Hey everyone,
I recently rebuilt my Mcculloch 890 I stumbled upon. Found for $50 in Northern California, it came to me blown up with the thin ring piston and a 3:1 gear reduction. 103cc. So I ordered a LRB piston and rings, and started the crank-up rebuild. After installing everything and rebuilding the transmission, it was time for the first start! After about 15-20 seconds of running, a ticking noise made me stop the engine. After that, it locked up only on the upstroke of the rotation. So I took a look in the exhaust port and a big chunk of the piston and rings were gone. After a final teardown inspection, it was determined that the top ring gap somehow ended up in the exhaust port, which then got hung up and exploded the top piece of the piston. Fortunately, there was ZERO damage done to the block, with only chunks on the piston left behind. Now, I am here with a broken piston (p# 62877), and no standard sized pistons available. Now, the solutions are
1) - Bore Cylinder .30 oversized for a new Mcculloch piston available online
2) - Re-order the LRB piston and hope for the best
3) - Find a new standard size, or .10/.20 oversized piston and rings.
This is my second Mcculloch rebuild, with the first being a 1-50. Never had any experience with the Mcculloch gear drives, only the bigger homelite gear drives. Any chance someone can give some insight?
I recently rebuilt my Mcculloch 890 I stumbled upon. Found for $50 in Northern California, it came to me blown up with the thin ring piston and a 3:1 gear reduction. 103cc. So I ordered a LRB piston and rings, and started the crank-up rebuild. After installing everything and rebuilding the transmission, it was time for the first start! After about 15-20 seconds of running, a ticking noise made me stop the engine. After that, it locked up only on the upstroke of the rotation. So I took a look in the exhaust port and a big chunk of the piston and rings were gone. After a final teardown inspection, it was determined that the top ring gap somehow ended up in the exhaust port, which then got hung up and exploded the top piece of the piston. Fortunately, there was ZERO damage done to the block, with only chunks on the piston left behind. Now, I am here with a broken piston (p# 62877), and no standard sized pistons available. Now, the solutions are
1) - Bore Cylinder .30 oversized for a new Mcculloch piston available online
2) - Re-order the LRB piston and hope for the best
3) - Find a new standard size, or .10/.20 oversized piston and rings.
This is my second Mcculloch rebuild, with the first being a 1-50. Never had any experience with the Mcculloch gear drives, only the bigger homelite gear drives. Any chance someone can give some insight?
