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Husqvarna 701 Enduro Only

Initial Husky Ride.jpg
 
Has anybody replaced their front master cylinder with something different? Mine has shit the bed with 9000 miles on it. Started slowly and now if it sits for a few months, I have no front brake. I'd rather replace it with something besides stock as I've seen others with the same issue.

ETA: I've bled it more times than any other bike. It has probably seen 5 bottles of brake fluid pushed through it.
 
The natural environment of my bikes is mostly in one shop or another :-)

I was considering an AJP PR7, but opted instead for a mechanically new 2021 Husqvarna 701 (2,500 miles) as a starting point for major project that will span months and cost a lot of money. Having ridden 690s and a 701s in the past, I wrote them off as incurably odd, having objections in the cramped cockpit ergonomics, narrow ratio-spread Supermoto transmission (high 1st gear and lower 6th gear), glue slow and harsh suspension, a semi-brick for a seat, and general clutter, like ABS. Nevertheless I found the motor brilliant and interesting.

This year I made a decision to ride more in this bigger (for me) bike category. I already had/have one of the world's most technically developed Gen 1 KLR 650s (685, actually), and during my test rides of 690s and 701s in the past kept coming away with my KLR being superior overall. Again, not ordinary KLR.

For some odd reason I decided a few weeks ago to afflict myself with the technical challenge of 701, to make it in my image. I justified the expense after thinking through and finding fixes for all the details I previously found objectionable. The bike fortunately came with a few smart upgrades great skid plate and HDB bars and bark buster setup based on the KX high bend, which was tweakable to my preferences.
In the following video, I blabber on about my ergonomics obsessions:

https://buffalodream.smugmug.com/Husqvarna-701/i-2C4bR4h/A

The other part of the cramped cockpit ergonomics issue was fixed by choosing the truly huge XL-size Bosley pegs in 3cm down and 2cm back configuration. Radan in Czechoslovakia makes these fine pegs to order. Within a week I had mine in hand. I had to remove a little material here and there off the pegs and forged aluminum clevices for a very good fit, but that was small details compared to the positive affect they have on everything! (I used to make pegs like this but ran out of laser cut components and these days I'd rather someone else make them for me).

Trials got me away from hugging the frame or the 'tank.' I keep an open stance, which allows me to move the bike around immediately. Normal-dinky pegs force my legs up near the frame and feel insecure being so small. The 690/701 is very wide under the seat. Sliding back on the seat you run out of pegs fast as the bulges back there push your legs out. Now I can lean way back and still have full purchase on the pegs. Also, the sitting-to-standing transition is now naturally and much less energy intensive. When riding off road, I tend to stand, a lot. With bars back and the small/high/forward foot pegs, standing results in arm strain and strained instead of relaxed arms hinder steering response.

Bosley XL 3cm Back 2cm Down - Right.jpg

The foot brake will soon get tossed... but that's a later story.
 
Has anybody replaced their front master cylinder with something different? Mine has shit the bed with 9000 miles on it. Started slowly and now if it sits for a few months, I have no front brake. I'd rather replace it with something besides stock as I've seen others with the same issue.

ETA: I've bled it more times than any other bike. It has probably seen 5 bottles of brake fluid pushed through it.
I see this is an old post, but just found it. On my 2005 450 EXC I could never keep that mc bled. I ended up replacing with a new Nissin mc from a CRF 450R. Never had an issue again, worked perfectly, all that was needed was the correct banjo bolt to make the switch.
 
Regarding the front brake master cylinder, maybe this will help?

What fails most often on master cylinders is the cup seal. One tiny and cheap elastomer part has a problem and pfft! The seal in yellow:
Typical Front Brake Master Cylinder Piston.jpg


Cup seals push outward under their own compression, but also are forced to expand outward under braking pressure. When the lever is out, there is zero hydraulic pressure on the seal because it is upstream of the brake fluid refresh hole that connects to the reservoir. When you pull the lever in, it immediately passes over the refresh hole. The hole is really tiny, but if it is microscopically tiny bit on the sharp side, the edge of the hole can erode or even cut a smiley chunk out of the cup seal lip. The symptom of a failing cup seal from hole erosion or cutting is normal brakes most of the time, but every now and then suddenly nothing when you pull the lever in. A frantic pump or two will magically bring the brakes back until the cut gets bad enough to have the brake fail as though from the next failure mode.

Another failure mode of cup seals is degradation of the elastomer such that elastomer fails to exert natural sealing from compression in the bore. Over time, the seal relaxes back enough to not hold pressure after sitting a while because the seal hasn't been forced to expand outward for a while by hydraulic pressure.

Elastomer failure can happen if mineral (petroleum-based) oil seal compounds are exposed to the alcohol based DOT 3 & 5 and certain 5 fluid elastomers. Unsure about the other way around, DOT fluid seal elastomer compounds exposed to mineral oils.

The cure is to buy a new piston with seals kit and make sure to use the correct fluid to match the seals. Much cheaper than a whole new master cylinder. And the designs are typically simple and easy to fix. Can't say about that mongo master cylinder on the 701 as I have not had that one apart before, but it's usually a snap ring once you get past whatever seal is in front of the snap ring. Then it's just a piston with a spring behind it. Very simple to work on the things, except when manufacturers make getting past the outer sealing boot a royal pain in the ass.

A rare failure with front brake master cylinders is cylinder scoring or wear, in which case the master cylinder is toast. A failure that is uncommon on hand brake and a little more common on foot brakes because there's more dirt 'down there' and there is more side force applied to the piston on foot brakes from the activation rod.
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On another issue, tonight I removed the kickstand to weld on a larger foot (for sink-into-ground reduction). I noticed then the magnet in the tab that is for informing the ECU the kick stand is down via the infamous 'kickstand switch' has the magnet swung away from the sensor when the stand is up. So I'm like well duh, why not just remove the tab to make the switch permanently un activated?

Kickstand magnet tab attached:
Magnet On.jpg

The tab is probably a powder-metal part from the the ejector-pin marks. The magnet is small and in the end of the tab. It swings out of the way when the stand is up, and in front of the sensor when the stand is down. So I thought well duh, what if you just remove the tab, like this?
Magnet Off.jpg


The proof that this works to at least get rid of the irritation of no start with kickstand down is with kickstand removed the bike starts.

In the old days the kickstand switch was indeed a simple 2-wire switch. Not any more. They are now more 'sophisticated' in communicating yes-no to the ECU. I did order a kickstand dongle, which has yet to arrive. The dongle fools the ECU into believing the 'switch' is still there and the kickstand is up. Simply. Not wasted money because if the sensor fails for whatever reason the evil thing can strand you in the boonies. So best to toss it in the bin.

And who knows what this 'mystery loop' thing on the kickstand is for?
Mystery Loop.jpg
 
If I've learned anything from a lifetime of owning KTM's, it's gonna inexplicably eat kickstand springs. Mystery loop is so you can tie to bastard up after the spring launches in to the woods and you're far from home 😁
 
Question for you all. Would you rather me start my own separate tech thread related to my 701 project bike (and tech musings)?

The character of this thread was more my-bike-in-the-wild photo oriented than technical or long-post oriented. Rather than have two 701 threads, I jumped in here. Knobbytracks, want to respect your original thread intent and respect the cultural milieu. Don't want to 'misread the room' as it were :-)

LMK
 
All righty, then. A one-way conversation is an answer.

I will start my own thread with title that is more technical, akin to my former "Engineering & Experiences" threads. Or get new video editing sortware and jump back on YouTube.
I'll follow along, don't have a 701 but they have intrigued me for a number of years.
 
Question for you all. Would you rather me start my own separate tech thread related to my 701 project bike (and tech musings)?

The character of this thread was more my-bike-in-the-wild photo oriented than technical or long-post oriented. Rather than have two 701 threads, I jumped in here. Knobbytracks, want to respect your original thread intent and respect the cultural milieu. Don't want to 'misread the room' as it were :-)

LMK
Hi Motobene,
Sorry for the late response! It seems there wasn't much traction in this thread, nor the trials group (lots of the same repeated content over on AdvRider), and was never receiving notices of new content.
I like the idea of a new thread with technical content. This way, we aren't scrolling through miles of posts looking for particulars like the AdvRider forum has.

Thank you for the consideration and respect.

Knobbytracks (Mike)
 
Mike with this relatively new forum of - I suspect - many ADVRider refugees, there is less volume to try to elbow past.

Searching on Google is most effective way I have found to search forums.

I stuck with my handle, but thought about just being me by name. In some ways I wish everyone was 'here as themselves.' I may have met you before or know you now, but don't recognize the handle. Sad to say I've never ridden a WY trials event. At least I'll be up there doing the BDR in August.

I see you have a 2018 701. I hope you've been able to get something useful out of this thread.
 
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I'll follow along, don't have a 701 but they have intrigued me for a number of years.
Thanks for letting me know.

For a very long time I thought of the 690/701 as just weird in many ways. The more I get into this design, and the more I'm fixing the stuff I knew I'd not like, the more I'm taking a shine to this heavy beast.
I'm really not a big-bike guy and consider the 701 to be at my upper limit, weight-wise. Only more riding, as I tick up the mods, will determine the 'percentage of unicorn.'

Rode the venerable KLR 685 a few days back and for the first time in a decade thought, "Hmm. Should I sell this long-term friend? Certainly not some kid wanting a first bike :-0 Or should I care?
 
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