New project CB750F1

Cheers mate, I'll have a look around the rear brake switch, that makes sense otherwise the cable run to the coils would be a bit sloppy.
I've connected the oil and neutral warning lights ready for testing the electrics but when I turned on the ignition switch I got nothing so will go back to the battery and start testing for the power, could be a fuse as I didn't check them when the harness was off.

Loki
 
hinksy said:
Mine come from the points and go into the harness at the rear brake switch , then onto the coils
Click to expand...
Thanks for that they were down there, I'd even labelled them POINTS!! so that's that piece of the puzzle sorted, just been sorting out the footpegs after blasting and painting had to refer to the drawing as too many permutations for the component parts!

Loki
 
So on with the electrics, checked power to the ignition switch and all good there, after plugging it in and out a few times the oil light suddenly came on but no neutral light, all indicator lights checked after finding a fault with the black lead to the indicator lights, ran in a new cable and all good.
Next tried the start circuit but was met with silence from the starter solenoid, took it off and gingerly opened it up to find the plunger seized, spent some time with WD40 and easing it up and down until it was free, although they looked quite clean I gave the main contacts a good clean and after putting it back together and testing it got zero ohms across the studs when energised.
So once I have some oil I should be ready to spin the engine over with the plugs out until I have oil pressure then I can do a compression test for a baseline figure.

Loki
 
My starter relay was the same , ish . It initially blew fuses when I touched the starter . So to check if it was the switch I jumped the relay and it must have been frozen , as it took a couple of hits till it worked and no more blown fuses . Dont know aboot the neutral light , but its default is on . So when they shit themselves you will always have a light if you have power . So check continuity to the light and the bulb , and they are not hard to get out and clean . Sometimes the spade connection can be dirty or oil sediment can leave muck in it , so it needs a clean out ( So I was told )
 
A few gremlins in the electrics seem to have gone now with making and breaking the plug in connectors around the harness I think the neutral light switch is a bit sluggish as initially when I found neutral nothing then while trying to get the starter solenoid to work from the start button the neutral light magically came on, then just as magically the starter button started to work as it should.
Think I'll go round all the connectors with electrical cleaner just to be sure, I've already replaced several of the bullet connectors which were either missing or mismatched.
Hopefully my new battery is coming today so I can get the engine to spin over and check the oil light goes out, got my oil and put about 1 litre in the engine and 2 litres in the tank.
My starter solenoid was completely stuck and I had to work it up and down with a good dose of WD40 until it was working freely without sticking up or down, seems to be OK now it's getting the amps it needed to throw out.

Loki
 
Yesterday I refitted the rear wheel then today had to take it off again as I'd fitted the thin metal disc behind the sprocket instead of in front of it, bike is still sitting on my trolley but plan is to get it up on the centre stand after cranking up to get the oil going round then I'll fit the front pipes before trying for a first start, will do a bench synch of the carbs to start with. More updates as I make progress.

Loki
 
Eventually got oil flowing, had to take the oil filter off to get the pump to prime but got there in the end! Next job is get it up on the centre stand so I can fit front pipes at least, waiting for a 12mm adaptor for my compression tester so I can check compression then fit carbs and go for a start.

Loki
 
I did mine on a milk crate . So easy then to just roll it onto the centre stand , which I already had fitted
 

Attachments

  • IMG_20240703_161805.jpg
    IMG_20240703_161805.jpg
    376.4 KB · Views: 12
Those mikcrates certainly come in handy! I have a couple in my garage but my VW Golf engine removal trolley has many and varied uses.
I intended to take pictures but it went together so fast I didn't get time.

Loki
 
So yesterday I mounted the carbs and airfilter box, had a quick check of the jets and found one slow jet blocked so cleared that, also gave the mixture screws a good clean then set to 1 turn open, did a bench synch of the carbs and set the choke flaps up so hopefully ready for the first start.
Compression tester adaptor is coming today so can do a cold test before I go for the first start, must remember to switch on the kill switch!

Loki
 
Well the 12mm adaptor came for my compression tester, all cylinders cold were about 145psi will do another check once the engine has a few hours on it.
Finally managed to get an attempt at a first start and she started straight up, full choke and a touch of throttle and we were up and running, had an anxious moment when it stopped and wouldn't start until I looked at my fuel pot and it was empty! I didn't put much in it in case the carbs leaked but they were mainly good, just a slight dribble from one overflow pipe which cleared after a few minutes running.
Exhaust was clean, no sign of oil burning, ran smooth with no sign of misfires.
I'l carry on with the electrics next.

Loki
 
Still working through the wiring step by step, main loom is good so far but a lot of the front end wiring has been butchered so proving to be tedious at best but I'll get there!

Loki
 
Completed the rear end, tail light connected up and new wiring run in for rear indicators once they are fitted, tail light works when key in park position. Next the rats nest which is the headlight bowl!

Loki
 
Loki said:
Completed the rear end, tail light connected up and new wiring run in for rear indicators once they are fitted, tail light works when key in park position. Next the rats nest which is the headlight bowl!

Loki
Click to expand...
The hardest part I found was not getting tied up in knots . It is easy to just start connecting the matching colours , but you will soon find it hard to get them to mate up in the harness . Try to plan which goes with what and lay them out in there areas . Once I did that , it went together a lot better and gave me room to fit the headlight . Does the F1 have as much in there as an F2 ? You have that clump under the steering head , so wouldnt that cut down the amount going in ?
 
hinksy said:
The hardest part I found was not getting tied up in knots . It is easy to just start connecting the matching colours , but you will soon find it hard to get them to mate up in the harness . Try to plan which goes with what and lay them out in there areas . Once I did that , it went together a lot better and gave me room to fit the headlight . Does the F1 have as much in there as an F2 ? You have that clump under the steering head , so wouldnt that cut down the amount going in ?
Click to expand...
The drawing shows a junction box outside the headlamp is this the clump you mean? btw I don't have the box! Does it attach to the small bracket at the top of the lh front frame tube?

Loki
 
Yes it is . The F2 is different , so dont really know what it is , flux capacitor maybe
 

Attachments

  • 122737157.jpg
    122737157.jpg
    232.7 KB · Views: 13
Looks to be some kind of junction box, listed as Box, Harness 32400-392-000 in the parts list, I've just got a small junction box from Amazon so will see if it helps to reduce the number of wires in the headlight bowl.

Loki
 

Similar Threads

W
CB750KA Project
Replies
1
Views
265
Loki
L
L
1977 CB750F rear caliper
Replies
5
Views
534
Loki
L
L
Possible Frankenstein!
Replies
1
Views
461
Loki
L
JTech
Update on the '78 CB750A project
Replies
7
Views
1K
Kab wilcox
K
L
Steering lock removal
Replies
2
Views
570
Loki
L
Back
Top