Need help with 04 King Cat

[800CatRider]

I need some help with my 04 King Cat. Burnt up the Mag side. Not even two miles down the trail, it just completely shut down. Took it apart that night to find that the Mag side cylinder and piston were completely destroyed and that the PTO side cylinder had some scratches that I had never seen before. The engine has had a little modifications done to it. Ported and polished by Dakota performance and had slp twins.

If you have ever had this happen or have any idea of why this would happen please let me know. It would help a ton. I want to diagnose the problem before i put it back together so it doesn't happen again. Thanks
Oh, and i dont have any pictures of the side that burnt up because it is being repaired at the moment.

 

[diggerdown]

I just looks like it got too hot. The 900 runs pretty hot at mid range and twins won't help that. Looks like you should have raised your needles and possible bigger jets, I don't see much of a wash on that piston.

 

[800CatRider]

im at 3000 feet and i've got 440 and 430 mains. they dont get much bigger. Plus, i ran it hard all day a week ago and the plugs looked good and the piston wash was fine.

 

[scotth]

Wow, seems like you had big enough mains! Any cracks in the carb boots? Bad gas? Bad fuel pump? Kinked fuel line? Clogged fuel filter? Bad oil pump? Sure looks like it got hot.

 

[900kingkitty]

mine looked the same when the oil pump went bad

 

[Meatman]

there is no wash on that piston, twins make the lean spot worse, your jets arent big enough and you should drop your needle 1 clip

porting your cylinders create more airflow therefore your mains should be much bigger, 460/470 mains stay outta the mid range as much as you can.

you say other 'mods' what mods are you talkin about?

 

[800CatRider]

Just the porting and twins. And Meatman, I know why you would thing the jetting isnt right, but I rode it in the exact same spot 6 days ago with the same set up.

 

[Meatman]

and I'm willing to bet 6 days ago is when the damage was starting. I bet she ran like a raped ape, crisp as ever. did you ever take a look at your plugs 6 days ago? and then take a plug reading after you smoked your motor? do you have the plugs? take pics and upload them

 

[800CatRider]

I'm always checking plugs. 6 days ago everything looked normal. Plugs looked good and the piston wash was fine.

 

[Meatman]

well if everything looked good then it could be a crank seal which would affect one side or the other, failed oil pump which could be the case. I would do the oil pump delete if i were you that way you take the guess work out of the equation and KNOW what your running when you premix.

One thing to remember that many dont realize is that the King Cats run a hotter CDI box that advances the timing about 1.5-2 deg. If you are running at a lower elevation such as 3k you should be running a little better fuel.

 

[800CatRider]

Thanks, i'll try that and keep lookin the sled over to see if i can find any thing obvious

 

[diggerdown]

What was the temp on both days, a twenty degree temp drop will play havoc with jetting.

 

[woodtick]

broken

Question? Did you let it warm up really good before you took off. Looks like you could have cold seized it. They don't like to be run hard when cold. I never take off before the heat exchanger is warm. I know a lot of sleds that go down because of this. Just my 2 cents worth, JIM

 

[sumptercat]

a friend of mine had this happen, have you ever blown a drive belt? he found that the crank had twisted when the belt blew and was causing a vacuum leak at the mag side bearing seal. food for thought. after several mag side melt downs, he finally figured it out.

 

[800CatRider]

What was the temp on both days, a twenty degree temp drop will play havoc with jetting.

It was actually warmer by 5 or 6 degrees when it melted down.

 

[900kingkitty]

i was told i cold seized mine too , but it was the oil pump,