike: I went for the Stage 3 and sweet baby Jesus, the power difference is in-your-face noticeable. I’ve put just over 2k miles on it since and have been thoroughly impressed. Not a hiccup or weird noise and the oil is great when I change it. I’ve taken this bike to the Michigan Upper Peninsula where it shined and kept up with friends on orange bikes no problem. Here in Northern AZ, I don’t feel limited at all by the CRF. Just yesterday I had to slab it home for 250 miles and it cruises very comfortably at 70 and 80 is there when I need it. Stock gearing too! This thing also lugs up the steep rutted tracks with ease. All this with low-maintenance intervals? Yep. Thanks Ari!

If you own a CRF300L and haven't done the 301cc Big Bore Kit, you're seriously leaving power on the table. This kit is the real deal — a race-proven setup with championship wins and a lap record to back it up. The jump to 11.5:1 compression combined with the full Stage 3.0 package transforms what was a capable but underwhelming commuter into an absolute riot to ride. The throttle response is crisp, mid-range torque is dramatically improved, and highway cruising feels effortless in a way it never did stock.
What really sets this apart is the attention to detail. Ari pre-gaps the rings, pre-installs them on the piston, and drops the whole assembly into the cylinder for you — so installation is far less intimidating than it sounds. The dyno numbers don't lie either: +25% torque and +34% horsepower with Stage 3.0, and even more if you go with the CNC ported head. For a platform that Honda deliberately detuned, this kit gives you everything Honda left on the table and then some.

First off, many thanks to Ari for all the remote assistance! He was great to tutor a “not ready for prime time mechanic!” I learned a lot.
Be sure to read all the documents fully before starting. And watch his video. Also get a good manual!
1. I was able to not have to disconnect the air box from the throttle body, I used a cam strap to pull it to the rear which gave me enough room for the head to pass by.
2. Use a “magnet on a stick” to retrieve the head nuts and washers. Stuff a rag or paper towel in the cam chain tunnel so nothing drops down there.
3. Be sure to closely inspect the case where the stock cylinder sat, we missed a small piece of gasket that had broken off, requiring a round 2..the photo below shows where it was, just in front of the coolant channel.
4. Getting the rod connected to the 301 piston while it is inside the cylinder is not to tough. I used a 1/4” long extension with a 8mm socket to help the pin through. The wrist pin can be a challenge so practice on the stock one you removed to practice working it into where it sits. I used a small flat head (not micro small) to work it in.
5. The forward cam chain guide is a bit tricky, Ari has instructions. The trick is to get it to sit into the slots in the head, so look at the head carefully and understand what has to happen.
6. When placing the head nuts/washers I used a couple tricks a friend showed me. Place a piece of electrical tape inside the 14mm deep well socket, make sure it’s secure so it doesn’t fall off in the head. This holds the nut to the socket. Next apply a bit of grease to “stick” the washer to the nut. This works really well.
7. After torquing the head nuts. Place the 2 long bolts back into the cam chain tunnel. I broke one of these, requiring round 3. In the photo you’ll see that it’s best to use a 1/4” drive socket rather than a 3/8”. The 3/8” pushed the bolt head out enough that it damaged the threads causing the bolt to break, luckily it was in only finger tight!
8. Be careful when using a screw gun to put the body bolts back in. I got one in a bit off center and love those headaches.
Print out Ari’s instructions and have a hard copy of the workshop manual.
Lastly, I will remind everyone just how hard it is to get general nuts and bolts for a motorcycle these days, gone are the days of going to the shop and having bins of them. So take your time and have a system for accounting for which bolt/nut came from where.

2025 Rally with everything Ari offers, except the ported head.... I may end up doing the ported head also....
Did big bore, intake, valve train, chip, Graves exhaust (blue) looks great, and the -40 mm Rally Raid suspension with rear remote. I am Loving this bike. Does anything I ask it to do. Im no motorX stud but can ride just about anything and these upgrades have just enhanced that about the bike
Ari is professional, thorough and just a pleasure to do business with. He explains the process and even how and what to expect from the upgrades. I am an attention to detail kind of guy and Ari met all my expectations, Thank you!!!

I have been planning this upgrade for over a year now andI just got the Cylinder Head Service, with the Valvetrain Upgrades, to go with the Big bore Kit to get my CRF 300 Rally to Ari's 4.5 Stage which should give the Honda +52.3% more Peak Power.
It looks a beautiful the head, what workman ship, seems a shame it won't get seen. I can't wait to get this engine back in the bike and creating a perfect bike for may ability.

I have all the rest of the Upgrades for the Honda, so will get on with the Rebuild in New Year.

Ari just finished 2 CRF 300 Rally builds for my wife and I. We ride KTM 790’s but wanted to add to our stable with 2 lighter bikes with low maintenance for more technical riding. Ari built up 2 fantastic 300 rally’s with full big bore kits, suspension, handlebars, foot pegs, hand guards, tires and a few odds/ends. We received them this week via Alan’s motorcycle transport (highly recommend) and the bikes are fantastic. Ari was amazing to work with and his builds exceeded expectations. HIGHLY RECOMMEND!

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 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.

This kit does wonders for the 300 platform. Do set huge expectations as far crazy power. What you do get is usable power through the whole rev range now. 3rd and 4th gear are phenomenal! My bike will pull 6th gear up a hill now. You don't have downshift as much before a turn to be able to power out of it. I did the install myself with no issues. Ari is great at answering any questions or concerns in a very timely manner. I would definitely recommend this to any on the fence about doing it. You will not regret it. I would do agian in a heart beat.