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| Peasnall |
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 Peasnall Two Stroke Sniffer
Joined: 22 Oct 2004 Karma :    
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| MarJay |
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 MarJay But it's British!

Joined: 15 Sep 2003 Karma :     
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| Peasnall |
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 Peasnall Two Stroke Sniffer
Joined: 22 Oct 2004 Karma :    
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| sychosis |
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 sychosis Crazy Courier

Joined: 21 May 2004 Karma :     
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 Posted: 12:34 - 22 Oct 2004 Post subject: |
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If you have a bike already try this on your drive, put it in first, then slowly let the clutch out, when you feel the bike move and the engine noise change apply a little throttle, then slowly release the clutch some more and you will start to go forward. When you change to another gear, throttle down, pull in clutch, change gear start to release clutch whilst reapplying power slowly, this way the engine won't snatch.
edit: Just noticed you don't have a bike yet, when you take you're cbt, the instructor will show you all this anyway. Also it's a good idea to keep your foot on the back brake. ____________________ Bikes owned: Aprilia RS 125 GP1 2003 (Now sold), Suzuki GSX-r600 1997 (streetfightered), https://www.bikepics.com/members/sychosis/
psy?cho?sis (si-ko-sis),n. pl. psy?cho?ses (-sez) ,A severe mental disorder, with or without organic damage, characterized by derangement of personality and loss of contact with reality and causing deterioration of normal social functioning. |
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| Peasnall |
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 Peasnall Two Stroke Sniffer
Joined: 22 Oct 2004 Karma :    
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 Posted: 12:47 - 22 Oct 2004 Post subject: |
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Thanx mate, i have a KX250 in the garage but its too snappy, so i will try it when i get my bike  ____________________ 2000 Aprilia Rs50
Arrow Exhaust, Dell'orto PHBG 19mm, Custom Hanger |
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| sychosis |
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 sychosis Crazy Courier

Joined: 21 May 2004 Karma :     
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 Posted: 12:50 - 22 Oct 2004 Post subject: |
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Try it on the 250, put the front wheel against a wall so you don't suddenly go forward, and just get a feel for the bite point ____________________ Bikes owned: Aprilia RS 125 GP1 2003 (Now sold), Suzuki GSX-r600 1997 (streetfightered), https://www.bikepics.com/members/sychosis/
psy?cho?sis (si-ko-sis),n. pl. psy?cho?ses (-sez) ,A severe mental disorder, with or without organic damage, characterized by derangement of personality and loss of contact with reality and causing deterioration of normal social functioning. |
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| instigator |
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 instigator Super Spammer

Joined: 19 Oct 2004 Karma :   
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| stryker |
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 stryker Brolly Dolly

Joined: 30 Aug 2004 Karma :  
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| mr jamez |
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 mr jamez World Chat Champion

Joined: 04 Aug 2003 Karma :   
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| Peasnall |
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 Peasnall Two Stroke Sniffer
Joined: 22 Oct 2004 Karma :    
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| 27yo kid |
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 27yo kid Renault 5 Driver
Joined: 08 Oct 2004 Karma :     
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| Peasnall |
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 Peasnall Two Stroke Sniffer
Joined: 22 Oct 2004 Karma :    
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| stryker |
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 stryker Brolly Dolly

Joined: 30 Aug 2004 Karma :  
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| sychosis |
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 sychosis Crazy Courier

Joined: 21 May 2004 Karma :     
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 Posted: 16:07 - 22 Oct 2004 Post subject: |
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I've found it works from 2nd to 1st, but not from any other gear ____________________ Bikes owned: Aprilia RS 125 GP1 2003 (Now sold), Suzuki GSX-r600 1997 (streetfightered), https://www.bikepics.com/members/sychosis/
psy?cho?sis (si-ko-sis),n. pl. psy?cho?ses (-sez) ,A severe mental disorder, with or without organic damage, characterized by derangement of personality and loss of contact with reality and causing deterioration of normal social functioning. |
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| Bomberman |
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 Bomberman World Chat Champion

Joined: 17 Aug 2004 Karma :  
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| Ste |
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 Ste Not Work Safe

Joined: 01 Sep 2002 Karma :    
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 Posted: 17:22 - 22 Oct 2004 Post subject: |
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Quick point, they'll cover about using the gears and clutch in your CBT so you don't need to know about them to do your CBT.  |
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| nick.h |
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 nick.h World Chat Champion

Joined: 12 Sep 2004 Karma :     
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| Ste |
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 Ste Not Work Safe

Joined: 01 Sep 2002 Karma :    
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| MarJay |
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 MarJay But it's British!

Joined: 15 Sep 2003 Karma :     
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| pipnet11 |
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 pipnet11 Brolly Dolly

Joined: 17 Sep 2004 Karma :  
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| mchaggis |
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 mchaggis World Chat Champion

Joined: 10 May 2004 Karma :    
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 Posted: 04:04 - 23 Oct 2004 Post subject: |
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Okay, you asked for it. A detailed response you shall receive. See the attachment.* This is going to be referred to throughout. Oh, and don't expect technical drawing standard, ISO and everything... If you don't get what it all is, best to look on the urls I put at the bottom, they've got all sorts of interactive and animated gubbins.
| Quote: | -Set off
-Changing gears
How to use the clutch with the throttle when setting off and changing gears |
First, an explanation of the picture, which is essentially a 3 speed constant mesh car gearbox (I got lazy…). I know bikes have sequential gearboxes and wet clutches, but the basic principles are the same. The engine turns the crankshaft, turning the flywheel. The clutch cover is rigidly attached to the flywheel (bolted to it indeed). The clutch pressure plate is attached to turn in unison with the flywheel.
The clutch plates are splined onto the primary shaft, so they can move along it longitudinally, but not around it (i.e. they turn together with the input to the gearbox). What I haven’t shown is the mechanism with which you release the clutch, but it’s somewhat too complicated for me at 2:30 in the morning…
With the clutch fully ‘let out’, the clutch springs force the pressure plate onto the clutch plates, which in turn is forced onto the flywheel. This means the output shaft from the clutch, (the input to the gearbox) will turn at the same speed as the engine. Obviously, the smaller force pushing the friction surfaces onto the pressure plate and flywheel, the less frictional forces will be generated between them.
The frictional force can be given by: Frictional force = Normal force (at 90 degrees) x coefficient of friction between the surfaces.
Eventually, the force produced by the engine will be greater than the frictional force generated by the amount of clutch you’re using. When this happens, the clutch plates slip; the engine is running faster than they are. This means that the output to the gearbox is slower than the engine speed, obviously if you get it right, you can increase the output speed from zero to the engine speed by slowly increasing the amount of clutch application force. (Letting the clutch out more.)
The point of the clutch is to provide a way to disconnect the drive from the gearbox (for changing gear and standing still), and to allow drive to be provided from zero driveline speed, as the engine will not produce torque from zero.
The drive goes into the gearbox primary shaft, transferred to the layshaft, and transferred back to the main output shaft. This then goes to the wheel(s). The gears on the main shaft and layshaft are constantly meshed, so they are all turning at once. The main thing to remember is that the gears around the output shaft are perfectly free to turn around it. These gears are attached to the output shaft by means of dog clutches, which are little toothed wheels which fit into a corresponding recess on each of the gears. The dog clutches are splined onto the output shaft, but can slide along it to engage the different gears. To get these to engage properly, you need to match the engine speed through the clutch (or throttle) with the speed of the wheels, so that the dog clutch will slot neatly in without grinding it’s teeth against the gear. The dog clutch is pushed back and forth along the main output shaft by forks which sit in a groove around the circumference of the clutch.
So then, to set off, select first, rev the engine reasonably highly, perhaps to 4000 rpm, then [i]slowly[/i[ let the clutch out. This lets the plates slide and so the drive is taken up through the gearbox slowly, allowing the wheel speed to match the engine speed gradually. If the wheel speed is not allowed to slowly achieve the same as the engine speed by slipping the clutch, the resistance to the wheel pushing the ground will stop the engine from moving, hence a stall.
If you increase the throttle so as to keep the engine speed constant whilst the clutch is being let out, it can also help keep you from stalling, as the engine is producing more torque so more force is needed to stop it.
For changing gear, you need to disengage the gearbox from the engine by pulling the clutch in. Then you press up on the gear lever, which will push the dog clutch into engagement with the correct gear, and if they’re synchronised, the gear will be engaged, whereupon you let the clutch out and accelerate again. The principle is the same dropping down gears too.
A handy technique is called ‘clutchless upshifting’. This is controlling the matching of speeds using the throttle, controlling the engine speed directly, rather than slowly allowing the gearbox to match it. Basically, when you are going to change up, the gear ratios mean that the engine will be running more slowly after the change. Hence, when you are wanting to change up, place a little pressure upwards on the gear lever, and blip the throttle down. Hopefully, the pressure on the lever will engage the next gear while the engine drops in speed when you blip the throttle.
More than an hour’s work later (half hour writing that, and half hour on MS Paint), and I hope you appreciate the effort! I knew this degree course would come in useful for something…
Also see https://www.howstuffworks.com/sequential-gearbox.htm and https://www.howstuffworks.com/clutch.htm.
*The drawing is only in MS Paint, and while is more or less complete in detail, there are significant parts missing, particularly in the clutch, bearings and oil drainage plugs. edit: Oh and also there's 3 gears missing too.  |
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| CBRPETER |
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 CBRPETER Scooby Slapper

Joined: 29 Sep 2004 Karma :     
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 Posted: 09:59 - 23 Oct 2004 Post subject: |
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Ok simply from a off bike, Hold in clutch while turning key will start the bike, Tap down to first, ease off the clutch while you ease on the accelerator, you'll get the feel of how much to give as you go along, to change to 2nd get off the accelerator, pull in clutch, ease off as you ease on accelerator.
No-one covred this - When braking, hold in brakes while shifting down gears, BUT keep the revs up while your changing gears by giving a bit of accelerator.
As for your theory on how japanese bikes have great gearboxes. Have you ridden the new gsxr 750's, i've had 3 false neutrals on it and iv'e only ridden one twice, probably just me. ____________________ Shes my life, shes so rad and shes the best ride i ever had!! |
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| pipnet11 |
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 pipnet11 Brolly Dolly

Joined: 17 Sep 2004 Karma :  
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| Gazdaman |
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 Gazdaman I did a trackday!!!

Joined: 12 Aug 2004 Karma :    
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| proximity |
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 proximity Crazy Courier

Joined: 08 Oct 2004 Karma :  
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Old Thread Alert!
The last post was made 21 years, 240 days ago. Instead of replying here, would creating a new thread be more useful? |
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