Compression HIGHER than spec. 2003 txt 295cc

rockfordpi

Ok, really confused here. I bought a cart from a dealer, 2003 txt with 295cc engine. Dealer told me cart smoked (which it does), was down on power (which it seems to be) and needed new rings.

However, when I compression test the two cylinders, I get 180psi using a calibrated tester.

Cart is hard to crank, but runs ok when it does, though it does act like worn rings.

Could there be enough oil getting into the cylinder to increase a cart with bad compression up that high?

Could this be a product of bad valve guides leaking oil into cylinder (oil gushes up with valve cover removed.

Since cart runs, I am thinking not a firing issue (coil had 3.5 Ohms) but spark does look a little weak.

I don't see how this can be a valve timing issue. However, I did notice a rusted fine thread bolt in the dash like the one used to pull clutch. I wonder if previous owner had removed clutch to see or mess with the timing belt.

The LAST thing I want to do is put rings in a cart that does not need them. Any ideas or suggestions are appreciated...

BGW

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Cartmaster

If it is burning oil, this would suggest the problem is not with the timing but with oil getting into the cylinder. This can raise the compression reading as the excess oil is helping seal the rings. i suggest first of all checking that the PCV valve is working correctly and not sending oil into the carb! oil in the filter box will be a symptom to look for, then move on to removing the head and following your instincts regarding the valve guides, and then possibly stripping the engine to inspect the rings and bore. If the inlet valve heads are worn it can possibly cause oil passing the PVC and up into the carb but i suspect compression would be reading low in this scenario.

CP241

It's pretty simple really... smoking engines burn oil. Burning oil usually leaves quite a bit of carbon buildup on the piston and head, which can raise compression. Also the extra oil in the rings can bump compression a little bit as well. You're not much above spec, if at all really. I dont recall what spec is on those but I think its 170 or 180psi.

Just because the compression rings are good doesnt have to mean the rings arent worn. The oil control rings can break or stick causing it to smoke but the compression rings are fine. This isn't uncomkon.

But if it is smoking, the engine probably needs to be torn down and rebuilt, period. Theres 3 common causes of smoking.
1. Overfilled with oil. This is easy enough to check.
2. Rings
3. Valve seals. If the valve seals are shot, you still have to basically pull the motor out and take quite a bit apart. You may as well just replace the rings at the same time.


I'm assuming if the dealer that sold you the cart said it needs rings, then it needs rings. They typically don't make assumptions about that.

rockfordpi

Update. Ran the cart for about 5 minutes, then checked compression when hot, immediately went to 160 lbs. Oil is overfilled by 5/8 to 3/4 inch.

Will change oil and try again and update. Thanks everyone for the advice and tips.

DannyAbear

OVerfilled oil is usually caused by carb needle not sealing allowing excess gas to leak into clyninder, leaking past the rings, ending up in the crankcase

rockfordpi

Thank you, will check when I drain oil