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2003 MXZ 600HO, I was riding last weekend in Tug Hill, NY and my engine locked up. After it cooled for a few minutes it freed up. I am looking for some advice on the cause, here are the details,

5100 miles on the engine, rings were done last season

MAG side cylinder had the problem, PTO is okay

There are no signs of detonation on top of the piston or in the head.

Approx 30 miles before this happened I lowered the needles in the carbs and installed 370 jets as recommended in the "optimizing your 600" post.

About 5 miles before this happened I installed v force reeds.

I know it is easy to say that the reeds were the cause but has anyone else had to fatten up there carbs after installing aftermarket reeds?

I put approx 200 miles on the sled before making these changes, the engine ran great before and after, may biggest problem was bad fuel economy. The original reed cage was starting to delaminate and the reed peddles would not close all the way, there were no external air leaks. Could have this been the start of my problem?

I planning on putting the carbs back to stock when I put the engine back together but since I really do not know why this happened to begin with I am hesitant, any advice is apprieciated.
 

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Could there be an air leak around one of the new reeds? Any Isopropyl in the gas? Where did you fill up?
 

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Discussion Starter · #3 ·
MX-Z Man said:
Could there be an air leak around one of the new reeds? Any Isopropyl in the gas? Where did you fill up?
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I removed the jug with the reeds attached so I could inspect for air leaks looked ok. Fuel is something I did not think of.

Thanks
 

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Always...fatten up with new reeds....never go leaner until you establish a safe zone. The warning is right on the instructions from V3.

2ndly...did you check your PTO seal for grease leaking out?
 

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I have seen were the MAG side crank bearings go bad, they are selaed off like the PTO side but Rotax doesn't use hardly any isoflex grease on that side. Is it pulling the right about of RPMS before it locked up.
 

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Discussion Starter · #8 ·
cluby262000 said:
I have seen were the MAG side crank bearings go bad, they are selaed off like the PTO side but Rotax doesn't use hardly any isoflex grease on that side. Is it pulling the right about of RPMS before it locked up.
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I did not notice anything abnormal before it stopped running.

I had the clutch off recently, the PTO seal had some grease on it but nothing I wouldn't expect after 5k. There was some belt dust mixed in, no sign of fresh grease though. I think doing the crank seals is cheap insur. at this point, there is no snow anyway!
 

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With aftermarket reeds, don't drop your needle.........the reeds breath better than stock, especially in the mid........not as big of a deal on the MAIN JET...but deffinitely go back to stock with the needle
 
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