SOHC.co.uk Forums > Project Board
CB750K4 New project
Rob62:
Thanks K2.. i wanted to see if anybody could shed some light before i tried the other way round as i dont want to cause damage but i think its the only other option.... The other doubt thats now creeping into my mind is the big square metal mounts on the coils which are earths right?, since they are mounted to the frame they must be?... its just that none of the diagrams I’ve looked at show any earths on the coils and when i connect all the wires up with the coils just sitting there not screwed down onto the frame bracket, the fuse doesn’t blow....
What a frustrating day, and to cap it all off i managed to stand up next to the bike, hook the clutch lever around my brand new foooking expensive varifocals and knock them lense down onto the floor and scratch the lenses..... grrrrrr
K2-K6:
As I understand it the main, structural, earth on the coils is the neg side of the High Tension circuit that completes the spark circuit.
The low tension, low voltage side of the coil is effectively separate and just connected via the wires you describe through both the supply positive and negative switching by the points.
Rob62:
Ok...the solution. First off as many of you no doubt already know, the big iron mounting bars on the coils are not earths, according to all the diagrams they dont seem to form any part of the circuit? You were right K2, the earth for the ht side is the cyl head.
The clue was in the fact that the fuse only blew when the coils were clamped down, when they were free standing i could connect up all the wires without any problem. These replacement coils have spade connectors coming from the moulded body. On the left side coil (1 & 4) the spade connector gets slightly pressed up against the frame mounting when the coil is tightened up, but its got a protective plastic sheith so should be ok, but this one had a tiny split and was shorting out. 2nd problem was that the polarity of the wires was wrong, i wrongly assumed that the black wire was the positive feed but in fact it was the other way round. There is a crude + and - moulding in the coils thats not so easy to spot unless you have a good look.... I’m not sure that would have caused a problem anyway, i think it might have run but its the right way round now.
So after much frustration she now starts and runs on all four again... next job carb balancing. I’ve bitten the bullet and bought a set of £107 sealey gauges which i hope will work ok.
Rob62:
Had a quick go at balancing the carbs yesterday.... was getting late so packed it in but was struggling to get her running evenly. Ended the day worrying that there may be a problem with the motor ie compression. So tonight i double checked all the valve clearances, which were ok, then I ran a compression test. Cold engine, left 3 plugs in the motor, throttle wide open, 5 seconds on the strater motor, 150 psi on each cylinder, so I was happy with that. Again it was getting late so i made some adjustments to the carbs and just fired her up for a few seconds, seemd to be running better but still not too smooth.. Will balance the carbs at the weekend and then i reckon she just needs a good run. Im going to send off my registration application tomorrow so i took a couple of photographs of her to support the application. She is now virtually complete, just needs the side panels lacquering and a few decals adding. Hopefully I’ll be riding her in a couple of weeks 😄
Rob62:
Mine is all done now... just waiting for a reg number. I think its the first resto that i have actually completed before i started riding it. Usually i am finishing off loose ends weeks after first riding them. Will have a few snags to fix after the first shakedown no doubt, cant wait
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version