The Sprag Thread

[dezmoduo]

Hello Supersport Hounds,
I'm really in it and need your help.
Where I stand now, is a disassembled timing side cover, rotor off, flywheel/startergear/sprag off.
Why? Because the sprag was slipping ALL the time and I couldn't get it to turn over at all. I pulled the sprag and installed a great lil spring from the CR 19778 seal. I figured this whould do the trick but after buttoning it up and hitting the starter, it fired 1 time for 15 seconds. (FCR's take 2 or 3 tries in the morning). BUT after the engine ran for that brief time, the sprag would NOT hook up.
So I broke it down today again. The hub of the timing gear does not look very bad, infact I'd say it looks good and not worn out. Theres a wear line but no real roughness ala LT's book.
So before I put the left side together and move on to other SS issues, I really only want to do it 1 more time..........
I'd appreciate your experience, knowledge, and opinions.
I just miss sitting in this bike and turning the throttle SO much. (And having it run at the same time)

Gary
aka Dez

[Ducman851]

Heres how I have done it on my 851. Im guessing you can get the flywheel off? Anywho, note this flywheel is from a 4v but the sprag is the same.

Put flywheel on bench


Remove starter freewheel gear


Remove snap ring holding sprag (note how it comes out and mark it, they are directional) Its not marked BTW


Note sag in spring?

[Ducman851]

Part Deux


Remove spring, find end and untwist. Or replace with new spring.


With sharp side cutters, cut small amount off end of spring that is twisted on the outside of the other


Reverse procedure for installation, remeber to note how sprag came out and how it goes back in. Make sure to torque and loctite the flywheel nut.

Pretty simple huh?

[dezmoduo]

DucMan,
YOu get the first cold beer for first response.
I have the sprag in hand, actually 2 of them. I have an old one from a prior replacement. I have swapped the springs out with a smaller spring, and tighter I might add. Its quite snug. The radius is about 1/4 inch less, diameter 1/2 in perhaps less overall then the loosie goosie one I removed.
There is actually an arrow on on of the outer "races" of the sprag cage.
I find no reference as to which way it means to put the sprag back in but I do know that one way works and the other doesn't. A quick stab of the starter button proves this out before reassembly.
One of these free wheelers, as they are called in the "manual", has smoother lobes than the other. I'll use that one next. They both have tight springs.
I curious if anyone has ever had to replace a timing gear. Its not something you really hear about on any of the lists.

Good pictures DucMan. I ought to shoot some while its apart for reference as well.

[edwyun]

U think you need a new starter? [grasping at straws]

[dezmoduo]

Hi EY,
The starter spins like a top. Free Monday afternoon?
I will probably put it together tomorrow afternoon, while YOUR RIDING !!!

[edwyun]

Working Monday OF COURSE (don't rub it in!)

[Ducman851]

Originally Posted by dezmoduo

DucMan,
There is actually an arrow on on of the outer "races" of the sprag cage.
I find no reference as to which way it means to put the sprag back in but I do know that one way works and the other doesn't. A quick stab of the starter button proves this out before reassembly.

Hmm thats interesting, Ive got several and because of your post I went to look at them. None have an arrow. I simply took an engraver and made my own on both the sprag and the flywheel. That way I dont have to do what I did the first time I ever did this job many years ago....well you know where Im going with that huh?

[dezmoduo]

Ducman,
Oh yes, I know exactly where you were headed!!. I don't want to admit why I have a NOS left side cover on my bike now.
I installed the sprag that looked more smooth. Sealed and buttoned up. It cranked with plugs out, it cranked 6 times in a row with plugs in, but the battery is low at this point and it will need a boost to actually fire and run.
Tomorrow, now I'm gonna watch Moto 250 and relax.
I'm feeling optimistic.
Thank you for your response and I will post the outcome.

[dezmoduo]

Follow up,
In the end I dressed/polished the starter gear hub with crocus cloth, because I had some handy.
I use the better of the 2 sprags in my possession. The difference in lobe surface was visually almost indistinguishable to the naked eye, 'specially a 53 yr old one.
(Both sprags had been modded with the CR seal spring)
I put a solid charge on the battery and next morning the bike cranked over like a 2 stroke and operated as designed, for the most part.

Thanks for reading.

[edwyun]

Nice story with some twists but alas a happy ending!

[Panzerkampfwagon]

Which is the cr spring as being referenced earlier in this thread, and where would I pick one up at? I have my bike torn apart and the old sprag spring on my table as I type.

Thanks!

[dezmoduo]

From my email archives:


The part # CR 19778 is for an oil seal (CR is for Chicago Rawhide - the manufacturer). The seal has a spring around the inside of the rubber lip. That spring is a perfect replacement for the starter sprag spring in the starter sprag assembly. Throw the seal away and keep the spring... that's all you need.

Here is the detail from Chicago Rawhide:

http://tinyurl.com/bfu9l

This seal is for a 2" (50MM) shaft so the spring that is inside the seal is what you need for the starter sprag. I have yet to make this repair myself. Just going by the research that I have done in "preparation" for this one day.

[Panzerkampfwagon]

FOR FOLLOW UP:


This is where you would find a distributor, give them the part # once you have located which one you want to go to.
http://www2.chicago-rawhide.com/distributor_locator.htm