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| zombie_dave |
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zombie_dave
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Joined: 24 Mar 2010
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 Posted: 10:57 - 24 Jan 2011  Post subject: coils...... |
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having now sorted the wiring for the cb 125t project im working on i have a question regarding coils......
the original engine was 6volt unit (so the coils are 6volt aswell)
will these be ok to run on the 12volt engine or will i have to replace them with 12volt units??
- apologies if this seems a silly question to you all, but i have never had any dealings with 6volt systems before.... 
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| Benson_JV |
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Benson_JV
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| greetingsfrom... |
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greetingsfrom...
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| N cee thirty |
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N cee thirty
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| zombie_dave |
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zombie_dave
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| Teflon-Mike |
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Teflon-Mike
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| Posted: 15:30 - 28 Jan 2011 Post subject: |
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| rob yarrr wrote: | just gt some 12v coils
maybe teflon mike on here might have some,he has 4 cb-ts the greedy bastard |
Actually, I have seven..... and you know what, if I'm REALLY lucky, I MIGHT just about be able to make one 'good' one out of them all! lol!
I'm not greedy.... just masochistic!
And he's talking about CB125T's which are the earlier twin-shock bike, not the later TD 'Super-Dream', which is a mono, and shares about three common components!
Dave, I take it I'm correct, in thinking you've got the Twin-Shock bike, built from '77-81, and have fitted the later Super-Dream motor to it?
In which case.... whats the state of play?
As far as I'm aware, the Super-Dream motor doesn't drop straight in, becouse of the starter motor in front of the engine...
Next up, IS it actually a Super-Dream lump or is it a Benley engine, or CM-cruiser-motor?
The Super-Dream engine uses contact-less CDI ignition, rather than points. 'T' engine apart from being 6v uses points.
On the 'T' points live in the generator housing, which doesn't accoodate the starter motor.... hence question about fitting, becouse could be convoluted mish-mash of bits to sort here, if you have used the Super-Dream or CM/CD engine, with the 'T' cases on it.
Now, presuming you have the super-Dream engine, complete, inside the genny you have the 12v generator rotor. That has split charging coils, for the general electrical system and the ignition.
It also has TWO contactless ignition triggers at 180 degrees around the rotor, which when the lump on the rotor pass them induce a current triggering the CDI units, which amplify the signal and fire the coils.
CDi coils have a lower impedance than points coils, even if they are still 12v, becouse the amplified signal is stronger and faster, so the field colapses faster.
Using points coils with CDI or vica verca tends to fry them, and in your case, using 6v coils, also likely to fry the CDI units, which is the critical bit!
Some cars, actually use a 6v coil rather than a 12v coil, and on start-up, give it the full 12v, to boost starting energy and compensate for voltage drop from high-power starter-motor sucking amps out the battery, but then as soon as the starter relay is dissengaged a 'balast-ressistor'; is switched into the circuit so it only sees its rated 6v. also used to be a common mod to mess around with 6 & 12v coils of fdifferent ratings to get higher energy sparks, .... BUT.... in this case, the weak-link in the system is those CDI units, so probably not worth the risk.
My advice is to set the system up to the book, with whatever components are most suitable.
So if you are basically running Superdream electrics, run super-dream CDI's and coils. If CM or CD motor, run CM or CD CDI and coil.
CM & CD only have ONE of each, as they have a 360 Deg crank arrangement, and fire both plugs of a singe coil, both pots getting a spark on each crank rev, one of them on the exhausts stroke, so the spark 'lost' while the others on the compression stroke, so finding it more useful! CB with 180 crank has to have two CDIs and two coils to get the sparks on both pots timed rigt.
Short answer... use CDI's AND coils for the engine fitted!
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My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?' |
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| zombie_dave |
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zombie_dave
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| Posted: 10:39 - 31 Jan 2011 Post subject: |
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@ Teflon-Mike
Thanks for thew very informative reply.
You are indeed correct in thinking that my bike is a 1980 "t" model - also that the engine is the later (TDJ) superdream engine. (180 cranck)
I have swapped the wiring loom and CDi's from the same bike from which i purchased the engine.
The front mount has bee made up to accomodate the starter motor on the engine.
All the bulbs have been changed for 12v ones and obviously the battery has been swapped for a 12v unit aswell.
Sooooo my question is do you have any 12v coils?? 
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| Teflon-Mike |
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Teflon-Mike
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| Posted: 15:19 - 31 Jan 2011 Post subject: |
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| zombie_dave wrote: | @ Teflon-Mike
Thanks for thew very informative reply.
You are indeed correct in thinking that my bike is a 1980 "t" model - also that the engine is the later (TDJ) superdream engine. (180 cranck)
I have swapped the wiring loom and CDi's from the same bike from which i purchased the engine.
The front mount has bee made up to accomodate the starter motor on the engine.
All the bulbs have been changed for 12v ones and obviously the battery has been swapped for a 12v unit aswell.
Sooooo my question is do you have any 12v coils?? |
Yes, I do thank-you.....
Next Q.... No you cant have them.
Snowie.... bless.... managed to crack the spares!
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My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?' |
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zombie_dave
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Old Thread Alert!
The last post was made 15 years, 54 days ago. Instead of replying here, would creating a new thread be more useful? |
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