S Stage Tuning Kit 138cm³

I have used and abused the bore up kit for 2,500 kilometers of hard trail riding, steep hill climbs, river crossings and all day hi way runs to get to the trail. In my opinion, the quality is as tough as the factory block. I have used a different performance camshaft from Taiwan using the stock valve springs. Take note and change to a 7 or 8 spark plug heat range. Paired with a free flowing muffler and 26mm round slide carb with the correct jettings, the output and response will be similar to a KLX 150L or CRF150L. For trail, try the 13 53 sprocket combo and it will crawl the steep hill climbs that the stock engine can't.Here's a video of my xtz in action: https://www.youtube.com/watch?v=fX5T-xDRnGk&t=2520sI hope there will be a 65.5 takegawa bore up kit.

Nice upgrade for XTZ while it was running.Package nice, arrived on time. Installing was easy, broke in went without problem, after that engine was running more quiet, smooth than stock. (Process: Installed RPM gauge, 1500km/30h, 4x oil change 20w-50 Yamaha mineral oil, 95RON, from short rides on low rpm end till extended rides at top end).1-2 horse more, consumption ~25% increase, more response, no top speed gainAfter broke in:Oil 10w-50 fully synt (used with stock engine for 15000km without any problem) and it got overheat (stopped forever) from the first 180km of motoride (cruising only with 6500-7500rpm - as used to do same with stock)Total made 1700km. Item sent back for inspection (big thanks to Webike staff). Takegawa said (without inspection): Designed for Japan domestic gasoline! After inspection they said: it was not broke in well. (Would say the same, if I did not do that broke-in process above)I say: this kit not designed for longer rides, or if you do so, use very thick oil only (non performance - mineral).One more thing: Since the sidewall is tiny u cannot go up even by .5mm later. Webike staff: 5 stars plus!

It's well made and the performance is fine
You will definitely feel the torque up
It's not a Large wide Bore up, so it's still very Engine friendly
The cheap ones made overseas were inaccurate or had to be machined to be installed, even if they were expensive In some cases, it may be cheaper to buy from a reliable manufacturer It is

I purchased the kit for my Yamaha YB125SP without camshaft as I was unsure of the performance value. But after installing the bore-up kit I immediately order the sport camshaft at a later date. The kit really add more torque and high-end power, making it more enjoyable to ride.I'm quite heavy (88kg) but the bike now accelerate fast and achieved top speed of 120kmh on highway (I think the real speed may be more than 120 kmh because the stock speedometer is limited at 120 only). With passenger, acceleration is still good and top speed is limited at 115kmh.I find this kit worth every penny and will recommend anyone consider buying also get the camshaft combo.

I was able to install it almost as a description, it was for YB125SP but there was a bit of anxiety and ordered with without Camshaft I regretted it, (Purchased at a later date) As Torque rose from 125 to 138, traveling became easier, like a young man I can not run but I'm satisfied but I am going to disassemble a part of Engine, so Gasket and O- Ring should have a new item ready