Honda CB750 K2 - Ignition primary circuit - chasing volt drops Ep.6

With the new parts for the front brake caliper on order we can now crack on with the repairs to the ignition system - remember that weak spark we discovered during the initial check over of the bike? Well, now I finally have the time to dig a little deeper to find out the true state of the wiring on this bike.
Using the basic 'Volt drop' test we can quickly identify points of high resistance along the wiring that makes up the Ignition system circuit....
The method used in this video can pretty much be applied to any electrical circuit & is a very useful way of identifying problems.
Follow me through these checks & we will get one step closer to getting this legendary bike back on the road.
Andy
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Andy

[@andywheat1411]

This is EXACTLY the information I was wondering about presented in usual thorough fashion.

[@trompelemonde4728]

Amazing video, super helpful, I went through all my wiring before I saw this so I was very much following along. THANK YOU

[@bobdelaplage690]

This is exactly what i needed....have a bmw rs100 , 79 year.....and after making contact + terminal with frame by accident, i have nothing left of electricity , nowhere....no dashboardlights, some part probably blew and blocks my battery voltage....i have same oldschool schematic in my haynes....wish me luck🤩🩺Bob Belgium

[@daveco1270]

I bought a 75 CB750 two years ago. I'm so glad I haven't found any shit like this in the wiring system. So far everything seems to be stock and in decent condition. It's been a great bike to learn maintenance on.

[@zeez9053]

Great that I can see you have a logical mind at electrical problem solving

[@jondwyer3037]

CREW DONT FORGET TO HIT THE THUMBS UP BUTTON ABOVE, THANK YOU.

[@brucewaller8074]

Hi Andy great video thanks, Just what I need to plug some of the gaps in my electrical knowledge. I'm currently diagnosing a few gremlins on my 1977 CB 550. Keep up the detailed video format as it is very helpful to self taught mechanics, All the best from Huddersfield West Yorks.

[@arthurfricchione8119]

Andy, marvelous job and an outstanding informative video. Will keep a lookout for the next one. Stay safe and well. Artie 😊

[@mohammadabouaudi2443]

so brilliant

[@aussiejas6599]

looking good Andy

[@zeez9053]

Quality content

[@bobkinney2430]

Hey Andy, just a tip....invest in the clip leads for your meter. Well worth it when checking wires. 👍

[@AndyMechanic]

God yes.....I really need a couple of sets but just keep forgetting to pick some up! It's on my wish list! Thanks for the reminder :-)

[@KillswitchBB]

Awesome breakdown on electronics Andy,,, now tell me ? do i owe you royalties from the amount of times you mentioned my name throughout the video ? 🤣🤣 ( Killswitch ) 😁

[@KowboyUSA]

Surest route to headaches is having lots of crappy wiring splices.

[@benjaminrich9396]

Nice videos mate but if I may, just a tip: Unless I'm mistaken you've had the coil 'on' for long periods of time here. In normal running as you know it's obviously not permanently on like this, (the duty cycle is obviously not 100% as it were). As you understand, Kirchhoff's voltage law being what it is, you need the circuit 'on' and current flowing to check all these volt drops. But you'll cook a coil leaving it permanently on like this for minutes . As ideally the only load in the circuit, you can disconnect the two coil primary connections and put a test light in its place. With the contact points closed obviously current will flow through this circuitthe same, but you won't do any harm. You're still looking ideally for the battery source voltage across the load (now the test light, in place if coil) with any other volt drops being undesirable but you can take all day doing this without harming the coil. Doing volt drop testing around the circuit your way will totally kill the coil! You said yourself they were getting hot. ;) Rookie error really chap. ;)

[@benjaminrich9396]

apologies for the typos :)

[@AndyMechanic]

Potentially, however, these ignition coils are going in the bin. We have new Dynatech coils to fit..... on another note, I have not read anywhere in am owners manual 'yet' not to leave the ignition turned on for long times. Ignition coils get very hot even in normal use. Also this video was edited & there were times where the ignition was turned off for say 15 or 20 mins at a time. I'd say the longest time they were left on in one continously period would be around 20 mins or so. Coils were never too hot to touch & I have felt coils much, much hotter than these on vehicles where the engine has been running for long periods - say a 2 or 3 hour ride for example You do make a valid point & appreciate your feedback. Cheers Andy

[@Cobra427Veight]

Hi Love your intro's ! Andy is there a free website you get your diagrams from ?

[@bobdelaplage690]

Im suspecting a fuse.....but can it be that there is no fuse at all to be found, not in my diagram, not in the flesh? Im gonna look for one!

[@johnnuttall6112]

hi Andy dont you need a 1to2 ohm balance resister with your new coils as standard coils are 5 ohm and your using 3 ohm will they coils not run hot ?

[@AndyMechanic]

Hi John, you raise an interesting point. Dynatech have not indicated this. I'm going to be sending them an email covering the proposed wiring if the Primary circuit on the bike before I do the work - I'll raise that point in my email too. Thanks :-)

[@johnnuttall6112]

you only need it with points setup@@AndyMechanic

[@AndyMechanic]

Rodger dee.....in that case we should be just fine :-)

[@VanekLarson]

Getting famous off of comments day 162,so I can live the dream, live life to the fullest🤙

[@tomtheunknown4875]

Am i in time i hooe am not late😀

[@simonrawle7885]

cant stand choc blocks . almost as bad as wires just twisted and taped up. if you need vintage style connectors i highly recommend the lads at kojaycat.co.uk . realy know they stuff

[@AndyMechanic]

Yep....the minute I spotted them I knew the maintenance standards on this bike had hit an all time low!! Lol

[@Istilllearning]

6th