1981 SUZUKI GS250 Ignition woes, please help

[Anonymous]

Hello,

I am considering buying a 1981 sukuki gs250 that only gets spark to one cylinder. Both coils are good, they can be swapped out and it will spark , but only on one side, does this sound like a "bad ground" issue , or a "CDI" problem? I really need help on this one. Thanks everyone, for taking the time to bail me out of hot water.-----Mick

[IanFrancisco]

Could be a ground, could be an ignitor, could be a power supply problem. Sounds like you have already eliminiated the coils. The ignitors are the same for many of the smaller GS's, GS250, GS450 and GS550 all used the same ignitor, since the four cyl. models use the "wasted spark system". I have found the ignitors show up on ebay pretty regularly. The ones that look clean get many bidders. I got one for around $40 but the price can get pushed up by competitive bidders, as high as $100. Still beats the dealer price for a new item! I would check the harness, power supply at the coils (orange w/ white wire, maybe) and grounds before spending money on an ignitor. There are past posts with good solid testing procedures for the ignition and charging systems. People have been down this road before you and you are not alone. Check for articles by Earl (earlfor) and Keith Krause. These are experienced, knowledgable, gentlemen who know these bikes well.

[Anonymous]

Thanks for the info . I did go ahead and buy it. Now the daunting task of getting it to fire is upon me. I guess first thing I need to ask, " Is there any way to simply test the CDI and rule it out of the equation?" I cannot find ohm specs for the cdi module. It does show output to both coils , but the side that doesn't fire has a slightly higher voltage output. This bike is a 1980 gsx250 with the 8 valve tscc engine.

[IanFrancisco]

Thanks for the info . I did go ahead and buy it. Now the daunting task of getting it to fire is upon me. I guess first thing I need to ask, " Is there any way to simply test the CDI and rule it out of the equation?" I cannot find ohm specs for the cdi module. It does show output to both coils , but the side that doesn't fire has a slightly higher voltage output. This bike is a 1980 gsx250 with the 8 valve tscc engine.

MY factory service manual describes the ignitor as an set of switching NPN transistors. There is (or should be) a constant positive 12VDC to the coils(more actually if the harness and battery are good) whenever the key is on. That would mean the ignitor switches the ground circuit to fire the coils. Not absolutely positive on that! (pun intended). Actually a fully charged battery should put out closer to 13VDC. I would charge the battery and make sure it is good or replace it if not good before doing anything else. Then disconnect the ignitor from the harness and really clean the connectors. If any corrosion is present replace the connectors or solder the connections together. I might resolder the wire to the old connector and take fine sandpaper to it to get clean metal to metal contacts. Same for the coils and charging circuit. A pristine, non-flaky wiring harness is crucial for good reliable running, with extra ground wires for the RR and elsewhere as needed. There's tons of threads regarding electrical issues of all sorts here. Use the search feature, you won't have to rely on new replies.

Best wishes getting your GS250 roadworthy again. Check out this link. This guy's got more bikes than he can use and has a beauty of a GS250. I think his is also the 8-valve version. Nice bikes if not as fast as a (whispered) Ninja 250. Can I say that here? I also like the Honda VTR250's, but I think my old GS450 is almost as fast as these, maybe with someone else riding it!

http://www.ronh.org/mcpage.htm