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Discussion Starter · #1 ·
i need some awnsers please!!! 06 440 running on one cylinder i'm running 115 octane @32-1 ratio took the carb apart every thing looked great, spark on both sides, changed plugs, only running on the right side no matter what i change ran a comp test right side at about 110 left at about 125 .
 

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ITs WINTER!
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Time for a rebuild bud. their is way too much of a variance, your over double the allowed variance!
 

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Try and find friend or get a mechanic to do a compression test with a good tester. Thats an 06 i can't see how it would be that low already. Also i don't think that would make it run on one piston.
 

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ITs WINTER!
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It doesnt really matter about the quality of the tester, in this case its the variance thats the problem not the overall compression.

And yes, having one cylinder with over 5% compression difference will cause it to start running on the cylinder with the most compression.

To simplify things, The cylinder with more compression will be more efficient and produce more power and the other cylinder cant produce enough power to keep up and basically just gets flung around by the other jug.
 

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What your saying does make alot of sense but why would an 06 have compression like that? It can't have much more than 5 hours on it.
 

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If compression test is inaccurate you cannot assume that the variance is accurate. I agree with revski, have the compression tested again with a different gauge.
 

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ITs WINTER!
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You can try another tester, which may show 130/120 but your still in the same boat...

As for the low compression and large variance on such a new motor, could have been some bad gas you ran in it or a bum crank seal.

For how easy it is to pop the head and take a peek at the jugs you should do it. You may be surprised to see a melted piston or some foreign object damage in there.
 

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In addition to testing the compression again, I would switch the carbs and retest. Also, what do the plugs look like on both sides? The engine could have a broken reed and that would completely flood the one side out so check that closely too. I assume you have already changed plugs.

I would not trust the gauge because it is possible that the oring on the gauge (where it seals off on the cylinder) is allowing the pressure to pass by. If this is the case, comparing the two readings is misleading because the amount of leakage around the oring varies each time the gauge is installed. This is just one possibility of many by the way.
 

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Discussion Starter · #9 ·
broken reed on the left and cracked on the right. i get a new set tomarrow i'll let you know if that was it .
 

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ITs WINTER!
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So theres why you have the compression variance, foreign object damage...

Throw some new reeds in it and bag the crap out of it, then when its on its last legs rebuild it.
 

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ITs WINTER!
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And the way you said "broken reed" tells me your missing a piece. In which case it went through the motor scraping and gouging everything it could before it got blown out the pipe.

Or it could be another non related issue causing you to have that low of compression, you should take my advice i gave you before and pop the head and see whats going on before you nuke the whole thing!
 

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its worth the few seconds its going to take to pull the head and look inside...for sure...but...stay optimistic...ive blown a few reeds over the years and so far i havent "nuked" anything...yeah its left behind a dusting of damage, but nothing of any significance...really.

swap out the reeds that are buggered...put it all back together and do another full compression check and get back to us...im pretty sure youll find your motor is right back to where it belongs...nice and new...the way an '06 should be

oh...and dude...take it easy on the hot button...no doubt thats what split and spit your reed on you.
 

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Discussion Starter · #15 ·
got a new comp gauge it was still low 145 and 130 i need a set of rings part# 420815145 any body have any in the grand rapids area!!! or going to greenville tonight where i can buy them from you there.
 

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My 04 440 had 115 compression at 1050 miles and blew at 1200 miles, lc heads, 91oct, but I left the holeshot button connected.....me stupid...the holeshot button is the only thing I can think of that would blow the left piston and reduce the compression on both cyl's. Just goes to show ya that milage and year is not always the problem.
 
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