Just put a new cylinder and piston on an Echo CS670 saw, ran an hour, scored again, appears to be running lean, scored on exhaust side. Does not appear to have seal or crankcase or intake boot leakage, that would cause lean running. any other ideas?
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Re: just put a new cylinder and psiton on an Echo
Pin hole in fuel line can cause lean running condition. Also, be SURE the fuel is fresh and 89 octane or higher. Stale fuels can will give you pre-ignition and detonation issues that are nearly impossible to chase down. Ethanol blended or Oxygenated fuels are a NO-NO in high reving 2-strokes!
If fuel type and fuel line check good, go to carb inlet needle settings and then on to carb passagways.
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take the muffler off - have a look at piston / rings and bore , i suspect you did not put enough oil in the petrol or forget to put oil in petrol and ran on straight fuel or on a very very lean oil mix
if you see quite deep scores and gaulls on piston / rings / bore - might pay to invest in a new saw or a new piston and cylinder kit for these machines
Remove the muffler and check the condition of the piston/ring(s) and cylinder. If badly scored, you have probably drawn in enough debris to damage these items. The fix is to replace these parts--warranty, if any, won't cover this type of damage, and the cost of repair approaches the cost of a new saw. Hope this helps!
sounds like it has leaking crankshaft seals...or I have had them break a ring and score piston and cylinder...you can verify this by removing muffler and checking piston through there ...if no scores, I would think seals are faulty...
The cylinder (if engine running too lean) would be badly scored as well as the piston and rings. Knowing today's prices for parts and labor, $300 is probably not too far off. At that price though, he might consider replacing the entire saw rather than repair. I have noticed a number of Echo saws that don't seem to 4-stroke when running at speed, but not cutting. A properly tuned 2-stroke should always 4-stroke at speed, but immediately 2-stroke when cutting--this produces the most power and least heat. The fuel should always be premixed in the can, agitated well during mixing and again before using in the saw. Agitate the saw after adding the new fuel as well. At 50:1 ratios, there isn't much spare lubrication in the engine. He might consider another brand of saw if buying new. Hope some of this helps!
Sorry to echo the bad news you heard but... often metal transfer from the piston to the cylinder feels like compression. Try part 3 of this, Attempt to shine a light into the plug hole through while inspecting above the exhaust port. Most often in a run lean condition metal transfer occurs above the exhaust manifold. Starter Handle difficult to pull: 1.Remove the starter cover. •Inspect the flywheel and crankshaft under the starter cover. Are the woodruff key slots on the crack shaft and flywheel aligned and the key intact? If not; Please consider taking the saw to a good local saw seller/mechanic for a written diagnosis before authorizing any repair or ordering any parts; if yes continue. •Does the starter operate smoothly? If yes, reinstall the cover and continue with 2, if not repair the starter. 2.Is the saw equipped with a decompression valve? Yes continue, no proceed with 3. •Leave the ignition off, set the valve and pull the starter. •Pull gently to release the valve. Is there a difference in the effort required? •If yes continue with 3, if no repair or replace the decompression valve. 3.Was this saw perhaps operated in a lean condition (metal transfer from the piston to cylinder wall)? This may be caused by many things including but not limited to; leaky intake connections at the engine or carburetor; leaky crankcase seals; cracked fuel delivery lines; running on gasoline containing no 2-cycle oil. •Disconnect the spark plug wire and remove the plug. Remove the muffler (clean it and the spark arrestor before reinstalling), hold a light at the plug hole and inspect the cylinder through the exhaust port. Is it smooth and shiny or does it appear speckled with dull gray spots or smears? •Pull the starter slowly, inspect the piston as it rises and falls. Is it a dull gray without scratches and gouges? •Hold the light at the exhaust port and look through the spark plug hole, inspect the cylinder above the exhaust port. Is it shiny and smooth or speckled with gray spots or smears? Please Note:Any spots or smears on the cylinder or deep scratches and gouges in the piston indicate the saw was operated in a lean condition. Repair of this on a home owner quality saw often exceeds replacement cost. A repair estimate by an independent saw shop should be considered.
take the muffler off and look inside.....if you see scoring on the oiston then you need a new piston and cylinder,alot of new saw come from the factory adjusted too lean and it burns up the piston and cylinder.you need to call husqvarna if they are scored........should be under warranty........they will send you to a husqvarna dealer to repair the saw. hope this helps,let me know...............
if your saw didnt lock up ,or overheat it should run again, take out spark plug, with switch off, put your thumb over the hole and check for compression when you pull the cord. if it pops your finger off the hole you probably didnt cook the rings, or burnt the piston, the raw gas may have washed the cylinder down enough to temporarily lose compression (lack of oil seal). refill tank with proper gas/oil mix, squirt a small amount of oil in cylinder and pull it thru a few times , this should seal up the rings again , put in a new sparkplug, and try normal cold start, you may have to clean the plug a couple times before it runs. if it runs but lacks power my guess is the rings got to hot and lost their temper or scored the cylinder. dont use alcohol blended gas this will ruin fuel lines , they soften up and fall apart etc. premium regular if you can get it, check the fuel line to be safe for pinholes as they will **** air and not start if you get alcohol blended gas. anyway good luck. geo_1
Generally, these saws are set at the factory and aren't supposed to be adjusted. If you can remember how far you turned each screw I would suggest you turn it back to where it was. Turning the screws clockwise leans out the mixture and although it would seem to make it run better warm, it is too lean to start properly. If the engine doesn't start at the factory setting you probably need to take the carb apart and clean it and put a new kit in it.