Low compression

[Jeff Downing]

Originally Posted by Lochlin

Yeah, I remember that now. Nothing is ever easy

So I checked ring gap and it’s good and so is piston. I put it back together and still 60 lbs. I could have bad gauges. What the cart does is, it takes 30 seconds to crank and will run but die then pick up again and die again. Never goes completely dead. Almost like your pulling foot off of gas pedal.

[willis68nova]

Jeff,

I just got an '82 cart and have been doing some digging on info. Here are some things I have found out, bad crank seals can cause loss of compression, I have heard of gauges being kind of sporadic with readings. Also are you doing the test with the gas at WOT?

[Lochlin]

Originally Posted by Jeff Downing

So I checked ring gap and it’s good and so is piston. I put it back together and still 60 lbs. I could have bad gauges. What the cart does is, it takes 30 seconds to crank and will run but die then pick up again and die again. Never goes completely dead. Almost like your pulling foot off of gas pedal.

I am surprised it's running at all at 60 psi. My Columbias also have factory compression at 90 - 100 psi and no freaking way they will run at 60 psi but who knows with that '82. You may want to check another gauge to be sure. I know that low compression sure does kill power just like you are describing. You are probably leaking air in the top somewhere.

Did you put new head gasket / base gasket on it when you reassembled everything? Washer on the bottom of the plug in place and ok? Cylinder isn't scored at all? Even a little bit of wear in the cylinder can be a crusher.

[Spicyunicorn]

Originally Posted by willis68nova

Jeff,

I just got an '82 cart and have been doing some digging on info. Here are some things I have found out, bad crank seals can cause loss of compression, I have heard of gauges being kind of sporadic with readings. Also are you doing the test with the gas at WOT?

Disagree crank seals can not and will not cause loss of compression... On two strokes compression starts when Piston is above ports in cylinder and ends at tdc thus leaving crank seals out of the question

[raydhd]

My 82 HD/Columbia would not start even on starting fluid at 60 psi. AS mentioned surprised it runs at all

[Lochlin]

Originally Posted by Spicyunicorn

Disagree crank seals can not and will not cause loss of compression... On two strokes compression starts when Piston is above ports in cylinder and ends at tdc thus leaving crank seals out of the question

I contemplated this as well. Logically, I can't see how anything beneath the piston can impact anything above it when measuring compression. During a leak down, sure, as air naturally is going to squeeze past the rings and through the bad seals. Compression tests are too fast to have that same effect though. Just 1 guy's opinion.

[willis68nova]

Originally Posted by Spicyunicorn

Disagree crank seals can not and will not cause loss of compression... On two strokes compression starts when Piston is above ports in cylinder and ends at tdc thus leaving crank seals out of the question

Good point. Didn't really think too much about it but I have seen many around the interwebs think this will cause loss of compression. But now that I am actually sitting here thinking about your response, it doesn't make sense that leaking crank seals would cause a compression issue. But definitely if they are leaking a good maintenance items is to replace them. Thanks for the reply and making me think about my statement. I am editing as we speak....if I can find the edit button....

[mikeasis]

yea the crank seals are just going to cause a lean condition and no vacuum which kills the vacuum operated fuel pump. To many electric fuel pumps installed due to this very reason in my opinion.

[Spicyunicorn]

Originally Posted by mikeasis

yea the crank seals are just going to cause a lean condition and no vacuum which kills the vacuum operated fuel pump. To many electric fuel pumps installed due to this very reason in my opinion.

Agreed lochlin and I have debated this many of times lol

[Jeff Downing]

Ok, so I used a different gauge and compression reads 90 psi.
The starts and goes about 40 yards , will die down but not quit and the it picks back up. Could it be the reed valve ?