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gregk

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About gregk

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  1. gregk

    Anders wins 1st race on BMW

    Some stainless steel have both a good resistance to corrosion and a very good mechanical characteristics. Those are labelled HEL (for High Elastic Limit). In fact, I think they are as good mechanically as non-stainless (some non-stainless have an even higher elastic limit, or hardness...but they are more brittle (meaning they do not absorb energy by deformation, but tend to crack if sollicited above their elastic limit). Given the sollicitations of offroad, I guess those would be too brittle...) That's what BMW advertize, HEL stainless steel...Sound good to me, only drawback I see is that - it is far more expensive than normal steel, and more expensive than classic stainless steel. - it is more difficult to weld, with thermal treatment usually required after welding if I remember correctly. More expensive should not be a drawback, I guess it is not really noticeable on the final price given the amount of material. More difficult to weld is an issue, I hope BMW can deal with it...I am quite confident thay can, but I do not expect shops to be able to fix a broken frame, even less so than with an aluminium one... Well, I am not 100% sure to be accurate, but that's what I recall from my metallurgy lessons and it match the info I found on internet so... ;-) He He, in fact I designed a crash test measurement device, and we used such a stainless steel as impact plate. Simply the hardest non brittle steel we found, corrosion resistance came as a free extra ;-) It had to be thermal treated after machining, not before else it was too hard... So as far as stainless is concerned and BMW know how to select it and weld it, I would not be too concerned...I am more affraid of stone hitting the engine casted shell....a squidplate directly fixed on the engine seems a little weak as the only protection for a quite brittle aluminium casting. I hope they designed this plate well, here we do not have any high resistance frame tubes doing most of the work...
  2. gregk

    BMW Motorrad @ WFO Enduro

    I wonder too if this pivot at the sproket innovation will not have adverse effects on jump landings. I was told (on this forum ) to land rear wheel first, on gas, when flat landing, because beeing on gas stiffen the rear shock and prevents bottoming out (not that I jump high enough for this to be a problem ). If pivot at the sproket completely decouple transmission effects from suspension effects, maybe this technique will not work anymore? Or maybe I did not get the reason why beeing on gas for landing is good? Bottoming out is also more of a concern on linkless suspensions it seems (less stiffening at the end of the rear shock stroke), and the G450X has a direct-mounted, linkless, shock... That being said, I like the bike, from an aesthetic point of view (seems that I am in the minority here ), and because it has a lot of innovations. I wonder which ones will work and get copied BTW, could someone compare its weight to current enduro bikes? It is quoted weighting 120 kg full of gas (should be 110 kg dry weight, right?), and light...I wonder how much other bikes weight, to get an idea how much lighter (if lighter) it is, compared to the competition...
  3. gregk

    Auto clutch - would you own one?

    I agree with mowtown: I am crappy rider, but I live in Europe and never had any motorized vehicle without a clutch (well, except a moped :-p ). Clutch control is not chalenging when I ride a dirtbike, not at all. Balance and power control is (and is the fun part). Compared to a car, I like the power, balance and the fast gear change...Clutch is not really funny, it is just there and before reading thumpertalk I was not even aware of auto-clutch for dirtbike (and I still never saw any). I do not own one, but if it is reliable, and does not wear faster than a regular clutch, i am all for it. I will reduce my left arm pump and may save me tipping over when I am in panick mode and too busy hanging on the handlebar to be able to reach that damn clutch. Hell, I would go buy one today...except it is too expensive for my dirtbike budget and I do not know where to get one. BTW I would not think of having an automatic car: changing gear IS funny, and I do not have "hanging on the handlebar and hoping I will go through it" moments, nor left-leg pump, in a car :-).
  4. Oups, sorry...french only term I guess...I will remember the proper english term for next posts, thanks!
  5. Sorry, can not really help you on this: I never looked after "ready to plug" dual sport kit. You may want to reconsider though, and think about making your own: you will save big bucks and it is not difficult... I am a bad mechanic (mainly due to lack of experience and proper tools) and would not try for now anything complex like motor or fork disassembly. However, electric stuff on a bike that already have an AC and DC supply (alternator AND battery) is really easy, just access to wires, connect new derivations, add fuse for protection, and you are done. Basically you need wires, eventually new fuses, switches, 2 or 4 LED turn signal with the associated electronic on/off box (take the 2 wire variant, real easy to use), and a commodo (the stuff you mount on your bar with all the commands), that you can get from any street bike (check that it is the same diameter as your bars). Compared to other task, electric is easy, clean (no grease!), dot not required a lot of strength (no sweat with bad screws or seized parts, no need to lift the bike on a stand), and require only a mutimeter and a cutter as special tools...with maybe the soldering iron as a nice to have. It may be me only, but I wish all the other stuff are as nice as electric work, as long as you take your time, think about wiring before you cut, nothing bad can happen ....I tried to change a tire for example, and even if advices from the net and instruction video helped, I still ruined my tube and scratched my wheels...
  6. I have exactly the same model, bought used and with only headlight and taillight on AC, and a broken hydraulic switch on the rear brake wired to the stop light (so no stop light...). I got quite far in the street legal stuff (stop light, head light with high beam, low beam, "parking beam" and turn signals. Basically for DC I just added new wires directly to the battery, negative directly on the battery - connector (mass), and the positive behind the battery fuse box (so that it is fuse protected). You could go to + and - direct connection to the battery connectors, but I would add an additional fuse in this case, to avoid fuseless wiring which may be dangerous imho...The new wires are simply routed under the seat, along the stock ones... Used the DC for turn indicator (LED) and 1 of my head lamp (I call this "parking beam". The second lamp of the low beam and the 2 high beam lights (I have a 4 halogen headlight plate) are wired to the old AC. So I have 3 position: parking= 1low light, low = 2 low light, high = 2 high lamp + 1 low lamp. The tail light and stop light are both aslo wired to AC, so there is no big drain on the battery, but I still have 1 front lamp without the motor running, and the wiring is simple. The commodos is a used street bike commodo I bough on Ebay, I even used the horn switch as a new killswitch (my original kill switch has bad contact adn was becoming more and more difficult to use, I had to press like crazy on it to make it work ). I have adapted a mechanical switch on the front break lever, and probably will replace the rear hydraulic switch when changing brake oil. Not sure as the front brake is the main brake on the street anyway I guess this setup is not strictly street legal in your area, but may pass. Here in Belgium I guess it is, as the WR is sold with just front and tail light, not even stop light, as street legal here (We are lucky! but not so for land use regulation :confused:), I added all the stuff because I was tired of using my arm as turn indicators and it make it safer to drive at night if I am late coming back from a trail...having a stoplight is also a plus for security, even without rear brake (which would not show motor braking anyway). No problem of drained battery or unreliable electric system, so I am quite happy with my simple solution (no rectifying diode needed, just a few meter of electric wires) and it can give you ideas even if you have more legal requirements than I did... Greg
  7. I may throw a little bit more info about this . First a caveat: I have never ridden an Al framed biked (and even if I did, my level as a rider would probably not let me feel the difference....unless it is huuuuge ). I am however a mechanical engineer, so on the theoretical level I can help... Birdy is 100 % right telling steel and alu have the same stiffness/density ratio, meaning that at equivalent weight steel and aluminum will have equivalent TRACTION stiffness (stiffness if you pull or compress the tube). However, bending stiffness (for plates or solid tube) and buckling resistance (for hollow tubes) do not depend on the stiffness/density ratio, but more on the stiffness/density^3 or stiffness/density^2. This is the reason why planes are made of alu and not steel, they are build using a sandwitch contruction and the most critical design factor is usually avoiding buckling failure....where Alu is far superior than steel at equal weight. For bikes, the tubes making the frame will be more stiff bending-wise for Alu than steel, even if in traction/compression there are the same. This means that an Alu frame should indeed be globally stiffer than steel for the same weight, and that the feel should be different, as the stiffnesses under different solicitations will be different for the 2 types of frame. This is why the comments that the Alu frames feel harsher and more precise than steel ones makes sense to me... Regarding respective resistance (stress before failure) it is difficult to tell, I guess it should be about the same. However, the steel frame should be about to flex more before being damaged, so for 2 frames of about the same global stiffness, I expect a steel one to handle crashes better...
  8. Lol...I love duct tape as much as anybody, but here it may be just a little too weak and not water tight enough...On the other hand, everybody know it is perfect for fixing a split frame or swingarm ...
  9. Hi all, last time I went to my (unofficial ) motocross track, after about 1 hour of jumping attempts I detected a leak in my left fork seal. Not a large leak, but the brake caliper looked wet (which seemed strange, as the track was almost completely dry), I checked and it was oil, not water...the oil did come from the fork, leaking slowly along the chrome inner tube and wetting the caliper. The jump (yes, THE jump...there is only one on the track ) have a flat reception, and my landings were a little bit rough...However, I am a beginner and do not jump high, so I rate the probability of me (75 kg) breaking something in the fork of a WR450 2004 with standard spring as really really low (or maybe I progressed faster than I though and my jump are not as ridiculous as before? ). More likely, I compressed the fork more than usual and some dried dirt got trapped under the seal. I do not want to attempt seal replacement, fork disassembly is quite frightening and I think the 35mm film trick is better to be tried first, given that the leak is not very strong... Now for the dumb question: I first tried to do the film trick under the dust seal (I did not know there were 2 seals....noob, I told you ), there was an improvement in the leak, it looks like it was more or less solved, but reading thumpertalk I realised my error and I think the oil is simply accumulating above the dust seal and will leak again when I jump a few times... I would like to clean the oil seal properly, but question is, how do I remove the dust seal in the first place???? I have removed the fork gard and it's guiding nylon ring, but the dust seal is still fixed quite strongly. Do I have to take it down by inserting a screwdriver between it (rubber) and the bottom of my upper fork tube (aluminum)? Pulling with fingernails only it does not seems to come down, and there is no obvious fixation system (I hoped the nylon ring was somehow responsible for holding the dust seal, but it is not the case obviously). There is nothing about this in the manual, unfortunately, they just say "remove the dust seal" Before I start applying some force with a screwdriver on a rubber part, I prefer to ask the board than risking damaging something.... Thanks for any help! Dummy Noob Greg. PS. While I am at it, a technical question about jumping...The better rider seemed to land rear wheel first (slightly first, but the rear wheel did land before the front) and adviced me to do the same. I tried to and managed (before, I had a tendency to nose-dive and land on my front wheel). However, while landing front wheel first is scary (especially when the nose dive is significant...you definitely feel you sucked big time and you better correct your take-off before you land on your helmet ), landing flat felt the best. In fact, landing with front wheel just slightly down is not as good but still felt smoother than rear wheel first. Landing rear wheel first seemed to make the front fork hard, like if the force on the front wheel when it hit the ground was not aligned with the fork and tried to make the wheels further apart (not easy to explain, but I hope the experienced rider get what I mean). That's what I meant when I said I had a few rough reception, in fact feared it could be the cause of the leak, but looking at the pro I guess my bad receptions are not possibly rougher than a good rider perfect reception, given the difference in jump height . So what do you think? Is landing rear wheel first really better, or flat landing on flat reception is best and the advice "rear first" is just for security, as it is better to land too much on the rear than too much on the front? Or maybe it is rear first but there is something else I do incorrectly and make it rough...
  10. I tested my quick fix (welding the reservoir with a soldering iron, and adding some silicone for good measure...). It seems to be ok, no real stress on this part so I guess any fix having a minimal resistance and water-tight is enough. If other have this problem, you know that 5 minutes and a soldering iron is enough, no need to buy new part . Greg.
  11. wow, thanks but I think it is a little bit of overkill: the reservoir is not under pressure, so I agree with previous poster that it should not be too hard to fix it: today i melted it with a soldering iron, and added a bit of silicone afterward for good measure....I hope it will be strong enough, tomorrow or sunday I will test it some...Except if my rear tire hit it on a jump reception, I expect it to be ok....and as I am not good enough to jump as high as I would, it should not be a problem
  12. Hi all, since a few ride I have noticed the level in my coolant reservoir dropping quite fast to just under the low level mark, and then going down much more slowly....I was quite worried as I did not notice obvious leaks (coolant on the floor of my garage), and was fearing a faulty head gasket or worse.... Luckily (sort of), it is nothing serious: today I had a short commute trip to office (road only) and overfilled a little bit my reservoir before going. I identified a leak in the coolant reservoir itself, which has escaped me before because it is at the high level and was hidden by the mud during my last offroad rides...when I cleaned the bike the coolant was already under the leak point so I saw nothing.... There is no hole, rather the reservoir has split along its central welding line (it seems made of symmetric plastic parts (left and right), welded...maybe a faulty plastic welding...or a hair crack due to vibration?). This is invisible under normal circumpstances, and the leak is very small, almost non-existent when the bike is not running....but I guess it is more significant under vibration and large if I compress the reservoir manually (I can see the 2 part separating and coolant going out...). Do you think it is possible to fix this, rewelding the reservoir using heat? (glue seems a bad idea, I guess it is polyethylene and gluing this plastic is almost impossible)... Or do I just have to buy new a new one (I expect to be out of luck finding that stock...bad luck for the WE ...but I guess it is not expensive) BTW I have a WR450 2004, but I guess the coolant reservoir is very similar on all WR... Thanks for any idea dealing with this, Regards, Greg
  13. I would like an electric bike, if it had the same performance or better than current dirtbikes... I am a bad driver, so current 450 are overkill for me...but the fact that you can spin loose the rear wheel or wheelie at will (well, for wheelies, it is to know I could....if I had the balls and the technique ; ) ) is a big part of the fun for me. I think something in the 40-ish Hp and current weigth is ok, or even 30-ish Hp and 10 kg less and I am happy....but I need to have at least 4-5 hours of mixed driving (some hard, some mellow) for autonomy and be able to charge it in less than one night (5-6h charge is ok) from a normal plug....Add to that a fast charge mode (15 minutes charge for 1 hour of hard driving) would be nice (at the tracks, a charge stop can be done, people would buy the electricity instead of the gas, it should even be cheaper...) and I am very happy, it would be more than enough for my style of rides. The noise of current bikes do not really bother me...I even like 4 stroke with stock enduro exhausts ( 4 stroke mx bikes are too loud, and 2 strokes sound like moped except when full on...and then they are too loud too. I like the smell of the pre-mix though ). However, a completely silent bike is better for me...a little bit less thrill maybe, but the stealth-mode riding is priceless...at this time, any track available to moutainbikes would be available to electric bikes too (some eco will try to prevent that, but they will get no popular back-up and will fail....even if it pass, legislation will not be respected and impossible to enforce. Noise is what make the majority of people against dirt-bikes, remove the noise and you remove the opposition of the majority of the population. Hard-line eco's will still be against it, but they are a minority and can be defeated by any well organised off-road user association ( moutainbikes, horses, offroad-vehicles - if silent). Only thing that will be a problem is the first time somebody is hit by a dirt bike (especially if children), this will again put dirt bikes in bad term with the majority...Unfortunately, it is almost certain to happen with silent bikes...: ( Anyway, it is not for short term, if ever, imho...The battery technology is not there, and it is not garanteed that it will be possible to have battery with the energy density required. There are physical limits to this energy density using chemical batteries, and we are close to it with current Li-Po....in addition, they are expensive and have a limited amount of charge/discharge. If your battery has lost half of its capacity after 300 charges, you could end up with a bike that goes 2 hours between charges instead of 4 after 2-3 years, and the price of a new battery almost as much as a new bike...not too good, especially for people used to buy used bikes only (like me). Condensator technology may improve that maybe, but using the rates at which battery technology has improved in the last 10 years to extrapolate is risky, and using cell phone autonomy improvements as a predictor is crazy optimistic: a large part comes from electronics, while for bike ones your motor is efficient (and electric ones are, extremely so), you can not use less power for the same fun, 30 Hp at the rear wheel will always be 31-40 Hp drain on the battery.... Hybrid is not a promising solution for dirtbikes imho - too heavy and complex (more than current thermic-only kind), and same problem of noise... So current electric bikes are interresting prototypes, but I feel I am still a long time from owning an electric bike, if ever :/ PS: some of those e-bikes are butt-ugly...but this is not a problem, nothing easier to improve than the look
  14. gregk

    Can you flatfoot your bike?

    I flat foot one side, toe both side on my wr450 2004...I am 1.75 m, and given my level, I wish I could flat foot on both sides simultaneously, it would be more confortable and prevent some humiliating tip-over I moved the fork up in the clamps as much as possible, and decreased rear spring pre-stress, gained maybe 2 cm, before I was just touching ground with toes, now it is still toes only but less strained and more comfortable already in slow difficult stuff, less tip over, easier paddling, bike even seems more agile (or maybe I start to suck a little bit less as a driver...I hope it is that ). I did not notice any adverse effect even when going faster, bike do not seems less stable...So I am happy with this, only thing I could do is to lower the suspensions (but I find it too expensive, and I am not good enough yet to really appreciate a full suspension setup) or a lowering link (which would be equivalent to a softer spring/less pre-stress as far as I understand. I can lower the pre-stress free, and I feel my rear spring soft already, so I do not want to go this route either). I am thinking shaving my seat a little bit, could gain maybe another 2 cm ... but it is quite thin already, I would have to change the shape of it, make it less flat, by removing foam at the lowest point of the seat.... So not so sure it is a good idea, it will make the seat more similar to old bikes, and maybe discourage proper positioning in the turns, because it will be less natural to move further forward to the tank? On the other hand, my seat now keep water after I wash my bike, just on one particular area but it is 2-3 days before it is dry, and having a wet butt before hitting any water is anoying . Maybe if I shave it I can also duct-tape the seat housing area at fault, to prevent water to impregnate the foam under ? That would be added benefit: a lower bike and a dry butt!
  15. gregk

    Photo's of subframe munching my chain!

    Yes I have a 2nd hand 2004 since 1 month, and I have noticed almost exactly the same wear on subframe. Fixed it by gluing aluminum profile with epoxy, and I have checked the profile for new wear: none so far, I guess as a beginner I am not hitting the gas hard enough BTW, check also the wear of your swingarm under the plastic chain slider: mine was badly eaten too (previous owner did a lot of riding in the sand...). Fixed it with help of epoxy/aluminum paste and glued the slider with silicone....For now I do not see any drawback to this mod, but if my slider wear too fast I plan to glue a thin inox sheet under it and let it slide on it, as advised in the forum... Also the fork tubes had wear from the plastic headlight plate rubbing on it! Sand again I think, aluminum and sand do not go well together and yamaha design is not helping things... So 3 wear points to check when buying a used WR, I spotted only the fork wear when buying it... Except for that, nice bike!
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