invader 340 vs 440 heads

[jasoniowa]

are the 340 heads the same as the 440 heads?

[Invader440]

No, look the same, bolt on the same, but your bore is a different size.

[jasoniowa]

Will it hurt it if i were to put them on? the motor only has 122 PSI of compersion.

[Lloyd (ljm)]

 They might not seal very well.

 If you try, Let us know how well it works

Lloyd

[JDmatt]

Will it hurt it if i were to put them on? the motor only has 122 PSI of compersion.

122 isn't that bad as long as both sides are close to that, bare minimum to run is usually 90.

[jasoniowa]

Well the problem I have is that the sled is super fast pulls the skis off the ground for about 10 mins then bogs and wont move carbs have been gone threw new crank seals pistons and rings. its not a true inavder 440 motor i have john deere liqufire heads on it so thats my last option was to put invader heads on it any suggestions will be great.
Jason

[JDmatt]

Does it start up OK again when it cools off?  Sounds more like an spark problem.  Stators, coils, or CDI can fail once they get heat-soaked, then work again when they cool off. 

[jasoniowa]

It starts up just fine runs good when its cold but its super boggy and then gets so boggy it dont move this sled has the old ignition system on it like my 82 liqufire has the newer could that be the problem? I know there was issues with the older ones.. this ignition system was on a intruder 440 that i have on my invader 440 now.

[Lloyd (ljm)]

 I would be really surprised if heads would make any difference.

 I know this sounds obvious but have you changed sparkplugs?

 I have a 440 Drifter that was doing the same thing. I spend hours trying to figure it out.

 Had good spark on both plugs cold, sled ran really good till it warmed up, then would hardly move itself. spark tester showed spark on both sides, Finnally I changed the plugs and problem went away.

 If someone had told me a plug would would work cold and not work hot I would have had a hard time believing that. But now I check that on all my sleds first.

Good Luck
Lloyd

[jasoniowa]

I've tryed several differnt plugs all the same, also it heast up with in five minutes of running thermostat opens and works fine just heats up really fast.

[Interceptor398]

I think if you put 340 heads on the 440 the piston would hit the head around the skirt.

[jasoniowa]

Yeah im gonna stick with the liqufire heads on it im just gonna pull the motor and go threw it again i think my seals are no good again.

[gixxer6]

Well the problem I have is that the sled is super fast pulls the skis off the ground for about 10 mins then bogs and wont move carbs have been gone threw new crank seals pistons and rings. its not a true inavder 440 motor i have john deere liqufire heads on it so thats my last option was to put invader heads on it any suggestions will be great.
Jason

I had a ski-doo that did this exact same thing.  It ended up being a bad CDI box.  I don't think the Deere heads would cause this issue. 

[JDmatt]

Agreed, it sounds like an ignition issue. 

[jasoniowa]

Thats what im starting to think too. If any one has a cheap igniton system let me know thanks