[REpozer]

I have done everything possible to avoid sprag problems.

1) Filled the primary side to 1liter 20w-50 oil
2) Installed a resistor( thanks CMW) in parallel on the Pulser coil wire leads to TCI.
3) Just received a new TCI unit( thanks CMW) that is sprag friendly.
4) Kick start 50% of the time.

I think that's about it, should be fine.

[Tiny Tim]

Not wishing to pee on your cornflakes but.......

My sprag went when the engine stalled on low tickover when cold and sort of half fired backwards.

The stalling was accompanied by a loud metallic clang - and one siezed sprag.

Sometimes, there's no escaping the sprag demon!

[Joe28]

Well heck!
Keep us posted.
I, like you am trying to get my Military," Sprag piece proof" !
I SUPER checked everything when I replace my sprag, I'm not going to ride the bike till the new ignition comes, Added a new pilot jet and raised the needle, (to rich en it up to get rid of the lean surge, easier to start cold), turned my idle up.
But, I wen t with 0-30 synthec oil in the primary, 700 cc to keep everything moving free.(It's cold here in Pa., and that the reason I bought THIS bike, to ride in the winter).
I think one it goes, then you good for life!, (At least that's what I'm hoping)!!
Joe
Here's my Royal Enfield, and here's my BIG box of tools!

[ace.cafe]

Believe it or not, at one time RE did offer a Bullet model that never ever had a problem with the sprag.

In fact, it was available in all of the pre-2002 Bullets, and some were still avaliable until about 2005.
 

After an engineering study which deemed the Bullet to be far too reliable, which threatened to ruin its reputation, they added further complexity in the form of an ES with sprag which was sure to break, thus eliminating the possibility of the Bullet ever getting a reputation for good reliability, and thus "saving the marque".

[PhilJ]

There's always a silver lining. 

[t120rbullet]

Believe it or not, at one time RE did offer a Bullet model that never ever had a problem with the sprag.

In fact, it was available in all of the pre-2002 Bullets, and some were still available until about 2005.

Both of my bullets are old sprag free improved models.
At the hospital I work at the beds have a small sprag to control the up/down feature of the bed. Guess what the only problem we have ever had with those beds is?
The older Homelite chainsaws had a sprag on the recoil start spindle.
Guess what the only problems I had with those saws?



 
 

[HRAB]

Any of you have an automatic transmission in your cage? They are called "One Way Clutches" AKA Sprag Clutches.

Most small engines, especially motorcycles, with electric starts have a sprag clutch on the starter. They are compact.
jim

[clamp]

There a sprags in the stators of your torque convertor. I believe some of your American transmissions have up to 7 stators. How often have you replaced a convertor?

[taildraggin]

Stators are 'indirect' drives, pumping vanes of hydraulic fluid.  A hiccup moves oil.  The RE starter is a direct lockup and a hiccup blows it up. 

Sprags aren't designed to 'go backwards' at all.  If the RE shaft does - boom.  Does the RE engine go backwards occasionally, why, yes.  Boom. 

It's a bad place for a sprag.

[jonapplegate]

Vince of Vince's Motorcycles In Olympia, WA. machines another oil galley into the sprag when they replace destructed ones and of course increases primary oil. He is confident this increases reliability quite a bit. Vince really knows these bikes so i would believe it. Perhaps look him up under dealers and give him a call.

[Vince]

     Thanks for the plug, Jon. The modifications I worked out do seem to be a considerable help, but are not a cure all. Of equal importance is the rider. The more persnickety you are about keeping the engine tuned, and riding regularly, the less likelihood there is of a damaging backfire. My higher mileage guys have very few problems.

[Laurence]

Vince wrote:  "Thanks for the plug, Jon. The modifications I worked out do seem to be a considerable help, but are not a cure all. Of equal importance is the rider. The more persnickety you are about keeping the engine tuned, and riding regularly, the less likelihood there is of a damaging backfire. My higher mileage guys have very few problems."

Sounds like all good advice. I have 2700 miles on my 2008 AVL Bullet and blown two sprags. As a newbie I'm sensitive to often checking things( like plug condition, listening closely to what the engine is saying). I'm looking forward to my dealer getting the replacement ignition unit and a  new sprag from our host.

But having it go out twice now, and with Vince's caveat - there is no cure all, I can't see myself using the ES but very rarely, and then only in an emergency, like stalling at a traffic light on a hill with a line of honking vehicles behind me and crossing my fingers twice (on both hands).

I'm hoping things will go fine except for that always lingering doubt when I hit the ES button. When kick starting there have been a few times when I didn't kick strongly  enough and the kick starter lever would kick back a little, suggesting that the engine had reversed in mid stroke. I don't think this will hurt the sprag, but not completely sure - when I had the last one in my hands the two halves would free wheel both ways - it seemed to be all right except for all the missing gear teeth.

Am I thinking right on this? that kick starting mishaps won't destroy the sprag?

[REpozer]

Tiny Tim on reply #1, shelled out a sprag on low tick-over( low idle) .
It looks like there is no 100% cure, only ways to reduce failure.

I don,t know of a kick-start only kit for the AVL engine. That would be the only cure all.

[Vince]

[qu

Am I thinking right on this? that kick starting mishaps won't destroy the sprag?
[/quote     Laurence, it is the kick BACK, not the kick start, that does the damage. whether from poor tune, low idle or whatever, anu back fire can cause damage.

[Laurence]

Vince - thanks. So when I get a new sprag and new improved ignition unit provided by our host, and then NEVER use the ES, a kick- back might well destroy the sprag.

[ace.cafe]

All electronic ignition models should obtain the new ignition module, as the first preventive step.
Here is a service bulletin from the factory that I just pulled off the web, which circulated a couple of years ago:

16th May 2006

TIPS FOR FIELD SOLUTION FOR SPRAG CLUTCH FAILURE IN ELECTRICAL START
VEHICLES

I. Steps to follow when metallic noise & slippage occurs in the
Sprag clutch

a) Dismantle the Starter Motor, Chain case inner and the Drive
cover.

b) Remove the idler gear , sprag clutch drive & driven gears
assembly and the shims. Keep a track of the number of shims that were
used.

c) Separate the Drive and Driven Gears. Inspect the thrust washer,
for any rough surface, bent or disfigured condition.

d) Inspect the sprag carefully for: Damage to the sprag ends
(individual bearings), damaged / broken/ sticky movement inside the
sprag bearing cage.

e) Carerefully look for deep dent or impression on Sprag track in
the sprag clutch drive and driven gears.

f) If there are deep dent marks in the sprag tracks either in the
gear inner OR the outer, then replace the entire assembly (part No.
560042/a) with a new set after carefully cleaning and lubricating the
same.
(the sprag assy should be cleaned without dismantling

g) Carefully also inspect the following:

- Spindle on the drive cover for tightness (by hand), check oil
flow through spindle with oil can. If the oil does not flow through
the spindle, ensure this is not due to a block. The spindle should
not be free to rotate when pressed into the drive cover.

- Check the bushes in the chain case inner and the drive cover for
any cracks or recession into the housing. (bush top must be level
with the housing boss)

h) Reassemble the sprag clutch assy in the Chain case inner and take
care to reassemble the shim washers, gasket, drive cover. Check the
assembly is having the correct end float of 0.25 to 0.30mm after
tightening the drive cover screws fully. (Manual is incorrect in
stating 1.5mm.) The gears must rotate freely and very minute end
float must be felt. Refit the assembly onto the vehicle.

II. Steps to follow when Sprag Clutch / Gears are BROKEN

Note: One of the prime causes for the gears and/or the sprag to break
is the engine backfiring and/or the bushings in the chain case inner
have dislocated or damaged.

Dismantle the chain case assembly and the sprag gear assembly as
above.

Inspect the Bush in the chain case inner and in the drive cover

Inspect oil flow through the spindle.

Check for proper tightness of the spindle in the cover.

In classic (Cast iron engines) Check thoroughly if the ignition
timing is
advanced beyond 0.8mm BTDC (due to incorrect settings OR due to the
advance fly weight mechanism in the distributor is stuck in open
position) The advance retard weight could get stuck due to its
catching on the rear side of the condenser OR weak springs OR bent
posts OR the locating tab getting stuck inside the groove of the
flyweight.

In Lean Burn engines, if the sprag or gears are broken, please ensure
that the New TCI Part No. 147100/c is fitted to take care of a
backfiring caused from premature ignition.

If the sprag or the gears are breaking for the first time in a bike,
check the above and replace.

If the sprag is failing for a second time in the same engine, it is
best to check the above and also replace the chain case inner
assembly as appropriate to the bike to avoid any further failure.