Fork Diameters... front end swap

there is a lot of "stuff" floating around in this thread geezus. a few things you should know in your brain for this endeavor.

- you can swap entire front ends from something. then your main concern would be attaching it, and triple clamp offset. if its new enough, most stuff has 28-30mm offsets these days anyways, so that becomes less of a concern. then the concern is, getting the right stem. you can have a stem machined for yourself relatively easily from a bunch of machinists somewhere. by doing it this way, at least you know the forks, wheel, calipers, rotors, wheel spacers, etc... all line up as they should. it also makes getting replacement parts easier when you know your entire front end is "from a 2015 Yamaha R1."

- you could go the route of piecing shit together. then like was said, you need to worry about caliper spacing (but there's only 2, 100mm or 108mm, excluding like 2 years of R1 production that was 130mm. easy enough), rotor bolt pattern and offset (i think there's only like 2 or 3 different offsets that anything can have so also not the end of the world), wheel spacers from bearings to fork ends (also not the end of the world, Kenny from MRP had to spin me up a set on one of my bikes), fork spacing width in the triple clamps themselves (another thing where i think there's only like 2-3 variants, but you need to know the number), for tube diameters upper and lower (lots of variation here, there are charts all over the internet you just have to be creative and look), axle diameters in regards to bearings and spacers if you're throwing random wheels into random forks.

- so the dead easiest will be to find something from the same brand, in the same fork diameters, that everything can just plop right over. RSV to Mille is probably going to be that choice. upgrade the carts if you don't like the OEM stuff. some OEM stuff was factory R&T like the Ohlins that came on the 2006 R1 for example. just depends what's in it.

- 2nd easiest is gonna be entire front end from something and then get a stem made. swap wise and maintenance wise.

- harder becomes mix-matching all types of random shit, as seen by the 2nd bullet point.

- also know that there are companies that re-coat shit, kashima, TiN, DLC, all colors, anodizing, whatever... so don't let a color choice dictate any of this.

p.s. - i've now just got done doing this for 2 different bikes. one required caliper spacers, wheel spacers, and a new stem. the other required custom built triple clamps, but all the rest of it matches perfectly. pick your poison and analyze your wallet pain threshold.

 

^^^ You forgot steering stop issues.

 

haha that too. nothing an angle grinder and/or a couple little blocks of aluminum can't solve haha.

 

Let me walk you thru both of mine...

1) Supersingle YZ450f chassis. Common swap is R6 entire front end, just need a stem modded. R6 forks are 50/54mm diameters. R1 from the mid 2000's are the same. Same brake calipers stock. Same fork offsets. Same spacing. Got a set of R1 R&T Ohlins forks for SUPER cheap of a guy parting an R1. Got some M4 calipers on sale in 108mm. Found an ex-AMA dude on craigslist selling a forged mag Marchesini with two Brembo SBK iron rotors on it for $500 off one of those old Graves R7 Formula Xtreme bikes which there was no way i could pass up considering one of those rotors alone normally is like $800 a piece. wheel has special endurance bearings though that differ from a regular Yamaha setup. Felt like i may want some future tunability, so i get a set of R1 triple clamps from Attack. Geoff at GP Tech uses R6 front ends a lot and so he was offering conversion stems for Yamaha stuff as it was, got one of those. Kenny turned me some captive wheel spacers that fit into the endurance bearings and spaced the wheels right. rotors already had the correct offset/alignment for R1 fork spacing so good there. Calipers had to come out like 8-10mm for the 320mm rotors on M4's so got those and done there. Fast Frank quick change axle. triple clamps have adjustable bump stops on them, forks will probably need a re-spring/valve whenever i ever finish putting it together. done and done.

2) Aprilia RS250 chassis. Want a new front end that's trick, that all comes from the same thing, that can swap over, that can be serviced easily, that parts are readily available. RS250's have 35mm offsets stock. Nothing any more has that offset. That means custom triples for anything besides using stock triples and something that fits in them. I want adjustability, I want to start from stock as far as making changes. What to do. So I decided, having an entire R1M front end will be easy to find parts and easy to get stuff done. I order Ceracarbon forks and tell him i want R1M diameters. He starts them from a set of R&T forks for an R1M then does his thing with the stanchions and outer tubes. Somehow when finished though, the diameters are 52mm top and 54mm bottom instead of 50/54. Getting custom triples anyways, no big deal. R1M BST wheel/spacers, R1M Braketech rotors, R1M quick change axle, 108mm Brembo GP calipers... at least i know it'll all just bolt up how its supposed to. call Attack, tell them i want R1M fork spacing, but 52/54 diameters, and a 35mm offset instead of the standard 30mm for an R1M, stem to match an RS250 headtube/bearings. added a few extra features, bump stops the same spacing apart as normal RS250 triple clamp ones are. sent them an OEM RS250 stem as an example. 3 months and a bunch of money later, they're in the mail. everything should drop right in to everything else clean as a button.

So... neither of those are THAT crazy... but make a decision, and map it out ahead of time so you know what you're getting into and don't get caught in a jam.

 

It’s a lot of work. I just did this on my 2012 RSV4 factory. Amauri was a great help and modified the forks so now I essentially have the same geometry as a 2019 RSV4.
I used Ohlins FGRT 204, IMA triples, had Fast Frank make a custom axle, used a GSXR 1k fender, and had to have custom spacers and caliper spacers made.

It helped to stick to forks that had similar measurements as the Aprilias. Actually the Ohlins FGRT forks for certain years of GSXR 1k are very close in measurement and offsets to the RSV4 and I’m assuming the Tuono as well. They also use the same diameter axle.

Amauri was a big help. It’s kind of hard to get the Ohlins specs to find out what the fork measurements are.

There’s a lot of factors involved, swapping a whole front end is probably the easiest. I guess I don’t like the easy, or cheap way out.....









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Where the hell so you find all these ex-factory parts deals.

 

well... now i got a bunch of places where GP and BSB and WSBK parts come up regularly, or people i could ask if i was looking. i just don't need anything else right now. wheels, swingarms, brakes, dry-breaks, clipons, rearsets, exhausts, radiators, forks, shocks, fuel tanks, brake masters, carbon rotors, etc... stuff comes up all the time. i think with a couple of these dudes, they either know people personally, or have made themself the go-to for teams to get rid of stuff with. Spain, UK, Japan... talking 2-stroke GP racey bike stuff with old grey haired European dudes has introduced me to more old dudes, which has snowballed a bunch. guy who just made all my carbon fairings makes carbon fairings for BSB and WSBK teams and used to make all the cranks for Haga's old R7s back in the day. that kinda thing. shit man the guy i got my Mike Hailwood signed picture from didn't want to ship it to the US from England. i start talking to him, he starts telling me all these personal stories about being Joey Dunlop's friend and showing me his entire room of his of memorabilia. agrees to ship it to my friend in London, who in turn shipped it over to me... never know where bike convos/people are gonna take you i guess.

Specifically to that last post... back in the day there used to be a website called Crazedlist.com (craigslist compiler). it would search any and all cities/regions at a time if you wanted it to. sometimes when i was bored, i'd just hop on and type things like "marchesini" or "ohlins" and see what comes up. found a dude selling the ohlins forks and shock off an anniversary 2006 R1 for like $1200 like 45 minutes from my buddy in AZ. asked him to grab it, he did, shipped it to me, sold the shock for $500. boom, R&T forks for $700. that Graves R7 wheel came up the same way. dude was in Cali, i hit him up, he told me some cool AMA racing stories, had hurt himself real bad on a dirtbike and his wife was making him liquidate everything, that wheel/rotors was the last thing he found in his storage, was willing to ship it. the brembo GP calipers came from a dude on here. P4's with the vented Ti pistons from basically the early-mid 2000's era of things. totally fits the build, works for me.

the one thing that got away from me so far... some euro dude was considering parting his Harris YZR500 on racebikemart before it got overrun and ruined by scammers, i asked about the works Ohlins damper that was TiN with a magnesium body. he was hesitant to sell it if the bike was gonna sell whole and didn't want to give it up. i never followed back up. i now still see that bike come up for sale here and there on some of the FB groups, but definitely that damper got replaced by a regular one in the pics, which means either he's keeping it or he sold it to somebody else. i was kinda keen on having that puppy, they're impossible to find.

if i had more money, there's way more cool stuff to acquire and just let sit on a shelf popping up all the time, but i don't have THAT kind of expendable income. seen a few RSA250's come up for sale, a couple Suters, Moto2 bikes, etc etc... but i'm no boccarp by any means, not even close. found Mika Kallio's KTM 250GP chassis/airbox/forks/triples/fairings for sale like a year ago. no shock tho. no setup or spec info. i'm probably too big & fat for it and it was expensive, decided no dice. had to use google translate to talk to the dude in Germany, but its doable these days no matter who you are. used google translate to get my exhausts/airbox from italy, my engine from italy, my forks from belgium, my race buttons from netherlands. generally... FGR forks can be had for $5-6k (instead of like $12-15k new). masters for half price. newer GP calipers for like 1/3 to 1/2 of the retail price. gas tanks and radiators that would be thousands normally for a steal. the one thing that still doesn't compute of all the things i've seen in the past 2 years or so, is the Nissin GP stuff. even used it costs a FORTUNE. i guess if you really really want Nissin, but i dunno why its so much more than Brembo of the same level.

 

Probably because they’re sexy AF.

 

lol touche. even used with the master dudes still ask like $8k for them. haha i'm not that pressed to say i have marquez' brakes on my bike. they are pretty though. i can stare at cool machining work for hours and hours. swingarms, shock links, triple clamps, calipers, fuel tanks... all of it. i want those fork bottoms! haha

 

In the late-90’s heydays, there was 916SPS on the Chicago streets, fully-equipped with all the WSBK goodies. It had all the magnesium bits, like engine covers, triple, swingarm, etc. WSBK-spec 955cc engine. The shop who built it told me the front suspension and brakes were an actual Foggy frontend and came directly from his team. Everything was CF. The exhaust was a WSBK Termi system that simply looked otherwordly in diameter. I probably spent an hour looking at the thing, stripped in the shop’s service area. Just amazing something so crazy and expensive was being ridden on the street, back then. Good times.

Fuel Race Parts, in the UK, has tons of the old WSBK Ducati stuff in their stash and regularly restore the bikes. Worth a follow on FB.

https://www.facebook.com/fuelraceparts/

 

Did you buy these from Nemes?

 

I swapped the Showa BFF forks from a 2018 GSXR-1000r onto my 1991 GSXR-750H2 Hybrid today.

I still need a few parts to finish it, fender, brake lines and wheel spacer.

 

Talk about a goldmine.