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Discussion Starter #1
I have a 2004 Polaris 340 classic that will idle and run good when cold. Once it warms up it will idle ok, but it will bog down when you give it gas (almost when the clutch engages).

We have cleaned the carbs, took the clutch off another sled and tried that. Neither changed anything.

Both cylinders have good compression and there is plenty of spark.

Any ideas?
 

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Will it bog down and die if you hold it? If so, let it do that and then pull the spark plug(s) and see if they are wet or dry. Wet = flooding out. Maybe the choke is not closing?

Or the float level is to low. (leans out).
 

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Discussion Starter #3
Thanks for the reply.

It will bog down if I hold it. If I feather it, it will start going again.

I've checked the choke cables and they work correct. Everything with fuel seems to be good.

The pugs do not get wet after it stalls (it does not flood out).
 

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compression, fuel and spark. Must be one of them.

Weak coil is rare, but possible.

So if you give it choke while taking it off idle, what happens?
 

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Discussion Starter #5
When I take it off choke when idling it idles fine. When it sits there it idles fine.

spark is good.

This all started last year and when it was acting up, we lost spark at one wire. Replaced the coil and we don't have that issue any more, just the bogging down when it is warm. Compression is at 120 on both sides.

We are going to check the stator tonight.

We are running out of possible options. My buddy thinks the CDI box, but not sure about that.
 

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What are the air screws set to? Try one turn out from lightly seated. If it bogs, turn the screws IN 1/8 of a turn and retest. Keep testing until the bog goes away. If you bottom the screws with no change in performance, the pilot jets or the air and fuel passages to the pilot jets are clogged.

Bog can also be related to the clutching. Is the belt riding just out of the secondary when you come to a stop? How much clearance is between the belt and the primary sheave? Both of those can contribute to bog, as well. Sometimes a new belt will be the answer for that one. You can also adjust the secondary to reduce the belt deflection and get it to ride higher in the secondary. If you need to adjust the secondary, take the pressure off of the adjusting screw by opening the sheaves before you adjust. That helps prevent snapping the adjuster. It's a fragile little thing...
 

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Discussion Starter #7
Thanks for the reply

Actually we are going to be working on that tonight. On Saturday we adjusted the air screws and that seemed to help, but did not completely get rid of it.

We looked at clutching and the belt sits correct and is new. We actually took the secondary clutch out and put in another secondary clutch and it was doing the same thing.
 

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The air/fuel ratio in the carbs is controlled by the pilot jet circuit in the carbs from idle to about 1/4 throttle. Any idle problems and off-idle bog that can be attributed to fuel comes from that circuit in the carb. If you adjust the air screws IN, you are decreasing air which makes the air/fuel mix at idle richer. If you adjust the air screws OUT, you increase air, making the mix leaner. Does the bog get better with the choke 1/2 on? If so, you are lean at idle. If you turn the air screws IN all the way, and there's no change, there's a clog in the idle circuit somewhere or you need bigger pilot jets.

Sometimes you have to clean the carbs more than once to get rid of any varnish in the air/fuel passages. The pilot jets can also built up varnish that may need mechanical removal to get rid of it. I use a single strand of cat-5 cable (or telephone cable) with the insulation on to poke and prod into the air and fuel openings. I will use the same cable without insulation to "floss" the jet to make sure there is no varnish build-up.
 

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Discussion Starter #9
We will work on that tonight and I will respond tomorrow and see if that worked. We are going to put new pilot jets in as well tonight.

I know when it started to bog down, I choked the sled and it instantly killed it.
 

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clean the new pilots as well. manufacturing "scraps" can get caught in there. I've had 2 that had metal shavings in them from the dealer.

I use a very powerful magnifying glass to look at them.
 

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Thanks for the reply, I,ve tried all the fuel related things with no change. It only fails after a run of about two miles. Then I have to let it cool down for 20 minutes and it’s good for another run. I think I’ll try a coil and see what happens.
 

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I just bought a 2005 that seems to doing exactly the same as your saying. Runs a few minutes then bogs down and shuts off, let it sit 20 minutes starts up again..went through the carbs and fuel lines still does same..any suggestions would help..thanks
 

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I would check for spark when it dies to see if there is an electrical problem. Sometimes a coil will work fine until it warms up, then as it warms and expands, it develops an open circuit and kills the electrons. Letting it cool for 20 minutes shrinks the coil enough for the wire that is open to touch again and off you go.



Welcome to the forum!
 

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I just bought a 2005 that seems to doing exactly the same as your saying. Runs a few minutes then bogs down and shuts off, let it sit 20 minutes starts up again..went through the carbs and fuel lines still does same..any suggestions would help..thanks
I just bought a 05 340 polaris for my 9 year old and i does the same thing. Did you ever figure it out? Anything to save us time working on this would be great.
 

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I just bought a 2005 that seems to doing exactly the same as your saying. Runs a few minutes then bogs down and shuts off, let it sit 20 minutes starts up again..went through the carbs and fuel lines still does same..any suggestions would help..thanks
I just bought a 05 340 polaris for my 9 year old and i does the same thing. Did you ever figure it out? Anything to save us time working on this would be great.
 
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