We have had this cub for about 10 years. It has always had an issue with back firing on shut down and low power at start up. We had a guy that (former small engine repair man for IH dealership) that tried to adjust the timing but it made no difference. The engine starts fairly easy but has extremely low power until it has run about 5 minutes - when good and hot it runs good and has the expected amount of power. At start up up it can barely pull the tractor and rider around and has virtually no power to run the deck - no misses or cut outs, just extremely low power. On shut down no matter how long you let it idle to cool off it sounds like a shotgun going off.
My son pulled the head - he thought the head gasket might be leaking but nothing was obvious. He cleaned the carbon up with a brass wire brush (there was a lot) replaced the exhaust valve and reassembled with a new muffler (old muffler was horribly carboned up). Started it - and it runs exactly as it did before he touched it - no power when cold, good power when hot, huge backfire on shut down.
What are we missing?
My son pulled the head - he thought the head gasket might be leaking but nothing was obvious. He cleaned the carbon up with a brass wire brush (there was a lot) replaced the exhaust valve and reassembled with a new muffler (old muffler was horribly carboned up). Started it - and it runs exactly as it did before he touched it - no power when cold, good power when hot, huge backfire on shut down.
What are we missing?