Yamaha forks on a BMW F650GS Dakar

I completely removed the ABS and my entire front end (wheel, forks, caliper, master) is YZ only with the exception of the rotor where I chose a 270mm unit. I find there is a noticeable difference in breaking between the stock BMW rotor and the one I got, and I am happy with it.

I did the YZ conversion with the plan of using the bike with a knobby tire (T63 currently) on the front, I also plan to ride year round. A knobby will have less grip than an 80/10 tire, especially when it's wet and cold. I am far more concerned with locking the front wheel (especially in an emergency) than not having enough brake. If I had to nitpick I would have gotten different pads for more grip, the current ones (I forgot which) are a bit hard, but other than that I'm good.

As far as comparing bike rotors to the ones on cars, it's apples to oranges. Even my old '94 VW Golf the rear rotors were much thicker (2x) than on any bike and the front ones were vented. It's not just the diameter of a rotor that determines how much it will brake but also the thickness. For comparison the stock BMW rotor is about 5mm thick with a minimum thickness of 4.5 mm. The 270mm & 320mm rotors in the eBay kits are less than that (I think 4 - 3.5 mm). And this is without even taking brake pad area and pressure applied into consideration.

Most people who get the kit to keep the BMW wheel & brakes do it for the ABS. Given that you don't have ABS on your bike, you could go the cheaper route with the YZ parts and step up to the 320mm rotor.

Before you make any choice, you should decide what is the purpose of this bike for you? Single track with enough street riding to get to the fun parts or lots of highway with the occasional gravel road?

Hope this helps and I haven't just wasted your time.

This bike will be my wife's cross-Canada bike that we will take a many gravel roads is possible - Northern Quebec Hydro roads, trans-Labrador and when we are in BC we do a lot of back roads and in between mult-day 120km/h highway runs - so really I the bike is a true "GS" where the English translation would be "gravel" and "street". We don't do a lot of single track and technical off-road but the gravel roads we do ride are filled with potholes and are rough.

I intend on running the BMW master cylinder, so what I am looking for is the same braking power as the OE BMW setup, which I think is more than adequate! Is the 270mm adequate for our application or do we need the 320mm ?

I have the 320 kit and it works well once you bed in the pads. That said, the 270 kit with the right pads should work fine for most riders. I am running soem EBC pads right now but will probably go to Galfer greens pads next season. With the 270 and galfer greens it should work just fine. If you want more braking the 320 will work too.

To compare the YZ and GS braking systems is comparing apples to oranges, the YZ system is used across the board on the YZ 125 to 450 models and many other Japanese makes and models but note the WR250X moves to a 300 mm disc. The basics are :-

GS - Brembo 32/30 mm two piston caliper - Pads 108.9 x 41.3 x 7 mm - EBC 209/2 - Disc 300 x 5 mm

YZ - Nissin 27/27 mm two piston caliper - Pads 94 x 34.2 x 7.5 mm - FA185X - 250 x 3 mm

Oversize Discs - 280x3 mm or 320x3.5 mm or 4.0 mm - EBC STD Disc MD6017DX Oversize OS6028C 280 x ? mm (floating) or SM6028C 320x4 mm.
The YZ may be OK for a light desert flyer like NotMyModelName's beast but is underrated for a dirt road tourer loaded with gear for longer trips and higher speed

The 320 mm oversize disc starts to address the issues but is still hampered by the smaller piston size of the YZ caliper

Alleged.

Been a while since there's been any documented progress with that project

His build thread was promising until a KTM 450 threw an wrench in the works ...

There's also Tacos F650GSDakar Strip and Rebuild thread that was killed by a WR250R.

I think the 270 would be adequate for your needs. But the truth is that there's only one way to find out: try both and see what works...

Right - so what we're saying here is BMWs brakes are pretty decent. So wheel @ $100 plus $250 for the 320mm brake for a total of $350 or adapt the BMW wheel and brake for maybe slightly more.... that is the question - and to complete that question now, who is selling the brake adapter and axle and how much is it going for?

The price I got from Richard Wilson at House of Horsepower are: axle, spacer(s) and brake adapter kit (no ABS-bracket) for 575USD and progressive fork springs with lowering spacer and shims for 275USD.

//Linus

What is your timeframe to get the bike done?

Have you got a better deal? I'm just about ordering a kit from HOH...

…including wheel, brake rotor/caliper, forks and triples. I did have to make up a brake line with proper banjo bolt fittings for the YZ caliper and BMW (Brembo) master cylinder (which were different sizes). I've got over 21K miles on mine and have been very happy with this setup. The YZ brake disc (250 mm?) seems more than adequate for me, so I never added the larger 320 mm brake disc kit for it.

My conversion like this was very inexpensive since I didn't have to buy adapters for the BMW caliper, spacers, or new axle. I think I paid around $350 shipped for the YZ front end that already had stiffer fork springs installed. Then I sold the stock BMW 21" wheel with brake rotor for $300.

One unexpected benefit I've noticed after a few sets of tires since the conversion is noticeably less cupping on the tread of dual sport tires vs. the stock BMW setup. I'm unsure if this is due to the taller geometry, less aggressive brake or other factors, but 50/50 DS tires like the Michelin T63 used to cup badly after 3-4K miles are not cupping at all now.

Anyone have thoughts on this? BTW, on my Dakar I also had an 18" rear wheel laced to the stock hub simultaneous to the fork conversion to help level out the taller forks, which I didn't have shortened.

What has to be done to the bike to make a 18" rear wheel fit? Longer chain? Any changes in rear suspension?

I would say you could put on an 18" wheel without any modifications. At the most add 2 links to the chain length. Std - 512. Make it 514. Plenty of space to play as the box length is 520.

Or you could always just raise the rear 1" with a 17" wheel.

What's the pro/cons on changing to a 18" rear wheel? Or is it only to get the end up 1" to match the taller forks when you do the mod?

tyres

Perhaps those 5's should be 1's there Aquatic (112, 114, 120), been a long day in the sun up there in Qld ? or are you going troppo to fit in better

Same chain - 112L with standard 16/47T sprockets. I have used a 140/80-18 Heideneau K60 and it had about 1/2" clearance at the swing arm. Also since I've used a 130/80-18 T63 and presently have a 120/80-18 Shinko 705 mounted (can't get a 140 or 130/80-18 in the Shinko).

BTW, these Shinko 705s are great for my riding on this bike as I got tired of burning thru more aggressive DS tires riding 90% on the road. A set from American Motorcycle Tire is less than $110 shipped ($52F and $55R) and the rear goes about 7K even in the 120 size. And both times I've ordered they were at my door the next day with free shipping!

The 705s aren't bad on gravel roads and I've even done some single track (not deep mud or sand) without any problems. On the road they stick well in wet or dry, are quiet and balance up well. At nearly 7K miles the front still looks brand new.

My overall tire of choice would be the K60, but I only got about 6K miles from each of the two rears I ran (front was still good at 12K) and for the $160 price of a single K60 rear I can buy two rears and a front in the Shinkos. That said, if money weren't a factor and I was doing closer to 50/50 riding the Heideneau would be my top choice.

Click on the Dakar link on my sig line below to see a photo of the bike with the K60s mounted from last year. Note that with the 140/80-18 Heideneau the bike is effectively geared taller, roughly equal to one tooth on the countershaft sprocket, due to the larger diameter of the 18" tire plus 18" wheel. To get standard gearing (or very close to it) I had to go to a 15T front sprocket.

Correct you are! It is the spawn that have me sleep deprived.

Here's one for you. I just put new sprockets and chain on Dennis's (Inglsman) bike.
The last set was put on by Motorlife BMW here on the Sunny Coast.
Full length chain, 120 links and 2 sets of farked chain tensioner bolts, nuts and alloy inserts. The bolts were over tightened and the nuts did a number of rotations and rounded out the cavities in the 2 cast plates. Throw away!!!
I had to give him mine so he could go on his way. So I am now without until I purchase new ones
Idiots!!

Ah that is life in Qld, perfect one day then Faaarked the next cause the sun is too much and they all go troppo in the wet season

Seeing how it is currently -10C and snow everywhere I have the better part of the winter to do the project, yet I don't want to wait for the last minute. At $575 for the HOH kit... there's no way I would go that route - I think that's a lot of coin for an axle, some spacers and a machined but of alloy. Heck the 320mm EBC disc brake comes with a machined bit of alloy about the same weight and complexity as the HOH kit and it's $225 and includes a disc brake!

If there's a cheaper under $300 setup coming down the pipe soon, I can wait or at least say i'd get it as I have a 2013 Sertao with ABS!