Hard Starting SX700s

C

Cherrypicker

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Joined
Dec 8, 2010
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88
Age
78
Location
Michigan
We have 3 SX700s and a 98 SRX700, and they are all hard starting when cold. I have resorted to pouring some premix down the air box top opening to "prime" the carbs and sleds usually fire with 3 or 4 pulls. Some of the fuel will run out of the box, but it hasn't been an issue. Yesterday I went through this procedure and ended up setting the SRX on fire. To make matters worse it was on the 4 place trailer, with 3 SX700s still attached to my pickup. I was able to quench the fire with the second of 2 fire extinguishers, some windshield washer fluid and as much snow as I could gather.

I don't understand why this hard starting is happening, I have other small engines Honda and Briggs and Stratton that almost always start with less than 3 pulls, obviously it's a fuel primer issue, has anyone else incorporated a priming system in their sleds, much like some older Skidoo models used to have?

Never an issue when the sleds are warm, usually 1-2 pulls at most, even after they have set for an hour or two.
 
try doing the choke plunger mod.Remove the plungers and grind or file 1 mm off the tip..this will allow more gas for starting.Some swear by it.I have done this on my Srx also,but haven't tried starting it yet..waiting for snow...
 
i usually pump the throttle 3 times then full choke it when cold, started first pull yesterday. i cant imagine that the same thing is wrong with all four sleds.
 
s10mike said:
i usually pump the throttle 3 times then full choke it when cold, started first pull yesterday. i cant imagine that the same thing is wrong with all four sleds.
Click to expand...
Pumping the throttle isn't going to do a thing other then exercise your thumb! They don't have an accelerator pump.

Sounds like the chokes might be out of adjustment. Are the carbs clean? After these I would say do the plunger mod and you shouldn't have a problem.
I have never had to "prime" any of my sleds.
 
First off, honda,briggs etc are FOUR stroke with 1 carb hence the no mix gas. Horse of a totally different color! Carbs clean? Agree with choke being suspect. When pulling the choke flipper look at carbs and make sure they are full travel/fully choked. I adopted my buddies method a few years ago. Give they sled 2-3 preliminary pulls. Not pulling quite as hard. Gets everything moving and builds vacum in pulse line. Then give it a couple good pulls and fires right up! Even the 00 srx responds well after sitting a couple weeks.
 
What do you mean by cold. Sitting over night or 30 below zero. I have two 700 and usually start with 2 pulls in the morning unless it is below zero. Got tired of pulling ( 700s are no fun to pull when it is -30) and installed electric start on both. Make sure your carbs are clean ( and make sure you pull every thing apart when you clean). A little Seafoam in the fuel wont hurt either.
 
Cherrypicker said:
We have 3 SX700s and a 98 SRX700, and they are all hard starting when cold. I have resorted to pouring some premix down the air box top opening to "prime" the carbs and sleds usually fire with 3 or 4 pulls. Some of the fuel will run out of the box, but it hasn't been an issue. Yesterday I went through this procedure and ended up setting the SRX on fire. To make matters worse it was on the 4 place trailer, with 3 SX700s still attached to my pickup. I was able to quench the fire with the second of 2 fire extinguishers, some windshield washer fluid and as much snow as I could gather.

I don't understand why this hard starting is happening, I have other small engines Honda and Briggs and Stratton that almost always start with less than 3 pulls, obviously it's a fuel primer issue, has anyone else incorporated a priming system in their sleds, much like some older Skidoo models used to have?

Never an issue when the sleds are warm, usually 1-2 pulls at most, even after they have set for an hour or two.
Click to expand...
do you have a pic of the fire damage on the SRX.I would use Quick start before dumping pure gas down the airbox...
 
gbic1 said:
What do you mean by cold. Sitting over night or 30 below zero. I have two 700 and usually start with 2 pulls in the morning unless it is below zero. Got tired of pulling ( 700s are no fun to pull when it is -30) and installed electric start on both. Make sure your carbs are clean ( and make sure you pull every thing apart when you clean). A little Seafoam in the fuel wont hurt either.
Click to expand...


It hasn't been that cold, 5-13, but clearly it's a carb related issue, since I go through the carbs annually, don't think it's dirty carb, but I will tighten up the choke cable and see if maybe I'm running with too much slack. This is only an issue when sitting for a few days. I agree with difficulty pulling these things over.
 
bluemonster1 said:
do you have a pic of the fire damage on the SRX.I would use Quick start before dumping pure gas down the airbox...
Click to expand...
Externally it looks fine, pop the hood and the airbox foam, top cage, are melted,
I have some belly pan damage as well. It is still sitting outside away from other combustibles in case I missed an ember somewhere. I will likely get it inside later in the week, and pull the motor, check the wiring, see if I want to take the time and expense to resurrect it.
 
Devilin AblueDress! said:
First off, honda,briggs etc are FOUR stroke with 1 carb hence the no mix gas. Horse of a totally different color! Carbs clean? Agree with choke being suspect. When pulling the choke flipper look at carbs and make sure they are full travel/fully choked. I adopted my buddies method a few years ago. Give they sled 2-3 preliminary pulls. Not pulling quite as hard. Gets everything moving and builds vacum in pulse line. Then give it a couple good pulls and fires right up! Even the 00 srx responds well after sitting a couple weeks.
Click to expand...

Granted they are 4-strokes, the Honda and B&S, but don't understand what the difference in fuel whether mixed or not would make any difference. I would say they have superior or richer starting circuits. I may have the choke cable a bit loose, as I want some free play when I release the flipper, so I'll try that first, next do a search for the "choke mod?"
The carbs have been gone through, prior to riding season, (annual practice)
I usually do a slow pull at least once, as one of the sleds (milled) is a bit reluctant to spin. Thanks
 
I beleive you are right with the superior/richer starting circuit. By pouring gas in air box that efective what you are doing. My point is/was average B&S or Honda engine from from tank to muffler fuel travels how far? versus 2 stroke it runs down around crank and bearings and back up to be combusted. A closer comparisonwould have ben how hard to 4 stroke sleds start?
 
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