My rear F@ conversion.....

Looks nice, don't forget to rethink the chain setting when you raise the ride height by lengthening the shock. I raised mine 1.5 inches, checking it on the centerstand my chain slack needs to be at 47mm now instead of the stock 30mm setting. Otherwise when the swingarm is in the centerline (about mid travel)... countershaft sprocket/swingarm pivot point and axle in line the chain will be extremly tight. I'm running 16/42 gearing.

 

Okay as Jamie said, hondavfr.org is the best step by step...The ENTIRE rear wheel is what u need. Cush drive, sprocket(F2), rotor and everything and the VFR Rear AXLE...now the rear caliper bracket is up to you. If u use the VFR real caliper bracket, u just have to get it cut and rewelded SHORTER to fit the the CBR F2 rear rotor and bend the torque arm into "S" shape OR just GRIND the INSIDE of the TORQUE ARM DOWN...and the stock spacers should be fine. For the CBR F2 rear caliper bracket, u just have to move the torque arm to the outside and drill and tap the CBR F2 caliper bracket. (No need to bend the torque arm). the only challenge is finding the best spacers cause the CBR F2 caliper bracket is not as THICK as the VFR caliper bracket. but its not as hard as the Front i think. Ive been slow rebuilding lately but im pretty much done with "HARD STUFF". Ill get pics of each component TODAY...ALSO if u are using the F3 shock which is what i HAVE u wanna make sure the EXHASUT still fits....Ill take pics of that ALSO so u can see what i came up with.

 

ok fatso, that brings up a few questions....

(1) can the F2 caliper bracket be used with the VFR caliper?

(2) if the VFR bracket is to be used, exactly *where* would it need to be cut (as in i know its about 11mm of bracket that needs to be removed, im just not 100% sure as to which 11mm of material it is in question).

(3) where and how does the F3 shock interfere with the aftermarket exhaust? i have a 4-2-1 Laser baffle on mine now and I'd really like to NOT jack around with modifying the exhaust if i can get away with it.

(4) would grinding the torque arm/link compromise its strength/integrity? if not, I may just be lazy and do that to handle that aspect of the build.

 

Nope, the VFR caliper does not fit the F2 bracket. It's never that easy!

Yeah, cutting and welding the bracket is a bit nebulous. As long as it's perpendicular to the line going from the axle to the center of caliper you should be ok.

 

might anybody have an example of the work done on the VFR bracket?

 

What spring rate have you come up with for the F3 Shock? Anyone know the stock F3 spring rate, I think it's 750 lb but not sure.

 

(1) can the F2 caliper bracket be used with the VFR caliper? b Like Jamie nope wont work.

(2) if the VFR bracket is to be used, exactly *where* would it need to be cut (as in i know its about 11mm of bracket that needs to be removed, im just not 100% sure as to which 11mm of material it is in question).

Thats why its a lot easier to just DRILL and TAP the CBR CALIPER BRACKET...and u can use the CBR REAR CALIPER and BRAKE.

(3) where and how does the F3 shock interfere with the aftermarket exhaust? i have a 4-2-1 Laser baffle on mine now and I'd really like to NOT jack around with modifying the exhaust if i can get away with it.

I am using a 4 in 1 yoshi, and because of the design of the Yoshi, it would HIT the lower part of the modified shock. So i added some "extenders" to the headers making them an inch or so longer so when exhaust would be BEHIND shock and in front of REAR wheel i take pics in a few.

(4) would grinding the torque arm/link compromise its strength/integrity? if not, I may just be lazy and do that to handle that aspect of the build.

Not sure if the grinding will mess with integrity...but the "S" shape seems easier...just a vice and some heat...

but ill take pics right now.

 

im not sure...thats actually a Jamie Dautghtery question.

 

where do i find the URLS for the uploaded pics i put in my gallery?

 

i think this is one of the pics you were looking to post here...its a good one of the spacer between the torque arm and the caliper mounting bracket...

IMAG0185 - VFRworld Photo Gallery

 

IMAG0185 - VFRworld Photo Gallery
u can see rusty spacer between torque arm and caliper a little better...

IMAG0184 - VFRworld Photo Gallery
CBR F2 520 sprocket, i'm gonna go to F2 530 sprocket so if anyone is interested in 520 sprocket..I GOT 1...i think its up 2 over stock..dont remember...

IMAG01831 - VFRworld Photo Gallery
exhaust bracket i fabbed up...

IMAG01821 - VFRworld Photo Gallery
stainless steel brake line, tried to get spacer thats between torque arm and caliper..i think i measured it at 14 mm. i think.

IMAG01811 - VFRworld Photo Gallery
CBR F2 brake caliper and caliper bracket. bolt is where i drill and tapped for torque arm..

IMAG0180 - VFRworld Photo Gallery
had some extenders/adaptors welded to the headers to make headers a longer so that the yoshi exhaust would not hit modified shock.

IMAG01791 - VFRworld Photo Gallery
Modified CBR F3 Shock.

IMAG0178 - VFRworld Photo Gallery
91-93 CBR F2 , with Gold valve emulators installed

IMAG0177 - VFRworld Photo Gallery
CBR600RR Tail.

IMAG0175 - VFRworld Photo Gallery
How SHE sits now.

 

Here is a comparison of the stock bracket and one cut down for the CBR rotor:



Here is another one:



And one more:

 

I had a new stay arm built, rather than grind the stock one. Didn't cost much, and works great. Did have to drill out the bolt holes in the caliper bracket and swingarm tab to accept 3/8" hardware instead of the 10mm because I used american-size rod ends.

Pic:

 

My 87 has been thru several iterations that may help with folks deciding on ride height issues.

When my GF owned it, we installed a shorter 18" tire on the rear - 70 vs 80, or 60 vs 70, or 10% less sidewall than whatever was stock. Maybe even 20%, I dunno, it was ~18 years ago. And we lowered the forks in the triples a bit, 'cuz she was short. The important part is this: when I bought it from her, put a stock size tire back on and put the forks back to stock it handled NOTICEABLY better, more responsively, lighter.

Later, I put on a Fox shock, which was awesome. This was still with stock 87 wheels/tire sizes. Then I raised the rear ride height ~12mm over stock. It was even MORE awesome! You do NOT want to lower the rear of your VFR. Do the mods right and get the ride height where it belongs!

Then I did a CBR swap and got a Penske shock. Oh, and put in a 750 motor... That was ~10 years ago and it's still apart. I am REALLY going to put it together this year!

HTH

kevin

 

is it possible for you to take measurements and find the specs on this arm? I know of a fabricator who could most likely make this pretty easily given the specifics of it (ie arm length, eye size, eye to eye length, etc).

also, how much material (ie the length...i think ive read 11mm, but im not 100% sure) had to be cut off of that bracket to accomodate the CBR wheel & rotor?

 

@ VFR750F3, as for the motor, I've done some research on that one and I've found that the only 2 differences between the 750 and 700 motors are just the crankshaft and connecting rods. both engines use 70mm pistons, and pretty much the rest of the internals are all the same (which is why I've already scored a 750 crank & rods from eBay). Based on this, I've decided that one of my big projects that will be lined up for my the old viffer will be to do a full on 840 conversion (which will obviously require the 840 big bore kit and having the engine cases bored & sleeved). But alas, the engine rebuild comes AFTER the brake line swap, which will have to come AFTER the big suspension overhaul project, of which I am now in the middle.

 

According to the VFR.org FAQ, you need to shorten the caliper bracket by 21mm.

Center-to-center on my caliper stay is 12-1/8", and it's adjustable. If you can find rod ends that take a 10mm bolt, that'd be best. I don't recall the size of the tube I used, but a fabricator who is experienced with rod ends will know what size is appropriate.

see ya
kevin

 

wow chris u are really digging in there...how much research did u do on the BIG BORE KIT...i thought that mod was only for the FI motors. or it would cost and arm, leg, and your first born to get it done for the gen 2 models. Im like VFR750F3, its been about 7 years for me with all the mods and what not i did...but next summer for sure...my baby will be back on the road..chris please keep us updated on all the mods.

 

lets just say that with more time on my hands than money, ive been focusing on research lately more so than actually getting shit done. I find thats a double-edged sword, as I've learned a LOT about these 2nd gen bikes (thanks to a number of people that are just badasses with old VFR knowledge), but I havent ACCOMPLISHED anything yet.

I've been buying up the parts to do this suspension project lately and once I get all the donor parts, then comes the upgrading/rebuilding of said donor parts, then I have finally found a master Honda tech locally who actually knows about these bikes (youd be truly amazed at how many seasoned motorcycle mechanics know jack shit about the older Viffers) to get the installation done.

As for the big bore conversion, I've seen a number of folks with 86 model 750's install the big bore kits and start running with the 840 (okay, 837)cc engines and they tend to be very happy with the results. I've been in touch with JE Pistons, who made the kit originally, and I hate to say, they want close to a grand for the kit (which is kinda lame, cause all the kit consists of is a set of four 74mm pistons, the wristpins, circlips, and piston rings). Now the kit alone will make a 700 into what, roughly a 790, but to really get the whole 840 out of the kit, you have to install a crankshaft and connecting rods from a 750cc engine, which I've already scored from eBay.

So far, I do want to thank everybody who has contributed to this thread, cause if you read the whole thing end to end, it's collected a MASSIVE amount of useful information about this wheel swap and what goes into it, and that's what these forums are really all about.

 

I don't think the 840 requires sleeving... Dave Gowland had one. I don't think he still owns the bike, but it must be around here somewhere. RWB, USD GSXR front, undertail exhaust, etc. A place called DynamoHumm in Canada built several 840s, but I believe the business has been taken over by the guy's brother and is no longer doing VFR stuff. I think Andrew Reveles' bike (founder of vfr.org, partner in Perfection Fiberglass) was an 840 too.

You should be able to find details buried in the VFR List archives.

kevin