Suzuki GN250 charging system component testing

When this GN250 came into the workshop a couple of weeks ago with a no crank-no start issue I immediately suspected the charging system - a common fault on many Chinese built motorcycles these days....
A new battery had been installed only a few months ago by the previous owner, prior to selling the bike. Sure, the new battery would have resolved the problem of starting the bike but more often than not it's not the primary fail, be it a no-charge or over-charging issue.
Completing a thorough inspection of the bike's charging system components & comparing the readings to the manufacturer's specifications is, in my opinion, the only way of reaching a conclusive diagnosis.
In this video I use a standard multi-meter to check for DC charging rate at the battery, resistance & ground tests on the stator and even include the full test procedure for the regulator/rectifier unit - something which is not often provided by the manufacturer.
I also grab my oscilloscope & obtain visual live graphs of the output waveform from each of the 3 stator windings - an excellent way to check output performance & far more informative than just a mere AC voltage reading on a meter.
This is a classic example of a 'shoot from the hip' diagnostic where the owner 'assumes' just because the battery is discharged that it must be faulty. Sure, they may have put it on charge overnight and tried it again on the bike. But we have to look further 'why did the battery fail?' and to know that we must check each component in the charging system.
There will no doubt be a 2nd video in this case study covering the repair and final testing to confirm the system is back to full working order & meets all of Suzuki's test specifications.
Included in the video are the official Suzuki test procedures & specifications.
If you have any questions just add them to the comments section below & I'll get back to you just as soon as I can.
Andy Mechanic

[@tiagomarcelino7599]

I'm surprised you dont have more views, this is absolutelly brilliant. You have sucessfully tackled the most comom issues on these bikes and how to pin point the actual fault. Hat's off to you sir

[@caiosarrea]

Hy Andy. I'm Caio, from Brazil. I'm sorry for my bad english, but I hope you understand. I'm so pleased with your videos, my gn250 is in "eletric troubles", and I'm triyng to fit it by myself. Right now I will check out your channel and watch more videos about this bike. Very thanks!!!

[@johnhauton9170]

Top man - Great video Andy - thanks for all the help

[@uilifecteau4841]

Hi Andy, Great video, lots of testing and great explanations. i'm down in Wellington here with a related issue. The battery isn't charging from running the bike, and I'm going to have a look at the rectifier. THis video has given me some confidence to have a look myself before I take it down to the mechanics if I can't figure it out. Have a go, with a back up of taking it down the road to the pros. Cheers for the great quality vid, not that many other with such a clear description on GN250s. Uili

[@Kruizzader]

Did you fix the problem? My bike is having the same problem

[@philfee8675]

@@Kruizzader did you? im having the same issue on a 125

[@user-ot1dv6ri4f]

Amazing video

[@simonrawle7885]

a good video Andy it will help someone. my first bikes where second hand 80s Hondas in the late 90sso something i am more than familiar with bike charging systems lol . you covered all the point well

[@AndyMechanic]

+Simon Rawle Cheers Simon :-)

[@ryantaylor4591]

Hi Andy great video. I have an electrical problem on my 2006 . Battery is full charge and starter solenoid is receiving and sending 12.6V, my spark plug is not getting any volts though. Do you have any ideas as to what it could be.

[@michaelchristophernz220]

Would it be the same for the 250lc intruder?

[@Ducky-Bob]

Thanks for the vid. I am working on one one of these in my garage. My customer states that his batt was dying at low revs during in town driving. He watched this video, tested the reg/rec, determined it faulty and replaced it with the cheapest one on amazon. The bike still wouldn't charge at low revs so he brought it to me, I do small engine side work. I tested the new reg/rec and found it faulty, I also tested the stator and found it passed resistance and voltage tests but failed the continuity test. I suggested we replace them both. When the new (cheapest on Amazon) reg/rec came in it also tested faulty in the same way as the other new one. I've yet to test the new stator but the repeated failure of new reg/recs has me concerned. Any advice?

[@ianspencer8865]

Sorry am i being dumb but the SUZUKI GN250 was japanese not chinese

[@AndyMechanic]

+Ian Spencer yes Japanese up until around 2006 unfortunately. Cheers Ian

[@aaronperry3426]

Can you supply the link you used to get the service manual?

[@AndyMechanic]

If you send me an email I can send you the link. Cheers Andy

[@leighthomas5070]

Can you help me please. I'm mounting a gn250 engine on a buggy. I'm not worried about the charging system but want to know what wires I run to the cdi from the magneto. There are 3 yellow wires (charging wires?) Which I assume I dont need?, And a green wire and a orange wire which I assume are the wires I run to cdi? Thanks

[@AndyMechanic]

Yes, the 3 yellow wires are from the stator for the charging. The other 2 will be from the pickup coil - you need to connect them the correct way round to the CDI or it won't rev correctly & could damage the CDI unit worst case. Cheers Andy

[@leighthomas5070]

@@AndyMechanic ok then thank you. Do you have any idea what colour wires on the cdi I run the green and orange wires to?

[@leighthomas5070]

@@AndyMechanic sorry to be a pain. Also what wires on cdi go to coil.

[@AndyMechanic]

You'll need a pin out diagram - may be in the Service Manual or you'll need to contact a local Suzuki dealership.

[@AndyMechanic]

You definitely need a wiring diagram so you'll need to do some research

[@dreamon220]

Hi Andy are the regulators expensive for the Suzuki gn250 I'm curious as i have one of these and no it's a common fault.

[@AndyMechanic]

The regulator/rectifier is around $200 here in NZ. The Chinese built GN250 does have poor electrics and lots of issues with the stator and reg/rectifier unit plus the starter circuit wiring is just too small a gauge too so lots of volt drop. Cheers Andy

[@hugopereira2005]

Hi Andy, great video! I am trying to take out the starter motor from my suzuki gn250, so I can check the brushes condition, but I am not succeeding to remove it, or to find a video that explains the process on this specific model. Do you know if there´s something else needs to be done, beside unscrewing the 2 visible bolts outside the body?

[@AndyMechanic]

No, I haven't done a video on it. However, just the power wire from the solenoid and the two bolts. There will be an o- ring which often gets tight as it'll be dry. It's located between the starter & the engine casing. You'll have to use a soft hammer & tap on the starter casing to get it to withdraw. Let me know how you get on. Cheers Andy

[@hugopereira2005]

@@AndyMechanic Thank you, I will try it tomorrow, and let you know:) cheers mate

[@hugopereiramusic1]

@@hugopereira2005precisely that Andy, after a few hits with the soft hammer the startet came out. Thanks

[@hugopereiramusic1]

@@AndyMechanic Hi Andy, I have another question. When I put the starter back in the bike it works, but I hear it spinning without really connecting with the engine gear! The fitting looks good and the bolts are tight. Judging by the sound, It seems to me that is not reaching the gear wheel inside the engine case.. Did you ever had this problem? Am I missing something ? Cheers mate

[@hugopereiramusic1]

@@AndyMechanic Hi Andy, I found a possible solution for the problem I got after checking the starter engine. It might be the starter engine case badly ensembled! www.motorcycleforum.com/59-motorcycle-repair/100906-starter-spins-but-doesnt-turn-engine.html post #17 Cheers

[@billyr9840]

Nice!