sprague: the problem, the reason, the cure?

i have had the sprague assessed by someone in the aircraft industry and i explain what are believed to be the problems and cures.

on the husaberg, the inner spins with the clutch basket permanently. the outer only spins with the starter. on an aircraft engine, the inner gear and the sprague sit still while the outer gear spins with the engine. on an aircraft the default is for everything inside to sit still.

if anything picks up or catches though with the husaberg, then the inner is dragged around and the sprague bearings are thrown out against the outer wheel. the sprague clip also can turn in it's groove.

the second problem is the spring. the spring is actually only stretched between each bearing, so much so that this is where the stretch in the spring is: roughly between every bearing. the spring gets no relief from this because it is wedged in. it never rotates to a fresh area and gradually it goes weak. the actual quality of the spring is insufficient.

i'm ordering 100 special springs to see if there is any difference. i've also been experimenting with the inner gear machined down ever so slightly.

on a slightly different but related note
finally, i had a camchain type rattle on a customers engine. it came in because it wouldn't start. usual story: tappets and kickstart decomp adjustment and away the bike goes. that was easy!

however, the rattle was going to be hard work till i saw the FP system cleared the cover. so i resolved to run it during each test w/o coolant or a tab washer and only 5 sidecover screws.

first test
i pulled the kickstart assembly out completely and i'd still got it. so i replaced it.
i pulled out the starter sprague = no noise
then the starter clutch out = the noise is back.
so it must be the sprague or it's bearings.
swopped the sprague for another one and it started fine and no rattle. so it's not the bearings
swopped the inner gear = no rattle
swopped the outer and sprague and just kept the inner gear - the rattle is back.

so there it is: a camchain rattle that is the inner gear of the sprague. i can't see any difference or measure any difference between the two except to say one has the round wheel perhaps over by 0.5mm? i can't see any difference in the pitch of the gears.

it was a dreadful racket: just like a camchain or the kick start key was permanently clicking......

it's definetaly been played with because the starter clutch isn't one! it's the solid 2001 type and i've left it in.

regards

Taffy

my point also being that the outer gear appears to be fine for all years but that the inner gear must be upgraded and there are no visible signs unfortunately... except an almost indiscernable difference which i measured.

regards

Taffy

RE: Re: sprague: the problem, the reason, the cure?

well i haven't heard of anyone actually shattering the starter gear teeth so i guess it's just an old wives tale to be cast along with 'aligators in the sewers of new york'!!!!

regards

Taffy

yes bob 2001 had a solid starter gear simply connecting the starter motor to the sprague. the next year the gear became a starter clutch. i was always told as a kid that a starter went around 200 times to one of the crank so to have a violent reverse thrust would be a lot of stress.

i never counted how many teeth as a kid and i'm not starting now.

bob, you may have noticed the factory part number for a UK starter clutch is OEM:1do12u.

this is because the english starter clutch teeth are green and crooked and with several missing! :BIG:

regards

Taffy