Another Inverted Fork Conversion (6th Gen)

[VFR800R 3]

Hi all,

I've collected almost all the parts I need to do my fork conversion, so I thought I would share my plans on here. Mine is an '04 Asphalt VFR800 with ABS; I have already pulled the main ABS fuse and rode around, and had no issues, so I don't think the de-link/de-ABS is going to be much of a problem. My goal is to improve the bike's performance to close to where it would be if it were receiving biennial updates to keep pace with the GSX-R750, which means losing weight, improving dynamics (braking and turning), and improving engine power and delivery. This modification obviously addresses the first two.

It started where many on here have already been, with RC51 SP1 and CBR929RR/954RR triple clamps. When I started seriously considering this conversion, I decided that I would need to have inverted forks with radial brakes. That eliminated the most common upgrade, the RC51 SP1, which automatically made the process harder. The next place to look would be at CBR1000RR forks, but they seemed too short (based on my research).

Inverted Fork Swap Data Excel 2003.xls

That opened it up to other brands, and after looking hard at the GSX-R family of forks, I finally decided on the '06-'07 Kawasaki ZX-10R (which I thought would have 743mm forks, but ended up 738mm). The Kawi forks use a 25mm axle, so I next tried to find a wheel to fit. Also, the ZX-10R uses 210mm fork spacing (the triples are 214mm), which means custom wheel spacers (and eventually, rotor spacers too...).

After a few dead ends, I decided to use a Ducati 748/916/996/998 wheel (since they use a 25mm axle, and the 5-spoke design matches my VFR's 8-spoke rear). Well, a couple days after buying a wheel with rotors on eBay (actually a Brembo wheel for Aprilia RSV-R's, which fits the Ducati) I found something even better: a cast magnesium Marvic Penta II for the Ducati 749/999. I jumped on it, and now I have a Brembo wheel to sell, but that's a different story...

Then I got a set of Ducati 848 rotors (which interchange with 749/999 rotors). After trolling some Kawasaki forums, it turns out the stock ZX-10R Tokico calipers were kind of weak, so I abandoned the set I had scored and instead bought a complete '04-'05 CBR1000RR braking system. I got a set of Vesrah pads from Kurveygirl and some lengthened Spiegler lines from the guys at Convertibars. The CBR calipers in conjunction with the 848 rotors resulted in needing 15mm caliper spacers, which I should have had machined but got lazy and bought from Dan Kyle.

So now, I just need to have some spacers machined (~5mm rotor spacers, which makes me a little nervous, and some axle spacers for the 999 wheel). So, if you know a good machine shop in the San Diego area, let me know. Although I will be moving to the east coast in a month, so I'm open to almost anything.

Parts List:

Triple Clamps - CBR929RR/954RR (I may use an RC51 SP1 upper if I have to put the clip-ons below the upper triple clamp)

Forks, axle - '06'-07 ZX-10R

Clip ons - Cycle Cat risers for Ducati Monster

Fender - Carbon fiber for ZX-6R/ZX-10R

Wheel - Marvic Penta II cast magnesium 5-spoke for Ducati 749/999

Calipers, Master Cylinder - '04-'05 CBR1000RR

Rotors - Ducati 848 320mm

Pads - Vesrah RJL for the CBR1000RR

Brake lines - Spiegler extended lines for CBR1000RR

Caliper spacers - 15mm from Dan Kyle

Custom bolts - stainless 70mm caliper bolts, 20mm rotor bolts from Pro-Bolt USA (due to caliper and rotor spacers)

Steering bearings - All Balls for Honda (CBR929RR/954RR and VFR800 use the same)

Axle spacers - (to be) custom machined; I have a couple chunks of 6Al-4V titanium sitting around...

Rotor spacers - also (to be) custom machined; I'll probably go 4.5mm thick

I also have a set of '04-'07 CBR1000RR Vortex rearsets sitting in my closet, with a 600RR rear master cylinder. I need to have new mounting plates machined to slap them on, which is also on the "to do" list...

Lacy

[Veefer800Canuck 822]

Oooh, can't wait to see the finished product.

As for the RC51 brakes, there are radial brake adaptors out there for the '51 forks, and although they are not as spiffy as a clean-sheet design for radial brakes, and probably slightly less stiff, it is possible and has been done.

Oh, and if you want a blingy upper triple clamp, look for one of these:

After black anodizing:

[VFR800R 3]

Rob,

Your GL800RR-SP2 is one of the builds that inspired me to give this a shot (along with Swiffer, ZRoyZ, and a few others).

I've seen the RC51 radial mount adapters, but thought going the ZX way would be cheaper (which it probably wasn't in the long run). Oh well.

By the way, I see you've been collecting new parts for your VFR; good luck with the eBaying and the healing, can't wait to see the rebuild.

Lacy

[Guest xerox]

From having done my RC51 swap, the only thing that I can say is test fit test fit test fit...

And of course, Good luck

[2FAST4U 91]

My goal is to improve the bike's performance to close to where it would be if it were receiving biennial updates to keep pace with the GSX-R750, which means losing weight, improving dynamics (braking and turning), and improving engine power and delivery.

I applaud your passion to conceptualize your idea and follow it through to fruition; however, in so doing, you're gonna have to shed about 100 lbs. off the bike and increase the engine's output by at least 30%. How do you intend to do this?

[Q-Dawg 17]

Anorexia and a bottle of nitrous? :happy:

[pres589 8]

My goal is to improve the bike's performance to close to where it would be if it were receiving biennial updates to keep pace with the GSX-R750, which means losing weight, improving dynamics (braking and turning), and improving engine power and delivery.

I applaud your passion to conceptualize your idea and follow it through to fruition; however, in so doing, you're gonna have to shed about 100 lbs. off the bike and increase the engine's output by at least 30%. How do you intend to do this?

Complete de-link is about 10 pounds saved, right? He's probably dropped a pound or pound and a half with the change in front wheel. Good titanium exhaust could save 15, and completely removing the PAIR system & a little work with a hole cutter to open up the airbox could be a couple pounds. What are we up to, 30 pounds? There's that lighter weight forged rear wheel for the 5th & 6th gens out now that saves a couple pounds, and then... uhm... I guess there's a swingarm swap to the Ducati stuff that's been talked about that can save a couple pounds. So if he throws a cubic yard of cash at this thing he might hit 40 pounds of weight reduction. That's an admittedly highly optimistic estimate on my part. And probably outside the lines drawn for this specific thread so I'll stop now.

[2FAST4U 91]

My goal is to improve the bike's performance to close to where it would be if it were receiving biennial updates to keep pace with the GSX-R750, which means losing weight, improving dynamics (braking and turning), and improving engine power and delivery.

I applaud your passion to conceptualize your idea and follow it through to fruition; however, in so doing, you're gonna have to shed about 100 lbs. off the bike and increase the engine's output by at least 30%. How do you intend to do this?

Complete de-link is about 10 pounds saved, right? He's probably dropped a pound or pound and a half with the change in front wheel. Good titanium exhaust could save 15, and completely removing the PAIR system & a little work with a hole cutter to open up the airbox could be a couple pounds. What are we up to, 30 pounds? There's that lighter weight forged rear wheel for the 5th & 6th gens out now that saves a couple pounds, and then... uhm... I guess there's a swingarm swap to the Ducati stuff that's been talked about that can save a couple pounds. So if he throws a cubic yard of cash at this thing he might hit 40 pounds of weight reduction. That's an admittedly highly optimistic estimate on my part. And probably outside the lines drawn for this specific thread so I'll stop now.

Removing the passenger footpeg assemblies, the chain guard, and centerstand might save another 15 lbs. He could also swap the steel sprockets for aluminum ones. Maybe he's gonna get CF bodywork all the way around. Maybe even fab an aluminum subframe.

[Baileyrock 832]

Removing the passenger footpeg assemblies, the chain guard, and centerstand might save another 15 lbs. He could also swap the steel sprockets for aluminum ones. Maybe he's gonna get CF bodywork all the way around. Maybe even fab an aluminum subframe.

I'd say those items are good for maybe 6-7 lbs(not including the sprocket change). :happy: I've gutted my 02 almost as much as possible, even a modded rear sub frame which I dropped to almost 1/2 weight, but that was only around 5-6 lbs savings there. Running a 5th gen sub or maybe an aluminum F4i sub could drop close to 10 lbs.

I haven't have a chance to get an accurate weight of my stripped Vtec as of yet, but will in the next few months(when I can walk again) :fing02:

I think you could buy a nice used 07 GSXR 750 for less that what it would cost to drop 50lbs off a vtec! :ohmy:

BR

[FotoMoto 38]

When I started seriously considering this conversion, I decided that I would need to have inverted forks with radial brakes. That eliminated the most common upgrade, the RC51 SP1, which automatically made the process harder.

After trolling some Kawasaki forums, it turns out the stock ZX-10R Tokico calipers were kind of weak, so I abandoned the set I had scored and instead bought a complete '04-'05 CBR1000RR braking system.

Stock RC51 brakes (full system) are serious kit and shouldn't be brushed off when upgrading but radials, of course, are more up to date and are easier to source. I, too, sourced adapters to mount cbr1000r radials (pictured). Better yet, I later found a set of mono-blocks for $40!!!!! :happy: They (not pictured) will require shimming on my mixed bag of parts configuration while adding even more brake bling :ohmy: :fing02: but hopefully will provide more feedback and sensitivity.

As for the zx10 brakes reputation, I suggest a big bit of pessimism as that bike has way more HP/performance than any Viffer. I think they'd more than adequate on the VFR.

My 2cents.

Lacy,

Good luck with the mods and give us an update when you get it all together.

[2FAST4U 91]

It would be cool if he could pull if off, though. :fing02:

Maybe he's gonna bore out the cylinders and put in some higher compression pistons, put in some radical cams, do some head work, etc. What's cool about that is it certainly sounds doable.

[whitelightning 109]

Is there anyone out there that has done a fork conversion w/o changing the brakes or front wheel? I have access to a full machine shop, so I'm not worried about custom fab work. I'm just wondering if anyone's done it, or knows the complications with it. I'm already working on building a alum rear subframe along with some other alum parts. My goal is to keep my bike as close to stock looking as possible while upgrading some things that I don't like (the linked braking I actually do like and want to keep).

[Baileyrock 832]

Is there anyone out there that has done a fork conversion w/o changing the brakes or front wheel? I have access to a full machine shop, so I'm not worried about custom fab work. I'm just wondering if anyone's done it, or knows the complications with it. I'm already working on building a alum rear subframe along with some other alum parts. My goal is to keep my bike as close to stock looking as possible while upgrading some things that I don't like (the linked braking I actually do like and want to keep).

I did a F4i front end on my vtec track bike which uses stock wheel and brake rotors, I did delink and use the F4i calipers & m/c but I'm sure you could fab the bracket needed to retain the linked brakes if desired. :happy:

[KevCarver 541]

Is there anyone out there that has done a fork conversion w/o changing the brakes or front wheel? I have access to a full machine shop, so I'm not worried about custom fab work. I'm just wondering if anyone's done it, or knows the complications with it. I'm already working on building a alum rear subframe along with some other alum parts. My goal is to keep my bike as close to stock looking as possible while upgrading some things that I don't like (the linked braking I actually do like and want to keep).

I did a F4i front end on my vtec track bike which uses stock wheel and brake rotors, I did delink and use the F4i calipers & m/c but I'm sure you could fab the bracket needed to retain the linked brakes if desired. :rolleyes:

Could you change out the internals of the fork to keep the original lowers and linked brakes? Although I'm in the camp of wanting unlinked brakes and 4 (or 6) piston dual sided calipers.

[VFR800R 3]

Whoa guys, we took a hard right turn into pessimism pretty fast. How many pounds has vfroem dropped off his VFR750? And how many horsepower has Toro added to his VFR800? Now, I'm not going as extreme as either of those, but they are examples of what is possible.

For the engine power, there is no way to get the VFR800 VTEC in the same league as a modern GSX-R750 with only natural aspiration. However, there is a lot that can be done to improve output and delivery while also dropping weight (Motad headers, single exhaust, aftermarket filter, Power Commander, etc.). I think 110 hp is reasonable, with improved drivability due to gearing and a Power Commander V (and taking note of Coderighter's work). So, that's giving up 20 hp to the Suzuki, but as has already been stated, it would be extremely expensive to challenge that without a Torocharger.

For the weight, as stated above, 100 lbs is about the difference you're looking at. The '08 GSX-R750 was 447 lbs wet, and the VFR800 VTEC (with ABS) is around 557 lbs.

http://www.sportrider.com/bikes/146_0808_ducati_848_suzuki_gsx_r750/final_tally_specifications.html

http://www.motorcyclistonline.com/features/2002_honda_vfr_800_interceptor/index.html

So, is 100 lbs reasonable? Maybe, but again it will be expensive. 50 lbs is certainly achievable, especially since I'm starting with a handicapped ABS bike (with a few extra pounds to drop). We'll see what I have the stomach and checkbook to do. I've already done the exhaust swap (stock duals to a single low mount titanium can), which dropped around 15 lbs.

Some other weight numbers:

- Removing the passenger pegs and grab handles is a total reduction of 5.7 lbs. I have no intention of removing the centerstand.

- The magnesium wheel sitting in my apartment weighs 7.04 lbs (including bearings and spacer). I expect that to be around 4 lbs less than the stocker.

- As stated above, the de-link/de-ABS will be some free weight. I won't speculate how much until I can put the stock stuff on my scale. However, I'm pretty sure the CBR calipers are also lighter than the VFR's.

As for why to do this with a VFR instead of a(n) [insert CBR/GSX-R/R_/ZX here), I think we've already debated that ad naseum. I have the VFR, it is very nearly paid off, and I like it. The V4 is unique in arrangement and sound, and I think the styling still looks fresh nearly 8 years after it was introduced. I'm a tinkerer, and even though I don't do any real engineering in my job, my undergraduate was in mechanical engineering.

My end goal is to return the VFR to where it was in its early history, as an all-conquering middleweight, while keeping its ability to tour. A bike that can do it all (on pavement): tour (sportily), strafe backroads with the best of them, and tackle the track on occasion. I know it can already do all of this, but I'm having fun expanding the envelope a little bit.

Discuss.

Lacy

[Baileyrock 832]

Whoa guys, we took a hard right turn into pessimism pretty fast. How many pounds has vfroem dropped off his VFR750?

Lacy

Lacy, please don't take it as negative, but everything you want to achieve on the Vtec has been attempted and or achieved or found to be impossible or extremely cost prohibitive for the last 8 years here on VFRD and by it's members. :rolleyes:

Hundreds of Vtec owners before you have delved into the exact same issues, so were not saying it can't be done because were pessimistic, it's because we've tried just about everything and you will find a thread about every attempt resulting as a success or failure. :blush:

For sure your bike has some extra weight with the ABS equipment for sure! How about finding a member to trade bikes of similar condition except for ABS as many members would love to have ABS. This could do several things for you, give you a bike with less weight and work to do to start with and maybe a few hundred bucks in your pocket to do mods on the lighter non-ABS bike.

I checked a few other weights for you:

-Rear linked brake lines/valves & brackets 2 lbs

-Center stand 3 lbs

-Par valve hoses/clamps & control valves 2 lbs

-chain guard 9 oz

-factory bar ends 8.8 oz

-vtec front brake calipers w/lines 8 lbs

-rear peg assy w/bolts (L&R) 3 lbs

-rear grab rails w/bolts 1 lb 2oz

-rear sub frame(if I remember right) 15 lbs

Good luck and keep us informed! :fing02:

[FotoMoto 38]

My RCBVFR is down to 491 lbs. wet (real world wet=full tank and all fluids). Getting another 40ish off it would, IMNSHO, be realistically impossible; 20ish, maybe but that would come at an extreme cost by throwing lots of carbon, ti, and magnesium at it, many custom bits. :rolleyes:

If weight loss is the ultimate goal and a worthy goal it is since it is always "working" unlike motor mods, then an F4i front end may have been a better choice. USD units are typically heavier and most utilize massive rotors (320's) which is good for braking but somewhat negates the mag wheel weight savings.

This is a path of diminishing returns. It's starts off easy and relatively cheaply (aftermarket exhaust, chunking stock parts) but gets progressively more difficult. We each have different levels for when this becomes silly. For me, it would be spending hundreds of dollars for mere grams of weight savings on a street bike (Ti bolts and screws, etc). Your best bang for the buck in weight savings comes from unsprung weight. Unfortunately that isn't very easy to do on the VFR rear end.

[2FAST4U 91]

I think you might be confusing pessimistic with realistic. Nobody is discouraging you from doing it. We're just saying that what you want to do, simply put, isn't realistic. The Suzuki GSX-R 750 is a serious track weapon and is not to be taken lightly. Another thing to consider is the wheelbase on your VTEC is over 2" longer than the GSX-R 750's. That certainly doesn't work in your favor and, strictly speaking for myself, I don't know what in the world you could do about that.

Personally, I've seen it all on a VFR. I've seen a supercharger and I've seen a turbocharger. I've seen a big bore kit and I've seen a nitrous kit. I've seen high dollar Ohlins rear suspensions, RC51 fork conversions, you name it. Sure, if you throw enough money at it, anything is possible. That goes without saying. However, without spending an exhorbitant amount of money, your VTEC simply can't come close to matching the Suzuki GXS-R 750's level of performance. If you think you can do it, then by all means go for it. I assure you we'd all be rooting for you. I know I would.

[SEBSPEED 1055]

Nothing wrong with a better VFR! Do it up as you wish sir!! :rolleyes:

[KevCarver 541]

Personally, the only thing about my 5th Gen I dislike is the slide caliper linked brakes. My main goal in a fork swap would be radial calipers. That said, I'm really happy with the RC51 stock brakes since I got mine a year ago. So stock RC brakes on my VFR would be dream for me.

Speaking of the RC51, that was designed to be competitive with 750's of the era. Now, it compares with the 600's of this era. Going to be pretty tough for a VFR to match up with the modern 750.

Bottom line: Build the bike that makes you happy! :rolleyes:

[VFR4Lee 478]

Torocharge the motor, and stuff it into a gixxer frame. :rolleyes:

[pres589 8]

Has BLS made an appearance in this thread yet? Maybe we should get these two together, get a little contract engineering work started. Between all the posts it looks like 50 to 60 lbs could be saved before things just get painfully expensive. Where would I say painfully expensive starts? When the cost of a new VFR has been invested in his new VFR. So, whatever could be done for 10 grand. Glad it's not my money...

And I haven't seen anything pessimistic or overly negative here yet. Actually a lot of really great suggestions have come up so far and I bet there are more to come. Here's a couple more;

If you keep the stock swingarm, Civic lugnuts work. Meaning, titanium lugnuts meant for a Civic work. You'll still be better off trying to get a different swingarm mounted if you care about weight as much as you seem to, but if you stick with stock, here you go.

The stock headlight assembly is kind of weighty, maybe look there, go to a single lamp and a dummy or something, I bet there's half a pound waiting to be freed up there if you're willing to forgo the excellent stock lighting and aesthetics.

If you can figure out a way to go to a single radiator and fan there's probably a couple pounds to be saved there, and you may get better cooling out of it as well when sitting still.

Solo seat.

[FotoMoto 38]

So, if you know a good machine shop in the San Diego area, let me know.

Paging BLS (busylittleshop), you have a customer on the parking lot. BLS, you have a customer on the lot. :rolleyes:

[FotoMoto 38]

Dang, pres589 beat me to it! :rolleyes:

[KevCarver 541]

You (I) can get titanium lug nuts for a Civic? :rolleyes: