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'78 Super 150 Mk II ported DR177, banded clutch, ASC Big Bore
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I just replaced a stator on my '78 Super 150 with a new one and ended up having problems since its tolerances were a little bit bigger than the original and the flywheel ended up rubbing into wiring.

I had the plate machined down a bit and redid all the wiring; I also installed a new HT coil.

When I was setting the points gap, I noticed a spark on the points as I was gently rotating the flywheel back and forth. IS THIS USUAL? I also felt a very light shock on the bulb system I was using to check timing (bulb lighting and dimming as the cam opened the points).

I had never seen a spark at the points nor felt a shock before over many times of using the old stator and HT coil. Could this just mean I'm getting a much better electrical charge from the new stator? What's weird is I hadn't noticed it with this very same new stator when I first installed it (before the flywheel rubbed into the wiring) and had check the points gap then.

Might the spark indicate something isn't right? Are the faces worn? Could the condensor not be doing its job? It started, ran for a bit, then died at idle with a backfire and I couldn't get it started again (probably flooded).

Thanks in advance for any replies.
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are you replaced the point and condensor when you install new stator?
point sparking maybe because of the points arcing, and arcing point because fault condensor
could cause you to have weak spark... which may cause gas fouling of the plug
and flooded could also rich mixture
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I'm think veloce75 is right about the condensor.

The sparks indicate that the condensor is not doing it's job preventing arcing across points.
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Thanks, gentlemen. I was thinking the same thing.

Veloce, the condensor is quite new (installed as part of a rebuild this past winter) but it may have gone bad.

When I got the new stator it came with new points and a condensor, but this one ended up having its wiring rubbed by the flywheel. I still have an older condensor that worked from before the rebuild...

I think I'll just solder new wires onto the newest condensor and go from there.

I've been doing SO much work with troubleshooting the electrics that it turns out a flywheel puller was the best tool investment I've ever made.

Thanks again!
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1965 Vespa SS180, 1963 Lambretta LI150
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yes yes ...blue spark at the points = bad condenser.
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I'd be more inclined to substitute an apparently good old condenser than an unknown new condenser.

If a condenser ain't broke, there's no reason to replace it, and often, when you do, you wind up with a failed new condenser shortly afterwards.

Many of the older condensers were much better made than the new ones (does not apply to capacitors in electronic components, in which new ones are often better). Many experienced antique motorcycle folks will keep the old one unless it has failed, and carry another one as a spare, rather than replace something that has been working well for years with something unknown from China.

- Eric
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MDchanic wrote:
Many experienced antique motorcycle folks will keep the old one unless it has failed, and carry another one as a spare, rather than replace something that has been working well for years with something unknown from China.

- Eric
AGREED.

-Eric
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Thanks very much for your input, gents.

I've got two working ones and one clearly bad one. I'll swap in a good one and keep one as a spare in my travel tool kit. I even keep the flywheel puller with me on the road, now, along with a rachet set with all required sizes and a rubber mallet. My screwdriver is pretty chewed up from using it to stop the flywheel from turning when popping it off or torquing it on

I used to just keep extra cables and bulbs, a fourth hand tool, and some odds and ends, but now I've had so many electrical gremlins I want to be able to pull the flywheel on the spot. Only thing I can't carry is the torque wrench.
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One more quick question (and thanks in advance for any replies).

Is it possible to connect a new condensor in place while leaving in the old one to make sure the former works and one is getting good spark before pulling the flywheel? The reason I ask is that in my junction box where the kill switch wire comes in there are actually two terminals -- one that connects to the red lead from the condensor and routes to the HT coil and another that's unused.

External inline image provided by member with no explanatory text
(Since that photo was taken I've reworked the leads and terminals, so there's no soldered connection but only the use of quick disconnects with male and female ends.)

I'm wondering if that unused lead is to quickly trouble-shoot a condensor problem by allowing a new condensor's yellow lead to be connected to that and then run the new red one to the HT coil while letting the old one hang loose. This would mean that two condensors would be in the circuit, but the one that's on the stator is presumably non-functioning, while the new one would be temporarily external. Does this make sense? Would the non-functioning one affect anything in any way or just let the current through unmolested?

The reason I ask is I once saw a friend quickly solder a new condensor right to the HT coil lead to check an electrical problem and it occurs to me this is what the extra female lead could be for. For that matter, it could make for a very easy road-side fix for when a condensor goes bad as you could temporarily install the new one externally without removing the flywheel.

Would it still work if the yellow lead attached there rather than like the original that's with the yellow wire in the stator that is a series of two coils right before the points?

Thanks again for any thoughts.
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Yes.

You can do that.

It makes absolutely no difference where, physically, the condenser is connected, so long as it is in the circuit between the hot side of the points and ground.

If the original has failed by shorting out, connecting a new one as you describe will not help, but if it has failed open, which seems to happen more frequently, connecting a new one this way will cure the problem.

As a long-term fix, though, the bad condenser should be replaced by a good one, as the combination of the two may be providing a slightly wrong amount of capacitance, which will damage the points over time.

- Eric
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Yes!
in emergency situation, like on rally... I usually squeeze a new condensor between flywheel cover and case without pulling the flywheel
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Update
Thanks, everyone. I'm finally am up and going again.

I had replaced the stator originally in the hopes of getting lighting all working and since I'd had some ignition issues in May. Now I'm wondering if it was just a bad condensor all along and I didn't need a new stator (I really got it to have new coils), but DAMN it ran well with the new stator until the wiring was rubbed...

Anyhoo, the new stator is useful as it allows for a finer adjustment of the points gap, and there's a new felt pad for lubing the flywheel cam... When I gave it to the machinist it still had some coils on it and, unfortunately, he nicked the copper on one so I couldn't trust it any more.

I made a compilation of parts -- new stator plate, some old coils for ignition, a new one for yellow and blue wiring (lighting), etc. etc. With the new (nicked coils) I got a nice bright blue spark and it would seem to idle well, but then suddenly out of nowwhere would just die. Not so with the older ignition coils installed, where it seems quite happy.

Now my spark is definitely not blue, but an orangy-blue (which would suggest a weak spark) but it's definitely how it likes to run. I've taken it for some longer test drives and that's definitely a sweet spot. [shrug]

As for the lighting, the harness must be wonky. I could only get the headlight OR the brake light to work, but not both. Either way I was seriously compromising safety. What used to work before the rebuild (junction box connections as above) definitely doesn't work now. I fiddled around with various connx and finally got the halogen headlight and brake like to work at the same time. I don't have a rear running light, but I've installed a small battery operated LED from Sylvania (like the 3 bulb DOT It light, but much smaller as it's only one LED). I installed this under the red lens and set it to flash for night time driving.

Now I'm going to leave it all alone and just enjoy rides.

Thanks again for your help!

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