hi guys. quick simple question. can anyone think if there is any reason why the frame can't be used as the main earth point for the bike. I can't think of one. it all goes round in loop anyway. just redoing all the electrics on the custom build and want to simplify the wiring. thanks.
There is often corrosion at any exposed point on frame for grounding. This corrosion gets worse and worse over time, leading to unreliable electronics. To prevent having to clean your earth points as regular maintenance, especially in rainy & humid climates, each circuit has dedicated ground wire as well. Look up "ground loop" issues caused by multiple earth points.
Multiple earth points are accepted design commonly employed by various manufacturers over many years. Not problematic when maintained, I don't find periodic cleaning of 2 ground points as a burden, challenging or difficult at all. Should it be?
hi thanks guys. there are no plastics on it. it's a naked bike to use the term loosely, in fact it is a one off shed build if you didn't know it was based on a EX you wouldn't recognise it. for instance there is no battery in the box [that where I keep a few tools] the battery wires are 3ft long from the back of the bike. when I built it I used a stock harness and components but moved those inside. some of the tails are far too long. thought it was time to tidy it all up. and simplify the wiring. re configuring the earth points makes a lot of sense to me providing there are no issues in doing so.
just to add. all the old bikes used a frame earth it is those oriental bike makers who swapped the system to wire earths using only 1 or perhaps 2 central points.
just to add. all the old bikes used a frame earth it is those oriental bike makers who swapped the system to wire earths using only 1 or perhaps 2 central points.
The largest electrical load most vehicles will see is the starter.
MUST have a ground wire to the engine, to ground the starter, as big as the wire going to the starter.
Going battery > frame > starter is asking for problems.
yeah that's one of my points short battery earth to frame, engine earth [can use the starter ground] to the frame to complete the circuit, making the frame part of the circuit allows all other earths to be short. there a lot of frame metal on a bike, and plenty of bolts to use. [if it works]
Depends upon how "simplified" he wants to make his harness. Remove all ground wires and earth each bulb to frame at their location? Now you've got 8-10 grounding points that needs to be cleaned 2x a year. Getting current through handlebars, triple-clamps, headset bearings and grease will be problematic on top of keeping frame earths clean. The increasing resistance over time may only dim lights, but will really mess up low-power circuits that control relays. There's reason bike circuitry evolved over time to have only grounds at battery, engine and starter.
Ground loops aren't so much problem on non-EFI bikes, but even ignition pick-ups won't work if well if there's slight loop causing voltage differential between their grounds and igniter's. With modern ECUs, there's actually two ground planes, power ground and floating sensor ground. These should never ever be shared. Most sensors will even use coaxially-shielded cables to protect their dedicated signal and ground wires from any inteference that may change their massive millivolt outputs.
I recommend using tinned-lugs on your wiring. Crimped, soldered and heat-shrink wrapped to your pre-tinned silicone insulated wiring. This is done in pro-motorsports, aerospace and military applications for performance, reliability and durability. Be sure to sand down earthing point to bare metal, removing any galvanising or primer layers which aren't as conductive.
Fasten to frame with stainless bolts & washers. Along with copper anti-seize in threads (especially if going into aluminium threads). Permatex or Never Seize has higher copper-content than most others. Once bolted onto frame, cover with terminal sealant to keep moisture out (many people use smear of grease).
I've spent lots of time living on coast in Santa Cruz and Santa Barbara and have had to ward off accelerated corrosion in these environments. Heck, even the chain will rust overnight.
yeah thanks for that. I'll take it all on board. I do understand electrics a fair bit and are aware of the component issues but to my thinking the starter, alternator, timing hall sensor, spark plugs temp gauge. are all earthed to the engine, which will not change. the engine is earthed to the frame anyway because it's bolted in there. but will be hard wired to make sure. the CDI, solenoid, flasher unit, regulator, fuse box, are all isolated being in plastic/rubber mounts or housings that will not change. the lights, indicators are already wired to the frame and work perfectly.
plus there is already a frame earth point on the thermostat housing. the main difference is I intend to utilise the frame as a main earth point to shorten the tails and delete those long starter wires save one. electrolysis can be an issue I agree but using the right materials should lessen the issue.
I am fairly happy I covered all the bases. but wanted to ask the experts on this peculiar bike. just in case I missed something.
@Apriliarider yes you got that pretty much correct, it has never seen a raindrop never mind any sea water spray. It's my play around with project and hobby constantly under re construction between rides if there are improvements to be had. I take all your points onboard and will make sure all the connections are water resistant and of the right grade. I'll let you all know what develops when I start.
right is done and works great. I ended up with 4 frame earths. starter ground to frame, engine ground to frame [extra wire]. battery negative to frame. and main black/yellow earth wire to frame. all the other grounds were left wired and just shortened with all the other wires on the tails to the components. all nice and neat now. used proper connections and weather proofed them.
quick note just in case anyone else does this. I added a new lead from the engine to the frame. because when testing the continuity and resistance found a very small amount of resistance between the engine and frame, [0.247oms] very small but still there. probably caused by the engine bolts going through the painted frame. if the contact of the bolts to the engine and frame were good and clean this step would not be needed.
I'd have done that anyway. Typically there are rubber isolators involved in engine mounts so an engine ground is a necessity.
Even if there were no isolators involved, like on my project 900SS bike, just the cadmium plating on the engine mount bolts, is in contact with the aluminum of the crankcase. Enough dissimilar, and sacrificial metal is present, that a little moisture is enough to accelerate the galvanic corrosion process.
It would be a short length of time before that ground would begin to show resistance and you'd be back in there doing maintenance.I've seen enough weird stuff happen when the primary ground circuit is "broken" that it is always my preferred practice to ensure a fault free one. Just my 2 pence.......sean
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