|
M42 posted:Interesting! I was convinced it was the gearbox, but looking at the video I recorded, it might have been the wheel after all. Rear was definitely locking up/drifting a little, I actually took a pic of the tire after the first time it happened Yeah it's hard to tell those sounds apart without some practice. A loud chatter and light hop from the rear is the tire, and a much more mechanical, metal on metal noise is likely gearbox. What you're really hearing is all the slack in the rear chain go all nutso as the rear wheel starts and stops in fits.
|
#
?
Mar 3, 2015 22:24
|
|
wee dorifto
|
|
| # ? Jun 5, 2024 19:27 |
|
|
Makes sense! Thanks man! Good feeling knowing you're not destroying your bike after all, haha.
|
|
#
?
Mar 3, 2015 22:28
|
|
|
I don't even worry about downshifts for panic stops.
|
|
#
?
Mar 4, 2015 00:26
|
|
|
nsaP posted:I don't even worry about downshifts for panic stops. This. Worst case you'll have to fight the transmission for 3 seconds
|
|
#
?
Mar 4, 2015 02:49
|
|
|
nsaP posted:I don't even worry about downshifts for panic stops. While I agree with you, I still think it's good to try and get it down a couple of gears in case you have to take off again. Most gearboxes will be annoyed at you if you try and shift without moving. Having said that, when I practice panic stops, I ignore the gears as well. I probably shouldn't.
|
|
#
?
Mar 4, 2015 03:07
|
|
|
I thought the idea was that if you're panic stopping, you can stop a lot faster than the guy in the car behind you, and you should be ready to immediately get moving once you avoid the forward obstruction before you get crushed.
|
|
#
?
Mar 4, 2015 03:09
|
|
|
Most bikes can't outbrake a modern car when you factor in ABS and rider skill.
|
|
#
?
Mar 4, 2015 03:25
|
|
|
Yeah, my MSF class taught us to downshift all the way while emergency stopping for the "take off again if you need to" reason.
|
|
#
?
Mar 4, 2015 03:27
|
|
|
Bikes can't outbrake cars, but most currently alive bikers can probably outbrake most drivers.
|
|
#
?
Mar 4, 2015 04:24
|
|
|
nitrogen posted:While I agree with you, I still think it's good to try and get it down a couple of gears in case you have to take off again. Most gearboxes will be annoyed at you if you try and shift without moving. Pop the clutch out a bit between downshifts if you're stopped. Enough to get things spinning but not enough to even try to start moving. It'll go right down effortlessly. Obviously there are some situations where it'd be better to be in gear and able to accelerate but imo most panic stop situation are more about stopping and swerving, less needing to hit the gas. I do downshift normally and with minor practice but those "oh poo poo" braking moments are always focusing more on the front brake and outs and less about the clutch/shifter/throttle. And I don't have to worry about my rear wheel hoppin all over.
|
|
#
?
Mar 4, 2015 07:14
|
|
|
M42 posted:Yeah, my MSF class taught us to downshift all the way while emergency stopping for the "take off again if you need to" reason. Yeah same here.. Pretty much if I panic stop I start downshifting. It has saved my rear end several times when I got just a little too close.
|
|
#
?
Mar 4, 2015 14:01
|
|
|
Downshifting in a panic braking situation doesn't normally include using the clutch to work every gear. Over spinning the gears while wildly downshifting is a real thing and something to keep in mind as well.
|
|
#
?
Mar 4, 2015 14:30
|
|
|
nsaP posted:Pop the clutch out a bit between downshifts if you're stopped. Enough to get things spinning but not enough to even try to start moving. It'll go right down effortlessly. I pretty much look at it as a "try and do it but dont freak out too bad if it doesnt happen." Great reason why practicing this stuff is a great idea even if you're not a newb.
|
|
#
?
Mar 4, 2015 16:40
|
|
|
I think in a panic stop you get to a point where you realize you're going to stop with a few feet to spare, and that's the time to worry about downshifting, not before. Or else you don't, and you hit the thing, and then it kinda doesn't matter what gear you're in.
|
|
#
?
Mar 4, 2015 17:05
|
|
|
EX250 Type R posted:Downshifting in a panic braking situation doesn't normally include using the clutch to work every gear. Over spinning the gears while wildly downshifting is a real thing and something to keep in mind as well.
|
|
#
?
Mar 4, 2015 20:36
|
|
|
So I bought an old 1993 Yamaha 535 Virago and within two weeks the loving engine seized up. I've got the time and effort to do an engine swap and I was kind of curious. Can you fit a 750 or 1100 Virago engine in that 535 frame or is it just not doable? I'm curious because I mean gently caress, if I can just put a bigger engine in there why wouldn't I if I've got to do it anyway? ArbitraryTA fucked around with this message at 17:04 on Mar 5, 2015 |
|
#
?
Mar 5, 2015 16:55
|
|
|
Rev. Dr. Moses P. Lester posted:I think it's the steel clutch plates that are technically the problem rather than the gears. Although I've never actually seen pics of a blown up clutch from over revving. Not on a bike anyway. Isn't the problem more like revving the engine way past its redline and lunching a valve or two? I'd have thought even the most ham-fisted "changing it into 1st at >100 mph" kinda fuckup probably wouldn't generate a gigantic amount of wear on the gearbox (after all rear tyre adhesion puts a pretty hard limit on the amount of torque that you can put through the gearbox in either direction) but it'd do a number on your top end as it tried to rev up past 20k rpm. (Yes shut up all of you getting ready to post how your particular bike does 100mph in first)
|
|
#
?
Mar 5, 2015 17:45
|
|
|
ArbitraryTA posted:So I bought an old 1993 Yamaha 535 Virago and within two weeks the loving engine seized up. I've got the time and effort to do an engine swap and I was kind of curious. Can you fit a 750 or 1100 Virago engine in that 535 frame or is it just not doable? Those frames are totally different. 750 and 1100 may swap relatively easily (I couldn't always tell the difference other than badging!), but not into a 535. Further compounding your problems, the motor is a stressed member in both series so just fooling with brackets would be dangerous. Go electric?
|
|
#
?
Mar 5, 2015 18:58
|
|
|
Rev. Dr. Moses P. Lester posted:I think it's the steel clutch plates that are technically the problem rather than the gears. Although I've never actually seen pics of a blown up clutch from over revving. Not on a bike anyway. You see it occasionally on drag bikes, but that's hardly a normal use case. goddamnedtwisto posted:Isn't the problem more like revving the engine way past its redline and lunching a valve or two? I'd have thought even the most ham-fisted "changing it into 1st at >100 mph" kinda fuckup probably wouldn't generate a gigantic amount of wear on the gearbox (after all rear tyre adhesion puts a pretty hard limit on the amount of torque that you can put through the gearbox in either direction) but it'd do a number on your top end as it tried to rev up past 20k rpm. A good point - thinking about what kills engines that have been over-reved, it's nearly always the valves floating and smacking the pistons, or excessive piston speed causing failure of con rods/wrist pins/etc - as long as you have decent oil pressure and you're not doing splash lubrication on the top end, the damage to the cams is less significant than the damage from excessive piston speed/valve float. Plus the transmission and clutch basket is riding on bearings, submerged in oil, so it's probably totally fine for a couple seconds of being (even massively) overdriven.
|
|
#
?
Mar 5, 2015 21:46
|
|
|
The only thing that would get immediately hosed inside the gearbox in that situation is the preload shims and bearings. Riding around subsequently with the shafts floating around every which way would eventually gently caress the gearbox but it's all irrelevant because you've just blown up the engine itself by making valves touch pistons, as stated.
|
|
#
?
Mar 5, 2015 22:12
|
|
|
Wait, if you're panic braking then why are you also letting the clutch out during/immediately after downshifting? Unless I've misunderstood how sequential transmissions work I thought you could just bang it down to first with the clutch in and then only let it out once you're going an appropriate speed for that gear to avoid over revving the engine (though obviously the actual gears would still be spinning faster than usual for a little bit)
|
|
#
?
Mar 5, 2015 22:25
|
|
|
You can, but then you don't get any engine braking and your brakes are doing all the work. Opinions differ on how you're supposed to do it but it really makes no difference because the much more important factors are front brake modulation, the state of your tyres, your reaction time, whether the bike has ABS etc. Coming down through the gears is not what you worry (or what you should worry) about when you're trying to avoid plowing into the side of a Q7.
|
|
#
?
Mar 6, 2015 00:36
|
|
|
Renaissance Robot posted:Unless I've misunderstood how sequential transmissions work I thought you could just bang it down to first with the clutch in
|
|
#
?
Mar 6, 2015 01:43
|
|
|
Rev. Dr. Moses P. Lester posted:If you do this from a high speed, you're spinning the clutch steel plates way way faster than they're designed to go. We were specifically told not to do this in dyno class at MMI because there's a chance of blowing up the clutch. But on a dyno the back tyre is being held down hard against the "road", and also you're dealing with a shitload more weight pulling the tyre round (the dyno mechanism normally weighs a lot more than a fully-loaded bike) so that's probably where the problem is there. In an emergency braking situation your back tyre's probably not actually doing that much at all.
|
|
#
?
Mar 6, 2015 08:22
|
|
|
Was riding last night and noticed it sounded a little more... throaty - if that makes sense? - anyway I get to a stop light and rpms just bottom out and the bike dies and refuses to crank. I had to let it sit out there for about a half hour finally was able to get it started by yanking the throttle as I hit the starter and limp back home. Any idea what could've caused that?
|
|
#
?
Mar 6, 2015 09:17
|
|
|
What bike? Sounds like you might have lost a cylinder - down on power and difficult idling once you got it running?
|
|
#
?
Mar 6, 2015 09:47
|
|
|
Z3n posted:What bike? Sounds like you might have lost a cylinder - down on power and difficult idling once you got it running? 81 Cm400c. The power was alright once it was started. But I absolutely had to keep it slightly revved in neutral or it'd die out again.
|
|
#
?
Mar 6, 2015 09:52
|
|
|
Wizard of Smart posted:81 Cm400c. The power was alright once it was started. But I absolutely had to keep it slightly revved in neutral or it'd die out again. When you say it wouldn't start - wouldn't turn over or turned over rough/wouldn't catch? Because that symptom and the throaty sound sounds like it's running rich and/or you've a hosed spark plug or coil, but if it won't turn over it could be something very wrong with your battery or electrical system.
|
|
#
?
Mar 6, 2015 10:11
|
|
|
goddamnedtwisto posted:But on a dyno the back tyre is being held down hard against the "road", and also you're dealing with a shitload more weight pulling the tyre round (the dyno mechanism normally weighs a lot more than a fully-loaded bike) so that's probably where the problem is there. In an emergency braking situation your back tyre's probably not actually doing that much at all. Unless the tyre locks up under braking, it's still spinning the gearbox and you risk overspeeding it. You can test this yourself (carefully) by shifting down at speed. It gets clunkier the lower you go, you can hear the whine as well. I'm with Slavvy, don't worry about the gears in such a situation. Concentrate on braking hard and well. Either you will crash and staying in 5th won't matter, or you will see that you've made it and you can tap-tap-tap yourself quickly down to a usable gear.
|
|
#
?
Mar 6, 2015 10:32
|
|
|
goddamnedtwisto posted:When you say it wouldn't start - wouldn't turn over or turned over rough/wouldn't catch? Because that symptom and the throaty sound sounds like it's running rich and/or you've a hosed spark plug or coil, but if it won't turn over it could be something very wrong with your battery or electrical system. It would crank-no-start but every now and then would try to catch.
|
|
#
?
Mar 6, 2015 10:57
|
|
|
Wizard of Smart posted:It would crank-no-start but every now and then would try to catch. Someone who knows about the dark wizardry of carbs will be along in a minute to talk about them, I'm sure, but check your plug(s) while you're waiting - if they're very sooty then that reinforces the running rich possibility. While you're down there make sure you've not got any leaks in your exhaust system and that the leads and terminals for the plugs are clean and undamaged too.
|
|
#
?
Mar 6, 2015 11:02
|
|
|
goddamnedtwisto posted:Someone who knows about the dark wizardry of carbs I believe the correct term is Stoichiomancer.
|
|
#
?
Mar 6, 2015 11:23
|
|
|
If you're panic stopping you can use your brakes to stop and just pull the clutch to keep the motor from dying. Shifting down gears while trying to stop ASAP seems like a bad idea.
|
|
#
?
Mar 6, 2015 17:14
|
|
|
Nah man I got the skills of Marquez and the MSF said so
|
|
#
?
Mar 6, 2015 17:18
|
|
|
goddamnedtwisto posted:But on a dyno the back tyre is being held down hard against the "road", and also you're dealing with a shitload more weight pulling the tyre round (the dyno mechanism normally weighs a lot more than a fully-loaded bike) so that's probably where the problem is there. In an emergency braking situation your back tyre's probably not actually doing that much at all. Depending on the bike and the street riding you're doing, this may not be that big an issue. But the question is, given the speed you're doing and the gear you're about to shift down into, how much over what would be redline if you let the clutch out are you gonna do? Even not letting the clutch out, you're doing some crazy stuff with some of the components in there if it's over that redline.
|
|
#
?
Mar 6, 2015 17:44
|
|
|
Rev. Dr. Moses P. Lester posted:Not sure what you mean by all that, but I'm just talking about pulling in the clutch at like 120mph, holding the clutch in, and shifting down into 1st. No letting the clutch out, no engine load, braking is kind of irrelevant unless you're changing the rear wheel speed so that it's not above what would be redline in 1st. Just spinning the input shaft on the transmission and the steel clutch plates to a million rpm. Ah, okay, we were talking at cross-purposes - I thought you were talking about dumping the clutch in that situation, I didn't realise you meant what wear/damage keeping the clutch in there would cause.
|
|
#
?
Mar 6, 2015 18:05
|
|
|
ReelBigLizard posted:I believe the correct term is Stoichiomancer. This made me very happy.
|
|
#
?
Mar 6, 2015 18:15
|
|
|
goddamnedtwisto posted:Someone who knows about the dark wizardry of carbs will be along in a minute to talk about them ReelBigLizard posted:I believe the correct term is Stoichiomancer.  I'll check the plugs after work today. Why would it all of a sudden start to run rich?
|
|
#
?
Mar 6, 2015 19:25
|
|
|
Check your coils and spark plugs. That louder, deeper noise plus difficulty idling is almost always a cylinder going out, and it's usually only "just happens all the sudden" when one of your plugs/coils/electrical system has issues. Check battery voltage and look for disconnected/frayed wires on the coils, damage to the plug wires, missing spark plugs, etc. Also worth checking fuel flow and making sure things didn't get blocked up somehow, but that's less likely.
|
|
#
?
Mar 6, 2015 19:30
|
|
|
|
| # ? Jun 5, 2024 19:27 |
|
|
Wizard of Smart posted:
Have you noticed how everyone who wanders in here asking about what bike to buy gets discouraged from buying something ancient? This is why. Enjoy. Take the plugs out and post pics. I'll bet one looks different to the other.
|
|
#
?
Mar 6, 2015 19:57
|
|