Sporadic Start Failure ( NOT "hard-start" issue....)

Tenman

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I had a warm hard start on my gen1 on a hot rainy day about 2 years ago. I pulled in front of a hotel entrance to put on a rain suit. I got ready to go and had an embarrassing hard start. I let it sit for about 10 minutes and held it wide open and it cough a time or 2 and redlined. I took it home and cycled the key at least 10 times and it fired right up. I killed it and cycled it about 20 times and it farted a couple of times. Then fired up and ran perfect.
 

sandro1973

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Here's some feedback from my mechanic....he thinks this "on / off" of the engine when cold, can be related with not enough pressure on the fuel pump on some random cold starts.

So, as a fail-safe on cold mornings, he suggested cycling the key twice, in order to create additional pressure on the fuel pump. I tested it today and will do it in every cold start morning in the winter, if the issue disappears, all good, "mistery" solved. Anyway, he'll test the pressure next time i take my bike to the shop.

 

StefanOnHisS10

Converting fuel into heat, noise and a bit motion
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I did find out that when the tank is full there is no problem for me. That would suggest lack of fuel too. Just waiting to see if it re-apears when the tank gets more empty.
 

Rare1

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I have been using SeaFoam injector cleaner for the last 3 fill-ups. Silly bike, it has been starting and staying running now for the last 2 weeks. The garage temperature has dropped substantially in the last 2 weeks since Fall is officially here. The garage is insulated and has a Garaga insulated door so keeps the temps around 13-15 C.
I will put it on my list to have my mechanic check the valves and decompressors in the Spring since the riding season is almost finished for me. I do not have a heated suit or vest and at my age I do not have any reason to expose myself to too much hardship. I have a 3 Season suit and did 300 km 1 day last week. The factory heated grips are awesome and make for a much more enjoyable ride. With 53 yrs of 2 wheeled freedom and about 1.25 million km under my belt I feel very fortunate to be able to throw a leg over and enjoy my passion.
 

sandro1973

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For all it's worth, i've been doing the 2x cycle on the ignition before cold starts to increase fuel pressure on the pump ( today 13ºC or 55 Fº ), bike was parked in the garage for 5 days.....so far, no issues. I'm running a SkyRich Lithium battery.

 

StefanOnHisS10

Converting fuel into heat, noise and a bit motion
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As promised earlier in this thread I would discuss this with my Yamaha-dealer (who I absolutely trust). Today I was there and they said the following:

Not uncommon for these bikes (and the R6). It is caused by too little fuel because the starterbutton isn’t pressed long enough. They advice people to keep it pushed one extra rotation of the crank after initial start. Could have to do with the uneven firing order. There is a relatively long non-firing period, it can’t pick up enough momentum to make it through. That is why it doesn’t always occur, and explains the stumbling. Releasing to soon can cause the bike to flood because it has already injected enough fuel to start and at the second attempt it does it again, and again and again (I haven’t had that, they have had multiple customers that did).

Hopefully it clearifies things.
 

Sierra1

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Now I know the technical reason why. I knew what happened when you "short start" it. My bike has never started as quick as sandro's. On all of my other bikes, as soon as I would hear the first cough, I would release the starter, and they would start. The Tenere would do the same . . . . most of the time. The times that it didn't start right off, and I released the starter, it was quite a pain to get her started. I now don't release the starter 'till she's running. And I'm pretty sure the starter kicks off as soon as she starts, preventing any damage to the starter.
 

Squibb

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It's been mentioned in this thread previously, but I think many of you are forgetting the fact that the S10 has an automatic decompressor system, so the initial rotation on start up will see one valve on each cylinder open slightly. Once the crank has spun up, the decompressor retracts & allows the engine to start. IIRC there is a YouTube vid explaining the principles. Obviously there is an opportunity to disrupt the system if/when re-shimming the valves.

Unlike some cars & bikes, where a quick jab of the start button simply instructs the ECU to start the engine, the S10 is old tech, so the start button needs a decent push until the engine picks up, but no more than 10 seconds per start attempt. Yes, they crank slow, whether with a 12 or 14 ah battery, a little faster with lithium I'm told.
 

StefanOnHisS10

Converting fuel into heat, noise and a bit motion
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It's been mentioned in this thread previously, but I think many of you are forgetting the fact that the S10 has an automatic decompressor system, so the initial rotation on start up will see one valve on each cylinder open slightly. Once the crank has spun up, the decompressor retracts & allows the engine to start. IIRC there is a YouTube vid explaining the principles. Obviously there is an opportunity to disrupt the system if/when re-shimming the valves.

Unlike some cars & bikes, where a quick jab of the start button simply instructs the ECU to start the engine, the S10 is old tech, so the start button needs a decent push until the engine picks up, but no more than 10 seconds per start attempt. Yes, they crank slow, whether with a 12 or 14 ah battery, a little faster with lithium I'm told.
Yes you are correct about the way it functions.
I don’t see that as a cause unless some wannabe mechanic has f*cked it up.

Their chief-mechanic told me they have a bunch of the S10’s with one customer who runs some sort of breakdown service. They are absolutely beaten down and well over 300.000 km. Only once a year maintenance with over 30.000km a year apparently and no problems from which the manufacturer is to blame.

So it seems overall we’ve got a good bike.
 

Sierra1

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. . . . Unlike some cars & bikes, where a quick jab of the start button simply instructs the ECU to start the engine, . . . .
I drove a Chevy Tahoe that when you turned the key and released it, the starter would keep turning until it actually started.
 

WJBertrand

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I drove a Chevy Tahoe that when you turned the key and released it, the starter would keep turning until it actually started.
My 2013 Mustang is like that. Surprised me once after changing the battery that it kept cranking for several seconds after releasing the key. I guess disconnecting the battery resulted in a longer start up sequence than usual. Some folks on the various Mustang forums have wired in a start button like some more modern cars.


Sent from my iPhone using Tapatalk Pro
 

sandro1973

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As promised earlier in this thread I would discuss this with my Yamaha-dealer (who I absolutely trust). Today I was there and they said the following:

Not uncommon for these bikes (and the R6). It is caused by too little fuel because the starterbutton isn’t pressed long enough. They advice people to keep it pushed one extra rotation of the crank after initial start. Could have to do with the uneven firing order. There is a relatively long non-firing period, it can’t pick up enough momentum to make it through. That is why it doesn’t always occur, and explains the stumbling. Releasing to soon can cause the bike to flood because it has already injected enough fuel to start and at the second attempt it does it again, and again and again (I haven’t had that, they have had multiple customers that did).

Hopefully it clearifies things.
Thanks for shedding some light on this with factual feedback. It makes all sense.

I also talked recently to someone that reprograms ECU's and mentioned this issue to him. His reply was similar, told me it is a "thing" on some Yamaha bikes, specially with 270º crank and uneven firing order, just like the XT 1200 and the crossplane engined R1.

I'll avoid cycling the key twice from now on and keep the finger on the starter for a bit longer ( even after starting ).
 

sandro1973

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Now I know the technical reason why. I knew what happened when you "short start" it. My bike has never started as quick as sandro's. On all of my other bikes, as soon as I would hear the first cough, I would release the starter, and they would start. The Tenere would do the same . . . . most of the time. The times that it didn't start right off, and I released the starter, it was quite a pain to get her started. I now don't release the starter 'till she's running. And I'm pretty sure the starter kicks off as soon as she starts, preventing any damage to the starter.
Installing a Lithium battery made a big difference in cranking power. I'm sold on that change....try it when you can.

Even the Yuasa 14S didn't feel strong enough, add on top of that this "hit or miss" random start...and it can be annoying....
 
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