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#142894 - 09/09/18 11:28 AM Bike Wouldn't Stop Cranking!
BigSm0ke Offline
Junior Member

Registered: 02/07/18
Posts: 62
Loc: QLD, Australia
Hey guys, I'm posting this just to inform others about what happened to me the other day.

I was out on the trails with my brother, we stopped for 5mins and were about to move on. I crank the bike and it WOULD NOT STOP CRANKING. I turned off the ignition, killswitch etc--still cranking. For like 2 minutes straight...[I hope the starter has not been damaged]

It drained my battery as we weren't quick enough to take it all apart/realise what was happening.

We later realised that the starter relay/solenoid had stuck on. Upon removal of the relay I saw that it was a cheap chinese one. GRR!

I temporarily replaced it with one from my parts XT, and plan to soon replace it with an equivalent car relay. (More reliable?)

One thing I noticed a few days leading up to this--

There was occasionally a 0.5 to 1 second lag between me pressing the starter and it actually cranking. It concerned me, but was minor enough that I ignored it. So watch out for minor clues your bike may give you!

Also one question:

What size car relay should I replace the original with?

Thanks everyone smile
The race was definitely underway. I had witnessed the start, I was sure of that much. But what now? What comes next?

#142896 - 09/09/18 02:52 PM Re: Bike Wouldn't Stop Cranking! [Re: BigSm0ke]
peejman Offline
Platinum Member

Registered: 06/03/13
Posts: 3196
Loc: East TN USA
Odd that the relay failed closed. Glad it didn't cause any greater damage. Did the bike not start and run? As for the starter.... 2 solid minutes is a lot. Just depends on how hot it got in that amount of time.
This shall pass, be still and know.
2006 XT225, UNI filter, ProTaper bars, MSR handguards, SS front brake line, Shinko 241's.

#142899 - 09/09/18 03:32 PM Re: Bike Wouldn't Stop Cranking! [Re: BigSm0ke]
Muniac Offline

Platinum Member

Registered: 01/16/04
Posts: 5717
Loc: Montrose, CO
It's likely the starter relay contacts heated (poor connection) and fused together. As for shorts, the start switch and kill switch are in series to ground the starter relay coil. Your main switch and starter circuit cutoff relay are in series from +12 to the coil. So it's very unlikely a wiring short would close the coil as you describe. I'd say this is mechanical within the relay body/armature (fused contacts).

The starter motor is wound to be somewhat small and produce high torque. Thus its duty cycle is very small. As for possible damage, that would require an inspection of the windings/commutator to see if they are burned. Hope that isn't the case.

Both our bikes (2003) have the original OEM starter relays. So far no issues with either. The Yamaha P/N for a 1997 Serow starter relay is 3AY-81940-00-00. It's additionally qualified with (MS5D-611) not sure if that's a house number for a Japanese relay company.

I'd replace your relay with an OEM unit. I doubt the Japanese used a Chinese part as OEM. Someone may have gerrymandered the electrical box. Check the connections to the relay for over heating, burned wiring, corroded terminals, etc.

Probably any SPST 12VDC automotive relay would work providing its contacts are rated for the starter load. Bosch makes a bunch of these. As for cranking amps, I'd guess 20-30 for the starter. Truth be known, I haven't a clue what this load is. If you search on Bosch starter relays many will show up. One example is HERE rated for 75A, 12VDC coil and SPST contact form. Good luck with your project.
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#142909 - 09/10/18 01:09 AM Re: Bike Wouldn't Stop Cranking! [Re: BigSm0ke]
BigSm0ke Offline
Junior Member

Registered: 02/07/18
Posts: 62
Loc: QLD, Australia
Thank you for your thoughtful replies.

Peejman, one thing that was different about this situation was I had parked the bike on a sharp angle downhill and for some reason at that exact moment it decided not to start immediately. (My XT always starts instantly no problem)

So I think the holding of the starter button for longer than I normally do was what contributed to this glitch- I'm glad it happened though as it revealed the shoddy relay etc.

I agree 100% Muniac, feels better to have an OEM one in there[although this one is a 1994 unit]. I may buy one new to REALLY ensure it doesn't happen again.

I have a bunch of Bosch relays lying around and will see what I can find/test- but as you say, you haven't had any issues with OEM...

The race was definitely underway. I had witnessed the start, I was sure of that much. But what now? What comes next?

#142914 - 09/10/18 04:01 AM Re: Bike Wouldn't Stop Cranking! [Re: BigSm0ke]
Rocky Baker Offline
Junior Member

Registered: 05/10/18
Posts: 49
Loc: Timmins, Ontario
This happened to me earlier this year as well. I have a 1992 Serow...any chance we have the same crappy solenoid? Luckily, my battery isn't great so it only cranked for about 15-20 seconds before it died. It doesn't seem to have damaged the starter because it has worked fine ever since.
Keep it simple


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