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Discussion Starter #1
Apologies for all the new topics - I'm hoping to get some answers to some of them!

I have done some diagnosis after my RD04 - RD07 engine transplant, and have the following:

When performing a spark plug test, I only get a spark on the initial crank of the engine - there is no repeated sparking when holding the plug against the engine and continuously cranking.

Also, the fuel is not flowing ... I have checked the pump is working, by shorting out the fuel cut out relay tucked up behind the clocks. The workshop manual tells me how to test things, but doesn't give me any way to interpret the result.

What drives the fuel pump - is it related to the sparking mechanism at all?

IE, HELP!!!
 

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Some thoughts

Hi Andy,

About the fuel pump: It is connected to ignition in that sense that it only works once the starter has turned (presumably ignition pulses have occurred). I have no idea how the circuitry really works, but on RD07 '98 the fuel pump feed stays active once it has turned itself on even when the engine has stalled.

You'll be able to bypass the pump altogether when experimenting by directly plumbing the tank into carbs and having a full tank of petrol. This allows you to rule out problems with fuel pump.

About your other problem, the ignition: The RD04 ignition system had two CDI units (built into one casing). The early RD07 ignition is probably the same. The later RD07 from '96 has only one CDI box. Again, I haven't had need to look into the subject more than this but would suggest that if your engine is of the later type you should also acquire the late model ignition gear (wiring loom, CDI box, ignition coils) to make the system work. Alternatively, you could maybe move the engine ignition parts from your old engine into the new one.
 

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Discussion Starter #3
Cheers for that ... I'm not sure how old the engine is, but I think it's from 2001.

Re. changing the ignition components, the only thing I've changed so far is the pulse generator ... is there something else I should look to change aswell?
 

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Generalissimo Tea Boy
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I seem to remember that when I switched to a vacuum fuel pump, there was a fuel pump cut out relay behind the left side panel which it was suggested I remove and bin. I left it so I can switch back to an electric pump if I want.

I always thought that once up and running (ignition on, kill switch off) the pump must run off of the coils, so that it pumps in time with the rising or falling engine revs. Is it the case that the RD04 has 4 coils (one per plug) and the RD07 only has 2. This could explain why you had less pins coming from your generator.
 

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Discussion Starter #5
Not sure about the 2 coil thing on the RD07, but I have replaced the RD07 pulse generator with the RD04 one, so that there are 2 pick-ups (and hence 4 wires in the multi-pin).

Perhaps the next port of call is to change the alternator, although the wiring appears to be the same.

Getting a bit baffled by this.
 

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Generalissimo Tea Boy
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I'll have a butchers at my manuals tonight and see if I can make head or tail of what the differences are electrically and fuel pumperly.
 

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Generalissimo Tea Boy
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What is it with you and enginey luck.....Think back carefully, have you recently turned down the offer of some lucky heather from an old woman on the street? Was she muttering and pointing at you as you walked away? I think it would be prudent to sacrifice a small goat before continuing.
 

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Discussion Starter #9
Yeah, yeah - I know what you mean. The local machanic (not a monkey) reckoned I'd be looking at 1500 quid for a rebuild of my RD04 engine, which is why I took it to pieces in the first place.

I reckon that I must have spent close to a grand on rebuilding the RD04, then buying the 07 engine (and collecting it).

Still, it's been an experience.
 

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about the fuel pump circuit

I have replaced my stock electric pump on '98 with a Pierburg electric wired with stock wires. It works like this:

1. With ignition on the pump stays off
2. Immediately when the starter button is pressed the pump electric feed activates and the pump stays on until the ignition is turned off regardless whether the engine actually runs or not. The pump also stays on if the engine stalls or is killed with the kill switch.

The stock pump appears to power off when the engine stops because it is a membrane pump that does not have sufficient power to keep on pumping against the static pressure against the closed carb needle valves. However, one can hear it to run continuosly when the bike has ran out of petrol and you leave the ignition on.
 
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