Hello Chris
do a search on this forum, try 'new starter what type' and it should bring up the mk 3 starter thread that i and others have contributed to.
Depending on what facilitys and skill level you have (or how deep your pockets are!) there are a few different options open to you.
Take a bog standard mk 3 for starters. !st Fit thicker cables, 2nd, ditch the prestolite solenoid and use one from a mini (lucas type)
Starter wise you have a few options.
If your bike has a functioning prestolite starter the first two things will improve its working, but, after forty plus years the inbuilt faults that the prestolite motor has, will surface and degrade its performance (the rotor will wear itself into the drive end plate until the windings start to short out) The original prestolites quality control wasn't the best, commutators machined out of true etc. That and they weren't weather sealed very well so they are prone to internal rustyness!
Cnw do a Mk3 norton starter, adapted from a new harley starter. Looks very similar to the original prestolite as harleys at one time used the same basic starter frame. $530
Dyno dave does a mk3 starter, i believe based on a hitachi or nippon denso starter. $375
Wosp do a starter that looks the same as the Dyno dave one. £315 on ebay
Holland norton works do one, looks like the DD one 369 euros
RGM do one, looks like a DD one £425
Norvil ditto £420
You can fit a four pole frame to the original prestolite and this will improve things, but, you will still be using a forty year old rotor and bush bearings. The four pole frame is from the new harley starters previously mentioned.
Don't pay more than £85 for the harley starter. There is one vendor on ebay punting these out for £125 Labeling them as 'Norton commando starter motor 4 coil case conversion'
This uses a four pole frame (as against the mk3 two pole frame) this frame can be swapped to upgrade the mk3 two pole motor. still leaves you with the rotor wearing problems.
If originality is your thing the original prestolite can be upgraded to much better performance, this entails fitting the two pole frame with four field coils, either replacements or additions to. Fitting the end plates with a ball race at the drive end and a needle roller in the brush end, and the four brush holder and brushes accordingly.
I have done this a few times for clients. Gives reliable starting from an original looking starter.
I have also converted quite a few Harley starters (Looks like the Cnw one) for customers, the last one i sold for £250
Like i said, depends on how deep your pockets are, and how bothered you are how the thing will look. The DD ones and its clones look to me like they were fitted to washing machines.
PM me if you want to know more. Where abouts in the uk are you?
Regards
Peter
