650 - A Couple Of Questions

[sparki]

ooo maybe not white... u mention beige. thats probably the same colour as i have lying in boxes.... let me have your address and i'll post ya one

[Kryten]

Not having a 650 and cannot recall what the coils on my 550 were like, but can some one tell me if they are the same as the 750/1100?

I might have a set of new generic HT coils that were going to go on Skruffy Kat in the shed (I don't think my brother took them for his ESD)

It does sound like an elastictrickery fault.

[G0FHM]

Hi Steve,

The coil that I replaced was one of the beige type, sealed unit hence why I couldn't change the leads when one broke down. The right coil (which covers 2 & 3) is a different type (Denso) that has a clip type thing that looks like the leads can be replaced.

I'm still a little concerned that moving the coils/leads about didn't move the misfire to another cylinder - But the coil arcing to the frame when a lead is removed (and getting hot) is not a good sign!

Will PM address.

Thanks,

J

[G0FHM]

Right, I thhink I've ruled out electrickery as the problem.

Just been to drain the float bowl on no 4 carb, and there was petrol all around the float bowl. When I gave the carbs a wriggle to take them off, on tipping them downwards slightly, petrol poured out of the wrong end! (ie air jet), and getting them outside revealed fuel coming out of the needle jet when giving them a gentle tip forwards or backwards.

Sounds like it's flooding, hence the misfire.

So it's either needle valve, or float height. They had new viton O rings a while back.

Having seen the prices of needle valve assemblies, this could get expensive

J

[Kryten]

Sounds like a route to investigate, but given that the coils are of a different manufacturer/age I would be tempted to replace one or other set with something that could be clased as a matched pair. you could well be running an unbalanced load on the low tension side of the ignition circuit.

[G0FHM]

Hi Krytie at al.

Well, I've had the carbs off (again) and checked the float heights (again). There were some pretty wild differences! 19.7mm on 1 to 26.4mm on 4. They have been set to within half a millimetre of 22.4mm now, with a digital measuring device.

We now have No.4 plug wet with petrol and the WD40 that I sprayed down the plughole when compression testing last night. Still only running on 3!.

The thing that bugs me, is when I pull the No4 plug cap off, there is a bright spark that can also be heard cracking nicely.

The coil wouldn't need to be earthed to the frame would it? Only at the moment, it isn't due to it being advertised as being for a GS650, but the hole centres for the mounting bolts are about 10mm out - And it isn't bolted down, as I don't want to have to "modify" the mounting holes if I'm going to be sending it back as defective. Along the mounting lugs, there are metal strips coming out of the coil itself that contacts with the mounting bolts. I've never heard of a coil needing to be earthed before, as it's the earth that gets switched in and out to create the jolt isn't it?

I'll go try that for starters, just stick one screw through the mounting lug on the frame and see what happens.

The only other suspect is the 2x new NGK plug caps that I bought to go on the ends of the leads. I wouldn't have thought they would be a problem, as Bosch & Champion ignition stuff has let me down before - But never NGK!

I'll go back to the shed and cry quietly into my cup of tea......

J

[callyboy]

Ahhh haaa. Thats were your going wrong!!!


Should be beer !!!!!!

Bolt it down.

Pete

[G0FHM]

I wish Pete....

Bloody medication!

J

[G0FHM]

Just been out to the shed, armed with an AVO.

Resistance across the primaries of both coils is just shy of 5 ohms (manual says 3-5R).

Secondary on new coil 17.4K and existing coil 15.8K. Just for fun, I stuck the meter across the secondary on the coil with the duff leads and came up with 11.3K.

The manual says (although that figure is not supposed to be gospel) 30-35K for the secondaries, if the windings are in sound condition.

DC voltage at the + of the coils is the same as at the battery with the ignition on.

What next to look at?

I did see a video on youtube of some American chap from the deep south having a dead pot on his 750. But once I decoded the constant profanities and filtered them out, it was basically him pointing under the seat and blaming a connector under there! Surely though, if it's wasted spark, then that would affect No. 1 too?

Would there be any mileage in scrapping the connectors between the ignitor, pickup and wiring loom for nice new bullets with heatshrink?

Also, the advance/retard on the pickup seems a bit heavy (compared to the distributor on a car). Again, would it be in order to take the pickup backplate off and give the mechanism a bit of lubrication? I did notice that when I turned the shaft by hand it didn't immediately spring back, but was rather slow.... I wonder if this is the cause of the revs being slow to drop?

And finally, by taking the pickup backplate off to access the advance/retard mechanism, is there any scope for me to inadvertantly alter the ignition timing? or is it fixed?

So may questions!!

Cheers,

J

[Kryten]

Just been out to the shed, armed with an AVO.

Resistance across the primaries of both coils is just shy of 5 ohms (manual says 3-5R).

Sounds OK

Secondary on new coil 17.4K and existing coil 15.8K. Just for fun, I stuck the meter across the secondary on the coil with the duff leads and came up with 11.3K.

The manual says (although that figure is not supposed to be gospel) 30-35K for the secondaries, if the windings are in sound condition.

OK so they are both down

DC voltage at the + of the coils is the same as at the battery with the ignition on. Good

What next to look at?

I did see a video on youtube of some American chap from the deep south having a dead pot on his 750. But once I decoded the constant profanities and filtered them out, it was basically him pointing under the seat and blaming a connector under there! Surely though, if it's wasted spark, then that would affect No. 1 too?

Would there be any mileage in scrapping the connectors between the ignitor, pickup and wiring loom for nice new bullets with heatshrink? Might be worth putting in a temporary bypass to the loom

Also, the advance/retard on the pickup seems a bit heavy (compared to the distributor on a car). Again, would it be in order to take the pickup backplate off and give the mechanism a bit of lubrication? I did notice that when I turned the shaft by hand it didn't immediately spring back, but was rather slow.... I wonder if this is the cause of the revs being slow to drop? Definitely

And finally, by taking the pickup backplate off to access the advance/retard mechanism, is there any scope for me to inadvertantly alter the ignition timing? or is it fixed? 100% certainty

So may questions!!

Cheers,

J

Hope that is of use

Sorry the blue does not show up very well on the black but as I'm using the Android Slab I can't change it easily

Looking like you have a mix of probs.

Although if you have a fault the does shift with the jt lead swap, then it is pointing to the carb on #4

Try swapping the coils over and see if it migrates to 2&3

Auto advance needs to nice and free to return, try a splash of WD40 first before taking it to bits.