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Old 04-08-2010, 09:09 PM   #1
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Default help me. What am i missing?

What could cause a terrible running engine. I have ruled out:

loss of compression
glo plug
engine case
air leaks
scratches on P/S
crank pin and rod fit
clutch
fuel system
head button/deposits
fuel
carb needles/orings/boot
pipe/manifold/gaskets

This particular P/S set has about a gallon. It just got finished breaking in and has just about zero pinch left. Has always been preheated etc. one day it just wouldn't tune and started running like crap. Bad crap.

I have dropped several P/S sets in this particular case/carb/head and they run perfectly. With this new 3 port it just runs like complete doo doo. And it's my best fitting P/S set with the most compression. I don't understand. The only thing i can come up with (that i have NO clue how to check or verify) is a stretched or bent rod.

Anyone have any ideas? I just cleaned it up again as it had some pretty bad deposits on one side of the piston. Real tacky like. But there is zero scratches on the piston or sleeve.
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Old 04-08-2010, 09:13 PM   #2
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Is this engine in a submarine?
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Old 04-08-2010, 09:25 PM   #3
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really? I ran it in a water puddle frank. That was over a year ago.
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Old 04-08-2010, 09:57 PM   #4
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if other p/s/r sets all work in this case then the problem is with the p/s/r set try replacing the rod with another one that has worked w/ other set see if that fixes the problem. BTW Is this p/s ever been pinched?
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Old 04-08-2010, 10:23 PM   #5
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Quote:
Originally Posted by xjqkz View Post
if other p/s/r sets all work in this case then the problem is with the p/s/r set try replacing the rod with another one that has worked w/ other set see if that fixes the problem. BTW Is this p/s ever been pinched?
no never been pinched.

Why would that matter? just curious...

and you confirmed what my next step was going to be. Just don't want to do it. Feeling lazy today.
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Old 04-08-2010, 10:34 PM   #6
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if someone has 'tried' to pinch it using the wrong tools maybe the sleeve is not in a perfect cylindrical shape. There's a guy at my track that pinches sleeves with a hose clamp
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Old 04-08-2010, 11:21 PM   #7
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When you took it apart did you lose any of the button shims? If it's nit shimmed properly it won't run
did you check your carb boot for small Holes or tears?
Did you take apart the carb and check for blocked, or chipped needles?
Are you sure your HSN and LSN are sealed good and not stripped?
Have you switched the carb from one engine to another to eliminate carb problems?

There's lots more to check Marcus. You have only scratched the surface of possible problems
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Old 04-08-2010, 11:33 PM   #8
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I am missing the bearings and airfilter in the list?
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Old 04-08-2010, 11:34 PM   #9
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Quote:
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I am missing the bearings in the list?
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