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American Legion Rider
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Shoot some carb cleaner in the air cleaner. If you have spark it should fire. However, year old or older fuel that wasn't properly stabilized could still be your main problem. And this does assume you actually have spark.
 

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Ace Tuner
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2,522 Posts
A spark provides a temperature high enough to ignite gasoline, regardless of the octane rating...
(y)
You need to run a high enough octane to prevent knock - that's all there is to it.
TRUE THAT. ^
Octane, as it relates to pump gas, has nothing to do with how easy or hard a stock V-Star 650 starts, hot or cold.
ake an 87 octane bike and give it 91 octane, then take it on a dyno; and come tell me it doesn't hurt performance...
There is such a small difference in the amount of anti-knock compounds in 87 oct and 91 oct fuel that your dyno will never ever know the difference.
I suppose this type of bad information comes from the time somebody tried to use actual high octane fuel (like 110 ~ 115 octane race gas) in a stock bike like a V-Star 650.
The V-Star will give poor performance on 110 oct race gas. It was designed to run on pump gas, not race fuel.

But the book says the bike is designed to run on 87 octane... Not so.
The book says it requires 87 oct minimum. There is a very big difference between 'required minimum' and what might be ideal.
The manufacturer will recommend the lowest possible octane that can be run in their bike.
It is a sells tactic.
Who would buy a bike that needs 91 (or 93) oct when the competitions machine can use 87 that costs less?
I've seen too many spark plugs showing improper octane (too high of combustion temp) when the customer was running 87 oct as recommended.
Sure it will run just fine on 87 oct but in the long run the engine will be much happier and live longer using a higher octane fuel, if the spark plugs indicate the need... Just don't try 115 oct race gas.

S F
 

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Ace Tuner
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2,522 Posts
might be the pickup coil.
My thoughts exactly.

Nick put up a video that shows one way to check the pick up (pulser) coil. (5:38 in the video).
More ways to tests would be to check that it does not go to ground and how much AC voltage it puts out.
I can not remember the voltage you should expect to find but if you need that number I can probably find it in my notes.

S F
 

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Did you gap the plugs before putting them in? How does the air cleaner look? Does that model Yamaha have the resistor in the spark plug wires? I don't know that's why I ask. I have heard they can cause starting problems.

Is the kill switch in the run position?

If the kill switch is in the OFF position, the motor will not turn over. Honda is the only mfgr (Japanese) that will allow the motor to turn over while the kill switch is in the OFF position.
 

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Retired twice: Navy and as a govt contractor
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I don't believe my Yami will turn over with the kill switch in the off position,

Saw Mikes reply and realized I miss-read your reply
 

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Visionary
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If the kill switch is in the OFF position, the motor will not turn over. Honda is the only mfgr (Japanese) that will allow the motor to turn over while the kill switch is in the OFF position.
I just discovered that fact the other day. My Honda was cranking and not starting. Then I noticed the kill switch was off.
Oops. :)


Sent from my iPhone using Tapatalk
 
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Premium Member
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You need spark. WWB gave good info on octane. If the fuel is fresh it should burn, but not without spark. The mission is to find the spark. It may crank over even if there is no spark, caused by a variety of safety switches. All bikes to not have the same safety stuff, and may have been fiddled with as well. Do not proceed until you get spark. UK
 

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Retired twice: Navy and as a govt contractor
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so it is fixed now? If so that is great.
 

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American Legion Rider
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Whatever you do, don't use Bosch plugs. They are junk. Stick with NGK or Nippon Denso.
I doubt the Bosch plug is the real problem but it might be they are of a different heat range than other plugs. I don't know how their's compares to others but BMW wouldn't be using them if they were of poor quality.
 

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I doubt the Bosch plug is the real problem but it might be they are of a different heat range than other plugs. I don't know how their's compares to others but BMW wouldn't be using them if they were of poor quality.
There must some feature that suits BMW. Bosch plugs are actually nothing but a piece of junk. I' prefer Nippon Denso if I need one. At least you don't have to think twice before a long trip.
 

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I doubt the Bosch plug is the real problem but it might be they are of a different heat range than other plugs. I don't know how their's compares to others but BMW wouldn't be using them if they were of poor quality.

You can do a comparison of Bosch against NGK and Nippon Denso. They have inconsistent spark, lower spark output,shorter life etc. I took a course, one year full time, on Small Engines and Motorcycle Maintenance and repair. The You Tube comparison showed a big difference with Bosch coming in at the bottom.
 
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