starter sprag

Hi Nigel

A lot of positive reports on the access norton site,  for the Chinese sprag  avaliable on Alliexpress. I have been using one for a couple of years  without any problems. 41.275*57.935*13.5mm DC41273C 

Nigel these dimensions came with a new AN sprag. You can cross reference them to Katherine's ones above.

Engine sprocket   06-4681   2.280"- 2.281"  I.D.

Starter drive gear 06-4731   1.6253"- 1.6248" O.D.

If your existing engine sprocket i.d. is smooth with no deep indentations and the starter drive gear o.d. is similar, the Chinese sprag Katherine mentions should work fine. It seems more tolerant of clearances outside the specs shown. The AN sprag works best on new parts.

My £15 Aliexpress sprag was fitted to a good used engine sprocket and starter drive gear in late 2019. No problems in over 8000 miles e start only. Use 20w 50 mineral engine oil filled until it comes out of the small drain plug hole rather than the quoted 200cc. The sprag needs plenty of oil for long term reliability.

I tried aliexpress a couple of years back and they were sold out. Have tried since and cannot locate the part. Has anyone recently found the part on the site? 

Which way round is easy to figure out - assemble loosely and try to turn the starter gear forward. If the sprag grips it's the right way round. Pinions etc. can stay in place so long as you have access, the various bits only slot in anyway once the support plate is removed.

I found the service manual was really clear and helpful. I played it safe and replaced the parts adjacent to the sprag. The flange goes toward the engine case.

IIRC, I removed the backfire device from its shaft, but did not dismantle it, as it is tricky to set to the right torque. But, I may only have done that because my previous sprag had been damaged by slurry from a loose primary chain grinding the primary case, so I removed everything, including chain and clutch for a thorough clean.

It is a good opportunity to give everything a good clean.

When I reassembled, I first lubed the new sprag and hydraulic tensioner system.

Ordered one a couple of days ago and messages say it is on its way. Same as Neill's link.

https://www.aliexpress.com/item/32611759425.html and click on DC4127(3C)

Thank you Katherine for the info. Seems from the Access site news that it might have less chance of 'rolling over' so I am going to replace my currently working standard spec one. But will compare both for fit when disassembled. Worth trying for £20.23 delivered incl. VAT.