BBR XR/CRF 100 BIG BORE KIT Review

CRF100 Owners - Got BBR?

BBR Motorsports is synonymous with trick components for four strokes. They have one of the strongest brand names is all of aftermarket dirt bike components. No introduction is necessary. If you have a four stroke there’s a good chance BBR produces something you’ll want and it might even be something you need.

If you have a CRF100F, or its predecessor the XR100, you’ve likely wanted more power...no you need more power! You’ve probably looked at BBR’s big bore kits for the fiddy’s and wished they produced something for the CRF100. The wait is over with BBR’s 120cc Big Bore kit..

The CRF100F has been considered a great transition bike for those too big for CRF50F but still too small to handle a CRF150/230F. It’s considered by most to be a mini, albeit a big mini. In its stock form it’s not a race machine but rather a capable trail bike with mild manners.

QUICK FACTS

Price: BBR Motorsports XR/CRF100 120cc Big Bore Kit - $399.95 Compatibility: Models years 1981-2007 Includes: Everything for installation

The BBR 120CC Big Bore Kit promises to give more punch to a rather lifeless motor. Our friends at BBR sent us a kit to install and review. We were stoked to get started. Our test machine is a bone stock 2001 XR100 with tons of miles on it. We had several test pilots lined up that ranged in age from 13 to 45. Our plan was to install just the kit and leave everything else stock to get a baseline appreciation for what the kit alone delivered. Then we’d work to open up the intake and exhaust tracks and rejet the carb.

The Kit

One of the first things you’ll notice upon getting this kit, it’s typical BBR top quality design, components, and workmanship. This goes from the packaging down to the very smallest component. Everything you need to install this kit is included except for the know-how and tools.

The kit comes with the following:
• Exclusive BBR "big finned" aluminum cylinder
• Piston kit
• High performance camshaft
• HD valve springs with aluminum retainers
• Rocker arms with adjusters
• Gasket kit

BBR XR/CRF100 120cc Big Bore Kit

Installation

One of the things you won’t find in this kit are instructions. That’s right…no instructions. At first you might think that’s just wrong. Actually, in my opinion including instructions would be wrong. With slight variances from one model year to another, such as torque specifications or the like , it’s best to rely on the original source for instructions on doing a top end rebuild. If you don’t have a Honda shop manual for your XR100 or CRF100F get one before you install this kit.

Components and Comparisons

If you’ve never done a top end rebuild on a four stroke don’t be intimidated. If you have reasonable mechanical skills and can follow instructions, the Honda shop manual will walk you through each step. It can also be a great project for you and your young rider to do together. They’ll get a great education on how their bike works and be impressed with your “mad skills” with a wrench. However, if this kind of work isn’t for you, your local shop would be happy to do the work for you.

While I won’t be going through a step-by-step install procedure I do want to provide some useful information.

Installation Tips

1. You’ll need to remove the motor from the frame.
2. You’ll need a clean work surface that has plenty of space to lay the parts out

Tools You’ll need

1. A valve compression tool to install the new valve springs. If you don’t have one and don’t want to invest in one you can take the head and new springs to your local shop and they’ll charge a small fee to install them.
2. Feeler gauge for adjusting the valves after the install
3. A quality torque wrench
4. Assembly lube

The installation went very smooth with no major problems. All of the components were a direct fit with only one exception. The spring for the valve chain tensioner was not the correct length for our model year XR100. Fortunately, it was too long and was easily modified to the correct length.

A word of caution on installing the valve springs. You may be tempted to try an install them without a valve spring compression tool. DO NOT succumb to this temptation! All you will do is damage the head and valves and end up getting the tool or sending it out to be done. Save yourself the aggravation and your motor the damage and get the correct tool or have a shop do it for you.

First Kick!

After installing the kit and getting the motor back in the frame I was anxious to fire it up. For those with who have direct experience with the XR100 or CRF100F you know these bikes can be hard to start at times. I was prepared to kick like a mad mule but was absolutely shocked when it started on the FIRST kick!

Some questions I had were immediately answered. For example, would I need to rejet the carb to get this bike started? No. Would I need to rejet the carb to have it run correctly? No. Would it sound different? Not much.

With it started I was now like a kid on Christmas morning with a new toy. I couldn’t wait to take it for a quick spin and check out the power. All I can say is wow! What a difference 20cc makes. The old adage “There’s no replacement for displacement” was once again proven to be correct. There was more power everywhere; down low, mid, and up top.

Keep in mind this is still a stock XR100 with the exception of the BBR 120cc big bore kit. No jetting changes. No needle changes. No intake or exhaust changes. Just BBR +20cc kit.

Conclusion

Our primary test rider was the bike’s owner a 13 year old young woman who has logged tons of miles on this bike prior to the big bore kit. After her first ride with the BBR 120cc kit she came back and all she could say was “Oh my gosh…I love it!” Her smile was at least 20cc larger if not more!

Since the initial install, our test riders have logged dozens and dozens of hours with the BBR 120cc CRF. First, the product is rock solid. There has not been a single problem with the motor. It runs strong and starts on the first or second kick. Second, it has not burned or lost any oil during our testing period. Third, our primary test rider is asked after each ride how she likes the power. The answer is always the same, “I love it!”