Classic British SparesKlempf British PartsBaxter CycleBritBike Sponsor SteadfastCyclesSRM EngineeringLucas Classic MotorcycleHepolite PistonsIndustrial tec supply

Upgrade your membership to: Premium Membership | Gold Membership | Life Membership | Vendor Membership | Site Sponsor Membership
Welcome to BritBike Forum!
Britbike forum logo
Member Spotlight
gunner
gunner
Farnham, Surrey, UK
Posts: 1,532
Joined: September 2004
ShoutChat
Comment Guidelines: Do post respectful and insightful comments. Don't flame, hate, spam.
Search eBay for motorcycle parts in following countries
Australia, Canada, France, Holland, Italy, United Kingdom, USA
Previous Thread
Next Thread
Print Thread
#844844 04/01/21 7:13 pm
Joined: Mar 2021
Posts: 3
J
Jcsus Offline OP
Novice poster
OP Offline
Novice poster
J
Joined: Mar 2021
Posts: 3
Last summer I acquired a ‘68 A65 bobber. It came with a Joe Hunt magneto. Rebuilt the whole magneto. Bench tested the mag with my impact gun and had great spark. Got all my TDC settings and mounted the mag, but no spark. Come to find out when I kick, the cam isn’t turning. It turns if I crank the alternator side with a ratchet. Question is, before I open it up, what could most likely be the culprit? I’m a moderate hobbyist, and I’m just wondering what I’m diving in to. Thanks again!

Support Your #1 BritBike Forum!

Check out British motorcycles for sale: British Motorcycles on e-Bay UK, British motorcycles on e-Bay North America
Joined: Nov 2012
Posts: 2,034
Likes: 56
K
Britbike forum member
Offline
Britbike forum member
K
Joined: Nov 2012
Posts: 2,034
Likes: 56
It sounds like the kickstart isn't turning the engine at all. While you can see the alternator nut, see if this is the case. Detach or totally slacken the clutch cable for this test.

If so, then its likely to be a problem with or behind the clutch. The entire clutch maybe just slipping on the mainshaft.

If its not already off, take the primary case off. It sounds like this will be necessary for whatever treatment is required. Who knows, you may even find there's no primary chain in there!

Joined: Mar 2021
Posts: 3
J
Jcsus Offline OP
Novice poster
OP Offline
Novice poster
J
Joined: Mar 2021
Posts: 3
Luckily I have a belt primary with a Norton Commando clutch basket. I’m learning the previous owner rigged a lot of stuff up just for the sale of the bike. I don’t think it’s a clutch problem though. If I put the bike in any gear and try to kick it, the bike pushes forward. In passing, I learned one of my gear box oil seals is bad. When I put the bike on the stand, the gearbox oil leaks out the primary side. So maybe I’ll get to replace that when I open up the gear side. I just wasn’t sure if it was a sheared pinion or a problem with the layshaft (as I had previously read about). Thanks again for the reply!

Joined: Nov 2012
Posts: 2,034
Likes: 56
K
Britbike forum member
Offline
Britbike forum member
K
Joined: Nov 2012
Posts: 2,034
Likes: 56
" I don’t think it’s a clutch problem though. If I put the bike in any gear and try to kick it, the bike pushes forward."

Even if you take the clutch off completely it will still do this.

Joined: Mar 2021
Posts: 3
J
Jcsus Offline OP
Novice poster
OP Offline
Novice poster
J
Joined: Mar 2021
Posts: 3
Thanks for the advice. That’s something I didn’t know. I’ll report back with findings. In case someone else gets into this predicament.

Joined: Aug 2001
Posts: 5,560
Likes: 60
M
Britbike forum member
Offline
Britbike forum member
M
Joined: Aug 2001
Posts: 5,560
Likes: 60
Right, the kickstarter turns the tranny mainshaft. If the clutch is engaged, the tranny mainshaft turns the primary drive, which turns the crankshaft.

The idler pinion (on which the dwell cam is mounted) is gear-driven off the crankshaft, so it must turn if the crankshaft turns.

If you're feeling some resistance in the kicker, then it's likely that all the parts are there and the clutch is slipping. It could be as simple as an adjustment. It's been a long time since I've looked at a Norton clutch, but I assume it has a pushrod clearance adjuster in the center of the pressure plate. Go there and back off that adjuster to where you know the pushrod is not in contact with the pressure plate, and see if the clutch still slips. If it still slips, then it's time to open the primary and see what's going on.


Mark Z

'65(lower)/'66(upper, wheels, front end, controls)/'67(seat, exhaust, fuel tank, headlamp)/'70(frame) A65 Bitsa.

Moderated by  Allan G, Jon W. Whitley 

Link Copied to Clipboard
Job CycleBritish Cycle SupplyMorries PlaceKlempf British PartsPodtronicVintage MagazineBSA Unit SinglesBritBike SponsorBritish Tools & FastenersBritBike SponsorBritBike Sponsor






© 1996-2021 britbike.com
Powered by UBB.threads™ PHP Forum Software 7.7.5