'08 XP 800R Bogging at Take-Off

[tollen77]

Sled idles well but won't pick up revs when I give it gas.

'08 800R Rev XP Summit X

This whole ordeal started a few weeks ago. Sled's been to the mountians and had four tanks of gas through it during December this year. Over Christmas I went sledding near Elk Point, AB and the thing ran fine. Dec. 27th, I filled it up after trailering it home and went for another rip and it started to bog down low... from standing still to about 5,500 RPM. Once I got going by feathering the throttle the sled ran like a top.

My initial thoughts were bad gas or bad plugs. Ran the rest of the gas out of the sled and changed the plugs without effect. Came back home and took the carbs off - plugged pilot jet maybe. Both main and pilot jets we're clear, no varnish or blockage. Bog is still there.

Ride it over New Years and the bog is still there, in fact, it's getting worse. Now I can't even feather the throttle to get the RPM's up, I actually have to turn the choke half on and then flip it off once I'm moving. Without the little choke trick, the sled actually dies.

Pull the plugs out, they're both fine. Pull the carbs off again, still no blockage. Drain the gas and fill it up with some fresh premium gas, stuff I know is good. I take it out this weekend and the bog is still there only getting worse. Now I have to use full choke to get it to move at first and then later full choke only allows it to run for a brief second and then idles right down. To get it back to the trailer I had to run full choke, let it accelerate hard at full throttle for a second allow it to almost die, let off the throttle and wait for a second and then do it all over again.

My thoughts are the reason the sled will only run for a brief second is it isn't getting fuel... the bowls are filled up by having the choke on which allows the sled to accelrate hard for a second, but the fuel flow can't keep up and so the sled dies. Waiting a little allows the bowls re-fill which once again lets the sled rev up once more. That still doesn't explain the low end bog though.

I haven't had any problems with this sled at all - over 1,200 kms last season, and another 250 kms this year before the problems.


Any ideas what to try? Thanks in advance.

 

[DaveB]

I'm not sure of the proceedure....but I would verify the fuel pump output. Used to be easy on the old sleds where you could actually SEE the fuel pump.

Is there a fuel filter? There seems to me there was an issue with the line coming out of the tank getting kinked behind the airbox.....might want to trace this as well.

 

[tollen77]

I'm not sure of the proceedure....but I would verify the fuel pump output. Used to be easy on the old sleds where you could actually SEE the fuel pump.

Is there a fuel filter? There seems to me there was an issue with the line coming out of the tank getting kinked behind the airbox.....might want to trace this as well.

I've been thinking about this some more and it must be a blockage in the carbs. I'm going to take them apart entirely tonight and see.

 

[tollen77]

Anyone else have any ideas about this?? DPM??? Can't find any blockage in the carbs at all.


Thanks

 

[jusgivner]

Is it just in the deep stuff or on the trail too?

 

[tollen77]

Is it just in the deep stuff or on the trail too?

It's all the time. On the trail, pulling out of my garage. I do think that the surge issue might have been due to the vent line being plugged in deep snow. But that still doesn't explain the bog.

I took the gas tank off last night to see if the mesh filter was clogged but couldn't get inside. There's a circular piece on the front of the tank that I assume screws off. Can anyone confirm that it actually does. I don't wanna wreck that.

 

[Chubbydog]

It could be the DPM. I've heard of a few cases of them going bad.

 

[tollen77]

Just found this from an old post by LRD;

------​

Main Jet - 0 effect just below 3/4 throttle with full effect by full throttle

Jet Needle - 0 effect just below 1/4 - full effect by 5/8 - tapered down to 0 effect by 7/8 throttle opening

Needle Jet - 0 at 1/8 - full by 1/4 - 0 by 5/8 throttle opening

Throttle valve - 0 at 0 throttle opening - full effect by 1/8 - 0 by 3/8

Pilot system - Full effect at 0 throttle opening tapering to 0 by 1/4 throttle opening

------​

This leads me to believe that maybe the jet needle and needle jet is the problem. I assume it could still be the DPM as I believe it effects the needle and needle jet.

Can anyone confirm this.

 

[Original Tetonice]

If you've been riding in very cold temps a cold pipe can cause the issue...When the pipe is hot does it run OK ? Seeing that you mentioned idle.

Your adjustable clip on the needle only cleans up your mid-range and does little to clean up bog at idle. with that said the 08 XP did have a needle update but not for the cure your seeking.

Is your carb heater On ?


OT

 

[tollen77]

If you've been riding in very cold temps a cold pipe can cause the issue...When the pipe is hot does it run OK ? Seeing that you mentioned idle.

Your adjustable clip on the needle only cleans up your mid-range and does little to clean up bog at idle. with that said the 08 XP did have a needle update but not for the cure your seeking.

Is your carb heater On ?


OT

The problem started while riding on some cold days -20C.... when I tried again this past weekend it was just above freezing though when the engine got really warm on those cold days the problem seemed to diminish. This past weekend when it was really warm the problem was there right from unloading off the trailer.

The sled idles fine, though quite high at 3,500 RPM and I do have my carb heaters on.

OT, have you ever taken the tank off your sled? Can I simply unscrew the round piece at the fron of the tank? I'm trying to check the screen in the tank.

 

[Original Tetonice]

The problem started while riding on some cold days -20C.... when I tried again this past weekend it was just above freezing though when the engine got really warm on those cold days the problem seemed to diminish. This past weekend when it was really warm the problem was there right from unloading off the trailer.

The sled idles fine, though quite high at 3,500 RPM and I do have my carb heaters on.

OT, have you ever taken the tank off your sled? Can I simply unscrew the round piece at the fron of the tank? I'm trying to check the screen in the tank.

Carb heaters must be kept off.

I couldn't tell you i have not had any reason to remove my tank. Give the dealer a quick call and he can bring up the fish assembly on the tank and tell you the answer best

OT

 

[Original Tetonice]

At the end of each ride condensation builds up inside your tank fuel line and carberator. At night when it freezes it turns to ice once cool enough. When you start your sled in the morning the ice melts and you have water/fuel in your system.....Adding a HEAT additive to each tank of fuel a good idea as is using a water tampon in your fuel tank designed to absorb water.

OT

 

[Keystone]

After the sled is boggy and you fether it to your mid range does the top end run clean? Is it worse when you come down a hill and your sled has been at a idle?

 

[tollen77]

After the sled is boggy and you fether it to your mid range does the top end run clean? Is it worse when you come down a hill and your sled has been at a idle?

The top end does run clean Keystone. As for how it is downhill, couldn't tell you as I've riding on the flats for the last while since the problem started.

Hope you have an idea.

OT;

Agreed on the condensation, that it might be the problem. It's been in a heated garage for a few days so it should be clear of water now.

I'll see how it goes soon.

 

[Snowbyrd]

At the end of each ride condensation builds up inside your tank fuel line and carberator. At night when it freezes it turns to ice once cool enough. When you start your sled in the morning the ice melts and you have water/fuel in your system.....Adding a HEAT additive to each tank of fuel a good idea as is using a water tampon in your fuel tank designed to absorb water.

OT

MIGHT WANT TO USE ISO HEAT, regular heat is not made for 2 stroke motors

 

[Original Tetonice]

MIGHT WANT TO USE ISO HEAT, regular heat is not made for 2 stroke motors

I use Polaris Isopropoline.....I think HEAT makes a 2 cycle additive.

OT

 

[Derekgeesler]

The top end does run clean Keystone. As for how it is downhill, couldn't tell you as I've riding on the flats for the last while since the problem started.

Hope you have an idea.

OT;

Agreed on the condensation, that it might be the problem. It's been in a heated garage for a few days so it should be clear of water now.

I'll see how it goes soon.

I am having the same exact issue rite now did ypu ever find out what was causing the issue?