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Discussion in 'Thumpers' started by Olas, Dec 3, 2007.
so maybe it wont be a cure-all, but a cure-alot is good enough for me!!!!
id buy one!
Build it and we will come!
Well, you can still break off most any shifter on any bike out there no matter what. The shifter still has to stick out in the wind far enough for your boot to shift it, so short of floor boards on a Harley, it's going to be vulnerable.
But even in a severe crash that sheared it off flush, the shaft and tranny should still be OK. With an extra lever in your "spares" kit, you'd be back on the trail in 10 minutes.
Most all the "other" bikes have all broken levers too, or there wouldn't be spares on the shelf at all the bike shops. The big deal and high profile nature of our bikes is that the shaft can shear and or transmission damage is highly likely. I carry spares for the clutch, brake and shifter so I don't get stranded a 100 miles from pavement. I'm confident my shaft and tranny will make it thru fine.
On a side note, an '81 Dodge truck packed me and the bike up from behind as I was making a right turn. I saw him slow in the rearview as I lit up my brake lights well prior to the turn so I continued slowing and made my right turn. Turns out that he was not slowing for me, but rather unconsciously backed off the gas as he was reaching into the back seat area of his truck to discipline his kids. Next thing I know I'm airborne.
Knocked the aluminum rear subframe over 8", and scrunched up my aux fuel tank on the right side. When it (we) came back down on the left side, it ground off the shifter and half the footpeg.
Bike's totaled of course, but I'm almost done getting it back on the road. My "spare" shift lever slipped into place like factory and the tranny works like the day I bought it.
Hopefully that's the extent of my R+D crash testing.
Well, almost done with my replacement aux fuel tank and then off to my next project.
Safe riding and have fun all....
Brilliant idea and execution!
You're accident sounds brutal. When did this happen and did you get a replacement XCo?
It's important to like your first bike!
But you gotta tell us about your handle. Where'd you come up with slemiswiatraum? And how do you pronounce it?
In case you plane to make extra parts for us there is something that could be very handy I guess.
Could you rebuild your piece so It includes the other function of protecting the bottom of the frame like the one here?
It could come in one piece so that It would reduce the thickness around the foot peg.
What do you think of It?
Posted an ad in the flea market but thought I'd mention here:
Lookin for an XCountry for the GF. She's kinda outgrew her XT225 and wants to do longer rides but trying to keep the weight down as much as possible so a Vstrom or F650GS/G650GS is out. Must have ABS (she's had a couple of front brake mishaps on the pavement that ABS would have prevented :eek1). So, the Xcountry w/ABS will be perfect I think. Her budget is $4500-$5000 depending on how it's equipped. Oh, want less than 15K miles, the less the better.
Will consider SoCal, SoNev, SoUT, SoCO, and NM for a ride and ride (I'll ride her on my GSA there and we'll ride home).
Or AZ of course.
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I built the extra protection into my engine/case guard. I'm not sure you can see the shifter side real good in these pics, but it's similar to the brake side. The engine guard provides for less of a protrusion and a little bit of a smoother "slide" across rocks and logs. Easy to add onto just the plate thou.
Gathering up some posts regarding spring rates on the OEM Sach shock...
According to Drone and leafman60 here on posts 6443 and starting at 6131:
http://www.advrider.com/forums/showpost.php?p=17991511&postcount=6131 Expand it and read thru the next page...
The OEM Sachs shock is 11 kg (I assume this means kg/mm).
Drone went with a 16kg spring and gets 1/2" of loaded sag. This is on the shorter stroke '09 shock.
Leafman60 (weighs 205lbs + gear) switched first to a 13kg and got 3.5" of loaded sag. This is on the slightly longer stroke '07 shock.
- Currently is running a 15kg and thinks he really needs a 16kg, despite John at Moto-Pro saying his data shows a 13 should have worked in the first place.
Now here is what I'm trying to decide about spring rate on my Wilbers shock.
I've been working with Ted at Beemershop to get a recommendation from Wilbers factory techs. My shock still bottoms on high speed squared edged bumps. No I'm not talking about catching air, just hitting 8" rain ruts and the like.
I am convinced my spring rate is fine based on my sag but that the REAL high speed compression damping is not adequate. Confirmed by a local shock guru (with a frickin' college degree in Mechanical Engineering specializing in Vehicle Dynamics or some such....)
After 6 weeks of waiting Wilbers recommended some shim changes but caution that I will "give up some comfort". This concerns me because fiddling with the high speed compression damping on the Wilbers it does seem to make it a lot stiffer - you can feel it just using your hands on the rear end. But I don't think I can really send a high speed impulse into it by hand, so I hope they don't stiffen up the low speed damping as well.
I can send it to Ted for free service (which is really nice considering it has almost been 2 years now) and I will, but I wish I could have somebody knowledgeable locally that coudld ride it and use their own knowledge. oh well.
Anyhow the spring rate question:
Obviously this is a different shock from the Sachs (with more damping valving, etc) yet I'd think the spring rates would compare, and I assume they are all straight rate.
This shock has a 160 N/mm spring rate (= 16.3 kg/mm), with preload compressing it 9mm (it is a 165mm spring compressed to 156mm). For comparison I think leafman60 said John said the Sachs hydraulic preload only compresses about 1/2 inch or so max.
I get about 2.5" loaded or race sag (item G46 on my .xls spreadsheet on my website) and this shock is longer than stock (wheel travel is about 8.8", item B23). 2.5/8.8 = 28%, a reasonable sag number.
So ballpark numbers I am running a 16 kg spring (I weigh 190 + gear). So why in the hell is MINE bottoming! I really don't think I ride that hard.
They are hinting "if I am taking big jumps" I should go with a 180 N/mm spring (18.3kg) !! with a little less preload setting.
I certainly think this is going too far.
So my choices are:
1) Keep spring at 16.3 kg and simply add more preload. No change to shim stack. (I should have tried this but don't have a good testing site, and too lazy to take the shock off to adjust it safely).
2) Keep spring at 16.3 kg and add more hi speed compression damping shim stack.
3) Change spring to 18.3 kg and reduce preload a LOT. No change to shim stack.
4) Change spring to 18.3 kg and reduce preload a LOT. Also add more hi speed compression damping shim stack.
Any opinions out there???
Drone, I am shocked that you only had 1/2" of sag (loaded? really?), I can't imagine it being that low for a 16kg sprint, and that you would like it like that.
I don't want to pay to ship this back and forth a zillion times...
Perhaps I can't compare directly as far as spring rates to the Sachs but... why is this so hard ;(
I'm baaaaak too. Snooker good to see you back.
I'm back on my quest to add range on the XC. Has anyone ever thought of adding one of these tanks?
Couldn't I just plumb into into the line where I removed the canister? I'm working out a trip to Central America in January and I need more range. I currently have a Rotopax and 1L tank where the canister was.
Problem is it's a pain to pull over and dump out the tanks as needed. I'm hoping I can plumb this so the Aux tank drains first and then the main tank.
Thoughts? Advice? Thanks in advance.
I went this way. I made a bracket to hold the 5l tank to the front of the bash plate. It worked fine.
But I moved it to here for a bigger trip. Again, no problems. The hose is critical though. It gave me a 200 miles plus range.
I preferred it on the side just out of worry that it might get in the way on the front although it never seemed to. Altogether it cost about £70. One of the bet mods I made.
Yes, John at Moto Pro tells me that the stock Sachs is 11kg/mm. This is an '09 model, not '07.
His calculations for my 205 pounds called for a 13 kg. That was too soft. Im running a 15 now but kinda/sorta wish I had a 16 kg.
I never have bottoming-out problems. Of course, as I say all the time, I ride this as a dual-sport. I do a lot of curvy paved road scratching around but I also do a lot of rocky, dirt climbing trails etc. I've posted pics of these places.
I rarely "jump" the bike with both wheels off the ground and Im not roosting it around in dirt pits. It's working great for me now. Compression dampening on the Sachs is ok and I have adjusted my rebound for optimal performance.
By the way, I was told by Moto Pro (and Cogent Dynamics) that they can rebuild and modify the Sachs to change the compressions specs if needed. Rick Tan at Cogent (who sells Ohlins and Wilbers) advised me that he can make the Sachs do pretty much anything the Ohlins would do for much less money !
I think 1/2 inch of loaded sag would be too little and not allow enough rebound travel thus creating "extension bumps" as the shock hits it stop on rebound.
I would lay down the cash to have a properly fitting aftermarket shock that worked better than the modified Sachs but, for now, I don't know what that would be.
If you are having bottoming problems, the issue must be either/or the spring specs or the compression dampening. I'd suspect the spring and try another, stronger spring.
I have a lot of experience with auxiliary fuel plumbing on the XCo. If you search back, Ive posted information and tips from my experiences.
Several quick things if you install an aux tank and plumb a gravity/siphon feed to the stock tank vent tube. This will work fine but I recommend disassembly of the stock tip-over valve mechanism where the vent tube enters the stock tank. Just remove the internal shut-off parts to disable the closing of this valve. (This can be replaced later if desired.) Otherwise, you may have a case where the shut-off valve closes under use and shuts of the pull from the aux tank.
Also, be sure the routing of the fuel line to the stock tank is such that it doesnt get squished by the seat. I use aircraft/automotive quality clear tubing ( so I can see any air locks etc ) inside split plastic conduit.
Be sure to vent the aux tank !
You biggest problem eventually will be the stock gas cap. This must be reliably air-tight and the stock cap will sooner or later leak. The result will be that the gravity/siphon feed will be broken and/or fuel will stream out of the stock cap and run down the side of your tank. I've posted a lot about this too.
Now, on the gas situation - an option that I have considered but not yet tried is to heat and swell the stock tank ! I even bought a spare stock tank to try.
Here's my thought. Seal up and cap-off the tank but provide an inlet for compressed air to pressurize the tank. Pressurize the tank. Then, using a heat blanket like used for heating and bending PVC pipe or a heat gun, warm the outside of the tank to soften it enough to allow the internal air pressure to blow the side out some and thus increase its capacity. There is enough space between your leg and the tank to accommodate a moderate expansion of the tank. A little bit of expansion would dramatically increase the stock tank capacity.
Think about it.
Leafman- If that works, It will be brilliant A custom aluminum replacement with some healthy bulges would get very expensive.
Ah yes, I knew I've read about this somewhere, I'll search back to your posts.
Good point - will do. I suppose in a tip over the gas will just go to the Aux tank.
I'm guessing the ACERBIS tank has a vented cap but I'll be sure to check.
I see your point. My first thought was to leave the Aux tank valve closed for the first 100 miles and then open it to feed the main tank. The idea being that the main tank would then never be full enough to leak out of the cap. Of course the problem is I would be shutting off the vent. I suppose I could have a second valve for the vent but now it starts getting complicated.
Thanks for the tip jtw. Is that the ACERBIS number plate tank? Could I presume that mounting the tank below the level of the gas cap solves the cap spilling problem? I'm not sure about the exposure of the tank on the side but I might be able to tuck one in the region of the HB Pannier brackets which is somewhat below gas cap level.
Leafman: Interesting idea about expanding the tank. Yes, I need to think about that.
I'm going to noodle over these ideas some more while pretending to work today I know there is an elegant solution somewhere. Thanks for the advice.
Fuel tank discussion.
This worked great in Mexico:
I put a brass barb on the end of the tube inside the aux tank to keep it down in the bottom of the tank. Drains every last drop of fuel.
Gotta give it to you for creativity. I just got one of these propane flame throwers that might help if you want to borrow it:
p.s. if you want some comic relief, check out the first review on Amazon called Holy Crap This Is Awesome You have my personal Snooker seal of guaranteed laughter or your money back!
I have done this on mx bikes before using boiling water and a heat gun. I bulged out mx tanks to get about 20% more volume. Some suggestions. First thing is to force out all the fuel vapours from the tank by filling it with water. Mount the tank in the bike when using the compressed air to expand so it doesn't grow where you don't want it to and then it's too big to fit. I would just plug the air nozzle right into the vent line, you don't need much pressure but you have to let it cool under that pressure and do it more than once as they shrink back in size somewhat. The hot water is good because it heats the inside up also as your hitting it with the gun on the outside. In this situation because you only want one a single concentrated area to expand, I think the hot air gun is the ticket. Depending how much you want to go, don't try and do it all in one blow, you risk getting the plastic to soft. If its a high temp heat gun move it around allot because the plastic softens faster than you think.
Long time lurker here...
So I've finally managed to convince the gf that I NEED to get a bike again after a 15+ year hiatus I'm considering a XC but have yet to see one in the flesh. Anyone here is located in the Bay Area so I could have a look and get "live" feedback on the bike?