Cold start information

[Mike P]

Makes perfect sense what you are saying. So basically what you’re saying is what gas you have available in your area is going to dictate weather you are going to have cold start problems or not. All I have available is regular and premium fuel. I believe 87 and 91 octane. Which would be better? I’m running the premium 89 right now.
So then what’s the rationale behind my kids pro rmk 2 stroke firing up at -30 in 3 pulls of the cord every time. Faster rpm with the cord vs the starter on mine?

That RMK is very different than the 4 stroke triple in your viper not to mention all of the other obvious variables.

 

[Mike P]

Fuel is always an issue for me when in Canada. Every time I come back from a bagger over the border, especially when in remote areas I will have heavy condensate on the bottom of my aluminum gas cap. After a week or so of riding in Quebec I will notice minor issues with performance.
Proper AFR with good spark should result in proper ignition. Bad air, bad fuel, bad spark, any one or more of these = improper ignition.

interesting read;
https://www.michigan.gov/documents/mda/Gasoline_Volatility_Information_-_endpoint_195239_7.pdf

 

[mbarryracing]

Fuel is always an issue for me when in Canada. Every time I come back from a bagger over the border, especially when in remote areas I will have heavy condensate on the bottom of my aluminum gas cap. After a week or so of riding in Quebec I will notice minor issues with performance.
Proper AFR with good spark should result in proper ignition. Bad air, bad fuel, bad spark, any one or more of these = improper ignition.

interesting read;
https://www.michigan.gov/documents/mda/Gasoline_Volatility_Information_-_endpoint_195239_7.pdf

Also point worth noting regarding conversations about battery voltage affecting starting. Likely it's not really the voltage at the ECU that's influencing starting (because all ECU maps have voltage compensation tables) but more so a higher voltage results in higher cranking RPM from the starter motor which directly results in quicker piston stroke speed which results in a quicker velocity of air flowing in the intake tracts promoting improved fuel vaporization into the combustion chambers and a better chance of combustion...
4 stroke cycle... suck, slam, bang, blow...

Keep in mind these 3 cylinder 1049cc high output engines have a way different intake and exhaust port velocity than your typical automotive or truck engine in order to make 130 HP. That’s 0.124 HP per CC, flowing a lot of air with big ports that do not have a very high velocity at low RPM (like during cranking).

If your 5.3L truck engine flowed the same amount of air to make the same power ratio it would be 657 HP on pump gas… but it’s not, it doesn’t flow the same air. Your are comparing apples and bananas.

Low vapor pressure / low volatility fuel + trying to vaporize in a low velocity / slow moving intake air = puddling and poor combustion.

IMO I still leaning towards it's all related around fuel atomization - vaporization... Volatility / vapor pressure of the blend of fuel in the tank, intake air temperature, intake air velocity into the combustion chamber (RPM from battery voltage). I have witnessed where we had to start a turbo Apex race sled on 87 pump gas in deep cold to get some heat in the head before switching over to the race gas choice, all because that race gas wouldn't vaporize and start the sled cold.

Yamaha indicates to use 87 octane fuel probably for a reason, that reason may very well be because it starts better in - deg temps. However in some of the places I ride, the fuel tank farms on the trail don't even offer 87 octane, it's 91 octane ethanol free. But just because I don't have the option doesn't mean it's not the actual fuel that causing cold start struggles.

 

[cannondale27]

Also point worth noting regarding conversations about battery voltage affecting starting. Likely it's not really the voltage at the ECU that's influencing starting (because all ECU maps have voltage compensation tables) but more so a higher voltage results in higher cranking RPM from the starter motor which directly results in quicker piston stroke speed which results in a quicker velocity of air flowing in the intake tracts promoting improved fuel vaporization into the combustion chambers and a better chance of combustion...
4 stroke cycle... suck, slam, bang, blow...

Keep in mind these 3 cylinder 1049cc high output engines have a way different intake and exhaust port velocity than your typical automotive or truck engine in order to make 130 HP. That’s 0.124 HP per CC, flowing a lot of air with big ports that do not have a very high velocity at low RPM (like during cranking).

If your 5.3L truck engine flowed the same amount of air to make the same power ratio it would be 657 HP on pump gas… but it’s not, it doesn’t flow the same air. Your are comparing apples and bananas.

Low vapor pressure / low volatility fuel + trying to vaporize in a low velocity / slow moving intake air = puddling and poor combustion.

IMO I still leaning towards it's all related around fuel atomization - vaporization... Volatility / vapor pressure of the blend of fuel in the tank, intake air temperature, intake air velocity into the combustion chamber (RPM from battery voltage). I have witnessed where we had to start a turbo Apex race sled on 87 pump gas in deep cold to get some heat in the head before switching over to the race gas choice, all because that race gas wouldn't vaporize and start the sled cold.

Yamaha indicates to use 87 octane fuel probably for a reason, that reason may very well be because it starts better in - deg temps. However in some of the places I ride, the fuel tank farms on the trail don't even offer 87 octane, it's 91 octane ethanol free. But just because I don't have the option doesn't mean it's not the actual fuel that causing cold start struggles.

Disagree. The fuel and ignition tables aren’t optimized so every bit of programming in that ecu and the ecu itself are suspect also.

 

[mbarryracing]

Cannondale27, I can't disagree that the ECU programming might not be optimal and CAT suspect (you'd think that wouldn't be an issue after several years of production and engineering fine tuning calibrations) but that doesn't explain why two identical Vipers, same year and same flash don't both exhibit the same cold start gremlin. I just don't think it's because one owner does a ritual of bouncing on one foot wiggling his nose while cycling the key before cranking to get it to start. I keep thinking there is something else, another variable being overlooked, and that variable no one speaks of could be the difference in fuels.

I'm not trying to "poke the bear", just throwing something out there to get others thinking about it and maybe get some to test the theory... I wish I could provide some real world testing myself but we are lucky to get below freezing temps here in NY this year. My Viper starts fine in my shop. LOL

 

[stomper]

That RMK is very different than the 4 stroke triple in your viper not to mention all of the other obvious variables.

This is all great info and I am learning a lot from this thread. There’s slot of knowledgeable people here that like to help others and that’s what makes this forum great. Thanks guys.
I agree that the rmk motor and my Chevy motor are quite different than the vipers and I didn’t mean to compare them to one another, even though my posts look that way. I was just trying to point out the fact that there are engine manufacturers all around the world that can make an engine that can start in cold weather, how come Yamaha can’t, not to mention that -25c isn’t even cold. That’s an average winter day here. I absolutely love the look , ride and handling of my viper. It performs flawlessly for my type of riding I do, I guess it was just the wrong choice of sled for the temperatures I ride in.
I will keep trying to figure this out because I like the sled.

 

[cannondale27]

Cannondale27, I can't disagree that the ECU programming might not be optimal and CAT suspect (you'd think that wouldn't be an issue after several years of production and engineering fine tuning calibrations) but that doesn't explain why two identical Vipers, same year and same flash don't both exhibit the same cold start gremlin. I just don't think it's because one owner does a ritual of bouncing on one foot wiggling his nose while cycling the key before cranking to get it to start. I keep thinking there is something else, another variable being overlooked, and that variable no one speaks of could be the difference in fuels.

I'm not trying to "poke the bear", just throwing something out there to get others thinking about it and maybe get some to test the theory... I wish I could provide some real world testing myself but we are lucky to get below freezing temps here in NY this year. My Viper starts fine in my shop. LOL

One other variable is flashing over the internet. I believe that is not reliable and never will be as reliable as flashing directly. Another reason I suspect either the tune or ecu is listen to a Wildcat XX idle and then listen to a YXZ. Identical Yamaha motors but Cat uses a China Ecu and Yamaha uses Tried and true Mitsubishi ecu.

 

[cannondale27]

Let’s also not forget valve clearance,throttle body sync and ignition pickup reluctor being out of time. All “variables” that one or more have without a doubt been seen in our sleds right from factory. What it comes down to is our glorious engine company has been cutting costs and this is the result.

 

[74Nitro]

Don't think it's a fuel issue.
Nytro's and Vector's started great no matter what fuel, which also rules out many other things like port velocity, etc.

 

[Vmax]

Great point!

 

[stomper]

Don't think it's a fuel issue.
Nytro's and Vector's started great no matter what fuel, which also rules out many other things like port velocity, etc.

Yeah that’s an excellent point. Not sure how I didn’t pick up on that because the other day when my viper wouldn’t start in -25c my wife’s attack started right up no problem. Probably didn’t pick up on it because was so furious with my viper.
My buddy who I do all my riding with has a 2010 nytro and has never had it not start.
was there this much cold starting trouble with the other Yamaha sleds before the viper came along.

 

[cannondale27]

Yeah that’s an excellent point. Not sure how I didn’t pick up on that because the other day when my viper wouldn’t start in -25c my wife’s attack started right up no problem. Probably didn’t pick up on it because was so furious with my viper.
My buddy who I do all my riding with has a 2010 nytro and has never had it not start.
was there this much cold starting trouble with the other Yamaha sleds before the viper came along.

Some had trouble with Phazer but Yamaha replaced decomp spring and ecu for them.

 

[WinderFab]

Not for anything but my main reason for selling my 2011 apex was it wouldn’t start in the cold.

My 07 Apex and 13 Nytro no problem starting down to -30c and lower but my 2011 gave my headaches starting.

 

[YukonMP]

IMO
The Apexs seem to flood on a cold start when it gets below -20c, what I did with my Attak is add a toggle switch to my fuel pump. When its very cold I start with my fuel pump switched off, crank the engine until it is spinning freely, then I turn the fuel pump on and just keep cranking until it starts and running clean. Using this technique also simplifies any starting issues as you know the engine is always in need of fuel and is not flooded.
I also shut the engine off at the end of the day by turning the fuel pump off until it quits and then turn the key off. This is a technique that has been used on piston aircraft for decades.
Works for me.

The above is by SideshowBob in another thread on the same topic from a year or two back. At the time another member who had experience starting fuel injected aircraft in the north said the same thing.

I don't think there is anything more frustrating than a no start machine ... any machine, period. I can work with predictable limits but if it starts at -25 I want it to always start at -25, not 50-50. I often wonder what the unknown costs of hard starting machines is. Does it make you more likely to have relay troubles, starter troubles, etc?

 

[Mike P]

I start every season with a new and fully charged battery. I will pull my battery at the end of the season and install it in one of my other sleds with a battery much older. I have not been having any issues with cold starts. Canada last year -20f for three days in a row and no issues.
Any time some one in the group I happen to be with has an issue with any sled, Viper, Apex, or Nytro the first thing someone does is get out the jumper cables and most of the time the sleds fire up.
Our problems are not confined to one symptom or explained with the routine by which the problem is solved at the moment. What works for one may or may not work for another. One issue may have been solved but the underlying problem has not been fixed however the clue is in the solution.
I know if my crank speed is too low my sled will not start. I will stop cranking and get it jumped. Is it the battery or the inability to vaporize properly at low temps or crank speeds, or something else.

"It started, thank god"