Wednesday

Suzuki 650 Burgman troubleshooting help?

OPERATION

Demo:--Click this link below to see working demo in manual and power mode:---

http://www.pirmil.info/scoot/ssiburg/650info_suzuki-1_cvtdemo.shtml (external link)

There are 3 modes in which a rider can utilize the CVT.

Auto

This is the mode the 650 is in when it is first turned on. It balances between fuel economy that scooters are expected to have, and the power the 650 is capable of.

Manual Mode

Manual mode allows the rider to switch the CVT primary pulley position manually between a fixed number of ratios, using a pair of up/down buttons on the left handlebar switch cluster. For K3/K4 there were 5 fixed ratios, and a 6th (Overdrive) was added for the K5 and above models. Note that Manual Mode does not provide full manual control – the ECU will not allow change up below certain speeds and will automatically change down below certain speeds. If the motorcycle is brought to a halt the CVT will automatically start off in 1st gear. Like a regular manual gearbox the CVT will not change up to the next gear unless specifically selected by the rider.

In manual mode the gear ranges available are as follows:
Metric
RatioMinimum Change Up PointAutomatic Change Down PointMaximum Speed in Ratio
1N/AN/A57 kmh
222 kmh17 kmh85 kmh
330 kmh24 kmh120kmh
440 kmh32kmhTBD
550 kmhTBD200 kmh (theoretical)
659 kmhTBD212 kmh (theoretical)


US
RatioMinimum Change UpPoint Automatic Change Down PointMaximum Speed in Ratio.
1N/AN/A35 mph
214 mph11 mph53 mph
319 mph15 mph76 mph
425 mph20mphTBD
532 mphTBD124 mph (theoretical)
637 mphTBD132 mph (theoretical)

Note 1: speeds stated above are according to the speedometer which reads 10% high.
Note 2: at ~13 kmh (8 mph) the clutch will automatically release. With the bike rolling (e.g. whilst coasting downhill with minimal throttle input) the clutch will not re-engage until 24 kmh (15 mph).

Power mode

Power mode is an electronically selected option (push button) that holds the CVT ratio lower with an approximately 1,200 rpm higher than regular RPM (author’s note: I believe this to correspond with the engine’s power peak whilst the Auto mode corresponds with the engine’s torque peak). The purpose of Power Mode is to improve acceleration performance, it also has a side benefit of providing stronger engine braking when decelerating.

Engine Braking

By Colchicine

Engine braking is a prominent feature of the 650. Although most people find it to be comparable to or less than some manual transmission motorcycles, it is a feature that bothers a lot of users while some others actually favor it. It is ideal riding in the twisties.

Here's an explanation for why there is strong engine braking in the 650.
Anytime you let off the throttle, the computer is setting the CVT up to be ready for the next throttle input. If the computer kept the same gear ratio as when the throttle was rolled off (therefore, less engine braking), there are going to be too many instances where the CVT is going to be in too high of a gear because the bike has slowed down, resulting in a lack of power or worse, lugging. The computer is monitoring the throttle position and speedometer signal and adjusting the pulleys to a gear ratio that maximizes available power when the throttle (or rider) calls for it. This also eliminates the possibility of lugging the engine.

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The following list of internal components is from the Suzuki official Service Manual.

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the Primary Pulley width is electronically controlled by the Burgman ECU (Electronic Engine Control Unit). The Primary Pulley accepts power from the engine and transmits it to the Secondary Pulley. The Primary Pulley Assembly is sold and described as single piece (Item 10 in the above diagram), however, for the purpose of properly describing the Primary Pulley it is necessary to break down the assembly into sub components.



The ECU is continuously monitoring a range of inputs in order to correctly set the Pulley position - including throttle opening, pollution controls, engine rpm, road speed, load on motor, current positions of the Primary and Secondary Pulleys and whether the rider has selected regular operation, power mode or manual ratio selection.

The ECU sends signals to the CVT electric motor to spin clockwise or anti-clockwise to vary the Primary Pulley width in or out. The CVT Electric motor spins very fast and turns the Primary Pulley by two plastic reduction gears (known respectively as the Actuator Counter Gear (ACG) andActuator Idler Gear (AIG). The idler gear then turns the Primary Pulley Slide Pulley Gear (SPG), which opens and closes the Primary Pulley faces via a worm drive.

While the Primary Pulley unit is sold as a single component and is NOT intended to be disassembled, it is actually constructed from four key parts:
1) the left side pulley (or fixed) face, which is fixed to the Primary Pulley shaft and does not move sideways, it only rotates
2) the right side pulley (or sliding) face that is adjustable
3) the Primary Primary Pulley Slide Pulley Gear(SPG)
4) a hub which is locked in place in the CVT by the Primary Pulley Stopper Bolt.

The right side pulley face is moved inwards and outwards using a worm (helical) screw between its extremities of operation. At the minimum width (inner) extremity, the right side pulley face bumps up against the fixed face, whilst at its outer extremity it is limited by a stop.

Adjustment Mechanism

As explained earlier, the sliding pulley face is moved in and out by the Primary Pulley Slide Pulley Gearwhich is rotated by the Actuator Idler Gear. Now a question comes to mind, how can the idler gear move the pulley face inwards and outwards whilst the sliding pulley face is simultaneously being spun, together with the CVT belt, around at high rpm? In short, the sliding pulley face is locked to the Primary Pulley shaft to ensure it turns together with the shaft – it can only slide laterally (sideways on the shaft) – whilst the Primary Pulley Slide Pulley Gear is turned against the hub, under acceleration or deceleration (including when the ECU is optimising the CVT position for cruise mode operation) to move the pulley face in or out.

Primary Pulley Stopper Bolt (PPSB)

Now thinking further, if we have a sliding (and spinning) pulley face, and a worm gear to cause it to slide, we must also have a reference position to both know how much we have varied the pulley width, and more importantly as a fixed position for the PPG to turn against. This function is provided by the hub which is locked into place in the CVT case by the infamous CVT Stopper Bolt. (Note: I personally have not had any experience of a stopper bolt failing in any of the 3 CVTs I own – one stopper bolt had traveled 60,000 miles with minimal wear and no requirement for replacement).

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