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

sandro1973

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Can we take it that no codes are registered currently?

I see your battery voltage dips down to 11volts, maybe less in the moment, when you hit the starter, which could be where the problem lies. Can I suggest you have the battery tested for CCA capacity. IIRC, the 14S should produce 230CCA. That & checking the terminals are tight/snug would eliminate the battery as the source of the issue.

Then we come back to the decompressor system, that has been mentioned already by @TABASCO. The 11.0:1 compression ratio is reduced to a pressure of 84-108 psi when cranking & rises to around 180-200 psi once running. Clearly if one, or maybe even both decompressors aren't functioning correctly, the starter/battery will have a far tougher job on a cold start.
The battery voltage dropping to 11V while cranking is normal i guess. Below 9 / 10 V can be an issue and mean the battery is weak, this is what i've learned over the years. Anyway, it's not an isolated issue on my bike and seems to pretty much happen randomly to many others as far as i've seen.

The bike also had a compression test made recently while doing valve adjustment, with no negative feedback.

Today it started just fine, like 99% of the time.
 
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Dshane

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The same thing happened once on my 2020 with about 2k miles on her. I just gave a little throttle and it started without issue, hasn't happened since. And it even happened on my 2018 FJR once in 10k miles. Funny thing those internal combustion engines, aren't they!!!!
 

Cycledude

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I must be the only one that believes the main issue is the starter simply is not powerful enough for this engine, sure it works fine most of the time but if it actually came from the factory with a more powerful starter we wouldn’t be having this conversation.
 

sandro1973

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I must be the only one that believes the main issue is the starter simply is not powerful enough for this engine, sure it works fine most of the time but if it actually came from the factory with a more powerful starter we wouldn’t be having this conversation.
That....or the batteries should have a bit more juice....even the Yuasa 14S isn't that much better than the 12S. I didn't notice a stronger cranking power from the 230cca. The bike still turns slow with a fresh charged battery when cold....some folks use lithium ones to make up for that. But the tradeoff in potencial hazard comparing to OEM spec, is not worth it for me.

As far as i know, 230cca's is the best when can find within OEM spec batteries.
 

WJBertrand

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I read somewhere that the starter is designed to turn the engine over no faster than 250 RPM. Turning the crank faster evidently causes the automatic compression release to disengage. Without the compression release Yamaha would have had to use a larger, heavier and more expensive battery and starter to start the engine with full compression. It seems there is a pretty narrow window of RPM where it's fast enough to start the engine but not too fast so the compression release remains engaged.
 

Cycledude

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I don’t really think the starter needs to crank much faster it just needs to crank stronger so it doesn’t sound like the perfectly good battery is half dead.
My Goldwing has 573,000 miles on the original starter and it has never sounded like the battery was half dead. Every Tenere I’ve ever heard start sounds like the battery is half dead but in my opinion the real issue is the underpowered starter.
As far as no start issue it only happened twice to my previous 2013 Tenere, fortunately both times happened at home in my garage. So far it has never happened to my current 2018 Tenere, I do carry a battery jump pack these days just in case and so far the only time I ever used it was to jump start a car for an owner that happened to be on oxygen, he was very relieved to actually see the thing work !
 
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sandro1973

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Hi guys, just an update....

This week i had a similar issue again..... the bike did start on the 1st try ( cold ), but it cranked so,so slowly i felt like battery was dying and barely got it running.....i then i rode for a few minutes, stopped at a gas station, engine already warmed up....and again the same "dying battery" feel that left little room for doubt that this one, was going to leave me stranded somewhere.

I took the bike to the shop and had to leave it there, getting it back tomorrow with a Skyrich Lithium battery already mounted and hopefully, that will be it for a while.

It was adviced at the bike shop and the general rider consensus seems to be that if you want to be sure this bike will start and crank decently everytime, Lithium is the safest bet. Also discharges much slower. I know a guy that had is S10 on the garage for 6 months and was able to start it 1st time. Regarding the cold weather, another portuguese biker made a trip to Nordkapp and back, on a lithium and Norway is not a warm country by any means. Fingers crossed. :)

HJTZ14-600x600.jpg

I never felt the 14S with 230cca had more power than the Magnetti Marelli ( 12S equivalent ) and its 210cca....i also noticed that the voltage never seemed to stabilize even after a couple of days on the garage. One week or even less after a full charge will have it dropping below 12.7 v. My feel is that i got something that already had a bit of shelf life and was never in good condition.

The previous battery, even after 10 days in the garage started the bike just fine, i thought i was doing a great move by getting a new Yuasa....guess i was wrong....
 

Highwayman

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You have two things going on there. Either the battery had issues like a bad cell and its fixed by replacing a bad battery, or cables. (or) Something mechanical IE, decompressor is acting up, leaky injectors, coolant getting in, and its still not fixed.

Myself, everyone I know and everyone else Ive ever heard from have had zero issues with a standard 12 or 14 Yuasa in good condition starting these bikes. I cant believe switching brands to a lithium battery over a standard Yuasa in good condition is the real cure for what was going on.

Anyone leaving a bike sitting in a garage should have it on a battery tender. I run 5 on tenders, really not a big deal to keep the battery plugged in and fully charged.
 

Sierra1

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I read somewhere that the starter is designed to turn the engine over no faster than 250 RPM. . . .
. . . . so it doesn’t sound like the perfectly good battery is half dead.
My Goldwing has 573,000 miles on the original starter and it has never sounded like the battery was half dead. Every Tenere I’ve ever heard start sounds like the battery is half dead but in my opinion the real issue is the underpowered starter. . . .
Every time my neighbor with the 'Wing hears my bike start, he tells me I need a new battery. Compared to his bike, he's right. His 'Wing has a very fast cranking starter. What Mr. Bertrand says explains everything. She's always been a slow cranker. Apparently designed that way.

The first couple of years, I wasn't able to keep the battery on a 'Tender consistently. Even after killing the battery twice, she starts fine every time. Now, if I'm not riding, she's on the Optimate. Five years old in January.
 

sandro1973

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You have two things going on there. Either the battery had issues like a bad cell and its fixed by replacing a bad battery, or cables. (or) Something mechanical IE, decompressor is acting up, leaky injectors, coolant getting in, and its still not fixed.

Myself, everyone I know and everyone else Ive ever heard from have had zero issues with a standard 12 or 14 Yuasa in good condition starting these bikes. I cant believe switching brands to a lithium battery over a standard Yuasa in good condition is the real cure for what was going on.

Anyone leaving a bike sitting in a garage should have it on a battery tender. I run 5 on tenders, really not a big deal to keep the battery plugged in and fully charged.
I usually ride on a daily basis ( 10 days is the most i had the bike sitting in the garage ), and the previous battery ( equivalente to 12s, from Magnetti Marelli ) didn't loose voltage like this one did. The 14s never felt stronger with its extra 20cca, as most mention, so i figure i got a bad one.

Charging system and voltage regulator work properly, the bike had the FI cleaned and synched, nem plugs, valves checked and adjusted, compression test was OK, new camchain. Everything on the bike works and goes just fine, in fact, much better than before i had all of the above checked.

I've had once a Motobatt delivered that was dead on 1st use, and this Yuasa had an unknown shelf life ( due to its price i doubt they're flying off the shelfs, most guys were i live don't like to spend too much on expensive batteries ), so who knows....no brand is "bulletproof".

It is also worth mentioning than on the same day this issue happened twice in a 10 minute period, after riding 30 kms to the bike shop, it started fine....and two days before i had the battery fully charged.

Now only time and usage will tell, if anything acts up from now on, then it can't be battery. But that's where i put my money in.
 
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sandro1973

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Starting after 3 hours parked, sounds and feels more stronger, but maybe it's just my feeling or expectation. Will have to check how it behaves overnight in the morning.

 

sandro1973

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Just an update....the Skyrich Lithium battery seems to make it easier to start bike, i no longer hear or feel effort from the starter motor...but it seems like the sporadic shutdown after just starting the bike, still creeps in from time to time, no apparent reason to be found....i know this is something that is not uncommon or unheard of, but it still annoys me a bit.

Anyway, just this week i heard a guy starting his KTM 790 Adventure in the morning and only on the 3rd attempt did it run.....so, it could be worse....

 
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StefanOnHisS10

Converting fuel into heat, noise and a bit motion
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As mentioned before, mine does the same. I dont turn the key on off and on again, i just press the start button again and she starts just fine.
I don't believe it is the decompressor but don't know what else it is. It is anoying, i will ask my yamaha-dealer (yes my US friends, a dealer, and a good one!) when i bring her in for valve check. Maybe we'll learn from them what it is.

For the record: i am running a lithium for years allready in hot and cold weather. Not one problem what so ever, well worth the money.

Stefan.
 

sandro1973

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As mentioned before, mine does the same. I dont turn the key on off and on again, i just press the start button again and she starts just fine.
I don't believe it is the decompressor but don't know what else it is. It is anoying, i will ask my yamaha-dealer (yes my US friends, a dealer, and a good one!) when i bring her in for valve check. Maybe we'll learn from them what it is.

For the record: i am running a lithium for years allready in hot and cold weather. Not one problem what so ever, well worth the money.

Stefan.
Thanks Stefan. Today it happened again, cold morning start. If "feels" like it's missing fuel in these initial moments when cold, but it's not happening always. I wonder if giving it a bit of gas as soon as it start, if it would prevent this.

It's not nothing that will have me wondering much longer, overhere ( Portugal ) other guys mention the same, others don't, but it's nor a "one off" occurrence....but as you say, it's annoying.

P.S: the Lithium battery seems to work great, no more weak starts ( so far, knock on wood ), the starter motor feels and sounds more "energetic".

 

sandro1973

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From the video it sounds like the OP has an after-market end can, so I am wondering if the bike is simply fuelling too lean. Maybe needs a flash or P.C. adjustment. This article explains the system: -

.......... https://motofomo.com/open-loop-vs-closed-loop-fuel-injection/
You're right, i have an Arrow end-can ( no DB-Killer ) and a K&N air-filter. The bike also does quite a bit of back-fire ( more like the "pop-pop-pop" sound of popcorns....lol ) on decceleration in the lower gears.

But i can also tell you that i know i guy that has everything stock, and it still happens to him randomly. My assumption is that it indeed related with fuel-air ration when the bike is cold....annoying when it happens, but not a serious issue.
 
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WJBertrand

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Thanks Stefan. Today it happened again, cold morning start. If "feels" like it's missing fuel in these initial moments when cold, but it's not happening always. I wonder if giving it a bit of gas as soon as it start, if it would prevent this.

It's not nothing that will have me wondering much longer, overhere ( Portugal ) other guys mention the same, others don't, but it's nor a "one off" occurrence....but as you say, it's annoying.

P.S: the Lithium battery seems to work great, no more weak starts ( so far, knock on wood ), the starter motor feels and sounds more "energetic".

Mine has done that a couple of times both when the engine is warm, say after a fuel stop for example, and when the engine is cold. More often with a warm engine actually. I just hit the starter button again and proceed. I'm past due for valve clearance check, and air filter / spark plug replacement though. Why are you turning off and back on the key? That seems like a way to possibly flood it.
 

sandro1973

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Mine has done that a couple of times both when the engine is warm, say after a fuel stop for example, and when the engine is cold. More often with a warm engine actually. I just hit the starter button again and proceed. I'm past due for valve clearance check, and air filter / spark plug replacement though. Why are you turning off and back on the key? That seems like a way to possibly flood it.
So the lights can be turned off and pose less of a charge on the battery, that already has started the bike moments ago. But i see your point.

I did all that maintenance you're referring to recently, but this had also happened before. Never on a warm engine, so far. No one seems to be able to put a finger on what might cause this...more of a annoyance than an actual "problem", i'm better off living with it than trying to find out the "why".
 

sandro1973

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OK, that makes sense. I've never had an issue just stabbing the button again though.
Yesterday i was talking to another local guy and when this happens to his bike, it's also always on colder morning starts, it seems like this is the "norm".

Later In the afternoon, after i started the bike to come back from worked ( it was parked outside, sunny day, for 10 hours ), as it happens most times, no issues at all, started just fine....

I also showed the video to my mechanic, who suggested cycling the ignition twice before using the starter. I suppose this might allow a bit of extra fuel on the fuel-air mix, like when using CHOKE on a carbed bike in cold mornings.
 
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