Troublesome XM

[maxwell]

Not very often I can’t figure these things out myself but I’ve got a friends 2016XM that’s falling on its face at 7000rpm. The sled has 4500km on it.

We have done the following

- rebuilt top end ( compression was down and it was time ) did not resolve issue

- changed injectors
- changed plugs
- inspected reeds And everything else while I had the engine apart
- rave valves cleaned and are operating properly
- checked fuel pressure 40psi and holds to 7000rpm

Not throwing any codes , around 7000rpm it just starts to stumble and lose power.

Only thing we haven’t replaced is the coils and stator

 

[kingcat162]

Turbo it - she'll push past 7 grand after that guaranteed

 

[kingcat162]

Plug wires would be next for me and maybe dig into either clutching or try some different coils - if you have a buddy that has an xm - trade primary's real quick

 

[ferniesnow]

Sean, I think it was Beachsled that had some similar issues. Drop Landon a PM as he may be able to help.

 

[maxwell]

Plug wires would be next for me and maybe dig into either clutching or try some different coils - if you have a buddy that has an xm - trade primary's real quick

Both clutches just rebuilt. Ran great for a few rides after that. , curios as to why you think that would be the issue.....if it is I’ll be mad LOL. Maybe broken spring?

 

[hbar218]

Turbo it - she'll push past 7 grand after that guaranteed

Not with 0 psi boost it wont

 

[kingcat162]

Both clutches just rebuilt. Ran great for a few rides after that. , curios as to why you think that would be the issue.....if it is I’ll be mad LOL. Maybe broken spring?

That's what I was thinking clutches hitting somewhere at 7 grand then not liking it - too much load for it - your fueling sounds 100% - if it is a spark issue it usually affects it well before 7 grand - air/fuel/spark - clutching

 

[kingcat162]

Not with 0 psi boost it wont

Lightest wastegate spring is 3lbs - that would probably push it past 7grand but just barely

 

[snopro]

Check fuel filter as well in the tank. We have seen more than a few that are plugged or have contaminants in the tank that suck into the filter and plug it off usually at full throttle as sled needs more fuel.

 

[maxwell]

Check fuel filter as well in the tank. We have seen more than a few that are plugged or have contaminants in the tank that suck into the filter and plug it off usually at full throttle as sled needs more fuel.

Did not know where was one in the tank? Hmm! . We replaced the exterior one and are reading steady 40psi last the filter so I’m thinking fuel is good

 

[snopro]

Did not know where was one in the tank? Hmm! . We replaced the exterior one and are reading steady 40psi last the filter so I’m thinking fuel is good

Its off the fuel pump Sean. The sled has 2 filters, one external and one internal. The inside one is where we have seen them plug. Also don't rule out the fuel regulator as well. I think there was a recall on those as they would fail as well. Either 2015 or 2016 models.

 

[MK4TDI]

Check the rave valve system, not the raves themselves but all the vacuum lines that control them.... the contraption between the reeds would be my first check.

42 psi I think is what the fuel system is supposed to maintain, have you checked the pressure when its stumbling ?

 

[maxwell]

Check the rave valve system, not the raves themselves but all the vacuum lines that control them.... the contraption between the reeds would be my first check.

42 psi I think is what the fuel system is supposed to maintain, have you checked the pressure when its stumbling ?

Yep changed out all the rave system from another sled including all that stuff just for good measure. It’s still around 40psi when it falls on its face I Teed in a pressure gauge so I could see it while riding

 

[brian h]

when I first started reading my first thought was primary clutch, like kingcat mentioned. I've seen it before people chase issues and try everything before looking at clutch. but you say they have been re-built. i will keep eye on post as for outcome and what issue is.

 

[xman2014]

hey maxwell we had the same problem with a 15 and a 16 both were staters and we changed fuel pumps we felt that the pumps w ere week and causing the staters to heat up .that fixed the problem .when you were climbing at full throttle after 3 or 4 secs it would fall off randomly especially when they were warmed up.

 

[Longhairfreak]

Not very often I can’t figure these things out myself but I’ve got a friends 2016XM that’s falling on its face at 7000rpm. The sled has 4500km on it.

We have done the following

- rebuilt top end ( compression was down and it was time ) did not resolve issue

- changed injectors
- changed plugs
- inspected reeds And everything else while I had the engine apart
- rave valves cleaned and are operating properly
- checked fuel pressure 40psi and holds to 7000rpm

Not throwing any codes , around 7000rpm it just starts to stumble and lose power.

Only thing we haven’t replaced is the coils and stator

I would check the stator.

 

[maxwell]

Ugh I hate changing stators in the sled lol

 

[maxwell]

when I first started reading my first thought was primary clutch, like kingcat mentioned. I've seen it before people chase issues and try everything before looking at clutch. but you say they have been re-built. i will keep eye on post as for outcome and what issue is.

Fully rebuilt but who knows I could have made an error or maybe the new spring was faulty. Will check that before checking stator

 

[skegpro]

How did you test the injectors?

I have seen something similar to this before and it was a partially broken injector wire.
Voltage would come through but at a full pulse it couldn't get all the current through the broken wire.

 

[Rotax_Kid]

With the others now that you've ruled out Rave issues. Stator. Injector system needs a pile of power to fire and if it doesn't get it, it will miss.

Stumble on one cylinder or both?