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What to Race in AFM 450 Superbike and Production

Often, I get asked what bike is a good choice for racing AFM 450 Superbike. I'm a little biased because I race a VFR400, but that doesn't mean this is the best bike for everyone. I'll give some details of each bike that is legal for the class and then you'll have to decide what is best yourself.

AFM 450 Superbike allows any bike from greater than 250cc to 450cc + 1mm. Generally, this means the Yamaha FZR400, Honda VFR400, RVF400 and CBR400, the Kawasaki ZXR400, and the Suzuki GSXR400. Also, because 600cc or less twins are allowed to run down a class, you'll find many of the AFM Formula 500 twins people running in 450 SB. These are mostly Kawasaki EX500s, but one person has been very successful on a GS500. Some singles racers (who are allowed to run down a class) race in 450SB, but they don't tend to be competitive, using the class for practice time.

AFM also runs 450 Production, but this class only allows bikes that were sold in the USA, and they must run the stock exhaust and airbox. This excludes all the grey market imports (VFR, RVF, CBR, GSXR, and ZXR 400s). You can run a 500 twins bike down a class in 450 Production, but I believe doing so, you would be excluded from running the same bike in Formula 500 Twins that day because you are not allowed to run Production and Formula on the same bike on the same day. Even before that rule existed, you would have to run 500 twins with a stock pipe and airbox. Being a formula class, you would be giving up a lot of potential power just to run a Production class. Most 500 twins racers run 450 Superbike and not 450 Production, leaving 450 Production filled almost exclusively with the FZR400.

A couple people have raced the Honda CB1, a 400cc four cylinder bike which was imported into the US for a short period, making them legal for 450 Prod. They haven't been competitive compared the FZR400, however.

It is worth mentioning that outside AFM, there is the "lightweight" race class, a class made up of bikes making around 50-60 HP in stock form, regardless of cylinders. For most of the '90's, the FZR400 dominated these classes, up until the Suzuki SV650 came out. The SV650 makes good low end torque that allows it to out power the FZR400, and now the SV dominates the lightweight classes. AFM, however, separates the 400cc fours from the 650 twins, which is unique in club racing in America, breathing more life into the venerable old FZR400.

Although most the bikes used in 450 Prod and SB were manufactured as 400cc bikes, the class limit is 450cc + 1mm. This is for historical reasons related to '80's model 450cc motorcycles that were common before the FZR400 came out (I forget the models). Because the rule has stuck, there are many 400cc bikes in 450 Prod. and 450 SB that are bored out to 450cc. Such bikes are capable of 80-85+ HP whereas the original 400cc engines usually made 55-60 HP. Other race clubs often allow up to 500cc four cylinder bikes in the "lightweight" classes.

What to race in AFM 450 Superbike and 450 Production
Details About Different Bikes

Yamaha FZR400

Most people race the FZR400 because they are very common and easily obtained. In 450 Production, the FZR400 is almost the only choice because the grey market bikes aren't legal. With an FZR400, you can race both 450SB and 450P on one bike. Unfortunately, Production legal FZR400s aren't very competitive against the best superbike machines, which have the advantage of running a full race pipe and significant carburetor mods. That doesn't mean you can't do well on a Production legal FZR400. People have made the podium many times on their Production machines, but as competition increases, it gets harder. Some people have two FZRs, one for Prod, one for Superbike. It helps justify the cost of two bikes, having the Prod bike as a backup for Superbike and being able to transfer most parts between the bikes.

The FZR400 was sold in the USA from '88 to '90. Because of the SV650 transition, there are a lot of decent race prepped FZR400's available. Many of these bikes will have significant modifications as well. Often, for $2000-$4000, you can pick up a bike with mods that would have cost you thousands more to duplicate (better wheels, brakes, frame updates, engine improvements, flat slide carburetors) including spares and other useful stuff. The down side is many of these prepped bikes have been raced for the better part of the last decade, so you have to be careful not to pay too much for a worn out or beat up FZR. I have seen several people buy old race bikes only to have them be a constant source of frustration. If you look around, or are willing to spend some time and money making the bike reliable, you can find some good deals. Look for a chassis with good upgrades, but don't trust the engine unless the previous owner can show that it is in good shape.

The FZR's one major problem is overheating. I chased this issue for a while and in the end, the only conclusion I came to is the problem is a combination of the cooling system being under-designed and that these bikes are now all over a decade old. They don't work like they used to. With diligence, it is possible to overcome this issue, but certainly part of why I moved to the VFR400 is because I was tired of being diligent.

The FZR400 is an excellent bike to start racing on, and very capable of carrying you through many years of racing. Even through the late '90's, an FZR400 with a FZR600 engine was considered to be one of the best 600cc motorcycles you could get, which says a lot for the bike's frame. As good as the frame is, however, it isn't the best 400cc frame available. A soft rear shock linkage and older damper rod forks limit the bike compared to the grey market imports legal in 450 SB. It is common to replace the stock forks with something better, but you can only go so far. In comparing the FZR400 to the VFR400, I feel that the FZR is an easier bike to ride initially, but eventually, the VFR provides a more precise performing frame that is more forgiving as you push it to the limits.

Stock, the FZR comes with an 18 inch rear wheel which has been a problem due to lack of tire choice. There is 18 inch rubber that is good enough for 450 Production. In Superbike, it is best to get a 17 inch rear wheel as slicks aren't available for 18 inch rims. This requires custom fabricated parts, or hopefully, finding a used bike that already has a 17 inch rear. Note, 17 inch wheels are legal in Production as long as they use the stock brakes.

The FZR400 will likely continue to be the most popular bike for the 450 classes simply because they are common and easy to buy for cheap.

Honda VFR400/RVF400 (NC30 and NC35)

The VFR400 (NC30) and RVF400 (NC35) are basically the same bike. The RVF has some minor frame changes, some improvements to the engine, a 17 inch rear wheel (vs. the VFR's 18 inch wheel) and upside down forks.

The fork internals are the same between the bikes, so many feel that the upside down forks only add weight. The frame modifications change the weight bias of the bike a little. Since I haven't ridden an RVF to compare, I can't say if these changes matter. Regarding the engine, the RVF has 2mm smaller carburetors and intake valves, but the carbs are a better design. Also, the RVF pistons are a little lighter. The RVF makes less power than the VFR, but that is more due to the Japanese regulated maximum power than the changes. The RVF was tuned for better low end compared to the VFR. Such tuning differences can be overcome with different exhaust, intake, jetting, and porting. Because the differences are so minor, and because VFR400s can be purchased for much cheaper than the more desirable RVF400, it makes better sense to chose a VFR over an RVF for racing. The money you save can be used to make a stock VFR much better than a stock RVF.

The rest of this article will comment mainly on the VFR400, but because of the similarities between the two bikes, most comments are applicable to the RVF as well.

The VFR is a noticeably more advanced design compared to the FZR400. This isn't surprising considering that a VFR400 is a 400cc duplicate of the Honda RC30 and that it came from Honda's racing division (HRC), not the street bike division. Just like the RC30, the VFR400 was designed from the ground up as a race bike. This is important for two reasons. 1) Honda considered reliability to be critical to the success of their racing program (hence why the RC30 was the #1 bike for endurance racing in it's time), and 2) the VFR400 is designed with many features not found on other bikes. Examples include the slipper clutch that allows down shifts without causing significant rear wheel slides, a close ratio gear box, a more centrally located weight bias (part of the benefit of the single sided swingarm), and a fairly extensive race kit available for the bike. Unfortunately, most the race kit parts are unavailable, or too expensive to buy, but after market duplicates of the most important parts are available.

Engineering differences are nice to compare on paper, but how much does it matter in the real world. Having raced both the VFR and FZR, I much prefer the VFR. There are two reasons for this, power delivery and the precision of the frame.

The Honda V-four offers some of the benefit that makes the SV650 so successful, the torque of a V type motor. In comparing my 74 HP FZR400 to my 72 HP VFR400, the VFR made the FZR feel anemic. The VFR has a broader power band, and the low end on the VFR allows the bike to pull out of corners harder, right from the apex, which translates to more speed exiting the corner. A VFR making 72 HP, for example, feels the same as an FZR making quite a bit more power.

The precision of the frame, however, is the part I like most about the VFR. I said the FZR has a good frame, but not the best. I don't know which 400cc bike has the best frame, but the VFR frame is noticeably better than the FZR frame. The best way I can say it is that the FZR seems like it is physically easier to ride than the VFR, making it a better bike for beginners. But, as you push the limits, the VFR seems to take it better. It is mentally easier to ride because it does what I ask with less complaint. When comparing both bikes back to back on the same track, the greater confidence the VFR gave me was good for 1-2 seconds a lap time improvement vs. my FZR400. The difference in the frame also shows up in hard braking. I have gotten my VFR into a stopie and partly turned sideways under very aggressive breaking (hitting the brakes harder than I wanted), but instead of spitting me off, it seems to hold its stability and keep a straight line like it was no big deal. The FZR, on the other hand, would go into a wobble when trying stuff like this.

Other things to note about the VFR are it's cartridge forks (with rebound adjustment) which are better than the FZR damper rod forks, the single sided swing arm which allows for easy rear wheel changes and no need to adjust the chain alignment, a more modern riding position compared to the FZR, and four piston front brakes (the same calipers used on the first CBR900RR). Plus, you get Honda reliability. Of course, the downside of the single sided swing arm is increased weight and complexity of design. For my purposes, I still prefer it due to the ease of maintenance. Also, the V-four engine is more time intensive to tear down. Getting to the pistons (to replace rings, for example) requires cracking the engine cases apart because the cylinders are an integral part of the upper case half.

Why would anyone race an FZR when the VFR seems so much better? Because a race prepped VFR will cost a lot more to find, or build. The big advantage of the FZR is they are everywhere. But, finding a VFR may require getting one imported and then you still have to build the bike up for racing. Importing a bike may cost about $3000 and perhaps another $3000 to get a good shock, race pipe, 17 inch rear wheel, race body work, and other stuff for racing. You can find VFR or RVF bikes already in the US, but they tend to sell for a premium because they are rare. If you find a race prepped VFR, chances are, you'll get a good deal on it compared to the cost of building one yourself, but such bikes are even more rare as current owners don't sell them very often.

Other 400cc Bikes

I have limited to no experience with other 400cc fours. The VFR/RVF400 seems to be the most common grey market 400cc sportbike found in America and the UK, but others can often be found. The CBR400, GSXR400, and ZXR400 seem to be similar to the FZR regarding power delivery. All of them are in-line fours, so by design, they make power more like an FZR - peaky - rather than a V-four. As for which inline 400 four makes the most power, I have no idea. In stock form, they are all limited to the Japanese 58 HP barrier. What can be gained by uncorking them is less known as fewer people have spent time and money researching these bikes compared to the VFR/RVF and FZR.

The Kawasaki ZXR400 is very much like an early '90's ZX7 with a 400cc engine. Many of the components are interchangeable between the bikes (and the frame is very similar I believe).

The Honda CBR400 is more akin to the CBR900RR in styling (and actually looks more modern than the VFR/RVF400 even though it is still an old design). It has a wide fuel tank and twin spare frame with a narrow seat. The narrow seat actually makes this otherwise wide looking motorcycle better for short people compared to the other 400cc fours as they can get their feet on the ground better. Like the ZXR, many components are interchangeable with the CBR400 and other American sold Hondas. Hence, some performance parts made for larger Honda bikes can be used on the CBR400.

My knowledge of the Suzuki GSXR400 is practically nil. I have only seen pictures and read very little about it. Styling is similar to the early '90's GSXR bikes sold in America, including some nice color schemes.

The FZR400 was imported into the US for only three years ('88 to '90). A later model came out with an enhanced frame and other improvements but was never imported to the US. It was the Yamaha FZR400RRsp. Yamaha decided to come out with a more serious 400cc race bike. The RRsp was the result, including a fairly extensive set of race components available from Yamaha. Unfortunately, I know very little about this bike as well, but my understanding is that the RRsp is noticeably better than the original '88-'90 FZR400, making it more competitive vs. the Honda machines.

Worldwide, the VFR/RVF400 seems to be the most popular 400cc sportbike. There are more V-four enthusiasts today than for the other bikes, including a continuing stream of new aftermarket parts being made for it. This popularity may be more related to the trick nature of the V-four and the single sided swing arm rather than actual race performance. After all, the VFR400 is a baby VFR750, which is considered to be one of the best street bikes ever made (according to many magazines) even if sales figures didn't show it. The FZR400 is probably the second most popular, due to the US market and a strong showing elsewhere. The CBR400 comes next, followed by the others. I may be wrong about this, and I would happily update my comments if someone can direct me to some actual statistics. The main point is, the Hondas and the FZR have a strong cult following, especially in the UK, and the others seem to be less popular.

Other Bike Options for AFM 450 SB and 450 Production - Twins and Singles

AFM rules allow twins and singles to run down a displacement category. Here is a summary about twins and singles in the AFM 450 classes.


The Kawasaki EX500 is the most versatile bike to race in 450 Superbike. It is legal and competitive in Formula 500 Twins and 450 superbike, and can be raced in AFM Formula I as well. An EX500 is a little down on power, but if properly built, and with updated forks, it can probably do well in 450 Superbike. Less popular (because it is harder to make power on them), a GS500 can also do well in 450 Superbike. Bobby Brousard has proven this after spending much time squeaking the power out of his bike.


I don't know much about Singles and how competitive they are in 450 Superbike. Generally, singles max out at 650cc, and a 650cc single doesn't make enough power to out run most the 400 fours or the twins. In the April 2003 AFM race at Sears Point, someone entered a Ducati Supermono and was doing very well, leading the race for 2-3 laps before pulling off the track. But, for reasons that were not made clear to me, that bike is not legal for the class (I think because they aren't actually street legal in any country - hence they aren't legal for Superbike in AFM). Regardless, it was interesting trying to chase down a $30,000 limited production race bike.

Parts and the Grey Market Bikes

It is obvious why the FZR400 is the most popular bike in the AFM 450 classes, being the only 400cc sportbike imported to the US. But, another reason for this is because of parts. Racing a grey market import means dealing with the issues and long delays to buy parts, most of which must come directly from Japan.

Thankfully, there are companies in the US that specialize in grey market imports and parts. GPStar deals with most all models, and G-Force provides direct support for the VFR/RVF400. Regardless, when racing a grey market import, it is necessary to make sure your spares kit is complete as some parts may take 2 months to obtain from Japan, or longer if you need to find them in a junk yard in a foreign country. With an import, at minimum, it is good to have a working spare engine handy in case the bike's engine suffers a failure mid season. Without a spare engine, you might be sidelined for months waiting for parts to replair the old engine. Luckily, with the VFR/RVF, G-Force is stocking most parts needed for an engine rebuild.

The best way to overcome the parts issue is to get connected with other grey market bike enthusiasts around the world. For example, the 400greybike BBS and web site is a central meeting place for grey market 400cc fours. There are forums for all the 400cc fours mentioned above, but this BBS is mostly a VFR/RVF list. For the FZR400, the best resource is the email list.

The Future for 400cc Race Bikes

It seems, for now at least, the age of the 400cc sport bike has come and gone. It started because of the Japanese licensing and horse power limits, and a customer base that desired 400cc sport bikes that delivered everything the bigger bikes had (except power). Through the '80's and early '90's, some of the most interesting motorcycles of their time were produced in 400cc trim (the FZR400 aluminum frame vs. the FZR600 steel frame, for example). More recently, however, the market has moved toward more standard style 400cc motorcycles (or twins). The new 400cc standards are of a cheaper design, and often technologically a step back as they are designed for a more novice market where price is more important than performance. Hence, the 10-15 year old designs remain the main choice for 400cc racing.

Perhaps the pendulum will swing back in a few years and the 400cc sport bike market will blossom again. Time will only tell. Whatever happens, it's important to remember that this pendulum swings in many different directions. Right now, it has swung in the direction of the 650 twin (a good race bike) and the standard 400 four (basically a beginners bike). The next swing might take us somewhere completely different. Regardless, investing in a bike for AFM 450 Superbike or 450 Production is likely to be a long term investment, as compared to having to buy the latest 600, 750 or open class bike just to remain competitive. All of the 400 fours (as well as the EX500 and GS500) discussed above are 10 year or older designs. Even if a modern 400cc sportbike came out, the old bikes would still likely hold up well against it.

(initially written May 4, 2003)

Last Updated: Wed, May 14, 2003

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