Hitchcocks Forum

Evening all,
My 700 twin starts ok and will sit and idle on the drive no real issues but does not wish to get very far before wanting to be pushed home! when I try to get her to leave the drive way, she starts off well enough but over the course of approx 1.5 miles she gets a progressively worse missfire until she wont go at all or re start. Fuel does not appear to be the problem so does the team think that it could be the Magneto (K2F) which I haven't had re-built or is she just a home bird that is frightened of modern traffic? Any ideas gratefully received.
Steve

Magnetos do deteriorate over the years, it's not unknown for them to spark OK from cold but lose reliability when they get a bit warm.

If that's a sixty year old mag on its original windings I'd be sending it off for a rebuild. You could convert the bike to electronic or points and coil ignition, but a proper working magneto is A Good Thing To Have On A Bike.

A.

Yep, what Adrian says.

Probably the condenser - typical symptoms.

A duff coil?

papasmurf wrote: ↑

Tue Aug 11, 2020 7:04 am

A duff coil?

If it had one, quite possibly.

But not possible if it has magneto ignition...

Thanks for the input gents looks like more open cheque book surgery for me then, can anyone recommend someone to rebuild the Mag? She's been a bit expensive this one

I forgot to ask, is your mag a K2F or the SR2? If it's the SR2 you can replace the condenser yourself quite cheaply if Rattlebattle is correct.

There are a few folks out there who will do a decent job, i.e. rewind with new capacitor, new bearings, points, slip ring and brushes, check the cam ring will have both sets of points opening correctly for a twin, replacing if needed, and a good jolt of re-magnetizing. Dave Lindsley rebuilt a knackered old BTH KC1 for me (good job but £££ ouch), you could also try Rutland Dynamos, The Magneto Guys have a note on their web site's home page to the effect that they're snowed under and not taking on new rebuilds at the moment. There are certainly other firms out there (listed below) that do this stuff.

Be aware that there can be quite a turnaround time depending on their workload, with the lock-down etc, lots of people have decided that NOW is the time to get on with THAT PROJECT, and a lot of the companies that have kept open have found themselves busier than ever.

http://www.davelindsley.co.uk/

http://www.rutlanddynamos.co.uk/magneto-services.html

http://www.vehicle-electrical-rewinds.c ... pairs.html

https://www.tjmagnetos.co.uk/

https://www.dhday.co.uk/

https://www.ribblesdale.co.uk/vintage-units/

https://sites.google.com/site/priorymagnetos/home

http://brightsparkmagnetos.com/index.htm

My apologies if I have missed out anyone's favourite.

The other option if you REALLY have the domestic finance committee on you side is one of the new BTH electronic magnetos, which is still a self-contained package (electrically, at least) using CDI technology.

https://www.bt-h.biz/FM2R-Flange-Mounted-Twin-Cylinder

https://www.bt-h.biz/K2F--Lucas-Replica-Flange-Magneto

OR you could even scour that well-known auction web site for a working replacement, rebuilt ones sometimes come up (get one with the correct rotation, I think the RE twins spin clockwise at the drive end).

OR EVEN buy this from our hosts!

A.



https://accessories.hitchcocksmotorcycl ... tion/26311

Many thanks Adrian, going to bite the bullet and see where it goes. Unfortunately it is a K2F so the condenser is buried in the armature I believe, gutted. The old girl is turning into a money pit!

Another for Adrian's list for magneto rebuilds that should not affect our host as they are mostly 70s Japanese bikes:

https://www.rexs-speedshop.com/

They offer three tiers of speed of service. Very simply, pay the premium, get it quicker.

John