SOHC.co.uk Forums > CB750
re-jetting needed?
totty:
I don't recognise the first 3 plugs, the NGK ones are resistor plugs, you can tell by the R in the name.
You shouldn't mix resistor and none resistor plugs on the same coil. I think but I'm not certain that you shouldn't have both resistor plugs and caps. Check your caps by part number or resistance.
El__burro:
The plugs in grey (24..)
are the ones that came with the bike a while ago, i have used them until now. No problem.
The blue ones are new, couldn't use them as I have just learned (thanks to you) that the cap has a resistor too (VD05F 5KO)
Any good tips to test the condenser on the points. Or eventually a good shop.
Tried loading up and look for a spark (like in clymer pic)
but none of the 2 have it..
Thanks
el__burro
Sent from my SM-G935F using Tapatalk
totty:
I'm not sure how to test a condensor, looks like the test in the manual is to charge it and look for a spark on discharge, I've just googled it and come up with two answers that I'll paste below, but a spark at the points makes me think a condensor has failed.
By the way I don't think condensors can give the symptoms you've described, but failed ones will wear out the points quickly so it's worth sorting out while you're on.
While you've got the meter out I'd check those plug caps are all still 5Kohm as rated as they can fail, and also the coil primary and secondary resistance - I don't know the correct values but someone on here will and they might be in the manual.
Once everything tests OK I'd then use the strobe, or carefully check that all exhaust headers heat up from cold to too hot to touch quickly and evenly to confirm that it's firing on all cylinders. Ignition should then be all sorted.
Capacitor test instructions from google:
Choose your tool. Even cheap digital multimeters often have a capacitance setting "– ...
Shut off the power. ...
Discharge the capacitor carefully. ...
Disconnect the capacitor. ...
Set the multimeter to measure capacitance. ...
Activate REL mode if present. ...
Connect the leads to the capacitor's terminals. ...
Wait for the result.
OR
To test the capacitor with a multimeter, set the meter to read in the high ohms range, somewhere above 10k and 1m ohms. Touch the meter leads to the corresponding leads on the capacitor, red to positive and black to negative. The meter should start at zero and then moving slowly toward infinity.
El__burro:
Latest update.
After testing the resistors and deciding they are gone, i have ordereda set this morning.
Not sure about coils testing
Here is my finding
Primary coil 4.6 ohms
Secondary coil, plug to plug 14.8,
Plug to (any)pigtail wire 1 .
The same reading for both coils.
All of this whith the coils mounted on the frame.
Fail or..?
Thanks
el__burro
Sent from my SM-G935F using Tapatalk
El__burro:
Monologue update.
I received the new condensers from DSS (1 day after order, Impressive)
Put them on, all good, bike starts and revs properly.
Still i see a spark on both points, 1-4 also bridging on plate too.
Also noticed 3 of 4 coils leads arcing onto the frame too at the top connection
Not sure how serviceable are the leads to plugs but they should be better isolated.
Concerned about the bridging sparks on the points. Then workon the needle position again.
Getting there
Thanks
el__burro
Sent from my SM-G935F using Tapatalk
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