85 - XJ700 air cooled, won't stay running.

Greetings everyone. I originally asked questions last fall and now that the warmer air is back here in New England I've begun to work on my bike again. I purchased thru here a total carb rebuild kit, including new air and fuel jets, and tore down, hot ultrasound washed components, flushed with carb cleaner ( must remember to get face out of way in future when spraying little passages, stuff tastes terrible) and put together with new pieces all 4 carbs. They look nice. I in stalled and tried to start. Freshly charged battery, new gas. Most of the time it sputters and on rare occasions it will run for 5ish seconds, then dies. My prime jet has been set at between 1.5 and 4 turns. Makes little difference.

After 30 min of trying, found exhaust piping hot on 2/3 warm on 1, stone cold on 4. Check spark on 4, nothing. I attempted ohm reading s on 1/4 coil, wire to wire 2.4ohm. wire to plug cable, OL. Removed end cap, found corrosion. Ordered new coil packs and replacement caps. Went to perform same checks on new, got exact same readings on wire to plug cable, OL. Can both be broken or am I missing something? Put original coils back on with new plug caps, seems to try and start on 2/3 but still issue with 1/4. My next thought is to go back in system and check points. Any thoughts anyone?

Thanks for the help.

 

I assume you're trying to check the secondary resistance on the ignition coils......to do so you'll check (for each individual coil) plug wire-to-plug wire ends (either with or w/o the hard plastic caps installed). The secondary circuit (plug wires) and the primary circuit (from the engine harness, and coming from the TCI actually) are not connected within the coil body, and thus there can be no reading if you try a plug wire (secondary circuit) to the either of the two wires that make up the primary circuit.

Checking the secondary circuit may well get you an OL reading......unlike the primary circuit (2.4 ohms is about right), the secondary circuit can be 10K (10,000) ohms and up. A lot of standard ohm meters will either:

a) not read that circuit properly, if the meter doesn't have a selector to choose particular "ohm ranges", or...

b) may not read it at all, even if there is a selector switch (and it's set to the correct range). 10K-up ohms is a lot of resistance for a 1.5V battery to push thru, and if the batteries are weak or the meter is really not designed to read that much resistance, you get the OL reading.

Note that the OL reading can mean EITHER an "Open Loop" (the circuit has a broken wire somewhere within it, and one end is no longer physically connected to the other end of the wire) or it can mean "Over Loaded".....meaning that the meter isn't set to the correct ohm "range", or that the meter can't push enough voltage thru that length of wire to create a determinable ohm value.

Some meters allow you to select an ohm reading "range" such as "Ohms x 10" or "Ohms x 100", etc.....in such a case, when you measure (for example) a 11,000 ohms circuit on the "ohms x 100" setting, then the display will only show 110 ohms (which is 1/100th of the true reading of 11,000 ohms).

https://geekyelectronics.com/how-to-measure-ohms-using-a-multimeter