Simple ignition upgrade for starting problem?

[kappy]

Hi friends,

New to the forum, just got a 1980 CB650, it did though come with starting problems.

I dropped it off at a mechanic who did a general service, cleaned the carborators, valve adjustments etc. (which he believed could be the reasons for the starting issue). Now he recently called me and mentioned that it still is very tough to get started (helps with starting fluid).

Having read through the forum my understanding is that the 1980ish CB650s often become tough starters, and I've seen the GM upgrade linked below (especially with the note on the startup booster).
- viewtopic.php?f=4&t=3142
- http://geocities.ws/loudgpz/CBheiModCavCoil.html

Me, having two issues...
1. Having limited experience of motorbike maintenance & electricity
2. Being located in Sweden, not sure where to acquire the parts needed (Wells C849 coils and Wells DR124)

...would like to reach out to the community and see if people might have any in between solutions / input?

e.g. would it make any difference acquiring a new ignition module (https://www.motoaction.se/tandpspole-st ... 80#v377065)

I found this post (https://www.hondatwins.net/threads/gm-d ... ost-137093) which seem to be a simpler version of the GM mod posted on this forum (although they do it for other bikes than the CB650..). Could that be an "easier" alternative with similar results?

Other "ready made" modules that could be utilized to support with the starting issue?

Br,
Kasper

[Volker_P]

Welcome here, Kasper!

New to the forum, just got a 1980 CB650, it did though come with starting problems.

Well, then it is a real CB650.

More precisely only cold start is an issue for most of us.
Most simple and straightforward solution is to close the petcock about 500m before you stop the bike somewhere for more than over night.

I assume you already have new plugs and reasonable ignition cables
Before you try an aftermarked ignition you still could check out if you can live with this proven CB650 cold start procedure
As I could live with that, I cannot help with own ignition mod experiences.

[kappy]

Haha!

I'll keep the petcock and proven cold start procedure tricks with me, I'll also forward the insights to the mechanic and see if he can try it out (unfortunately he's situated ~1 hr away so I'll just have to act as a messenger in this case )

Would still appreciate if anyone has any input on simpler replacement modules for the coils/sparks to improve the starting issue.

[kappy]

Still issues with this and I'm getting really tired about not getting to ride. The bike has been with the mechanic for 2 months now...

We ordered a set of replacement coils (https://www.ebay.co.uk/itm/272816183059) and after mounting it he says that it is still an almost invisible spark..

I've been doing some googling tonight and stumbled upon this: http://forums.sohc4.net/index.php?topic=53067.0

In Pinheads response he mentions the opportunity to create a bypass from the battery to the coils. Me, with limited electrical skills and no visual on the bike have a bit of a hard time to imagine what this would look like.

Anyone who could give some advice on what products I'd need and how a schematic for it'll look? I'm starting to get real desperate...

[Volker_P]

My first try would be to let it crank with a strong (car) battery and look if the spark gets stronger.
Basically one could connect the coils black/white cables directly to the battery for a try and see if it makes a difference.

Anyway I would first like to verify that plug cables and/or caps do not cause the problems, especially if they are still original.

BTW, the original ignition circuit operates with resistive caps (5kOhm) and spark plugs (another 5kOhm, label contains "R"). As two cylinders share one coil in series this means 20kOhm per coil (secondary circuit). Basically this should work fine but you may try without resistive components for comparison.

Note that the series arrangement also requires that the second plug of the coil remains connected when you look for a reasonable spark.