I installed the 290cc big bore kit on my YZ250F along with the hot cams stage1 cams. Nice improvement in the low to mid range power with no loss on top end. Allows me to be even lazier in the trails with plenty of roll on torque, LOL. Some tuning advise after installing this kit you will need to go down in jet size or it will be too rich. Yeah I know just the opposite of what you would think.
Installed this after 5 hours the pin found it's way out the side of the piston destroying the piston and cylinder. Faulty hardware
My son needed just a little extra out of his yz85, so 3 years ago I upgraded his top end to the 105cc big bore, and just like that he was back in the game, keeping up with the bigger bikes. Didn’t have a single problem with installation and even picked up extra set of rings and it lasted almost 3 seasons. Also no machining required.
Fun to install and what an incredible change in performance!!!! The sound of the engine is a much deeper tone. Great for someone who doesn't necessarily know alot about engines. Follow the instructions and feel like you own your engine and its capability. It's very enpowering.
I have recently installed the BBK and the stage 2 intake and exhaust cams. The power gain is amazing. My ‘08 DRZ 400sm had 33,000 miles on it. Instead of reringing it I dropped some coin and went with BBK and cams. I’m so happy I did. Installation was easy, I have almost 500 miles on the kit so far with no problems. I just recieved my fcr 39 and will be installing it tomorrow. This thing has really come alive with BBK and cams, can’t wait to see what the fcr does
This kit absolutely made my bike stomp all competition track and trail once paired with a ported racing cylinder head and the correct jets. This is money well spent. The last test the bike was clocked at 128mph on stock sprockets. Kudos to Athens and a list of other upgrades
Get your cylinder machined rather than buy this mass produced one. I dont think the quality is there. I would probably just take a stock 125 and do other mods to it. Not enough gain for the money imo.
I have 2 2004 CRFs, one stock and one big bore. Big difference in power and really aggressive bark. Much more torque on hand. You have to have intake valves on spec to start the extra displacement. I may go for kibblewhite valves to keep the compression over time.
Awesome part. Gave me alot more horsepower and a definately noticable difference in the corners. Overall worth every penny.
ATTENTION! To assemble the cylinder kit P400485100030 Ø 58 you need to make the boring of the engine crankcase.All ATHENA products, which are manufactured with higher displacement and power than those permitted by law of the country where the end user lives, are intended solely for competition-sports usage. Use on public roads as well as in aeronautics and marine is prohibited. ATHENA is not responsible for any different usage.The customer takes full responsibility that the distribution of the articles purchased from Athena is in line with the current regulations of his country and therefore frees Athena from whatever responsability in this matter.
Jet kits for the KLX110 come with a variety of jets so that you may fine-tune your jetting to your particular needs and conditions.