[siddharth_menon]

Originally Posted by Randhawa

Seriously I doubt that you got the new sprag. I have not seen a single failure with the new sprag. Post the picture when you get it replaced. If you get lot of tick tick noise while riding then the spring in the auto de comp is tight if not then it's a bit loose. It's all the fault of incorrect tension of the little spring. If your bike makes that loud tick tick on cold start for longer duration then 15 seconds then you need to sort out the de comp. Also get the plugs checked. Does the bike starts at first crank?

When I got the replacement last year he told me that these are new improved sprag. Well I have that tick tick noise for at least 1-2mins & sometimes its little hard to kick start as lifting the autocomp lid initially requires an effort.

Now I have more reasons to believe that my auto comp needs a overhaul.

Thanks again for the tip

[Sutripta]

Originally Posted by hexanerax

The main function of the sprag clutch is that it
......
Regards
Naren

Thanks for the post!

The main function of the sprag clutch is that it is a one way freewheel clutch similar to that found in a bicycle rear hub. Torque from the starter motor is transmitted to the crank through the gears but not vice versa. A running engine will not spin the starter motor since the sprag clutch will slip.

Agreed. The starter has to be disengaged from the engine when it fires and picks up speed. Otherwise the self-starter will spin at a zillion rpm and self destruct. This is the one and only work of the freewheel. Everything else is a side effect.
In cars there are alternative schemes for disengaging the starter once it had done its job.

The problem occurs when the engine turns in the reverse direction as happens when there is a back kick. The reversed rotation will cause the sprag clutch to lock , trying to transmit torque back into the starter motor. This , if repeated a few times will damage either the sprag clutch or the starter motor.

You can have freewheel designs where once disengaged, the driven side cannot cause engagement of the freewheel. Essentially the power transmission mechanism (rollers or balls etc) will be clear of the outer race, and only come into contact with it because of inertia, or centrifugal force. I take it that the rollers/ sprags in the RE design always touch the outer race?

Advanced timing on a cold engine is bound to occasionally cause back-kicks or rather reverse rotation of the crank.

Which is why vintage cars had a ignition retarding mechanism, generally controlled from the steering wheel. You would have a lot of broken wrists otherwise.

This happens because advance spark timing means that the plug fires well before Top dead centre position of the piston. A slow moving piston does not have the inertia to continue to compress the now ignited mixture, which forces the piston back down ,

Agreed. So my original question: why not retart the spark at startup?

The ecu on the C5 / CL 500 calculates crankshaft speed and the timing / mixture is adjusted to prevent full advance on a cold / low speed condition.

We'll come to ECUs later on. There is a reason for it.

The LB 500 and the electra 5s Es had issues not just due to the advanced timing but also because switching off the engine by means of the key or the kill switch traps compressed air in the combustion chamber which causes the piston to move down on an upstroke , causing reverse rotation for a few degrees. The common solution was to open the decompressor before cutting the ignition so the hi pressure air in the cylinder would release , allowing the piston to come to a smooth stop without reversing.

Why should the UCE differ. (Note to myself- Get full details of the auto-decompressor)

Another is to reduce load on the starter motor, allowing the crank to build up speed before the decompressor closes, starting the engine without extreme variations in the torque required on full compression.

Why can you feel the engine crossing over TDC on the kick?

Multi cylinder engines donot have this problem because of the high polar moment of inertia of the crank and the fact that other pistons are offering resistance to the one that is trying to reverse on shutdown.

They do, though very minimal. Watch any large genset being shut down. In any case it does no harm.

Cars use a Bendix starter that pulls back the spline shaft that transmits torque , totally disconnecting the starter motor from the engine once a certain flywheel speed is achieved.

Yes. Used in the Ambassador. Acceleration based, rather than speed. Not the most reliable of systems.

Would really like the answer to the ignition questions posted before. Too many queries.
Eg. Was the delay (AVL 500) a retarding of the spark, or a timed delay which prevented a spark till the starter had built up some speed so that inertia would carry the piston over TDC?

Regards
Sutripta

[hexanerax]

The UCE models have an auto decompressor that is actuated when the engine speed falls below a certain threshold. At rest , the decompressor causes the exhaust valve to remain partially open, allowing for lower pressure in the combustion chamber while starting. The same mechanism also prevents the exhaust valve from closing fully when the engine is being shut down , preventing kick back on shutdown. The system is deactivated by a centrifugal actuator inside the exhaust cam. A spring provides the necessary thrust. Check out
http://www.team-bhp.com/forum/motorb...review-19.html

for a rendering of the said mechanism.

Please note that the partial lifing of the exhaust valve is not equivalent to zero pressure and the pressure though lower is still much more than ambient and the TDC crossover can be felt. Retarding the ignition at low RPM and idle is an old remedy for the kickback and rough idling issues and ECUs have the programming inbuilt for starting. Both the extra rich mixture and retarded timing are incorporated in these systems.

Regards
Naren

[sudipta]

Friends, The initial pics for all of you.

[ArizonaJim]

@ aussigreg

Your stability problem on the 500cc C5 has been seen in the U.S. by many owners too.
If your bike has the AVON Speedmaster tires on it try lowering the tire pressure.
These tires have very stiff sidewalls and the lower pressure should greatly improve your bikes high speed stability.

If your not already doing this, try a pressure of 18 PSI (1.27 bar) in the front tire and 24 PSI (1.69 bar) in the rear. It seems to help.

[Rennjit]

Originally Posted by hexanerax

... At rest , the de-compressor causes the exhaust valve to remain partially open, allowing for lower pressure in the combustion chamber while starting. The same mechanism also prevents the exhaust valve from closing fully when the engine is being shut down , preventing kick back on shutdown. ....

In precise terms, the auto de-comp just lifts exhaust valve by a small bit for a short duration easing of some compression. We can't say ex valve remains partially open or is prevented from closing fully. Valve is forced open a second time per cycle towards end of comp stroke by the extra lobe pop of auto mechanism.

On pre-unit electra e/s the first firing has always been erratic, at times engine fires immediately or one may have to hold on for many seconds. Interestingly with last of LB500's engine 'seems' to fire up only on releasing start switch after a couple of spins. i need to check k/s mode though.

[siddharth_menon]

Originally Posted by sudipta

Friends, The initial pics for all of you.

Congrats ....


I see new front tyre threads.

[aussigreg]

ArizonaJim

I actually haven't been able to get the phantom problem to show itself yet, I've done 600km (400miles-ish) and only had it up to 100km/h (60mph) a few times. It sure don't handle like my other bikes but hell, I wouldn't want it to or I might've bought a W800 instead. Horses for courses, and I have no problems at all yet. I'll grant it does want to coke up a little with short trips to Kmart but if I take the long way home and get it hot it has great manners.

sudipta

Does your bike live out in the weather where it is pictured? Keep us updated on how the chrome finish is holding out. Also, is Hyderabad near the sea and salt air? I considered the chrome finish when I chose but having not seen an Enfield in the flesh at the time decided it was too risky.

[ruchirtnt]

Originally Posted by ashroy_6

HI, i have just purchased classic 500 desert storm on the day of its launch...trust me buddy the bike is giving me 35.1 kmpl (it ran for 320 km for 9.1 ltrs of petrol) and this is all in city driving below 50 km/hr.

Good to hear that, for me any mileage above 20 kmpl is welcome as said by randhawa as well

Originally Posted by sudipta

Friends, The initial pics for all of you.

good snaps, congrats

[sudipta]

Thank you Siddharth and Ruchirtnt.

Aussigreg, you are right. It is parked in the open. Hyderabad is not sultry or close to sea but we do get enough rains. I will keep you posted on how the chrome holds out.

Ashroy, please PM me if you have time.

[nasirkaka]

CLASSIC CHROME is so drool worthy..

Damn.. why did they not have this option when i bought mine..
Would have looked nice along side my Machismo

[aussigreg]

sudipta

I've managed to get a lot of extra life out of the finish of my everyday bikes by a few simple steps. 1 always use a bike cover, sun and rain are equally bad. 2 get rid of the exide elctrolyte battery and use a sealed no maintainence gel battery. 3 use cheap generic water dipersent spray cans to coat all alloy and chrome parts regularly (avoid seat and brake rotor). This stuff picks up dirt and looks filthy but anytime you clean the bike you'll see no rust or alloy corrosion.

I'm experimenting with silicon spray to make road grime release easily from hard to clean areas like among the fins, and I'm also experimenting anti spatter welding spray on the hi-temp exhaust as a release agent for tar spots which tend to cook on.

One final tip, if you get something like plastic melt on the pipe use a sharp piece of wood to work it all off while it is hot. Wood doesn't scratch the chrome unless there's abrasive dust involved. If you leave the "melt" on an exhaust for several trips it becomes more or less permanent. Hope all that helps.

[Sutripta]

Originally Posted by hexanerax

...
The system is deactivated by a centrifugal actuator inside the exhaust cam.
...

Please note that the partial lifing of the exhaust valve is not equivalent to zero pressure and the pressure though lower is still much more than ambient and the TDC crossover can be felt.
Regards
Naren

Originally Posted by Rennjit

In precise terms, the auto de-comp just lifts exhaust valve by a small bit for a short duration easing of some compression. We can't say ex valve remains partially open or is prevented from closing fully. Valve is forced open a second time per cycle towards end of comp stroke by the extra lobe pop of auto mechanism.

Any lift-theta values for the decomp? And where in relation to TDC?

Retarding the ignition at low RPM and idle is an old remedy for the kickback and rough idling issues and ECUs have the programming inbuilt for starting. Both the extra rich mixture and retarded timing are incorporated in these systems.

The TBTS does kickback.

Can someone give definitive information of the delay circuit of the older 500, and actual details of the 350 UCE ignition?

Regarding ECUs: In a car, before the ECU starts any work (Ign and FI), it first has to sync itself to the engine. Essentially it waits for an index mark. Logically from the cam (cycle = 720 deg). Then it gets down to the job of running the engine.
BUT
The RE kickstart has very limited travel. Does it waste one kick to just sync itself? (Note with a electric start, it is not a problem.)

Regards
Sutripta

[smoghe]

@ArizonaJim, @girishab
Thanks for your suggestions. I had tried to figure out if the leak was from oil drain plug, and although I felt that was the case, when I took it to the service center, it turned out to be related to some seal broken where the kick start joins the body. The service center has fixed it and I will monitor it for a few days to check if it has really stopped.

While I was at the service center, I also got the rear seat removed, replaced the side stand that was damaged and got the bike thoroughly cleaned and Teflon coated. It is looking so good that I can't take my eyes off. Got a lot of appreciative looks on my ride back from the service center.

[ArizonaJim]

Glad to hear you got your leak problem fixed.

@ Sutripta: The 500cc EFI, UCE engine has a crankshaft sensor to tell the computer where TDC is so the signal is sent every 360 degrees of crank rotation.

As for chrome, I would think there would be auto waxes made for clear coat paint available in India? (I use Meguiar's Gold here in the US)
These waxes thoroughly coat the surface with a layer of wax which keeps all moisture and oxygen away from the chrome and any bare steel that may be present.

They also protect the paint without scratching it and they leave a mirror like polished look when they are lightly buffed.

Admittedly I live in the desert but my chrome and black fuel tank and chrome fenders still look like new and I attribute much of this to the wax protection I applied.

On my 10 year old Mazda Miata, Meguiar's wax has kept the ultraviolet radiation away from the paint and the protection seems to last over 3 months if I can believe the water beading that the wax produces.

Even if the wax only lasted a month, as small as a motorcycle is it only takes a few minutes to apply a good coating of wax and buff it with a clean rag to a mirror like shine after the bike is washed.

With as much rain as you folks get in India you would have to wax the inside of the chrome fenders and chainguard and that would be kind of a pain but because these areas are protected from direct sunlight the wax should last a long time.

The only area where wax won't work is on the exhaust pipe and the silencer.
These get much too hot for wax to last over a few minutes.