1929Heisman
New Member
Hello Folks,
I've been pulling great info and advice off this site for years. Here's one where I need some tailored advice.
I have a PP335 trimmer for household use (pole saw and hedge trimming only) that I took to a shop because I just wanted it fixed. I had fuel backflow and carb issues after I rebuilt carb and still no start and leaks. Frankly, I didn't want to deal with it just told them to fix it. (I'm not new to rebuilding/fixing Chainsaws/lawnmowers and rebuilding truck transmissions--I"m just getting old and I just rehabbed my Briggs lawnmower eng & carb). They said the trimmer compression came back at 56psi and wasn't worth fixing. Typically I agree, but I do not belive their low psi reading...at least not that low. I always tune my carbs rich, open the mufflers and run richer mixture. My inspection after I got home and broke it down showed no gouges /scratches on internal cylinder or piston. Moderate build-up of carbon on piston top and exhaust port. Engine does not have a lot of hours. This is a strato engine/carb set up. (Also, the jug had the Husky emblem on it and a 3524 part indicator..go figure. Interchangeable).
So, using my dial calipers, I got:
A) Piston: measured 36.855mm above the ring and 37mm below the ring (adjusted to metric--variances could be off a bit as I was holding all parts by hand--not fixed surface)
Is it usual that a piston would have a slightly tapered top above the ring than below? Also, any benefits to changing the piston to plated?
B.) Ring: .054" and .052" depth; .046" thick--What are the usual specs when new?
C.) Gasket seals looked in good shape (but flimsy design). I'd rather use permatex.
I've been pulling great info and advice off this site for years. Here's one where I need some tailored advice.
I have a PP335 trimmer for household use (pole saw and hedge trimming only) that I took to a shop because I just wanted it fixed. I had fuel backflow and carb issues after I rebuilt carb and still no start and leaks. Frankly, I didn't want to deal with it just told them to fix it. (I'm not new to rebuilding/fixing Chainsaws/lawnmowers and rebuilding truck transmissions--I"m just getting old and I just rehabbed my Briggs lawnmower eng & carb). They said the trimmer compression came back at 56psi and wasn't worth fixing. Typically I agree, but I do not belive their low psi reading...at least not that low. I always tune my carbs rich, open the mufflers and run richer mixture. My inspection after I got home and broke it down showed no gouges /scratches on internal cylinder or piston. Moderate build-up of carbon on piston top and exhaust port. Engine does not have a lot of hours. This is a strato engine/carb set up. (Also, the jug had the Husky emblem on it and a 3524 part indicator..go figure. Interchangeable).
So, using my dial calipers, I got:
A) Piston: measured 36.855mm above the ring and 37mm below the ring (adjusted to metric--variances could be off a bit as I was holding all parts by hand--not fixed surface)
Is it usual that a piston would have a slightly tapered top above the ring than below? Also, any benefits to changing the piston to plated?
B.) Ring: .054" and .052" depth; .046" thick--What are the usual specs when new?
C.) Gasket seals looked in good shape (but flimsy design). I'd rather use permatex.
1. Do you think a new piston ring is enough? Also what is the typical depth (protusion) of the 38MM ring? [to determine wear]
2. I heard the piston rings for the 41.1mm piston fit these...is that true? If so, does it provide better seal/compression?
3. Thoughts on a good, inexpensive compression tester for small engines as it appears many rarely work right or are inaccurate.
Thanks in advance for your comments. Yes, I wish I had a Stihl, but I don't. I appreciate the warriors against throw-away-culture