BMW F650GS fork upgrade using YSS PD Valves

I decided to upgrade the forks on my F650GS(800 twin) by installing a set of YSS PD Valves. This video was intended to document what's involved and the end result, which it did, but it also morphed into a bit of a "how to".
The process was not too onerous and, as demonstrated, can be completed with just basic tools. I do however recommend using a torque wrench to re-assemble anything on a BMW motorcycle.

[@Moto.roller.]

Thank you for sharing this very useful content

[@neiljarvis8911]

Great video with excellent technical content. Covered the all important drilling of tdamper rods to completely negate the effect of the standard compression damping so that this is controlled by the valve emulators. Best video I have seen on this subject and principles will apply to fitting these pd valves to any bike having damper rod/ orifice bleed type forks. We done Sir, brilliant video.

[@oacmose281]

Thanks for the feedback.

[@eternallearner8185]

Good work. Just a heads up, the serious looking bolt at the bottom of the fork leg is NOT drain bolt and should not be used as one, it is what connects the inside of the forks, the damper tube, to the lower leg. Oil changes must be done exactly as you demonstrated, ie legs out and tipped upside down.

[@gianlucamarciano3695]

Very helpful video, i'll make the same job in my Honda PCX

[@expatbiker1907]

Great viy. Very helpful. My valves arrive next week. Cheers.

[@oacmose281]

Glad it helped.

[@louvega8414]

Great video, thank you!

[@simoncrooks7441]

Thanks, that was good to see

[@MyMike1946]

Brilliant 👍

[@CalmingAnxiety]

Thank you so much for how to get the sodding little clip out!!!

[@peternaur]

Just the video I was looking for! Thank you so much! I have the same bike and I am shocked (haha) at how easily it bottoms out the front. I am relatively lightweight (62 kilos), and whenever I encounter an incline with a bit of a step up, the fork bottoms out. I have been all over the internet to find the solution and found the YSS kit. It looks good. Would you say the PD valves helps the fork for offroad duties? I like the bike, but feel that the offroad-worthiness is very lacking, because of the poor suspension. The 19'' front wheel is fine for me, but the bike gets thrown around so easily. And the bottoming out is so harsh and sudden that it scares me to death. Do you think the kit would help with these issues? Greetings from Copenhagen where spring is beginning to heat up :D Best, Peter

[@oacmose281]

Hi Peter, glad the video helped. The real benefit of the valves is the plush action in say the first half of the stroke. Compared to standard that harsh action from square edged ruts just disappears. They are not really going to help with the bottoming out, however you could remove less or even none of the spacer and then there will be added preload. Might be worth checking your oil levels. I added a little extra after putting it all back together because it bottomed out too easily. More oil means less space for the air to compress at the end of the stroke so less harsh bottoming. But don't over do it as I think that can lead to too much pressure on the fork seals. The full YSS kit with new springs and adjustable preload caps may help address the bottoming. Regards Neil

[@lewiss66]

Hello. Thanks for the video. I'm about to buy a f650gs with 10 tousand miles on it and use it most on road though I'm found of offroad trails bikes but already using one like on my logo picture. Well I was wondering how well the upgraded fork performes now on the road. Thinking of riding it two up. Thanks and have fun !

[@oacmose281]

Hi Lewis. You'll find it good on any small potholes and edges where the standard ones are harsh. It doesn't really help with the extra weight of going two up. Might be worth replacing the springs to help with that.

[@mikeamphlett7913]

Hi how much oil in each fork? Im told 100mm from the top, fork compressed and no spring. or about 580ml?

[@tonyhatton5005]

Hello great video, I noticed you you have spoked wheels, are they off another bike or somewhere else. Thanks

[@oacmose281]

Hi Tony, well spotted. Custom built spoked wheels using an F800 hub on the rear with a 2.5/18" rim, and an older model F650GS single hub on the front with a 1.6/21" rim. Both hubs fit without modification. I also just recorded a video detailing this and will put it up soon.

[@oacmose281]

kzbin.info/www/bejne/kKWlhmVjoMqKg8k

[@rationalityfirst]

Can you tell what model are they? And what diameter is the fork leg on the twin F650? 41mm ?

[@oacmose281]

PD335 and the fork leg is 41mm. Now the YSS web site only lists the whole upgrade kit if you filter by that model, but if you search you can get to the PD335. I don't know what size adapter you need. yssaustralia.com.au/universal-products/32956-pd-fork-valves.html

[@rationalityfirst]

@@oacmose281 My bike is a F650GS single 2004. Same size fork, apparently the PD335 are good for mine too. I'll bite the bullet and order a pair, I got tired of vague front suspension. And I can't access that site from my location.

[@rationalityfirst]

So I ordered mine and they came but the instruction leaflet is just a small page and the oil height is not mentioned at all. How did you get yours? I see something on the site, "Oil height (mm): 140". But 140mm measured from where? Can you post a link with a more detailed manual, please? Also, mine don't have the adaptor collar mentioned in the link above posted by you.

[@oacmose281]

@@rationalityfirst Hi, you'll have to contact the supplier for a model appropriate adapter collar. I'm afraid I don't have a record of the exact size but the supplier should know from the model of your bike. The fork oil is measured from the top of the fork leg (see video) with the fork compressed. I set it at 150mm as per documentation that came with the valves but have since blown the fork seals. May or may not be related but I'm reluctant to make any definite recommendations. 140mm means more fork oil (than 150mm) so I'd put in a bit less then test ride it. If it bottoms out too easily add a little more but don't over do it.

[@rationalityfirst]

@@oacmose281 I had no mention in my documentation about the oil height, just on the Thai site I found a mention of 140mm. I took it for a few short rides and I also hit some big square bumps and no oil leak for now. the strange thing is that I had different volumes of oil for each leg, just going by the oil level measurement, the left one took less, no idea why.

[@atmoboof]

Made in China BMW. 😢

[@oacmose281]

Happily not. Despite the name it's the 800 twin. But I think some of the 650 singles were made in China. en.wikipedia.org/wiki/BMW_F_series_parallel-twin