One very interesting modification that I did was installing some bigger carbs, they come from a VFR400. Sound funny? Well the stock carbs on the RVF400 are 29mm and the VFR400 ones are 30mm and go right on the RVF400. The only things you need other than the VFR400 carbs are the throttle cables and fuel lines. I ran them with a jet kit from FI International. The carbs and jet kit are a big improvement, bike has better power all over and revs better on top, see more about this below. I was informed of this modification from Stefan Simons in New Zealand and would like to thank him. If you want the jet kit you can get it from the NC30 Owners Club in England. Like to check out the Club's web page? NC30 Owners Club

I was recently informed by Stefan that the RVF400 carbs are better.  He had both carbs flow tested and the RVF400 ones flowed better, I never had a chance to reinstall mine and see what I could get the bike to run like.

I installed an HRC ignition module and it does seem to help the mid and upper rev range power. The bike revs faster but not as fast as an inline 4 cylinder motor but there seems to be more power now, need a dyno to really confirm this.

I did some airbox modifications and carb jetting trying to get more airflow into the VFR400 carbs.  I obtained an extra airbox top and intake rubber piece.  After seeing the HRC racing airbox top and knowing how much it cost I thought I could modify a stock airbox top to flow more air, not as much as the HRC one but better than stock.  After some cutting and trimming I come up with a better setup.  Once I installing the modified airbox top and rubber intake piece I adjusted the main jets some.  I started out running 115 main jets in the front carbs and 118 main jets in the rear carbs with stock VFR400 carbs, a stock air filter and the stock airbox top, remember stock RVF400 carbs have 108 main jets.  I installed the K&N air filter and the midrange and top end went lean somewhat, but I expected that.  I next installed the FI International jet kit in the VFR400 carbs and had 118 main jets in the front carbs and 120 main jets in the rear carbs but was still lean.  I finally got it running good with 122 main jets in the front carbs and 125 main jets in the rear carbs.  At this point I still had not done the HRC fuel petcock mod (listed below) and could feel some slight hesitation at high rpm and speed when shifting sometimes.  I then installed my modified airbox top and intake rubber piece, boy it went lean, carbs were getting some air flow now.  I adjusted the main jets to suite the modified airbox top and ended up with 138 main jets in the front carbs and 140 main jets in the rear carbs.   The bike runs good and pulls great through the gears with no problems, midrange and top end power are allot better than stock.  It might be just a bit rich right now but that was when it was really hot.  I know the jets are allot bigger than stock but the bike runs good and the plugs look good.  For a comparison the smallest main jets in the HRC jet kit are 142s and they go up to 158s.   Also remember that I did the jetting and riding right at sea-level and that helps power.  If you would like to see some pictures of the modified airbox top go to my RVF400 picture page.

I did the modification to the fuel petcock that is detailed in the HRC RVF400RR setup manual. The manual states that this is needed in racing conditions to prevent a fuel shortage to the carbs. It has you remove 3 parts from the fuel petcock, they include a rubber diaphragm, spring & collar. The modification does away with the fuel petcock being vacuum operated and changes it to a constant flow type. I also removed the vacuum hose from the petcock to the #3 cylinder. I installed a screw in the vacuum hole, just like the ones in the other cylinders and then capped off the vacuum connection on the petcock. After the modification I have rode the bike and notice a slight increase in upper rpm range performance. The bike runs much better on top, very smooth engine performance. I was not sure if this was going to help but after riding the bike I can say it did help my RVF400. Before the modification I was noticing a slight hesitation in the upper rpm's but it is all gone now!

Chassis & other stuff

I installed Earl's steel braided brake lines and Ferado brake pads front and rear. The front brakes are awesome now, best I have ever had on a bike. Interesting parts note, the rear brake pads are the same as the ones that go on the RC45. The front Ferado brake pad part number is FDB533 and the rear is FDB496R.

The stock foot pegs have been replaces with some BEET racing rear sets and I liked them. The BEET rear sets feel good and the rear brake has 2 pegs which is nice, you do not have to move your right foot much to find one of them. I have some pictures of them on the RVF400 picture page.

I polished the frame on my RVF400 and it made the bike look really cool. I did it with wet/dry sandpaper and a polishing kit that I purchased from Eastwood Unique Automotive Tools and Supplies. Check out their site? EASTWOOD

I also tossed the rear seat and replaced it with a seat cowl made by a place in mainland Japan called Silhouette Japan. I think it made the bike look better.  The cost of the seat cowl was 14,000 Yen, about $120.00 at the time with the exchange rate. If you would like one for your RVF400 contact Silhouette at the following phone numbers: 06(685)0870 or fax them at 06(683)2415. Please remember it is a Japanese company and they might not speak perfect English so faxing might be best. I was able to order mine through a Japanese motorcycle shop while in Okinawa.  I have some pictures of the seat cowl on the RVF400 picture page.

I ran a few sets of Michelin TX15/25 Race 3 tires and have nothing but good things to say about them. This was the first time I have used the Michelins but have not been let down. I saw a tire test in a British motorcycle magazine, SUPERBIKE, and they picked these tires as the best and I have to agree. Before installing the Michelins I had Dunlop GPR 70s and they seemed good but after installing the Michelins I could tell a difference. The Michelins have more tread to start with plus they are allot smoother on the road. The Michelins need some heat in them to feel good but they are worth it.

The stock speedometer faceplate is in KPH only so I have replaced it with one that has both MPH & KPH. The MPH numbers are shown larger than the KPH numbers. I discovered this replacement faceplate in Greybike magazine. Seespeed LTD in England sells the replacement faceplates for the RVF400 and many other greybikes. At this time I do not know of a web site they might have but you can contact them at the following address. Seespeed LTD, 8 Binghill Park, Milltimber, Aberdeen, Scotland, U.K. AB13 0EE. Phone number 01224-733888. The faceplate for my RVF400 was 29.99 pounds.  

Another item that might interest RVF400 owners in the states is that the oil filter from a Honda CBR1100XX and Yamaha '95 and up V-MAX will fit the RVF.

Things that you might need or want (things for sale)

I purchased the RVF400 shop manual and owners book but only the pictures help me since they are in Japanese. I learned that you can get a Haynes shop manual in English from the NC30 Owners Club in England. I bought one and it is very good. The manual covers the VFR400 and RVF400. You can also buy this book from Amazon.co.uk. If you want one of these books here is that link.