Author Topic: I GOT THOSE BROKEN SIEZED UP SPRAG CLUTCH BLUES  (Read 5193 times)

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Tiny Tim

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on: March 28, 2009, 07:43:00 am
A short ride into town to fill up. Admiring glances for the bike from a couple of old fellers.

Helmet on, gloves on, hit the electric boot and there she blows. Ticking over nicely.

I'm just about to pull the clutch in and BANG!

Like a huge hammer landing on an anvil and the bike has done it's "Let's backfire and send the Sprag Clutch into orbit" trick.

It's siezed solid, no electric start, no kick start, no bump start - not much at all really.

For all of the "I always start mine on the kick", please note that this event had nothing to do with starting. It was a low tickover backfire. I have the latest green TCI unit fitted which is supposed to cure all known ills.

The only lesson I can draw from this is to give up my normal practice of setting the idle as low as I can and raise it up to ensure a little momentum.

REgards

Tiny Tim

"Whilst it isn't possible to polish a turd, you can always roll it in glitter"

2005 Electra AVL


PaulF

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Reply #1 on: March 28, 2009, 01:23:23 pm
Tim, sorry to hear that.

I think I did everything one can do to avoid it; run it rich, new TCI box, etc. And, yes, I use kick only.

I guess in the end, all you can do is pray.


UncleErnie

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Reply #2 on: March 28, 2009, 01:53:41 pm
Oh

my

God.

I didn't need to read this.  Prayer...
Can I only live in the land of denial and prayer until the unspeakable happens?

I've got a hair under 2K on the clock and 9 months left on my warranty...

Mr Tim, please keep us up to date.  I wonder why this happens?
Run what ya brung


scoTTy

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Reply #3 on: March 28, 2009, 10:42:35 pm
sorry to hear that Man.. I scoured U tubes for broken sprag blues  but this was all I could come up with   http://www.youtube.com/watch?v=gYiolTE2t2Y


Tiny Tim

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Reply #4 on: March 29, 2009, 10:33:55 am
I think that part of the problem, in my case anywhooo, is my love of a super low tick-over. For me, nothing can beat a big single thumping over  r e a l   s l o w.

But you have to consider that if it's that slow, then each time it's coming up towards comression, it's liable to stall against the hardest part of its 4 stroke cycle.

What I don't understand is, if it doesn't spark until after TDC, how does it fire before TDC and backfire?  If it's spurrious EMF interference with the TCI unit, then the new green TCI unit is supposed to guard against that?

Sufficit to say that once fixed, tickover will be set quite fast.
REgards

Tiny Tim

"Whilst it isn't possible to polish a turd, you can always roll it in glitter"

2005 Electra AVL


UncleErnie

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Reply #5 on: March 30, 2009, 02:25:26 am
I can't imagine that the idle speed has anything to do with a sprag gear going South.  There is a good-sized flywheel to keep things moving, for one thing.
Run what ya brung


Joe28

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Reply #6 on: March 30, 2009, 05:37:25 pm
When my sprag went to "Pieces Land", my scoot was cold, was a idling really s l o w and then Clunk it went.
Now, mine (at the time) was a new motor, (less than 200 miles), the OEM ignition box.
I have cranked up the idle  and never let it thump-thump, that sounds sooooo cool on this 1 lungers.
Keep up posted.
Joe
"Yeah, it running GREAT! I'm really happy with it-"   BANG!
"What was that"? :o


scoTTy

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Reply #7 on: March 31, 2009, 03:57:56 am
mine idles like a thumpthumpthump..  kinda blurry ..  fast idle


ScooterBob

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Reply #8 on: March 31, 2009, 07:32:22 pm
I can't imagine that the idle speed has anything to do with a sprag gear going South.  There is a good-sized flywheel to keep things moving, for one thing.


Oh ..... But it DOES. You see Tiny Tim is right about all that, except ONE thing .... the timing, even at idle, is BEFORE TDC ..... A really slow tickover with a lean (easy to ignight) mixture has GREAT potential to flip the old pig iron backwards to frag the sprag. I usually adjust the (warmed up) idle just a little fast on my bikes - then slow it down with the mixture screw - not radically, but just enough over-rich to "soften" the combustion at idle. You can hear the difference ..... it wil *POP* *POP* *POP* when the mix is PERFECT but it'll *THOOP* *THOOP* *THOOP* when the mix is just a little towards fat. This'll also aid in cold starting, which seems to be the death of many a poor sprag. The GOOD news is that the UCE engine has all that fixed as the starter was designed for the engine and vice versa. With the iron barrel and AVL's, the starter was really an add-on adaptation. My ULTIMATE solution to this may be to remove the gears, wrap them waxed paper and put them on the shelf - all my bikes will usually snort in two or three kicks on the worst days .....
Spare the pig iron - spoil the part!


Tiny Tim

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Reply #9 on: April 01, 2009, 11:33:40 am
Joe,

What you describe is like an slow-mo action replay of my disaster. The sad part is that this is the second occasion for me. I must be a slow learner?

Scooter Bob, thanks so much for staighening out the TDC puzzle. I have decided that a slow tickover is to be reserved for other people.

One of the main reasons I upgraded to the AVL engine from a 500 Iron Classic is that I have an arthritic hip which makes kicking no fun. I had managed to get the Classic tuned so that it would start "by hand" litterally, but if it was cold or if she was in a mood.....

Stripping down on Thursday, new sprag should be here by the weekend.

Must be why the sun's shining!
REgards

Tiny Tim

"Whilst it isn't possible to polish a turd, you can always roll it in glitter"

2005 Electra AVL


ScooterBob

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Reply #10 on: April 01, 2009, 02:03:10 pm
Tim - One of the things that you CAN do to an old Iron barrel is retard the timing a bit so that it DOES fire at TDC at idle. The antique engine engine doods have been doing this for years. Their stuff will tick over at 40rpm's going *POOF* ...... *POOF* .....*POOF* .... all day. So will an iron barrel. Since the timing on the AVL is "fixed", you can't do that ..... although I "heard" that you can slot the bracket on the pickup and move it and get about 4 degrees of movement .... that could help. The new (green) TCI unit skips the first couple of sparks to let the flywheel "wind up" and also delivers the sparks below a certain rpm pretty late to prevent sprag failure. It doesn't take into account the lean hiccup and low idle that shattered the poop outta yours ..... I hope you get 'er fixed soon so you can get back in the saddle! BTW - I have a "Sears and Roebuck" knee joint in the kickin' leg - I feel your pain ..... but I'm stubborn as hell and I'll kick 'er anyway! Hahaha! That's why my tuning skills have gotten better and better as the knee has gotten worse and worse .... ;D
Spare the pig iron - spoil the part!


UncleErnie

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Reply #11 on: April 01, 2009, 02:30:58 pm
> WHY <  does a slow idle stress out the sprag gear so much?  What difference does idle speed make?
Run what ya brung


ace.cafe

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Reply #12 on: April 01, 2009, 03:34:42 pm
> WHY <  does a slow idle stress out the sprag gear so much?  What difference does idle speed make?

The slow idle is not directly related to the sprag gear.
The slow idle creates a condition where the engine can be stopped relatively easily if there is a lean-hiccup, cough, or backfire. This is because there is not alot of momentum in the rotation of the engine at a low idle speed.
When any of these things happen, the engine can be stopped, and be pushed into a reverse direction with some force.
Since a sprag clutch is always engaged to the primary gear, and a sprag clutch is a "one way" device that only can work in one direction, the stopping and forceful reversal of the engine can destroy it instantly. It it's not a real bad kickback, then it might survive, but may have some damage that you don't know about, if it continues to work for awhile.

Using a higher idle speed can give some more rotational momentum, so that perhaps a hiccup or cough might not stop the engine, so it won't reverse direction, and this may save the problem from occurring.

So, a slow idle can make the engine stall easier from a variety of problems that might occur at a slow idle speed, particularly if cold. The result of the engine stopping, and reversing direction during the stoppage, with some force, can and will break the sprag clutch system in some cases.
« Last Edit: April 01, 2009, 03:42:55 pm by ace.cafe »
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UncleErnie

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Reply #13 on: April 02, 2009, 04:11:03 am
Thanks.
So why doesn't that happen when I turn the ignition switch off?
Run what ya brung


Tiny Tim

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Reply #14 on: April 02, 2009, 07:32:21 pm
UncleErnie,

no ignition = no spark = no backfire.

Think about it?
REgards

Tiny Tim

"Whilst it isn't possible to polish a turd, you can always roll it in glitter"

2005 Electra AVL


Tiny Tim

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Reply #15 on: April 02, 2009, 07:39:17 pm
OK so - good news / bad news time.

My good friend Henry Price ( a Prince amongst men) stripped her down today.

Good news: the sprag clutch is alive and well and shows no signs of damage itself.

Bad news: The the primary side gear has sheared three teeth. The teeth became jamed in the gear chain and it was this which jammed everything solid.

No real change to the problem or the solution.

The sprag assembly has been removed and the bike starts well on the boot. Tickover has been raised. I will ride to the UK importers next week and plead my case for assistance (free replacement) on pthe grounds of poor workmanship.



REgards

Tiny Tim

"Whilst it isn't possible to polish a turd, you can always roll it in glitter"

2005 Electra AVL


UncleErnie

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Reply #16 on: April 02, 2009, 08:36:44 pm
UncleErnie,

no ignition = no spark = no backfire.

Think about it?



Your cruel streak is showing...

I just had an aluminium tank fixed- allegedly.  I'm putting it back on tomorrow. (we'll see...)
Frustrating stuff.  May the force be with you ~
Run what ya brung


scoTTy

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Reply #17 on: April 02, 2009, 11:46:51 pm
ouch, man I hate seeing broken teeth on gears. :o.  but I have b4  >:(


Tiny Tim

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Reply #18 on: April 18, 2009, 08:36:24 am
So, after a short delay due to a couple of broken ribs (don't ask, another story!), I yesterday visited the UK importer, Watsonian Squire.

The sprag assembly that failed was one supplied by them, under warranty, some 13 months ago following a similar failure.

I was anticipating being able to maybe blag a replecement outer gear from them from any old failed sprag assemby they might have hanging around in the scrap bin thus saving me a weeks wages on a new sprag.

I showed him the problem and before I could put on my best "little boy lost" look he started showering me with gifts.

New Sprag assembly - complete, Ignition Delay module, resistor, inner and outer Primary Gaskets.....

I didn't hold out for the replacement ATF fluid.

All free and for gratis!!

I will raised the tickover and trust that this along with the New TCI unit,  Ignition Delay Module and Resistor should mean that I'm good to go for the next 18,000 + miles.

Which way is the wide blue yonder?
REgards

Tiny Tim

"Whilst it isn't possible to polish a turd, you can always roll it in glitter"

2005 Electra AVL


PhilJ

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Reply #19 on: April 18, 2009, 01:22:47 pm
The damaged ribs haven't slowed the sense of humor. Great!

Sounds like Watsonian Squire has done you well, except for pinching you on the ATF. ;)