Top End Rebuild Question

PeterG

New Member
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May 4, 2016
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Location
Gabriola Island, BC
Wanted to do a complete top end rebuild because I think my compression is starting to come down. Canadian supplier is out of stock on the complete kit (cylinder, piston, etc). Is it worth it to just put a new piston and rings in it?
 
a lot of work just to find piston & cylinder that fits with all the diff types out there now

if you used a compression gauge when it ran well, and it reads lower now, a top end *may* help

a muffler will clog over time too

I've always considered these motors as disposable, such that it is often cheaper & easier to replace them rather than rebuild them. Other folks enjoy rebuilding as a hobby.
 
Thanks for the responses. No specific problem. Just want to freshen it up.

Question is:. Is it beneficial to put a new piston and rings in a used cylinder?

I'm assuming the piston and rings will wear before the cylinder walls.
 
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it depends if the cylinders chrome plating has flaked off or not.
if still in place then it don't need to be replaced
 
Jag has the right answer. Only 10 minutes to pull the head and have a look at it. I'd suggest YES, replace the piston and ring.
Crassius is right about the muffler too, especially if you are using conventional mineral 2 stroke oil.
I had great luck with the Canadian supplier's $19.99 chrome muffler. Quiet and good revs and power.

Steve
 
Yep, cylinder looks fine. Already had a look. Muffler's fine too. Again, not trying to troubleshoot anything here; just want to keep it fresh. Seat of the pants (on the bump start) feels like compression might be down a shade. Was wondering if new piston and rings without a new cylinder was beneficial (sounds like a "yes"). Engine didn't get an ideal break-in (see my thread "chronic four-strokeing").
 
Yep, cylinder looks fine. Already had a look. Muffler's fine too. Again, not trying to troubleshoot anything here; just want to keep it fresh. Seat of the pants (on the bump start) feels like compression might be down a shade. Was wondering if new piston and rings without a new cylinder was beneficial (sounds like a "yes"). Engine didn't get an ideal break-in (see my thread "chronic four-strokeing").
What's your idea of an ideal break in? I don't see anything about breaking it in on your thread
 
Ideal for me would be moderate load and running freely through the rev range; roll-on / roll-off the throttle; don't lug it but don't rev the crap out of it either. Decent load on the engine to bed the rings; don't p**sy-foot around. Frequent stops during the first day or so to let things cool down. But everybody has their own break-in technique. I couldn't follow mine because it ran like crap.
 
my break in technique is to let the motor warm up and find the tallest and steepest hill in town and go wfo up the thing. works every time
 
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