diagnosing spark

[daktah]

hey guys, i recently picked up an 82 gs450tz (gs45 2cyl engine) thats been sitting in a guys backyard for probably 15 years for a paltry $80. its it decent shape for being abandoned, just needs some tlc and hackjobbery and a LOT of pb blaster to get it going and right now im trying to get it to spark when cranking.

i got new plugs and tested the coils with a 12v battery and theyre a bit weak but still work. the pickups measured 64-65 ohms each so i believe they are good. i guess that makes the final culprit the igniter (model 32900-47020 BB1201), but also i noticed when looking at the pickups that only one of the two magnets is still magnetic, the other doesnt attract my screwdriver even a little bit. im not sure this would cause a no spark, i would think it would cause periodical missing of spark but not no spark outright.

how do i go about testing this model of igniter to verify if it is the issue or not? i have a fully charged car battery hooked up for testing the bike so its got plenty of current and run time for the bike.

also i dont have the key for it so im using jumper wires to jump the pin pairs on the connector and made sure to jump the right pairs from the wiring diagram (red to orange, white to brown) and it does have status lights and cranks so im pretty sure its not an issue.

edit: i saw someone using leds to check pickups so i went ahead and tried it using some 2v red leds where the cathodes were hooked to the common ground and each anode went to the individual positives. it turns out even though both pickups have the same exact resistance and voltage generation when spinning the engine one will not light up its led, i swapped them around to make sure the led wasnt dead but it was the same thing, the same pickups did the same thing. does this mean one of the pickups is bad or what?
picture related:

 

[tom203]

If its like my 650 ignition setup, both signal coil pickups should be noticeably magnetic- not sure why, but might have something to do with creating a strong pulse to ignitor when trigger tab swings by.
The ignitor gets its power from the same orange/white wire that powers the ignition coils. If you got power there try swinging a small screwdiver blade past a signal coil face.... this duplicates what the revolving tab does... Spark plug should fire.
Obviously, check all connections in ignition system to make sure none have froze to death.

 

[daktah]

no no, i dont mean the pickups themselves i mean the thing that rotates between them to trigger them. both pickups are quite magnetic. ive tried running a screwdriver and a screwdriver with a magnet past it but it doesnt make any difference in not sparking. ive done the thing where you hook up a multimeter on ohms and a 1.5v battery to the pickup pins going to the cdi box to get it to spark and neither work. all of the connectors and connections are good with .001-.005 ohms and im getting 12v to the box yet the only way i can generate a spark is by hooking up the battery straight to the coil and rapidly tapping one of the leads to the post to make a human powered points breaker.

i was thinking rather than spending 3x the price of the bike on a used cdi box i could jimmyrig one out of those cheap ones meant for pocket bikes and stuff. in my head it seems like it would work and would run about $30 rather than $300.

 

[Nessism]

Your bike doesn't have a CDI. The ignition is what Suzuki terms an electronic transistor ignition or something to this effect and it uses what's denoted an ignitor. A CDI uses a completely different technology. At any rate, the ignitors on those 450's are prone to frying. There are about a bazillon threads on this in the archives. One of the reasons the ignitor fries is because the R/R grounds suck and the charging system overcharges and fries it.

Good luck.

 

[daktah]

everyone online when i was googling it and looking for replacements calls that thing a cdi box so i figured thats what it was. i guess makes it easier designing my own ignition box then. i can probably get away just using a few beefy mosfets to toggle the coils to generate a spark, no?

 

[Gorminrider]

maybe your screw driver is magnetized? and you are att south-south? anyways...you MIGHT try
Disconnect the signal coils and then, If you supply a very small current to the leads on the TCI that the signal coils attach to, you should be able to MAKE a spark at plugs. In other words, you are duplicating what the signal coils send to the TCI...a small aaa battery might do it...even an ohmmeter... you will have to have polarity right I suppose.

By the way, a spark is hard to judge outside the cylinder... you say you have spark but it's "weak". i would not be so sure of this unless I could swear the piston was getting gas...or a dose of starting fluid which even with the plug outside the piston, will pop...
OH! and another idea- if you think one signal coil better than the other or have spark on one side, swap connections of signal coils to suspect side of tci to get a spark or not. see if you can get a spark at the non-sparking side, if there is one??

If you go to Bass cliffs site you will find info about the TCI ignition. BikeCliff's Website

 

[daktah]

tried all of that, no dice.

 

[Nessism]

everyone online when i was googling it and looking for replacements calls that thing a cdi box so i figured thats what it was.

Great example of the amount of crap info there is on the internet. Try searching here for info. You can use google by using the following approach

site:www.thegsresources.com (search term)

replace (search term) with whatever you are trying to investigate. ignitor for example. You can even try CDI, but that may lead to more crap info.

Using GM HEI modules is one approach to fix spark. Another is to get a Dyna S ignition. Lots of info out there...

 

[daktah]

Using GM HEI modules is one approach to fix spark.

i never even considered using something like this, i think i have my solution. like i said i dont care how janky and cheap it is as long as it runs. also, any way to make sure the r/r gets a good ground to not fry these ones too?

 

[Steve]

There are a couple of problems with what I am seeing so far in this thread. :-k

The rotating magnet that triggers the spark is singular. There is only a single magnet on one side of that rotating part. That is why your screwdriver is only attracted one time.

All of the HEI modules that I have seen (from GM, Ford, Honda and Toyota) have been twin-lead modules. They work GREAT on a four-cylinder bike, but not so much on a twin, because the two plugs on a GS twin do not fire at the same time, so the second lead is going to be in the way. If you can find an HEI module with a single lead, go for it.

And when you are jumpering wires near the ignition switch, there is no white wire. The fourth wire in that connector is gray.

.

 

[daktah]

The rotating magnet that triggers the spark is singular. There is only a single magnet on one side of that rotating part. That is why your screwdriver is only attracted one time.

thats a relief. i thought it was kind of weird how only one magnet would totally die but the other one be perfectly fine.

All of the HEI modules that I have seen (from GM, Ford, Honda and Toyota) have been twin-lead modules. They work GREAT on a four-cylinder bike, but not so much on a twin, because the two plugs on a GS twin do not fire at the same time, so the second lead is going to be in the way. If you can find an HEI module with a single lead, go for it.

im not sure what you mean, a pair of 4 pin modules look like they would work great.

And when you are jumpering wires near the ignition switch, there is no white wire. The fourth wire in that connector is gray.

looks white from 15 years of degradation

 

[daktah]

so i got my hei modules and hooked em up and i have spark now . only problem is that when i try to get it to turn over (ether only, no gas) it keeps backfiring out of the carbs. it would continually backfire so i swapped which module powered which coil and now it only backfires sometimes but also tries to turn over, but it will backfire while its trying to go and totally stall the starter. any ideas?