sprag clutch (2015)

I am a first time Norton owner but have had several other brit bikes. I recently purchased a 1975 mark 3 and the electric start makes a terrible noise. Disassembled primary to check sprag clutch and it appears to be in fine shape as does everything else in starter works. Is there anything else that could make a grinding noise when cranking. Sprag was installed with flange inward, is this correct? I would appreciate any help as I get to know this bike.

groveman said:

I recently purchased a 1975 mark 3 and the electric start makes a terrible noise. Disassembled primary to check sprag clutch and it appears to be in fine shape as does everything else in starter works. Is there anything else that could make a grinding noise when cranking.

Click to expand...

One thing that can make what could be described as a "terrible noise" would be the overload anti-backfire device when it slips. Occasional slipping of the overload backfire device is to be expected, however if the OB device slips more-or-less constantly when the starter is turning then the slip-torque could be under-adjusted or the ignition timing may be too far advanced, or both?

https://www.oldbritts.com/e_start_backfire.html

http://britmoto.com/manuals/Manuals/850_man.pdf

groveman said:

Sprag was installed with flange inward, is this correct? I would appreciate any help as I get to know this bike.

Click to expand...

Sounds right. If fitted the wrong way then the sprag wouldn't turn the crank.

https://www.oldbritts.com/e_start_gears.html

groveman said:

I am a first time Norton owner but have had several other brit bikes. I recently purchased a 1975 mark 3 and the electric start makes a terrible noise. Disassembled primary to check sprag clutch and it appears to be in fine shape as does everything else in starter works. Is there anything else that could make a grinding noise when cranking. Sprag was installed with flange inward, is this correct? I would appreciate any help as I get to know this bike.

Click to expand...

is your bike running points? because if you are running boyer electronic ignition for example it dont get on too well with the sprag clutch,,,,,,,,,,,baz

Mine is crazy noisy for a few seconds then the 2 chain tensioners prime up with oil and then all is oiled and good to go. I was just on the VXB.com website researching DC4127 sprag and started counting the number of rollers in the product illustration. I counted 26. Forum members say it's 18 , as better than the standard 14. Perhaps it's just a generic photo ? Any feedback or ideas on this ?

I have the VXB sprag performing well. I believe it has 18. If either of the contact surfaces have roughness or are under/over sized, replace for reliable starting.

I threw my early Boyer in the trash and replaced it with a Pazon Altair. Low voltage and early Boyer don't mix. I also installed a DD starter and a three phase alternator as the original is inadequate.

My overload device was seized. No amount of torque would make it slip - another reason for sprag failure. As L.A.B. said, an incorrectly set one will make a hell of a racket.

All the above makes it a reliable electric start.

Well then let's assume the photo with 26 rollers is a generic photo placement. I'll be ordering in the sprag as it will most likely be the 18 roller one.