CB750 scrambler project
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wrote on 23 Jun 2020, 11:29 last edited by
The light only needs to be there if the side stand is down by the looks of it.
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wrote on 23 Jun 2020, 11:43 last edited by
@Calum that's what I'm thinking but if in neutral then it shouldn't Matter ,?
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wrote on 23 Jun 2020, 16:46 last edited by
I can’t get my head round the diagram at the mo. There are a lot of differences from what I know. What about the diode (number 7) condition?
I know that the live wires on the coils will only affect spark timing if wrong, they should still spark. So I’m guessing that the problem is with the side stand, neutral, cutout circuit somewhere, if there’s no spark still...
Sorry I can’t be more help at the mo’. Too many brewskies!🤪 -
I can’t get my head round the diagram at the mo. There are a lot of differences from what I know. What about the diode (number 7) condition?
I know that the live wires on the coils will only affect spark timing if wrong, they should still spark. So I’m guessing that the problem is with the side stand, neutral, cutout circuit somewhere, if there’s no spark still...
Sorry I can’t be more help at the mo’. Too many brewskies!🤪wrote on 23 Jun 2020, 16:49 last edited by@SpookDog yes it's a crappy diagram, I assume the second bulb is the neutral one.
I've never had a diode go wrong on anything but might test it.
I think it's the side stand ... I'll do more tests when the plug caps come.Thanks
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I can’t get my head round the diagram at the mo. There are a lot of differences from what I know. What about the diode (number 7) condition?
I know that the live wires on the coils will only affect spark timing if wrong, they should still spark. So I’m guessing that the problem is with the side stand, neutral, cutout circuit somewhere, if there’s no spark still...
Sorry I can’t be more help at the mo’. Too many brewskies!🤪wrote on 23 Jun 2020, 17:14 last edited by@SpookDog I think if I try to crank the engine over (on the starter motor) in gear but with the clutch switch pulled in... That would also prove if the silicon diode is faulty
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wrote on 24 Jun 2020, 10:06 last edited by
A diode only lets electric pass one way I think. I’d try a continuity/bulb test
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wrote on 24 Jun 2020, 11:26 last edited by
Yeah, it should only show continuity one way. Do a quick google for diode testing...
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wrote on 24 Jun 2020, 11:39 last edited by
@SpookDog thanks.. I tested the resistance and compared it to my spare one, seemed fine. I'm pretty sure it's the sidestand circuit....
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wrote on 24 Jun 2020, 12:32 last edited by
I recon it is as well. I’d connect the side stand and clutch switch stuff all up, put it in neutral and try it with the clutch pulled in.
With the coil connectors, I’d try one ‘one way’ and the other the ‘other way’ if that makes sense? One of them should spark. Once they are sparking it’s easy to figure out which is the outer banks and which is inner...
Good luck my amigo! -
wrote on 24 Jun 2020, 12:37 last edited by
a Diode is like a one way valve for electric. The live wire on the anode and earth on the cathode should have continuity (power flowing through). Reverse the wires and there should be none.
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wrote on 24 Jun 2020, 12:45 last edited by
One other thing! Are the coils making a good earth to the frame? I don’t mean the black &white killswitch wires. I mean where the metal bolts to the frame...
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I recon it is as well. I’d connect the side stand and clutch switch stuff all up, put it in neutral and try it with the clutch pulled in.
With the coil connectors, I’d try one ‘one way’ and the other the ‘other way’ if that makes sense? One of them should spark. Once they are sparking it’s easy to figure out which is the outer banks and which is inner...
Good luck my amigo!wrote on 24 Jun 2020, 12:46 last edited by@SpookDog pulling my hair out,
All the diode does looking at the diagram is. When the stand is down and the bike is in gear, it won't start unless the clutch is pulled in .... But surely is shouldn't allow the starter motor to operate as that alone can knock the bike off the stand,Also should the side stand light only come on when stand is down ( in gear )or all the time including neutral
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wrote on 24 Jun 2020, 12:50 last edited by
I don’t think it’d affect the starter. I think it’s just to stop you pulling away.
I recon it should be on as long as the stand is down.
How many fuses are there as well!
Wish I was there to help. It’s difficult trying to diagnose hands off!... -
wrote on 24 Jun 2020, 13:08 last edited by
Trouble is it could be any one of these switches:
Key Ignition
Handlebar kill
Sidestand
Clutch
NeutralOr these parts:
Pulse generator/pickup
FusesOr just a break in a wire.
I’d start off by checking fuses, then doing continuity checks on the switches, then the wires
Check for volts at the coloured coil wires, volts at pick up while cranking the starter -
wrote on 24 Jun 2020, 14:14 last edited by
I think I know the issue. The pulse generator had a load of oil in there. Doesn't put out 0.7v
When I crank the engine I can feel pressure of air blow past the crank seal
the crank seal itself might not be broken but the pressure bypasses it.
I can't see this seal on fowler's diagramsAll cylinders seem to have good compression so can think why the crankcase has so much pressure. Unless it's a blocked pcv.... Not sure if they have valves ....
Lots of ball aches...
I couldn't really test any of this before fitting the engine all together. -
wrote on 24 Jun 2020, 15:12 last edited by
Damn, wtf.... Surely you shouldn't have an access window to the side of the crank (bottom of engine)
https://i.imgur.com/7LrE6wS.gifv
See the video -
Damn, wtf.... Surely you shouldn't have an access window to the side of the crank (bottom of engine)
https://i.imgur.com/7LrE6wS.gifv
See the videowrote on 24 Jun 2020, 15:13 last edited by -
wrote on 24 Jun 2020, 16:36 last edited by
You mean the hole at 9 o’clock on the pic? Yeah, it could be oil bathed. Specially if the cover had a oil proof gasket. 4 strokes are ‘different’
I’d look into the voltage issue. -
You mean the hole at 9 o’clock on the pic? Yeah, it could be oil bathed. Specially if the cover had a oil proof gasket. 4 strokes are ‘different’
I’d look into the voltage issue.wrote on 24 Jun 2020, 17:33 last edited by@SpookDog yes I think my main concerns now is why is there so much pressure in the crankcase? Manual said 3.5L oil with a new filter..... I wonder if it's wrong and over filled
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wrote on 24 Jun 2020, 21:50 last edited by
Right, I thought "oh shit the crank seal is gone"
Looking at all diagrams..there isn't a seal!
Anyone else who wants to help confirm I'm not going made... Please do
The oil literally returns to the sump through that window where you can see the crankshaft web.... Strange right... But makes sense why there's a "return" to the sump
The side cover is a sealed type so that's why oil doesn't drip out.The oil is about 0.5l -.6L over filled from having the wrong information in a manual I have..
Manual states oil capacity (when replaced) 2.8L without filter and 3L with filter. (Dipstick still doesn't show anything... Perhaps from another bike)
I believe this caused there to be oil on the pulse generator = no pick up pulse.....
Drain the oil time tomorrow. Refill to correct level.
Clean up pulse generator... If still not producing 0.7v I need a new one.
This is the issue.