No spark with new Motobecane HPI CDI

I'm in the process of building an AV10, and I just installed the ignition (https://www.treatland.tv/MBK-HPI-CDI-ignition-system-p/mbk-hpi-cdi-ignition-coil.htm). I timed it (3mm BTDC) and got it all wired up according to the instructions (https://www.treatland.tv/v/vspfiles/assets/images/hpi-instructions.jpg), but I can't seem to get it to spark with a drill test. A cursory search through the wiki yielded nothing of use.

The big three prong plug from the stator plate is attached to the CDI box.

The orange cable coming off of the CDI box is plugged onto the blade connector on the coil.

The coil itself is attached to the stock coil mounting points and pretty well grounded to the frame.

The black wire coming out of the CDI box is grounded to the frame via one of the coil bolts.

The kill switch wire is currently not attached to anything, although I tried grounding it and it didn't make a difference.

I am using an NGK TBO5EMA boot and a BR7HS plug. I tried it with the plug grounded to the head and to the coil, and it didn't produce a spark in either configuration.

I feel like I'm missing something obvious here. Any ideas?

Re: No spark with new Motobecane HPI CDI

Nobody?

Re: No spark with new Motobecane HPI CDI

Do you have a ground strap ran from the engine to frame?

Re: No spark with new Motobecane HPI CDI

I was also going to suggest the bonding strap from engine to frame

Re: No spark with new Motobecane HPI CDI

I don't have a permanent grounding strap, but I tried running a little wire with some alligator clips from one of the fins on the cylinder head to the coil mounting bracket. No dice. I even tried grounding the plug directly to the coil, and that didn't work either.

Re: No spark with new Motobecane HPI CDI

Puzzling. A good ground strap is a must for sure on Moby, but it sounds like something else maybe up... my guess is a false ground. Hardly ever hear of a bum HPI out of the box. I would recommend double checking your ground locations. Recent paint or maybe the paint is extra thick there? Sand it down if needed.

Next check your resistances on the HT. Anything seem odd there?

Re: No spark with new Motobecane HPI CDI

The resistance from the coil ground to the plug wire lead was 5.6kΩ.

The resistance from the end of the plug wire to the electrode on the spark plug was 10kΩ. The boot and the plug both contain resistors, although that shouldn't matter from what I understand.

I checked, and I'm getting good continuity between the coil grounds and the head even without the grounding strap. I will probably run with one anyway though, just to be safe.

I don't know enough about coils to know whether or not that is a normal reading. What do you think?

Re: No spark with new Motobecane HPI CDI

Bumpity bump?

Re: No spark with new Motobecane HPI CDI

#CrazyWayne™ rocks. #CrazyWayne /

You probably killed the box with your bad ground and or your spark testing method.

The test plug must have a ground wire or the KV zap will back feed and kill the box.

P.S.

Re: No spark with new Motobecane HPI CDI

Thanks for that Wayne. I did spend several hours pouring over every piece of CDI troubleshooting information I could get my hands on to try to come up with an answer before turning to MA for help. I know better than to ask for advice before doing my homework around here.

When I tested for spark, I grounded the plug body to the head, which I tested for continuity with the coil ground and the frame. How would you suggest I test for spark in the future? Is there a way to test the CDI to determine if it's damaged?

Re: No spark with new Motobecane HPI CDI

#CrazyWayne™ rocks. #CrazyWayne /

Put/twist a ground wire to the threads of the plug and roch-clip wire to a head fin.

You timed it at (3mm BTDC) go to my profile and read it and the links links.

You need a ground wire running from the carter to the frame/ht-coil/headlight housing.

Bypass the moby switch use the de-comp to kill it.

Re: No spark with new Motobecane HPI CDI

Good to know.

I'll rig up a grounding wire, but I don't think that's what's causing my spark unless the CDI is burned out. I tested with a grounding wire in place and it didn't make a difference. I even grounded the plug directly to the coil, and I still didn't get a spark.

The class I'm racing in requires a handlebar mounted kill switch, and I don't have a decomp valve.

Re: No spark with new Motobecane HPI CDI

#CrazyWayne™ rocks. #CrazyWayne /

Do a ohm test on the cdi winding on the stater some times the wire braks at the grounding crimp.

Re: No spark with new Motobecane HPI CDI

To clarify, you are talking about checking continuity between the green arrow and the blue arrow, right?

Re: No spark with new Motobecane HPI CDI

Or rather the green arrow and the output to the CDI box?

Re: No spark with new Motobecane HPI CDI

#CrazyWayne™ rocks. #CrazyWayne /

The green arrow to the output lead/wire going to the CDI box

The crimp at the green arrow ground is where it brakes.

It shod be 48 to 62 oms 50 it golden.

Re: No spark with new Motobecane HPI CDI

Hokay, I'll measure it when I get home and report back. What about the resistance in the HT coil? Does 5.6KΩ fall in the normal range?

Re: No spark with new Motobecane HPI CDI

Hmm. So there is actually a 3 terminal connector coming out of the back of the stator plate:

I measured the resistance between each of the wires and the ground on the stator plate, but only the black one (which I assume is ground) had continuity. It had negligible resistance.

I also checked for continuity between the HT coil ground and the ground on the stator plate when the connector was plugged in, and it had good continuity and negligible resistance. That seems to confirm that the black wire is the ground.

Re: No spark with new Motobecane HPI CDI

Black wire is just a ground for the CDI box. The exciter coil is not connected to ground - it is floated. Exciter coil resistance is measured on the blue/white wires and should be around 350 Ohms.

If you are sure yours is bad, Jake P had some success re-wrapping one. I've run the HPI box off of home wound coils and non-HPI treats exciter coils. Hand wrapping it probably isn't as good as machine wrapped, but it's good enough to run and keep a curve and a helluva lot cheaper thany buying a new coil!

If you have a single coild CDI stator, you can hook the two wires from it up to the hpi where the blue and white are - where the black is ground to frame. The box will spark if it is good. If you try to run the bike, the curve won't be right though because the curve is voltage dependent and the voltage is determined by the flywheel dimensions and wrapping of the HPI.

https://www.mopedarmy.com/forums/read.php?7,3247052,page=1

(edited)

Re: No spark with new Motobecane HPI CDI

Ok, I just measured the resistance of the exciter coil using your method and I got 350Ω on the dot. That's awesome, since it means my exciter coil is good, but it also kinda sucks because I still have no idea what's causing the problem.

I'm not sure I followed your explanation of the CDI box test though.

Also, what should the resistance on the HT coil be? I still haven't been able to figure out a concrete answer for that.

Re: No spark with new Motobecane HPI CDI

#CrazyWayne™ rocks. #CrazyWayne /

Ops i was thinking digital i'm doing a selettra digital cdi ignition.

Digitalis are 50 to 60oms your analog is 280 to 360 oms.

(edited)

Re: No spark with new Motobecane HPI CDI

#CrazyWayne™ rocks. #CrazyWayne /

My HPI HT-coil is 0.5oms.

You need the run a ground from the stater/carter to the HT-coil housing/bolt or it wont zap

Re: No spark with new Motobecane HPI CDI

That's .5Ω measured between where and where?

Here's the grounding situation on the HT coil:

I checked, and I have good continuity between the HT coil ground and the ground on the stator (green arrow from the earlier photo).

I also just tried to take a voltage reading between the blue and white cables from the stator while using a drill to turn the engine over. The voltage jumped all over the place (which makes sense), but it never got above maybe 2.5v. Am I correct in thinking that's orders of magnitude lower than it should be? I didn't have anything hooked up, but the exciter coil isn't grounded anyway so it shouldn't matter.

Re: No spark with new Motobecane HPI CDI

#CrazyWayne™ rocks. #CrazyWayne /

Test HT-ciol housing oms to the HT-coil input tang you have the orange wire on.

That ground on the HT housing that's not the cdi kill switch lead is it? lol

Re: No spark with new Motobecane HPI CDI

Alright, I'll check that after work.

Ha, that was actually one of the first things I checked. No, the kill switch lead is only about 4 inches long and has a male bullet connector on the end. My understanding is that grounding the kill switch kills the spark, right? So it should spark with the kill switch lead disconnected.

Re: No spark with new Motobecane HPI CDI

#CrazyWayne™ rocks. #CrazyWayne /

You need a ground from the HT-coil housing to the fucking carter/stater dumb ass.

Do you need a bitch slapping or what?

Re: No spark with new Motobecane HPI CDI

I'm not sure how you interpreted that as me saying I don't have a ground from the coil housing to the stator, but alright.

That's what the black cable in the above picture is. It runs from the HT coil housing to the CDI, and the CDI ground runs from there to the stator (the black wire on the three terminal connector). The continuity of the ground between the stator plate and the coil housing is the first thing I checked.

Re: No spark with new Motobecane HPI CDI

Up grade to points

Re: No spark with new Motobecane HPI CDI

#CrazyWayne™ rocks. #CrazyWayne /

Wrong, Try this pull a plug wire off a plug on your car put a screwdriver in the plug boot.

Hold the metal part of the screwdriver with out touching the rest of the car have some one start it a rev it up.

now touch the eng and tell us what happens when you have a ground, lol

You need to send this cdi back to the vender and let them know your to fucking dumb to run a groung from the Ht to carter and most likely fried the box with your stupidity.

better yet just give the moped to some one.

Re: No spark with new Motobecane HPI CDI

Apparently you aren't getting what I'm saying, so let me spell it out for you:

If I put one lead on my multimeter here...

...and the other lead on my multimeter at the green arrow here...

...and my multimeter says this...

...that means they are connected to eachother. In other words, the HT is grounded to the stator.

Again, not sure where you got my alleged lack of grounding from, but I definitely don't appreciate being called a dumbass because you lack reading comprehension skills. Thanks for your help, but you don't have to be a dick about it.

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