Any reason why this shouldn't work?

[Dougie]

I was having a mooch around the GSResources last night and I found a thread about iffy starting.The bloke who started it had measured the low tension voltage at the coils and found the voltage to be between 9 and 10 volts,even with a fully charged (and new) battery,a drop of mebbe 25%.He reckoned that going from the battery to the coils the juice had to pass through at least 6 or 7 connectors,the ignition switch,the kill switch and a good bit cable,the resistance thereof causing the voltage drop.His solution was to run a wire from the + terminal of the battery to the coils via a fused relay which was turned on by the wire from the kill switch.He said the low tension voltage drop was now minimal at the coils,which meant a greater high tension voltage causing a much better spark with improved starting and running.I'm no leccy expert,but I can kinda see the logic behind this.Anyone reckon it's possible?
Here's a diagram I found.
http://i51.photobucket.com/albums/f377/PieeaterDougie/img-1127648526.jpg

[matthewmosse]

I test run my engines on the bench using a spare set of coils, 3 wires (2 for starter motor) and a spare set of carbs + exhaust:thumbsu:

[Dougie]

Sorry,but I don't see what that has to do with what I posted.I was wanting to know if running a wire direct from the battery to the coils via a relay would minimise voltage loss at the coils,thereby increasing the high tension voltage.The bike starts and runs fine enough,but can be a bugger from cold........:confused:

[matthewmosse]

Sorry,but I don't see what that has to do with what I posted.I was wanting to know if running a wire direct from the battery to the coils via a relay would minimise voltage loss at the coils,thereby increasing the high tension voltage.The bike starts and runs fine enough,but can be a bugger from cold........:confused:

Sorry half the message:o engine starts better this way then in bike, I'd geuss that if cleaning the electrical contacts fails then it might work but I'd be checking the carbs and choke for cold starting probs too, oh yeah and compression. One bike I had was a real sod if too hot or if cold, engine strip revealed missing rings on all 4 cylinders.:eek:

[Kicky]

Yup,I reckon getting all your joints clean will help with starting,tho cold starting probs are usually mixture/choke related.
Looking at your diagram,when the starter motor is cranking the engine the power going to your 10 amp fuse,ergo your coils,will be minimal.The starter motor drawing all the power,path of least resistance and all that.
The coils need very little power on the low tension side,hence the name,the coils being "step-up" transformers,your low voltage is turned into 33000 volts by the coil windings.

[Dougie]

You're still missing the point here.MY bike runs fine,the carburation's fine,the contacts are clean,compression is fine also.It lives in the street,is 29 years old and can be a bugger to start if left for a few days (cos it gets a monk-on:D).The fella on the GSR reckons that by doing this he got round the problem of voltage drop in the wiring harness,thereby improving the spark at the plugs and improving starting,power and fuel consumption,like fitting Dyna coils but a helluva sight cheaper.

[Kicky]

Auld bike?,ye might have said.
Check yer points and condensers if fitted.
Dampness is more likely to be yer problem.
Fit an electronic ignition conversion.

[Kicky]

And if it's a Kawasaki check the condition of your wiring harness.
Stripping back the insulation and seeing how far the "black" wire goes,there should'nt be black wire,but on auld Kawas there always is.

[matthewmosse]

You're still missing the point here.MY bike runs fine,the carburation's fine,the contacts are clean,compression is fine also.It lives in the street,is 29 years old and can be a bugger to start if left for a few days (cos it gets a monk-on:D).The fella on the GSR reckons that by doing this he got round the problem of voltage drop in the wiring harness,thereby improving the spark at the plugs and improving starting,power and fuel consumption,like fitting Dyna coils but a helluva sight cheaper.

Might work, try and see, some blame fuel going off etc. I've tried various electrickery that claims to fix what your describing, only thing I've found that sorts it is 'easy start'. I've not tried exactly what you describe but have suspected what kicky said as the bike also spends much time outdoors. I'm trying a boyer system out to see if it helps, as my bike has same problems:o

[Dougie]

NO,no,no!Yer STILL not getting it!To put it in another context,with radios,the further from the transmitter you are,the worse the signal unless you use booster or relay stations to boost the signal.Surely with electrics it's similar,the closer to the battery or generator you are,the lower the voltage loss will be as the resistance is lower.You see what I'm getting at?Therefore,even on a modern electrical system you will still get voltage loss due to resistance from connectors and switches.So,the higher the voltage at the L/T side of the coil surely the H/T side will be proportionately higher,and the higher the H/T voltage,the better the spark,and the better the spark the better the combustion,no?

[Dougie]

Might work, try and see, some blame fuel going off etc. I've tried various electrickery that claims to fix what your describing, only thing I've found that sorts it is 'easy start'. I've not tried exactly what you describe but have suspected what kicky said as the bike also spends much time outdoors. I'm trying a boyer system out to see if it helps, as my bike has same problems:o
Beware of Boyer systems,I fitted one according to the instructions and it NEVER ran right until one day it took out 3 coils the went pop.

[Kicky]

Getting you on the voltage drop.
But,no way should you be losing 20% over the length of a bike wiring harness,there must be something creating a "plug" in the supply chain somewhere,usually dirty connections or old corroded wiring which goes "black" like I said about the old Kawas.

[Dougie]

The wiring's fine,I rewired the bike myself a couple of years ago.I'm not getting a 20-25% voltage drop,it's the bloke on the GSResources.Seemingly a few blokes tried it and found it a good mod,even with wiring,carburation etc in good nick.I just wondered if anyone here had heard of it and tried it.For the price of a relay (less'n £5),a bit wiring and a few connectors it's worth trying,yes?

[v8_trike]

Dougie, I had similar problem with a reliant trike many years ago, ran fine, just a bugger to start.

I did a similar thing, ran a 12v supply to the points (thus bypassing the ballast resistor) had it on a switch, hi voltage to start, flick switch then ran through the ballast resistor for normal running.

Just had to remember to flick the switch once started, otherwise the points didn't last too long.

[harry]

Dougie what you are sugesting will help because all lengths of wire and all connections cause a volt drop so keeping them short and simple will increase the available voltage at the coils and if it keeps the voltage above the critical level the engine will now start whereas before it may not.
BUT the biggest volt drop when cranking the engine is because of the load imposed on the battery by the starter motor and the BATTERY voltage drop is not addressed by this simple solution.
This is why many now very old cars used the ballast resistor and a nine volt coil the resistor drops the voltage in normal running so the coil does not overheat but is then bypassed when the starter motor cranks the engine, but by then the battery voltage will be about nine anyway so the spark plugs still get a full voltage spark and starting will be easier.
Hope this helps

[odie]

I used to have an old GS850 trike.
I used to run 4 coils from an old XS750 / 850 (yes i know they are 3 cylindered beast's)
instead of the spark looseing half it voltage at the plug (wasted spark system on GS's), thus each plug got max power from each coil, it was crisp and quick, pity i sold it:(
hope this helps
Odie

[Borg]

If he was getting that amount of drop then yes it would work. Any flow through lesser wires and connections will provide more 'power'.

[Mitch]

Dougie...

just do it mate! :D You know it makes sense!

[Blackjack]

Dougie, I had similar problem with a reliant trike many years ago, ran fine, just a bugger to start.

I did a similar thing, ran a 12v supply to the points (thus bypassing the ballast resistor) had it on a switch, hi voltage to start, flick switch then ran through the ballast resistor for normal running.

Just had to remember to flick the switch once started, otherwise the points didn't last too long.

You wired it wrong in the first place. :D

You should have a wire from the trigger feed to the solenoid that bypasses the ballast resistor. That way when the starte is engaged, the coil gets 12v not the 9v that comes out of the ballast resistor.

Dougies thing, yeah it would make an improvement IF the wiring was ropy.

That said, if your getting a problem starting it, chucking all the fat battery/starter motor leads away and using new ones from a motor accessory shop is probably going to make a significant difference.

Crappy old battery starter leads can cause huge voltage drops, and even if your coils are seeing a practically direct feed from the battery, that isn't necessarily 12 voplts if the battery leads a shagged.

[v8_trike]

You wired it wrong in the first place. :D

You should have a wire from the trigger feed to the solenoid that bypasses the ballast resistor. That way when the starte is engaged, the coil gets 12v not the 9v that comes out of the ballast resistor.







got there in the end though... thats all that matters :thumbsu:

[Dougie]

I did it tonight and it works!Normally after standing for a few days,especially if it's cold and wet,the old beast needs a couple prods on the kickstart.I hadn't used the bike since Sunday,and last night and this morning we had a serious monsoon!Wired up the relay (a Bosch one,not the cheapest but I reckon it'll last),and she started off the button quite happily.Tickover seems smoother and acceleration is crisper.It may be wishful thinking,but it definitely seems better.:thumbsu:

[Grav]

Well done Dougie.:thumbsu:

[Zaphod]

this appears to be a happy ending to a very entertaining thread :thumbsu:

[Dougie]

Well done Dougie.:thumbsu:

Works with Kwaks too,Grav,it was originally off a Yank Kawasaki site.......:D