Repairing CB72/77 Points Backplate

[Phil-UK]

Hi All

Anyone got any tips on repairing the points backplate on a CB72 ?
The threads on mine are in an awful state - managed to take one of the outer ones to a larger
size but the inner ones ( nearest the wiring posts ) need a small head screw so they don't hit the cam.
Also there isn't room behind the plate at that postion to build it up behind.

Tried MIG welding a spare backplate which is an an even worse state but can't get the weld to take and fill in the holes so I can retap.

If necessary I can buy some plate and make a new one but anyone else found an easier way ?

A freind with a Suzuki GT750 said he thought the original screws were quite soft so they stripped before the backplate .. true ?

Thanks in advance

Phil

[e3steve]

Phil, I Recoiled mine with the M4 kit from RS and then used M4x6 cap-head Allen s/s screws; I keep all the Recoil kits handy, M3-M12, nowadays as a precaution!

The screws are originally JIS 4mm, not ISOmetric.

[e3steve]

I just looked at the Allen key that I use for the points' adjustment; it's a 2.5mm so I may have used M3 Recoils / screws -- I'll have to pull the cover and take a look when I'm in the garage tomorrow!

You need to Dremel the excess thread coil insert off, using a disc, but it worked well for me. I ran the insert all the way into the repair thread and then Dremelled off the excess from the back of the plate so as not to reveal disc marks when the points' cover is off. The plate is <2mm thick so you only get about 1 coil of thread in place.

[Phil-UK]

Thanks Steve

I'm off to Stafford on Saturday so will see if I can get a thread kit from Uni-Thread or similar.
Part of the problem has probably been incorrect screws if they were JIS, I noticed Silver's listed
the screws with a J suffix so could explain what happened.

Phil

[e3steve]

RS Components tend to be somewhat expensive, compared to many trade outlets; but they do provide great service (most of the time.....). I am mainly stuck with the Spanish franchise "RS Amidata" (Madrid), which is slowly improving but, as with many facets of life in Spain, QoS is something of an oxymoron; especially in Majorca where practically all of life's everyday products gets 'imported'. Amidata don't carry all of the UK's RS Components' lines, so I very often receive packages that I ordered from Amidata but they get delivered from Corby main warehouse; that delays delivery.

Life is bollocks here sometimes, but infinitley better than "home"!!

[LOUD MOUSE]

I can send ya one it ya pay the mail cost. ........lm

Hi All

Anyone got any tips on repairing the points backplate on a CB72 ?
The threads on mine are in an awful state - managed to take one of the outer ones to a larger
size but the inner ones ( nearest the wiring posts ) need a small head screw so they don't hit the cam.
Also there isn't room behind the plate at that postion to build it up behind.

Tried MIG welding a spare backplate which is an an even worse state but can't get the weld to take and fill in the holes so I can retap.

If necessary I can buy some plate and make a new one but anyone else found an easier way ?

A freind with a Suzuki GT750 said he thought the original screws were quite soft so they stripped before the backplate .. true ?

Thanks in advance

Phil

[e3steve]

That's a really magnanimous offer from Ed!

I pulled my points' plate off today (it's raining!) to mop some oil mist away and to replace the main screws. I was going to Recoil the threads, in the right-side casting, with M5 inserts, but those threads are already that thread (and they've not been fitted with re-thread inserts). Now, this is odd, as I was under the impression that 5mm and smaller were all JIS; my M5 screws went all the way in without any binding.

The plate re-threads are M4 -- and the Allen key is 3mm (not 2.5 as I thought yesterday).

Anyway, FYI, images below.