Motorsports 120cc Big Bore Kit with Cam 411-HXR-1001

The quality of the kit was fantastic. Everything fit well and the motor started up and ran well on the second kick. I wish the kit came with better instructions though. I spent a great deal of time searching in a service manual and on the internet for torque specs and information on how to properly set up the kit. For instance they make no mention of setting ring end gap for the kit. The service manuals talk about how to do this but it was not until I called the manufacturer that I found out this was already set. Overall a great kit. It added a substantial amount of power and the kit was well put together.

This kit was complete minus the side cover gaskets. Installation was straight forward but a manual will help with torque specs or if you’re not familiar with these XR engines. Played with the jetting a little and ended up with a 40 pilot and 108 main. Modified the air box by drilling the top and side cover to allow more air flow. Modified the stock exhaust as well. All in all I’m very happy with the end results.

This is a no Brainer!!! I bought a 2006 CRF 100f for my Son about six months ago the motor was locked up and I about factory parts to Rebuild it with. The piston was froze up in the cylinder. I had to bore out the cylinder by hand with a cheap three blade hone. Simply because I couldn't find anyone to hone that small of a cylinder for me. being cast iron that took a good while to accomplish. the bike run pretty good and had a good compression. The bike run good for about six months and the cylinder started to egg still had very good compression and run very good just started to smoke. I spent about $300 on the factory parts to rebuild the engine to .025 over. I should have went the BBR kit to begin with. This kit was so easy I should've went this route to begin with not to mention the amount of power it did add to the bike. Don't get it confused it didn't turn it into some monster racing machine that a 10 year-old cannot ride any longer. But there is a noticeable power gain. It took us about 4 hrs to install. But that is in a shop that is set up to do that. It is a mediocre task if you're not familiar with engines and how they work. All I can say is do not waste your time on boring cylinders that smoke by this Kit and be done with it. Seller shipped right away as well.

This is an easy upgrade and can be done in a day if all goes well. Avoid a lot of frustration and do some preparation to make sure you have the right tools and parts before starting. You will need a valve spring compressor, ring compressor, and a good service manual for the bike as the kit does not come with instructions. You will need to become familiar with valve adjustment, timing chain tension adjustment, ring gaps/installation, and carb jetting. For me, this kit added a significant amount of power, so much so that I had to replace the 14/50 chain sprockets with 15/46s otherwise 1st gear was useless and 5th wasn't high enough. I'll bet I gained 15 mph in top speed and a ton of low end torque. I just did the upgrade a few days ago so I can't comment on durability/longevity yet. My only suggestion to the seller is that I wish you would have included a new set of valve spring retainers. Not because they wear out but because they are so easy to lose!

Good kit but needed to adjust rings to correct gapping

I put this 120cc kit on my 1985 xr100r. Came with everything needed to do the job. The bike is running good and packs a bit more punch. Just needed to do some minor jetting work. I left the stock valve springs and camshaft in place. I didn’t use any special tools.

I installed this on my 2003 xr100r took about 2hr of work time pretty easy to install there’s a few videos on YouTube to help out, overall I do notice a good amount of power added and before I was only getting about 45mph now i get around 55-60mph on my gps. Super recommend this product!

Installed this kit and have roughly 6hrs on the bike now and it definitely woke it up a fair bit. The kit seems decent quality and everything fit well. Definitely recommend it.

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So awesome