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Need help... can i run a KWOB 8513 Nt400 cdi in a honda cbx750 rc 17

1624 Views 48 Replies 6 Participants Last post by  Classic250
Need help on wiring ... it has 4 pins adjacent to a 5 pin ...
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You guys know how to make an old car backfire? Extremely hazardous to your engine health but it's not difficult.

RC17 has a cable driven tach, not much chance the spark unit has any way to sense engine speed electronically there. If you research NT400 which was fitted with an electronic tach, you will find some reference to 'some units' (apparently not those sold in america) and those may feature an additional wire connection between the tachometer and the spark unit. (that would explain his Philippean NT400' fifth connector.) That info was gleaned off forums and not a service manual or Honda document. If anybody has a wiring diagram of a spark unit that does more then just spark, post it up so we can see how that works. Logically. if you were going to curb the revs on a motorcycle fitted with CV carbs, it would be pretty silly not to control revs through the carburetor vacuum control.

If y'all figure out what happens to all that excess fuel going out the exhaust pipe on your intermittent spark unit unicorn, post that up so we can see how that works too. Most likely, dumping raw fuel into the exhaust at top speed is not a feature that would make it past EPA, that concept might still fly in some third world country, at least right up until it catches fire.

I've never heard Toni Bou bounce his 4RT off a rev limiter so I seriously doubt mine even has a rev limiter, but I'm going riding now and see if I can find one.
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You so funny...We have spark kill ie rev limiter in the ignitions we use of bikes with carbs. It kills the spark progressively above a fixed (programmable) point.

Early TCI ignitions usually had the ignition curve built into the black box unlike very early units which used a mechanical advance. For example the old GS/GSX 250 and 400 twins had a mechanical advance in the first versions and later on the mechanical advance was ditched and the advance curve was built into the firmware.
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Period Spark Unit is an analogue device and to sense a rev limit it needs to do that mechanically or electronically. A tachometer circuit is required to control the ignition electronically but these are early 1980's spark units designed to replace breaker points ignition, there is no eprom inside, it's just a simple spark unit, there is nothing inside to programme. Only way to definitively know what is inside a sealed black box is to look at the wiring schematic for that device. We need the wiring schematics and then you will see how totally simple the circuit inside it really is.
I can 100% guarantee you that 90’s sport bikes had rev limiters incorporated into the cdi’s. The old Gixxer squid morons loved it! Quite often you could go to a bike night and they’d be lined up bouncing they’re bikes off the rev limiter, backfiring to kingdom come and turning their exhaust pipes into glow sticks.
Interesting video, but really adds nothing to the argument. We’re talking about two bikes, neither of which have mechanical (centrifugal) spark advance units, so the spark timing control is programmed into the spark unit…..and consequently so is the rev limit set point.
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You are arguing, I was trying to help him with a motorcycle problem.
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Hey felas... had to take a break. Anyway... thanks for doing the homework for me. But here are some pics ... maybe you guys can toss me over to the plugging part. Thanks guys. And yeah ... one of my mechanics got thiS bike fired up using 2 individual lefan cdi box's. It fired up but didn't last long. I think it burnt out or something.
Motor vehicle Automotive tire Automotive design Automotive exterior Automotive fuel system

Circuit component Finger Guitar accessory Gadget Electronic instrument

Circuit component Passive circuit component Green Blue Hardware programmer

Passive circuit component Circuit component Green Hardware programmer Engineering
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This looks like late 1980's early 90's electronics and you need early 1980's tech, I found links to documentation on the Honda and Oki IC chips but was unable to view the documents.
Ya, the Lifan only lights one spark plug, your bike fires 2 at same time.
lol maybe if you had 4 Lifan that might even work without cooking.
We call that a Bush fix :D no idea what you call it, maybe a beach fix
This looks like late 1980's early 90's electronics and you need early 1980's tech, I found links to documentation on the Honda and Oki IC chips but was unable to view the documents.
Ya, the Lifan only lights one spark plug, your bike fires 2 at same time.
lol maybe if you had 4 Lifan that might even work without cooking.
We call that a Bush fix :D no idea what you call it, maybe a beach fix
Lol. I have no idea what to call that fix. All I know is that I had to get rid of that mechanic. My bike is really old.. but she's my bitch I can ride and doesn't complain 🤪 lol anyway... you think she's gonna fire up if I'm just gonna go ahead and wire it like the diagram you posted? I wanna say something about the carry logic concept I've read but I'd rather not. I'm not even sure if I understood half of all that. Hahah too much little transformers and all.. I'd stick to this forum instead 😆 so I guess I'd leave it to yall for the help. I'd appreciate it if someone could call the shot if I'm pushing for the wiring or not... frustrated already
Motorcycle scrap yards here have a good supply of Honda 4 DOHC and similar parts bikes, I take it that is not a common thing where you live. Scrap yard visit would be the way I would deal with it, sourcing a black box replacement from a similar model machine will make it so much more simple and less likely to fail.
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I think we are looking for a Hitachi TID14-29
if you can't source one locally I can try the nearest scrap yard here.
Motorcycle scrap yards here have a good supply of Honda 4 DOHC and similar parts bikes, I take it that is not a common thing where you live. Scrap yard visit would be the way I would deal with it, sourcing a black box replacement from a similar model machine will make it so much more simple and less likely to fail.
Junk shops. That's what we call it here. Either way... junk here is literally scrap. Ur scrap yards there are surplus or slightly used items here. Atleast to most ..so it's merely luck if ever ud find a box here.
I think we are looking for a Hitachi TID14-29
if you can't source one locally I can try the nearest scrap yard here.
That'd be great boss. I'd appreciate that a lot. By the way... where u located
The yard I will be picking is near Perth Ontario Canada
Wheel Tire Bicycle Land vehicle Vehicle

it's like find waldo but outside in freezing temperature
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@Durtysouth garage I've got the part, PM me your mailing address and I can make it happen for you.
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@Durtysouth garage I've got the part, PM me your mailing address and I can make it happen for you.
He hasn't been here for almost a week. Maybe PM him.
He hasn't been here for almost a week. Maybe PM him.
How difficult is it going to be for him to import the used part to the Philippine :unsure: I never sent anything there before, can I just mail it and he clears it through customs or is it going to get complicated?
How difficult is it going to be for him to import the used part to the Philippine :unsure: I never sent anything there before, can I just mail it and he clears it through customs or is it going to get complicated?
If it has a stated value of less than $200USD on the customs form there is no tax/duty payable, but it might well cost him more than the value of the part to bring it here. I've often wanted to buy inexpensive items on Amazon but the shipping has generally been exorbitant, so I have had to pass. I don't know about the Canadian postal service but I have ordered from the US using USPS and it has taken over three months for orders to arrive, and on a couple of occasions - it has never arrived because they offer no tracking outside the US.

I appreciate your good intentions - but it's probably not a practical option....and once he read your reply 'Canada' to his location question - I'm guessing that he lost interest.

But maybe send him a PM and see what he says.
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Hi felas. Sorry for the late reply. Been busy for the holidays. Happy holidays to all thou... hang on.. let me back read some of the messages.
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