97 Vfr 750 To "vfcbr" Conversion (929Rr Forks / 600Rr Body)

This post will outline my 97 VFR to CBR 929RR suspension, electronics and CBR 600RR Bodywork. Like many people I've been waiting for the return of the RVF, a big 1000cc V4 in a sportbike package leaving the touring aspect behind.  I got tired of waiting so I did the next best thing.

NOTE:  The wiring is relatively straight forward, but you will need a 900rr temp sender to normalize correct temps to the gauge(notice the 255F pictured when cold) and you will need a SpeedoHealer V4 to correct speed differences, everything else works perfectly.

I left the coil packs in place but cut the long protruding fairing mounts off the coil pack mounts.  I clocked the coil pack mounts so that the radiator moves back just a little to provide clearance for the inverted forks at full turn. NOTE: turning radius is limited a little but only noticeable in a parking lot or when backing the bike into the garage at full clock.  The lower mount tab was oval'd out a little to pull the bottom of the radiator in as well.  I cut the hoses on my oil cooler and shortened them to mount directly under my radiator flush.  The fairings then used the factory bolt hole location on the VFR to finish bolting up. The upper covers of the fairings needed to be clearanced for the coil packs, the side covers needed to be clearanced fro the radiator hoses. Thats all.

I used a factory 06 CBR 600RR fairing stay, cut the tab off the end, cross drilled the remainder, and mounted it directly to the stock VFR fairing stay frame tab using 2 aluminum plates and 4 bolts. I have a 12 ton press so I sandwiched the aluminum plates between some steel ones to give them the bends but thats not required to make this work.

• 929 forks are shorter, period. Use fork cap extenders to gain length and clearance at full compression and or a custom upper clamp that can accommodate mounting them down lower. Both of these approaches are semi costly.
• Shorter forks also means less ground clearance, less rake, less trail, and less wheelbase. Understand these effects on handling and decide if this meets your riding style.
• 929 triple clamps have less offset. Understand this affect on handling. This brings the larger diameter forks closer to the headstock and thus closer to the frame which is why the forks hit the radiator/frame with less turning radius. 
• 929 forks have progressive rate springs so typical sag settings do not apply, if you are going to be pushing the bike hard then I recommend replacing these with linear rate springs setup for your weight. RaceTech has them for $99 US. You will need a special tool and some basic knowledge of forks to change them yourself.
•  As eluded to, while the front brake master can be made to work initially,  it is not an optimal long term solution, a modern Radial Master is recommended.

Awesome job.

Yep, great work.

Yes, very nice job.

I got to run the setup a bit harder today and everything is checking out good. I'll be finishing up the belly pan next and call it good.

Really nice work and especially nice to share your info with us. I had no idea it would be so easy to do. The thing that really surprised me was the simplicity of swapping over the gauges. Some lot of us went through save/replace/update the gauges on our V65 Sabres. I know you can't really compare a mid '90's VFR with a mid '80's Sabre, but still interesting. The Sabre was the first Honda that really went down the electronic road with gauges and doo-dads.

Thanks,

Glenn

Honda is really good about keeping the wire colors and functionality the same spanning some 30 years now. I'm about to do a digital gauge swap on an 88 Honda Hawk, same thing, looks straight forward!

Ignore my PM request, I somehow didn't see this thread. Awesome, awesome info! About time someone explained it in a bit more detail.

It seems a lot of people want more info on the 929 Fork swap and the resulting clearances. While the clearance lock to lock is reduced over stock, this is quite manageable. The shorter forks and loss of offset in the clamps however can pose a safety issue if you do not take the time to understand and account for the loss of available travel.  

Shown below are pics of my zip tie and measurement of the 5" of available travel. My zip tie showed I was not using the last 1 3/8" of travel even after purposefully mousetrapping a small wheelie. My fender showed no signs of contact but that doesn't mean it wasn't happening. It's important to note that i weigh 200lbs with full gear on these tests so your mileage may vary.

Removing the forks caps and compressing the front end shows exactly where the front fend first makes contact with the radiator, and the measurement shows this happens at 1 3/8" from full compressing, right where my zip tie was.

Any shims under the rear shock ?

The bike currently has the stock VFR rear shock installed with a set of raised triangle linkage plates (easy to make). This setup actually works pretty well other than the lack of any fine tuning. After tomorrows big round of testing on the front end, I will reinstall the CBR 929 rear shock and start testing that.

What an absolute blast this was yesterday. I spent a 4hr session in the hairpins, dialing in the compression/rebound and by the last hour the bike was performing better than it ever has. The forks never used the last 1 1/4" of travel leaving a good margin of remaining clearance as is. As a budget build goes, you CAN do this on the cheap with a little attention to detail. Pics of the session to come hopefully later tonight or tomorrow with before/after shots in the same corner.

My experience with fiddling around with front fork travel limits is, if the travel is there, especially on the street where road conditions can never be predictable on every ride, eventually your bike will find that bump or pot hole that will use it all up, even if you crank in all the preload you can, the front forks will eventually get bottomed out, somewhere, some time on the street. So it is still best if you can find a final, permanent clearance solution to the radiator/fender/tire encroachment issue.

You are somewhat correct in relation to stock forks, however, sometimes the preload is enough to accomplish coil bind before bottoming out. If you read up in the previous posts, I recommend using fork extenders and correct springs as a proper means to solve the clearance problem entirely before bottoming out. I do not currently have mine installed but wanted to give an update none the less for those considering the 929 swap. This kind of information allows planning and staging to making it all come together slowly rather an all at once.

Another low tech solution is to promote coil bind as a sort of bump stop before full compression, by cutting the spring down. While this is more often done on standard forks, it also works with inverted forks where the springs are too soft and ample range of motion remains. Cutting a coil spring down and increasing the spacer length will effectively increase the spring rate (even more on progressive springs like the stock 929 if you cut the softer side off). Clearly you do not just arbitrarily cut of a random length, there is some math and measuring involved to get this just right. I only bring these up as short term solutions to doing it right, for those limited on means.

Well that's a pleasant surprise, my bike made the VFRD feature picture.

Possible to move the radiator up or back slightly?

Unfortunately the radiator is as far up and back as possible. Only solution is longer forks and/or larger triple clamp offset.

Have you tried making new mounts?

For the radiator? Yes, I modified the stock mounts which allowed me to clock the radiator back farther but it is hitting the neck and front head. The solution I plan to use to solve my remaining clearsnce is to use fork extenders. This provides just enough length at $200.

You can cut your top-out springs in half too, and add the length to the preload spacer.

The 929 inverted forks do not have a top-out spring, that's typically found in standard telescoping forks. However, you could similarly cut the softer side of the progressive main spring down a bit and add a spacer so as to promote coil bind as a way to limiting travel. A side affect of this would also increases spring rate which in the case of the 929 springs would be a step in the right direction. Good low budget hacks for sure. As I'm not fond of the progressive springs to begin with I think I would opt for replacements like the racetech ones and use the fork cap extenders to retain full travel and no contact.

Cutting the top out springs doesn't limit the fork travel, it increases it.

I was drawing similarities between spring cut methods since the 929 inverted forks in my build do not have top-out springs, hence your method doesn't apply in this circumstance. On factory telescoping standard VFR forks, yes, you can gain distance from the radiator using your method. However, if you were using standard VFR forks you wouldn't have a radiator clearance issue to begin with ;)

sooooooooooooooo...can I bolt on CBR forks and not worry about dying? :cool:

I can't speak for you, your mileage may vary, but just doing the simple things I have outlined brought the bike to a respectable session on the mountain shown in the pics below.  In your specific case, I would imagine the only thing you will run into as a problem will be moving the radiator back a little and clip-on clearance as your stock bodywork will complicate these two parts. Aftermarket clipons will likely solve one, and a little bending at the coil for the body mounts could remedy clocking the radiator back as well.

I had a hard time recognizing the VFR in the pictures as it looks so different with the CBR fairings. By the 4th hour of testing I finally had the compression/rebound where I like it, the bike was entering the corners with confidence, holding a line and exiting where I wanted it.

A few odd corners on the hill require getting on/off the brakes on corner entry due to bumps in the road or lane position due to oil,dirt, etc. Braking stayed consistent all day.

Where I notice the biggest difference is in transitioning from one direction to the other in the chicane. The bike flicks over easier and has lost its little bobble when setting it down on the other side.  

I can't stress how much I like this thread. lol.

:) I've been riding it so much lately I don't have any new progress towards additional mods. I had a big scare with an animal in the middle of my lane mid corner on a twisty section of mountain and the bike panic performed like my ZX-6, hard brakes, rapid flick full peg to peg with no drama. I would surely have dropped it on the other suspension or tagged a guardrail. Big thumbs up on the brakes, geometry, and rigidity!

While the front end is all CBR 929rr now, the rear is still stock with an exception. Being 6' 200lbs, my 97 felt a little too low and plush even with the preload max'd out. To remedy this on the cheap, I long ago modified the swingarm plates to raise the ride height and to stiffen up the rear shock a little  looking for more lean angle and had great success. When I started sharing the bike with my 5'7" 130lb girlfriend, I had to think reverse and create a lowering kit. The geometry below is the result of many generations of plate testing for both scenarios. This last prototype I'm still running today has worked so good I really don't think about it anymore, so I never returned to make a final pretty set. 

I'm sharing the geometry below for those capable of making their own plates and not wanting to risk trial and error. A lot of time went into working out the triangulation so if you don't know what you are doing, I recommend you do not alter any of the measurements. The wrong triangulation can result in limited/exaggerated travel, too soft/hard of ride, or the worst of either of those simultaneously.

Nice engineering work there. I added a 4th gen dogbone to my 5th gen to raise it over an inch, might be another option for lowering the 4th gen with the 5th dogbone. Clearance is very tight though and I've played with alternate triangle configs.

Does the bike perform as well as the other bikes you run with ?

Looks like you run with a fast bunch .

Have you had any clearance issues w/ your left side exhaust and what tires and sizes are you running. thanks for sharing your setup

Switchblade

Does the bike perform as well as the other bikes you run with ?

Looks like you run with a fast bunch .

trjerm

Have you had any clearance issues w/ your left side exhaust and what tires and sizes are you running. thanks for sharing your setup

Sorry guys, I never received notification that you replied.

Switchblade, yes it is a fast group. The VFR is what it is when it comes to the modern bikes. Its heavy, down on power, and has a long wheelbase, all of which put it at a disadvantage. That being said, even in stock form, the bike can be made to corner really well. That means making sure the front/rear springs are setup correct for your weight, the dampening is setup correct, and by simply by raising the front/rear to gain much needed ground clearance ( using triangle plates as outlined above, using a 929 rear shock with the height built into the upper mount adapter, or a $$$$$ extendable shock like Fox, Wilbers, or Ohlins). I used stock suspension with triangle plates for a long time and did just fine, the VFR has exceptional drive out of the corners with the V4, and when geared down a bit will out sprint a lot of bikes above its class, to about 100mph and then the tables turn. The stock brakes had a hard time pushing hard for long periods of time on the mountain. This was my primary reason for wanted to go with the 929 inverted forks, big brakes!!!

Trjerm, I've had zero clearance issues with big tires and the left side exit header, it seems to have about the same clearance as the right side exit header.

Having run the 929 forks now for a good length of time, I'm very happy with them other than the length. I'm having a machinist make up a few sets of 1" Fork Cap Extenders, one for myself and one for a friend. If there are others trying to solve the length issue I might be able to increase this one time run. We haven't discussed cost yet, and I'm not going to make a business out of this, simply a few extra sets to the most needy, first come first serve. PM me if you are interested and I will let you know what the split would be between us. They will basically look like this in forged aluminum created with a CNC.

I currently have and have had lots of 2 wheel toys from 25 years of riding, countless trips on the mountain with them in all kinds of weather. I really love the VFR even though its not necessarily the best thing out there. It's just one of those rare intoxicating bikes to ride. But even stacked up against these little gems, I still choose the VFR every other weekend!

About a year later and this conversion is still doing great.

Looking good!!!!!

Pity all your previous pictures are gone.... 

I'm glad you said samething, I didint notice that.  I was able to backfill most of the pics so this thread is valid again! :)

Did you ever get the forks extended?  RC51 forks would swap right in, but would be significantly longer.  Might need to drop down to 320mm discs, though, and probably need a new wheel or some adapters/bearings.  Well within your capabilities, whatever the issues!

[EDIT: The difference in length between RC51 and 929 forks is 25mm, so there's your inch in old money.]

Ciao,

I never did extend the forks, and to be honest it doesn't really need it when positioned correctly. I looked into the RC51 forks and it was substantially more effort and money to source various parts to make it work when the CBR954 was a straight easy cheap swap.  I've put over 12k miles, mostly knee dragging the hairpins and with the VFR's additional weight I'm happy to have the bigger rotors. 

Update: The 05 CBR cluster requires the addition of a 1 watt 300 ohm resistor between the fuel guage and stock vfr fuel sender to read empty correctly. I'm looking forward to a good 300 mile San Diego mountain/desert tour tomorrow to put the CBVFR through the paces.

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Nice work! I always love those that take the plunge first and share the risk/rewards with others! My 599 went through a lot of this similar process thanks to the help of others.

I miss Palomar......

Beautifully done! #popcorn