starter sprague

kantdans · 2026-02-25T09:45:47-0700

hi everone ,i was wondering if a starter sprague will wear down . all the gears spin but motor won't engage.i think the dogbones wore down but don't know how to tell. i'mgoing to attach a couple pictures of it . i also want to say thanks to everone who gives advice and posts here. when i have a problem i can usually find a solution here.

Andy Higham · 2026-02-25T10:01:03-0700

The sprag, inner and outer tracks all wear. Sometimes replacing the sprag works but if not the other two parts will need replacing.
Trying to start with a less than full battery can kill a sprag almost immediately, even on 4 cylinder Japanese bikes

DennisMo · 2026-02-25T10:02:48-0700

I have an Alton with a sprague I have looked at. For me it is hard to know if it is worn without seeing it encased by the inner and outer races.
If you assemble it totally dry and rotate in each direction, it should lock up in one direction. Then do the same withe little lubrication
Dennis

kommando · 2026-02-25T10:42:26-0700

There is a sprag on Aliexpress that seems to work even on older inners and outers.

W

Thread 'DC 4127 sprag from AliExpress (2019)'

Apr 24, 2019

I hope everyone who ordered has received one.
My 2 showed up last week. They appear to be the same as the last one.
That sprag has done 150 or so starts now, no issues.
The minute I hear any slippage is when the old will come out and a new $17 unit will go in.
The $180 Norvil unit lasted about a day, this first $17 unit has done two years of light use so far.
I did not change the expensive inner and outer drive parts as recommended by Norvil.
It's all still running on the original stuff, which looked and measured OK.

Glen

worth a go before all new parts. If you do go new parts then CNW do properly hardened parts.

Torontonian · 2026-02-25T12:40:47-0700

A big powerful battery is essential .The quickest the sprag does it's work , the better .

Andy Higham · 2026-02-25T12:49:48-0700

My first version of electric start on my Gold Star, I used a sprag. It fired up beautifully.
When I stopped the engine the piston hit compression, bounced backwards and smashed the sprag. The current version uses a bendix from a RD400 kickstart mechanism. This means that after starting there is no way the crank and starter drive train can engage with each other

starter sprague

kantdans

Andy Higham

DennisMo

kommando

Thread 'DC 4127 sprag from AliExpress (2019)'

Torontonian

Andy Higham

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